diff options
Diffstat (limited to 'chromium/third_party/sqlite/sqlite-src-3240000/src/btree.c')
| -rw-r--r-- | chromium/third_party/sqlite/sqlite-src-3240000/src/btree.c | 10143 |
1 files changed, 0 insertions, 10143 deletions
diff --git a/chromium/third_party/sqlite/sqlite-src-3240000/src/btree.c b/chromium/third_party/sqlite/sqlite-src-3240000/src/btree.c deleted file mode 100644 index fb3b89fe139..00000000000 --- a/chromium/third_party/sqlite/sqlite-src-3240000/src/btree.c +++ /dev/null @@ -1,10143 +0,0 @@ -/* -** 2004 April 6 -** -** The author disclaims copyright to this source code. In place of -** a legal notice, here is a blessing: -** -** May you do good and not evil. -** May you find forgiveness for yourself and forgive others. -** May you share freely, never taking more than you give. -** -************************************************************************* -** This file implements an external (disk-based) database using BTrees. -** See the header comment on "btreeInt.h" for additional information. -** Including a description of file format and an overview of operation. -*/ -#include "btreeInt.h" - -/* -** The header string that appears at the beginning of every -** SQLite database. -*/ -static const char zMagicHeader[] = SQLITE_FILE_HEADER; - -/* -** Set this global variable to 1 to enable tracing using the TRACE -** macro. -*/ -#if 0 -int sqlite3BtreeTrace=1; /* True to enable tracing */ -# define TRACE(X) if(sqlite3BtreeTrace){printf X;fflush(stdout);} -#else -# define TRACE(X) -#endif - -/* -** Extract a 2-byte big-endian integer from an array of unsigned bytes. -** But if the value is zero, make it 65536. -** -** This routine is used to extract the "offset to cell content area" value -** from the header of a btree page. If the page size is 65536 and the page -** is empty, the offset should be 65536, but the 2-byte value stores zero. -** This routine makes the necessary adjustment to 65536. -*/ -#define get2byteNotZero(X) (((((int)get2byte(X))-1)&0xffff)+1) - -/* -** Values passed as the 5th argument to allocateBtreePage() -*/ -#define BTALLOC_ANY 0 /* Allocate any page */ -#define BTALLOC_EXACT 1 /* Allocate exact page if possible */ -#define BTALLOC_LE 2 /* Allocate any page <= the parameter */ - -/* -** Macro IfNotOmitAV(x) returns (x) if SQLITE_OMIT_AUTOVACUUM is not -** defined, or 0 if it is. For example: -** -** bIncrVacuum = IfNotOmitAV(pBtShared->incrVacuum); -*/ -#ifndef SQLITE_OMIT_AUTOVACUUM -#define IfNotOmitAV(expr) (expr) -#else -#define IfNotOmitAV(expr) 0 -#endif - -#ifndef SQLITE_OMIT_SHARED_CACHE -/* -** A list of BtShared objects that are eligible for participation -** in shared cache. This variable has file scope during normal builds, -** but the test harness needs to access it so we make it global for -** test builds. -** -** Access to this variable is protected by SQLITE_MUTEX_STATIC_MASTER. -*/ -#ifdef SQLITE_TEST -BtShared *SQLITE_WSD sqlite3SharedCacheList = 0; -#else -static BtShared *SQLITE_WSD sqlite3SharedCacheList = 0; -#endif -#endif /* SQLITE_OMIT_SHARED_CACHE */ - -#ifndef SQLITE_OMIT_SHARED_CACHE -/* -** Enable or disable the shared pager and schema features. -** -** This routine has no effect on existing database connections. -** The shared cache setting effects only future calls to -** sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2(). -*/ -int sqlite3_enable_shared_cache(int enable){ - sqlite3GlobalConfig.sharedCacheEnabled = enable; - return SQLITE_OK; -} -#endif - - - -#ifdef SQLITE_OMIT_SHARED_CACHE - /* - ** The functions querySharedCacheTableLock(), setSharedCacheTableLock(), - ** and clearAllSharedCacheTableLocks() - ** manipulate entries in the BtShared.pLock linked list used to store - ** shared-cache table level locks. If the library is compiled with the - ** shared-cache feature disabled, then there is only ever one user - ** of each BtShared structure and so this locking is not necessary. - ** So define the lock related functions as no-ops. - */ - #define querySharedCacheTableLock(a,b,c) SQLITE_OK - #define setSharedCacheTableLock(a,b,c) SQLITE_OK - #define clearAllSharedCacheTableLocks(a) - #define downgradeAllSharedCacheTableLocks(a) - #define hasSharedCacheTableLock(a,b,c,d) 1 - #define hasReadConflicts(a, b) 0 -#endif - -/* -** Implementation of the SQLITE_CORRUPT_PAGE() macro. Takes a single -** (MemPage*) as an argument. The (MemPage*) must not be NULL. -** -** If SQLITE_DEBUG is not defined, then this macro is equivalent to -** SQLITE_CORRUPT_BKPT. Or, if SQLITE_DEBUG is set, then the log message -** normally produced as a side-effect of SQLITE_CORRUPT_BKPT is augmented -** with the page number and filename associated with the (MemPage*). -*/ -#ifdef SQLITE_DEBUG -int corruptPageError(int lineno, MemPage *p){ - char *zMsg; - sqlite3BeginBenignMalloc(); - zMsg = sqlite3_mprintf("database corruption page %d of %s", - (int)p->pgno, sqlite3PagerFilename(p->pBt->pPager, 0) - ); - sqlite3EndBenignMalloc(); - if( zMsg ){ - sqlite3ReportError(SQLITE_CORRUPT, lineno, zMsg); - } - sqlite3_free(zMsg); - return SQLITE_CORRUPT_BKPT; -} -# define SQLITE_CORRUPT_PAGE(pMemPage) corruptPageError(__LINE__, pMemPage) -#else -# define SQLITE_CORRUPT_PAGE(pMemPage) SQLITE_CORRUPT_PGNO(pMemPage->pgno) -#endif - -#ifndef SQLITE_OMIT_SHARED_CACHE - -#ifdef SQLITE_DEBUG -/* -**** This function is only used as part of an assert() statement. *** -** -** Check to see if pBtree holds the required locks to read or write to the -** table with root page iRoot. Return 1 if it does and 0 if not. -** -** For example, when writing to a table with root-page iRoot via -** Btree connection pBtree: -** -** assert( hasSharedCacheTableLock(pBtree, iRoot, 0, WRITE_LOCK) ); -** -** When writing to an index that resides in a sharable database, the -** caller should have first obtained a lock specifying the root page of -** the corresponding table. This makes things a bit more complicated, -** as this module treats each table as a separate structure. To determine -** the table corresponding to the index being written, this -** function has to search through the database schema. -** -** Instead of a lock on the table/index rooted at page iRoot, the caller may -** hold a write-lock on the schema table (root page 1). This is also -** acceptable. -*/ -static int hasSharedCacheTableLock( - Btree *pBtree, /* Handle that must hold lock */ - Pgno iRoot, /* Root page of b-tree */ - int isIndex, /* True if iRoot is the root of an index b-tree */ - int eLockType /* Required lock type (READ_LOCK or WRITE_LOCK) */ -){ - Schema *pSchema = (Schema *)pBtree->pBt->pSchema; - Pgno iTab = 0; - BtLock *pLock; - - /* If this database is not shareable, or if the client is reading - ** and has the read-uncommitted flag set, then no lock is required. - ** Return true immediately. - */ - if( (pBtree->sharable==0) - || (eLockType==READ_LOCK && (pBtree->db->flags & SQLITE_ReadUncommit)) - ){ - return 1; - } - - /* If the client is reading or writing an index and the schema is - ** not loaded, then it is too difficult to actually check to see if - ** the correct locks are held. So do not bother - just return true. - ** This case does not come up very often anyhow. - */ - if( isIndex && (!pSchema || (pSchema->schemaFlags&DB_SchemaLoaded)==0) ){ - return 1; - } - - /* Figure out the root-page that the lock should be held on. For table - ** b-trees, this is just the root page of the b-tree being read or - ** written. For index b-trees, it is the root page of the associated - ** table. */ - if( isIndex ){ - HashElem *p; - for(p=sqliteHashFirst(&pSchema->idxHash); p; p=sqliteHashNext(p)){ - Index *pIdx = (Index *)sqliteHashData(p); - if( pIdx->tnum==(int)iRoot ){ - if( iTab ){ - /* Two or more indexes share the same root page. There must - ** be imposter tables. So just return true. The assert is not - ** useful in that case. */ - return 1; - } - iTab = pIdx->pTable->tnum; - } - } - }else{ - iTab = iRoot; - } - - /* Search for the required lock. Either a write-lock on root-page iTab, a - ** write-lock on the schema table, or (if the client is reading) a - ** read-lock on iTab will suffice. Return 1 if any of these are found. */ - for(pLock=pBtree->pBt->pLock; pLock; pLock=pLock->pNext){ - if( pLock->pBtree==pBtree - && (pLock->iTable==iTab || (pLock->eLock==WRITE_LOCK && pLock->iTable==1)) - && pLock->eLock>=eLockType - ){ - return 1; - } - } - - /* Failed to find the required lock. */ - return 0; -} -#endif /* SQLITE_DEBUG */ - -#ifdef SQLITE_DEBUG -/* -**** This function may be used as part of assert() statements only. **** -** -** Return true if it would be illegal for pBtree to write into the -** table or index rooted at iRoot because other shared connections are -** simultaneously reading that same table or index. -** -** It is illegal for pBtree to write if some other Btree object that -** shares the same BtShared object is currently reading or writing -** the iRoot table. Except, if the other Btree object has the -** read-uncommitted flag set, then it is OK for the other object to -** have a read cursor. -** -** For example, before writing to any part of the table or index -** rooted at page iRoot, one should call: -** -** assert( !hasReadConflicts(pBtree, iRoot) ); -*/ -static int hasReadConflicts(Btree *pBtree, Pgno iRoot){ - BtCursor *p; - for(p=pBtree->pBt->pCursor; p; p=p->pNext){ - if( p->pgnoRoot==iRoot - && p->pBtree!=pBtree - && 0==(p->pBtree->db->flags & SQLITE_ReadUncommit) - ){ - return 1; - } - } - return 0; -} -#endif /* #ifdef SQLITE_DEBUG */ - -/* -** Query to see if Btree handle p may obtain a lock of type eLock -** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return -** SQLITE_OK if the lock may be obtained (by calling -** setSharedCacheTableLock()), or SQLITE_LOCKED if not. -*/ -static int querySharedCacheTableLock(Btree *p, Pgno iTab, u8 eLock){ - BtShared *pBt = p->pBt; - BtLock *pIter; - - assert( sqlite3BtreeHoldsMutex(p) ); - assert( eLock==READ_LOCK || eLock==WRITE_LOCK ); - assert( p->db!=0 ); - assert( !(p->db->flags&SQLITE_ReadUncommit)||eLock==WRITE_LOCK||iTab==1 ); - - /* If requesting a write-lock, then the Btree must have an open write - ** transaction on this file. And, obviously, for this to be so there - ** must be an open write transaction on the file itself. - */ - assert( eLock==READ_LOCK || (p==pBt->pWriter && p->inTrans==TRANS_WRITE) ); - assert( eLock==READ_LOCK || pBt->inTransaction==TRANS_WRITE ); - - /* This routine is a no-op if the shared-cache is not enabled */ - if( !p->sharable ){ - return SQLITE_OK; - } - - /* If some other connection is holding an exclusive lock, the - ** requested lock may not be obtained. - */ - if( pBt->pWriter!=p && (pBt->btsFlags & BTS_EXCLUSIVE)!=0 ){ - sqlite3ConnectionBlocked(p->db, pBt->pWriter->db); - return SQLITE_LOCKED_SHAREDCACHE; - } - - for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){ - /* The condition (pIter->eLock!=eLock) in the following if(...) - ** statement is a simplification of: - ** - ** (eLock==WRITE_LOCK || pIter->eLock==WRITE_LOCK) - ** - ** since we know that if eLock==WRITE_LOCK, then no other connection - ** may hold a WRITE_LOCK on any table in this file (since there can - ** only be a single writer). - */ - assert( pIter->eLock==READ_LOCK || pIter->eLock==WRITE_LOCK ); - assert( eLock==READ_LOCK || pIter->pBtree==p || pIter->eLock==READ_LOCK); - if( pIter->pBtree!=p && pIter->iTable==iTab && pIter->eLock!=eLock ){ - sqlite3ConnectionBlocked(p->db, pIter->pBtree->db); - if( eLock==WRITE_LOCK ){ - assert( p==pBt->pWriter ); - pBt->btsFlags |= BTS_PENDING; - } - return SQLITE_LOCKED_SHAREDCACHE; - } - } - return SQLITE_OK; -} -#endif /* !SQLITE_OMIT_SHARED_CACHE */ - -#ifndef SQLITE_OMIT_SHARED_CACHE -/* -** Add a lock on the table with root-page iTable to the shared-btree used -** by Btree handle p. Parameter eLock must be either READ_LOCK or -** WRITE_LOCK. -** -** This function assumes the following: -** -** (a) The specified Btree object p is connected to a sharable -** database (one with the BtShared.sharable flag set), and -** -** (b) No other Btree objects hold a lock that conflicts -** with the requested lock (i.e. querySharedCacheTableLock() has -** already been called and returned SQLITE_OK). -** -** SQLITE_OK is returned if the lock is added successfully. SQLITE_NOMEM -** is returned if a malloc attempt fails. -*/ -static int setSharedCacheTableLock(Btree *p, Pgno iTable, u8 eLock){ - BtShared *pBt = p->pBt; - BtLock *pLock = 0; - BtLock *pIter; - - assert( sqlite3BtreeHoldsMutex(p) ); - assert( eLock==READ_LOCK || eLock==WRITE_LOCK ); - assert( p->db!=0 ); - - /* A connection with the read-uncommitted flag set will never try to - ** obtain a read-lock using this function. The only read-lock obtained - ** by a connection in read-uncommitted mode is on the sqlite_master - ** table, and that lock is obtained in BtreeBeginTrans(). */ - assert( 0==(p->db->flags&SQLITE_ReadUncommit) || eLock==WRITE_LOCK ); - - /* This function should only be called on a sharable b-tree after it - ** has been determined that no other b-tree holds a conflicting lock. */ - assert( p->sharable ); - assert( SQLITE_OK==querySharedCacheTableLock(p, iTable, eLock) ); - - /* First search the list for an existing lock on this table. */ - for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){ - if( pIter->iTable==iTable && pIter->pBtree==p ){ - pLock = pIter; - break; - } - } - - /* If the above search did not find a BtLock struct associating Btree p - ** with table iTable, allocate one and link it into the list. - */ - if( !pLock ){ - pLock = (BtLock *)sqlite3MallocZero(sizeof(BtLock)); - if( !pLock ){ - return SQLITE_NOMEM_BKPT; - } - pLock->iTable = iTable; - pLock->pBtree = p; - pLock->pNext = pBt->pLock; - pBt->pLock = pLock; - } - - /* Set the BtLock.eLock variable to the maximum of the current lock - ** and the requested lock. This means if a write-lock was already held - ** and a read-lock requested, we don't incorrectly downgrade the lock. - */ - assert( WRITE_LOCK>READ_LOCK ); - if( eLock>pLock->eLock ){ - pLock->eLock = eLock; - } - - return SQLITE_OK; -} -#endif /* !SQLITE_OMIT_SHARED_CACHE */ - -#ifndef SQLITE_OMIT_SHARED_CACHE -/* -** Release all the table locks (locks obtained via calls to -** the setSharedCacheTableLock() procedure) held by Btree object p. -** -** This function assumes that Btree p has an open read or write -** transaction. If it does not, then the BTS_PENDING flag -** may be incorrectly cleared. -*/ -static void clearAllSharedCacheTableLocks(Btree *p){ - BtShared *pBt = p->pBt; - BtLock **ppIter = &pBt->pLock; - - assert( sqlite3BtreeHoldsMutex(p) ); - assert( p->sharable || 0==*ppIter ); - assert( p->inTrans>0 ); - - while( *ppIter ){ - BtLock *pLock = *ppIter; - assert( (pBt->btsFlags & BTS_EXCLUSIVE)==0 || pBt->pWriter==pLock->pBtree ); - assert( pLock->pBtree->inTrans>=pLock->eLock ); - if( pLock->pBtree==p ){ - *ppIter = pLock->pNext; - assert( pLock->iTable!=1 || pLock==&p->lock ); - if( pLock->iTable!=1 ){ - sqlite3_free(pLock); - } - }else{ - ppIter = &pLock->pNext; - } - } - - assert( (pBt->btsFlags & BTS_PENDING)==0 || pBt->pWriter ); - if( pBt->pWriter==p ){ - pBt->pWriter = 0; - pBt->btsFlags &= ~(BTS_EXCLUSIVE|BTS_PENDING); - }else if( pBt->nTransaction==2 ){ - /* This function is called when Btree p is concluding its - ** transaction. If there currently exists a writer, and p is not - ** that writer, then the number of locks held by connections other - ** than the writer must be about to drop to zero. In this case - ** set the BTS_PENDING flag to 0. - ** - ** If there is not currently a writer, then BTS_PENDING must - ** be zero already. So this next line is harmless in that case. - */ - pBt->btsFlags &= ~BTS_PENDING; - } -} - -/* -** This function changes all write-locks held by Btree p into read-locks. -*/ -static void downgradeAllSharedCacheTableLocks(Btree *p){ - BtShared *pBt = p->pBt; - if( pBt->pWriter==p ){ - BtLock *pLock; - pBt->pWriter = 0; - pBt->btsFlags &= ~(BTS_EXCLUSIVE|BTS_PENDING); - for(pLock=pBt->pLock; pLock; pLock=pLock->pNext){ - assert( pLock->eLock==READ_LOCK || pLock->pBtree==p ); - pLock->eLock = READ_LOCK; - } - } -} - -#endif /* SQLITE_OMIT_SHARED_CACHE */ - -static void releasePage(MemPage *pPage); /* Forward reference */ -static void releasePageOne(MemPage *pPage); /* Forward reference */ -static void releasePageNotNull(MemPage *pPage); /* Forward reference */ - -/* -***** This routine is used inside of assert() only **** -** -** Verify that the cursor holds the mutex on its BtShared -*/ -#ifdef SQLITE_DEBUG -static int cursorHoldsMutex(BtCursor *p){ - return sqlite3_mutex_held(p->pBt->mutex); -} - -/* Verify that the cursor and the BtShared agree about what is the current -** database connetion. This is important in shared-cache mode. If the database -** connection pointers get out-of-sync, it is possible for routines like -** btreeInitPage() to reference an stale connection pointer that references a -** a connection that has already closed. This routine is used inside assert() -** statements only and for the purpose of double-checking that the btree code -** does keep the database connection pointers up-to-date. -*/ -static int cursorOwnsBtShared(BtCursor *p){ - assert( cursorHoldsMutex(p) ); - return (p->pBtree->db==p->pBt->db); -} -#endif - -/* -** Invalidate the overflow cache of the cursor passed as the first argument. -** on the shared btree structure pBt. -*/ -#define invalidateOverflowCache(pCur) (pCur->curFlags &= ~BTCF_ValidOvfl) - -/* -** Invalidate the overflow page-list cache for all cursors opened -** on the shared btree structure pBt. -*/ -static void invalidateAllOverflowCache(BtShared *pBt){ - BtCursor *p; - assert( sqlite3_mutex_held(pBt->mutex) ); - for(p=pBt->pCursor; p; p=p->pNext){ - invalidateOverflowCache(p); - } -} - -#ifndef SQLITE_OMIT_INCRBLOB -/* -** This function is called before modifying the contents of a table -** to invalidate any incrblob cursors that are open on the -** row or one of the rows being modified. -** -** If argument isClearTable is true, then the entire contents of the -** table is about to be deleted. In this case invalidate all incrblob -** cursors open on any row within the table with root-page pgnoRoot. -** -** Otherwise, if argument isClearTable is false, then the row with -** rowid iRow is being replaced or deleted. In this case invalidate -** only those incrblob cursors open on that specific row. -*/ -static void invalidateIncrblobCursors( - Btree *pBtree, /* The database file to check */ - Pgno pgnoRoot, /* The table that might be changing */ - i64 iRow, /* The rowid that might be changing */ - int isClearTable /* True if all rows are being deleted */ -){ - BtCursor *p; - if( pBtree->hasIncrblobCur==0 ) return; - assert( sqlite3BtreeHoldsMutex(pBtree) ); - pBtree->hasIncrblobCur = 0; - for(p=pBtree->pBt->pCursor; p; p=p->pNext){ - if( (p->curFlags & BTCF_Incrblob)!=0 ){ - pBtree->hasIncrblobCur = 1; - if( p->pgnoRoot==pgnoRoot && (isClearTable || p->info.nKey==iRow) ){ - p->eState = CURSOR_INVALID; - } - } - } -} - -#else - /* Stub function when INCRBLOB is omitted */ - #define invalidateIncrblobCursors(w,x,y,z) -#endif /* SQLITE_OMIT_INCRBLOB */ - -/* -** Set bit pgno of the BtShared.pHasContent bitvec. This is called -** when a page that previously contained data becomes a free-list leaf -** page. -** -** The BtShared.pHasContent bitvec exists to work around an obscure -** bug caused by the interaction of two useful IO optimizations surrounding -** free-list leaf pages: -** -** 1) When all data is deleted from a page and the page becomes -** a free-list leaf page, the page is not written to the database -** (as free-list leaf pages contain no meaningful data). Sometimes -** such a page is not even journalled (as it will not be modified, -** why bother journalling it?). -** -** 2) When a free-list leaf page is reused, its content is not read -** from the database or written to the journal file (why should it -** be, if it is not at all meaningful?). -** -** By themselves, these optimizations work fine and provide a handy -** performance boost to bulk delete or insert operations. However, if -** a page is moved to the free-list and then reused within the same -** transaction, a problem comes up. If the page is not journalled when -** it is moved to the free-list and it is also not journalled when it -** is extracted from the free-list and reused, then the original data -** may be lost. In the event of a rollback, it may not be possible -** to restore the database to its original configuration. -** -** The solution is the BtShared.pHasContent bitvec. Whenever a page is -** moved to become a free-list leaf page, the corresponding bit is -** set in the bitvec. Whenever a leaf page is extracted from the free-list, -** optimization 2 above is omitted if the corresponding bit is already -** set in BtShared.pHasContent. The contents of the bitvec are cleared -** at the end of every transaction. -*/ -static int btreeSetHasContent(BtShared *pBt, Pgno pgno){ - int rc = SQLITE_OK; - if( !pBt->pHasContent ){ - assert( pgno<=pBt->nPage ); - pBt->pHasContent = sqlite3BitvecCreate(pBt->nPage); - if( !pBt->pHasContent ){ - rc = SQLITE_NOMEM_BKPT; - } - } - if( rc==SQLITE_OK && pgno<=sqlite3BitvecSize(pBt->pHasContent) ){ - rc = sqlite3BitvecSet(pBt->pHasContent, pgno); - } - return rc; -} - -/* -** Query the BtShared.pHasContent vector. -** -** This function is called when a free-list leaf page is removed from the -** free-list for reuse. It returns false if it is safe to retrieve the -** page from the pager layer with the 'no-content' flag set. True otherwise. -*/ -static int btreeGetHasContent(BtShared *pBt, Pgno pgno){ - Bitvec *p = pBt->pHasContent; - return (p && (pgno>sqlite3BitvecSize(p) || sqlite3BitvecTest(p, pgno))); -} - -/* -** Clear (destroy) the BtShared.pHasContent bitvec. This should be -** invoked at the conclusion of each write-transaction. -*/ -static void btreeClearHasContent(BtShared *pBt){ - sqlite3BitvecDestroy(pBt->pHasContent); - pBt->pHasContent = 0; -} - -/* -** Release all of the apPage[] pages for a cursor. -*/ -static void btreeReleaseAllCursorPages(BtCursor *pCur){ - int i; - if( pCur->iPage>=0 ){ - for(i=0; i<pCur->iPage; i++){ - releasePageNotNull(pCur->apPage[i]); - } - releasePageNotNull(pCur->pPage); - pCur->iPage = -1; - } -} - -/* -** The cursor passed as the only argument must point to a valid entry -** when this function is called (i.e. have eState==CURSOR_VALID). This -** function saves the current cursor key in variables pCur->nKey and -** pCur->pKey. SQLITE_OK is returned if successful or an SQLite error -** code otherwise. -** -** If the cursor is open on an intkey table, then the integer key -** (the rowid) is stored in pCur->nKey and pCur->pKey is left set to -** NULL. If the cursor is open on a non-intkey table, then pCur->pKey is -** set to point to a malloced buffer pCur->nKey bytes in size containing -** the key. -*/ -static int saveCursorKey(BtCursor *pCur){ - int rc = SQLITE_OK; - assert( CURSOR_VALID==pCur->eState ); - assert( 0==pCur->pKey ); - assert( cursorHoldsMutex(pCur) ); - - if( pCur->curIntKey ){ - /* Only the rowid is required for a table btree */ - pCur->nKey = sqlite3BtreeIntegerKey(pCur); - }else{ - /* For an index btree, save the complete key content */ - void *pKey; - pCur->nKey = sqlite3BtreePayloadSize(pCur); - pKey = sqlite3Malloc( pCur->nKey ); - if( pKey ){ - rc = sqlite3BtreePayload(pCur, 0, (int)pCur->nKey, pKey); - if( rc==SQLITE_OK ){ - pCur->pKey = pKey; - }else{ - sqlite3_free(pKey); - } - }else{ - rc = SQLITE_NOMEM_BKPT; - } - } - assert( !pCur->curIntKey || !pCur->pKey ); - return rc; -} - -/* -** Save the current cursor position in the variables BtCursor.nKey -** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK. -** -** The caller must ensure that the cursor is valid (has eState==CURSOR_VALID) -** prior to calling this routine. -*/ -static int saveCursorPosition(BtCursor *pCur){ - int rc; - - assert( CURSOR_VALID==pCur->eState || CURSOR_SKIPNEXT==pCur->eState ); - assert( 0==pCur->pKey ); - assert( cursorHoldsMutex(pCur) ); - - if( pCur->eState==CURSOR_SKIPNEXT ){ - pCur->eState = CURSOR_VALID; - }else{ - pCur->skipNext = 0; - } - - rc = saveCursorKey(pCur); - if( rc==SQLITE_OK ){ - btreeReleaseAllCursorPages(pCur); - pCur->eState = CURSOR_REQUIRESEEK; - } - - pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl|BTCF_AtLast); - return rc; -} - -/* Forward reference */ -static int SQLITE_NOINLINE saveCursorsOnList(BtCursor*,Pgno,BtCursor*); - -/* -** Save the positions of all cursors (except pExcept) that are open on -** the table with root-page iRoot. "Saving the cursor position" means that -** the location in the btree is remembered in such a way that it can be -** moved back to the same spot after the btree has been modified. This -** routine is called just before cursor pExcept is used to modify the -** table, for example in BtreeDelete() or BtreeInsert(). -** -** If there are two or more cursors on the same btree, then all such -** cursors should have their BTCF_Multiple flag set. The btreeCursor() -** routine enforces that rule. This routine only needs to be called in -** the uncommon case when pExpect has the BTCF_Multiple flag set. -** -** If pExpect!=NULL and if no other cursors are found on the same root-page, -** then the BTCF_Multiple flag on pExpect is cleared, to avoid another -** pointless call to this routine. -** -** Implementation note: This routine merely checks to see if any cursors -** need to be saved. It calls out to saveCursorsOnList() in the (unusual) -** event that cursors are in need to being saved. -*/ -static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){ - BtCursor *p; - assert( sqlite3_mutex_held(pBt->mutex) ); - assert( pExcept==0 || pExcept->pBt==pBt ); - for(p=pBt->pCursor; p; p=p->pNext){ - if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ) break; - } - if( p ) return saveCursorsOnList(p, iRoot, pExcept); - if( pExcept ) pExcept->curFlags &= ~BTCF_Multiple; - return SQLITE_OK; -} - -/* This helper routine to saveAllCursors does the actual work of saving -** the cursors if and when a cursor is found that actually requires saving. -** The common case is that no cursors need to be saved, so this routine is -** broken out from its caller to avoid unnecessary stack pointer movement. -*/ -static int SQLITE_NOINLINE saveCursorsOnList( - BtCursor *p, /* The first cursor that needs saving */ - Pgno iRoot, /* Only save cursor with this iRoot. Save all if zero */ - BtCursor *pExcept /* Do not save this cursor */ -){ - do{ - if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ){ - if( p->eState==CURSOR_VALID || p->eState==CURSOR_SKIPNEXT ){ - int rc = saveCursorPosition(p); - if( SQLITE_OK!=rc ){ - return rc; - } - }else{ - testcase( p->iPage>=0 ); - btreeReleaseAllCursorPages(p); - } - } - p = p->pNext; - }while( p ); - return SQLITE_OK; -} - -/* -** Clear the current cursor position. -*/ -void sqlite3BtreeClearCursor(BtCursor *pCur){ - assert( cursorHoldsMutex(pCur) ); - sqlite3_free(pCur->pKey); - pCur->pKey = 0; - pCur->eState = CURSOR_INVALID; -} - -/* -** In this version of BtreeMoveto, pKey is a packed index record -** such as is generated by the OP_MakeRecord opcode. Unpack the -** record and then call BtreeMovetoUnpacked() to do the work. -*/ -static int btreeMoveto( - BtCursor *pCur, /* Cursor open on the btree to be searched */ - const void *pKey, /* Packed key if the btree is an index */ - i64 nKey, /* Integer key for tables. Size of pKey for indices */ - int bias, /* Bias search to the high end */ - int *pRes /* Write search results here */ -){ - int rc; /* Status code */ - UnpackedRecord *pIdxKey; /* Unpacked index key */ - - if( pKey ){ - assert( nKey==(i64)(int)nKey ); - pIdxKey = sqlite3VdbeAllocUnpackedRecord(pCur->pKeyInfo); - if( pIdxKey==0 ) return SQLITE_NOMEM_BKPT; - sqlite3VdbeRecordUnpack(pCur->pKeyInfo, (int)nKey, pKey, pIdxKey); - if( pIdxKey->nField==0 ){ - rc = SQLITE_CORRUPT_BKPT; - goto moveto_done; - } - }else{ - pIdxKey = 0; - } - rc = sqlite3BtreeMovetoUnpacked(pCur, pIdxKey, nKey, bias, pRes); -moveto_done: - if( pIdxKey ){ - sqlite3DbFree(pCur->pKeyInfo->db, pIdxKey); - } - return rc; -} - -/* -** Restore the cursor to the position it was in (or as close to as possible) -** when saveCursorPosition() was called. Note that this call deletes the -** saved position info stored by saveCursorPosition(), so there can be -** at most one effective restoreCursorPosition() call after each -** saveCursorPosition(). -*/ -static int btreeRestoreCursorPosition(BtCursor *pCur){ - int rc; - int skipNext; - assert( cursorOwnsBtShared(pCur) ); - assert( pCur->eState>=CURSOR_REQUIRESEEK ); - if( pCur->eState==CURSOR_FAULT ){ - return pCur->skipNext; - } - pCur->eState = CURSOR_INVALID; - rc = btreeMoveto(pCur, pCur->pKey, pCur->nKey, 0, &skipNext); - if( rc==SQLITE_OK ){ - sqlite3_free(pCur->pKey); - pCur->pKey = 0; - assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_INVALID ); - pCur->skipNext |= skipNext; - if( pCur->skipNext && pCur->eState==CURSOR_VALID ){ - pCur->eState = CURSOR_SKIPNEXT; - } - } - return rc; -} - -#define restoreCursorPosition(p) \ - (p->eState>=CURSOR_REQUIRESEEK ? \ - btreeRestoreCursorPosition(p) : \ - SQLITE_OK) - -/* -** Determine whether or not a cursor has moved from the position where -** it was last placed, or has been invalidated for any other reason. -** Cursors can move when the row they are pointing at is deleted out -** from under them, for example. Cursor might also move if a btree -** is rebalanced. -** -** Calling this routine with a NULL cursor pointer returns false. -** -** Use the separate sqlite3BtreeCursorRestore() routine to restore a cursor -** back to where it ought to be if this routine returns true. -*/ -int sqlite3BtreeCursorHasMoved(BtCursor *pCur){ - assert( EIGHT_BYTE_ALIGNMENT(pCur) - || pCur==sqlite3BtreeFakeValidCursor() ); - assert( offsetof(BtCursor, eState)==0 ); - assert( sizeof(pCur->eState)==1 ); - return CURSOR_VALID != *(u8*)pCur; -} - -/* -** Return a pointer to a fake BtCursor object that will always answer -** false to the sqlite3BtreeCursorHasMoved() routine above. The fake -** cursor returned must not be used with any other Btree interface. -*/ -BtCursor *sqlite3BtreeFakeValidCursor(void){ - static u8 fakeCursor = CURSOR_VALID; - assert( offsetof(BtCursor, eState)==0 ); - return (BtCursor*)&fakeCursor; -} - -/* -** This routine restores a cursor back to its original position after it -** has been moved by some outside activity (such as a btree rebalance or -** a row having been deleted out from under the cursor). -** -** On success, the *pDifferentRow parameter is false if the cursor is left -** pointing at exactly the same row. *pDifferntRow is the row the cursor -** was pointing to has been deleted, forcing the cursor to point to some -** nearby row. -** -** This routine should only be called for a cursor that just returned -** TRUE from sqlite3BtreeCursorHasMoved(). -*/ -int sqlite3BtreeCursorRestore(BtCursor *pCur, int *pDifferentRow){ - int rc; - - assert( pCur!=0 ); - assert( pCur->eState!=CURSOR_VALID ); - rc = restoreCursorPosition(pCur); - if( rc ){ - *pDifferentRow = 1; - return rc; - } - if( pCur->eState!=CURSOR_VALID ){ - *pDifferentRow = 1; - }else{ - assert( pCur->skipNext==0 ); - *pDifferentRow = 0; - } - return SQLITE_OK; -} - -#ifdef SQLITE_ENABLE_CURSOR_HINTS -/* -** Provide hints to the cursor. The particular hint given (and the type -** and number of the varargs parameters) is determined by the eHintType -** parameter. See the definitions of the BTREE_HINT_* macros for details. -*/ -void sqlite3BtreeCursorHint(BtCursor *pCur, int eHintType, ...){ - /* Used only by system that substitute their own storage engine */ -} -#endif - -/* -** Provide flag hints to the cursor. -*/ -void sqlite3BtreeCursorHintFlags(BtCursor *pCur, unsigned x){ - assert( x==BTREE_SEEK_EQ || x==BTREE_BULKLOAD || x==0 ); - pCur->hints = x; -} - - -#ifndef SQLITE_OMIT_AUTOVACUUM -/* -** Given a page number of a regular database page, return the page -** number for the pointer-map page that contains the entry for the -** input page number. -** -** Return 0 (not a valid page) for pgno==1 since there is -** no pointer map associated with page 1. The integrity_check logic -** requires that ptrmapPageno(*,1)!=1. -*/ -static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){ - int nPagesPerMapPage; - Pgno iPtrMap, ret; - assert( sqlite3_mutex_held(pBt->mutex) ); - if( pgno<2 ) return 0; - nPagesPerMapPage = (pBt->usableSize/5)+1; - iPtrMap = (pgno-2)/nPagesPerMapPage; - ret = (iPtrMap*nPagesPerMapPage) + 2; - if( ret==PENDING_BYTE_PAGE(pBt) ){ - ret++; - } - return ret; -} - -/* -** Write an entry into the pointer map. -** -** This routine updates the pointer map entry for page number 'key' -** so that it maps to type 'eType' and parent page number 'pgno'. -** -** If *pRC is initially non-zero (non-SQLITE_OK) then this routine is -** a no-op. If an error occurs, the appropriate error code is written -** into *pRC. -*/ -static void ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent, int *pRC){ - DbPage *pDbPage; /* The pointer map page */ - u8 *pPtrmap; /* The pointer map data */ - Pgno iPtrmap; /* The pointer map page number */ - int offset; /* Offset in pointer map page */ - int rc; /* Return code from subfunctions */ - - if( *pRC ) return; - - assert( sqlite3_mutex_held(pBt->mutex) ); - /* The master-journal page number must never be used as a pointer map page */ - assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) ); - - assert( pBt->autoVacuum ); - if( key==0 ){ - *pRC = SQLITE_CORRUPT_BKPT; - return; - } - iPtrmap = PTRMAP_PAGENO(pBt, key); - rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage, 0); - if( rc!=SQLITE_OK ){ - *pRC = rc; - return; - } - offset = PTRMAP_PTROFFSET(iPtrmap, key); - if( offset<0 ){ - *pRC = SQLITE_CORRUPT_BKPT; - goto ptrmap_exit; - } - assert( offset <= (int)pBt->usableSize-5 ); - pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage); - - if( eType!=pPtrmap[offset] || get4byte(&pPtrmap[offset+1])!=parent ){ - TRACE(("PTRMAP_UPDATE: %d->(%d,%d)\n", key, eType, parent)); - *pRC= rc = sqlite3PagerWrite(pDbPage); - if( rc==SQLITE_OK ){ - pPtrmap[offset] = eType; - put4byte(&pPtrmap[offset+1], parent); - } - } - -ptrmap_exit: - sqlite3PagerUnref(pDbPage); -} - -/* -** Read an entry from the pointer map. -** -** This routine retrieves the pointer map entry for page 'key', writing -** the type and parent page number to *pEType and *pPgno respectively. -** An error code is returned if something goes wrong, otherwise SQLITE_OK. -*/ -static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){ - DbPage *pDbPage; /* The pointer map page */ - int iPtrmap; /* Pointer map page index */ - u8 *pPtrmap; /* Pointer map page data */ - int offset; /* Offset of entry in pointer map */ - int rc; - - assert( sqlite3_mutex_held(pBt->mutex) ); - - iPtrmap = PTRMAP_PAGENO(pBt, key); - rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage, 0); - if( rc!=0 ){ - return rc; - } - pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage); - - offset = PTRMAP_PTROFFSET(iPtrmap, key); - if( offset<0 ){ - sqlite3PagerUnref(pDbPage); - return SQLITE_CORRUPT_BKPT; - } - assert( offset <= (int)pBt->usableSize-5 ); - assert( pEType!=0 ); - *pEType = pPtrmap[offset]; - if( pPgno ) *pPgno = get4byte(&pPtrmap[offset+1]); - - sqlite3PagerUnref(pDbPage); - if( *pEType<1 || *pEType>5 ) return SQLITE_CORRUPT_PGNO(iPtrmap); - return SQLITE_OK; -} - -#else /* if defined SQLITE_OMIT_AUTOVACUUM */ - #define ptrmapPut(w,x,y,z,rc) - #define ptrmapGet(w,x,y,z) SQLITE_OK - #define ptrmapPutOvflPtr(x, y, rc) -#endif - -/* -** Given a btree page and a cell index (0 means the first cell on -** the page, 1 means the second cell, and so forth) return a pointer -** to the cell content. -** -** findCellPastPtr() does the same except it skips past the initial -** 4-byte child pointer found on interior pages, if there is one. -** -** This routine works only for pages that do not contain overflow cells. -*/ -#define findCell(P,I) \ - ((P)->aData + ((P)->maskPage & get2byteAligned(&(P)->aCellIdx[2*(I)]))) -#define findCellPastPtr(P,I) \ - ((P)->aDataOfst + ((P)->maskPage & get2byteAligned(&(P)->aCellIdx[2*(I)]))) - - -/* -** This is common tail processing for btreeParseCellPtr() and -** btreeParseCellPtrIndex() for the case when the cell does not fit entirely -** on a single B-tree page. Make necessary adjustments to the CellInfo -** structure. -*/ -static SQLITE_NOINLINE void btreeParseCellAdjustSizeForOverflow( - MemPage *pPage, /* Page containing the cell */ - u8 *pCell, /* Pointer to the cell text. */ - CellInfo *pInfo /* Fill in this structure */ -){ - /* If the payload will not fit completely on the local page, we have - ** to decide how much to store locally and how much to spill onto - ** overflow pages. The strategy is to minimize the amount of unused - ** space on overflow pages while keeping the amount of local storage - ** in between minLocal and maxLocal. - ** - ** Warning: changing the way overflow payload is distributed in any - ** way will result in an incompatible file format. - */ - int minLocal; /* Minimum amount of payload held locally */ - int maxLocal; /* Maximum amount of payload held locally */ - int surplus; /* Overflow payload available for local storage */ - - minLocal = pPage->minLocal; - maxLocal = pPage->maxLocal; - surplus = minLocal + (pInfo->nPayload - minLocal)%(pPage->pBt->usableSize-4); - testcase( surplus==maxLocal ); - testcase( surplus==maxLocal+1 ); - if( surplus <= maxLocal ){ - pInfo->nLocal = (u16)surplus; - }else{ - pInfo->nLocal = (u16)minLocal; - } - pInfo->nSize = (u16)(&pInfo->pPayload[pInfo->nLocal] - pCell) + 4; -} - -/* -** The following routines are implementations of the MemPage.xParseCell() -** method. -** -** Parse a cell content block and fill in the CellInfo structure. -** -** btreeParseCellPtr() => table btree leaf nodes -** btreeParseCellNoPayload() => table btree internal nodes -** btreeParseCellPtrIndex() => index btree nodes -** -** There is also a wrapper function btreeParseCell() that works for -** all MemPage types and that references the cell by index rather than -** by pointer. -*/ -static void btreeParseCellPtrNoPayload( - MemPage *pPage, /* Page containing the cell */ - u8 *pCell, /* Pointer to the cell text. */ - CellInfo *pInfo /* Fill in this structure */ -){ - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - assert( pPage->leaf==0 ); - assert( pPage->childPtrSize==4 ); -#ifndef SQLITE_DEBUG - UNUSED_PARAMETER(pPage); -#endif - pInfo->nSize = 4 + getVarint(&pCell[4], (u64*)&pInfo->nKey); - pInfo->nPayload = 0; - pInfo->nLocal = 0; - pInfo->pPayload = 0; - return; -} -static void btreeParseCellPtr( - MemPage *pPage, /* Page containing the cell */ - u8 *pCell, /* Pointer to the cell text. */ - CellInfo *pInfo /* Fill in this structure */ -){ - u8 *pIter; /* For scanning through pCell */ - u32 nPayload; /* Number of bytes of cell payload */ - u64 iKey; /* Extracted Key value */ - - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - assert( pPage->leaf==0 || pPage->leaf==1 ); - assert( pPage->intKeyLeaf ); - assert( pPage->childPtrSize==0 ); - pIter = pCell; - - /* The next block of code is equivalent to: - ** - ** pIter += getVarint32(pIter, nPayload); - ** - ** The code is inlined to avoid a function call. - */ - nPayload = *pIter; - if( nPayload>=0x80 ){ - u8 *pEnd = &pIter[8]; - nPayload &= 0x7f; - do{ - nPayload = (nPayload<<7) | (*++pIter & 0x7f); - }while( (*pIter)>=0x80 && pIter<pEnd ); - } - pIter++; - - /* The next block of code is equivalent to: - ** - ** pIter += getVarint(pIter, (u64*)&pInfo->nKey); - ** - ** The code is inlined to avoid a function call. - */ - iKey = *pIter; - if( iKey>=0x80 ){ - u8 *pEnd = &pIter[7]; - iKey &= 0x7f; - while(1){ - iKey = (iKey<<7) | (*++pIter & 0x7f); - if( (*pIter)<0x80 ) break; - if( pIter>=pEnd ){ - iKey = (iKey<<8) | *++pIter; - break; - } - } - } - pIter++; - - pInfo->nKey = *(i64*)&iKey; - pInfo->nPayload = nPayload; - pInfo->pPayload = pIter; - testcase( nPayload==pPage->maxLocal ); - testcase( nPayload==pPage->maxLocal+1 ); - if( nPayload<=pPage->maxLocal ){ - /* This is the (easy) common case where the entire payload fits - ** on the local page. No overflow is required. - */ - pInfo->nSize = nPayload + (u16)(pIter - pCell); - if( pInfo->nSize<4 ) pInfo->nSize = 4; - pInfo->nLocal = (u16)nPayload; - }else{ - btreeParseCellAdjustSizeForOverflow(pPage, pCell, pInfo); - } -} -static void btreeParseCellPtrIndex( - MemPage *pPage, /* Page containing the cell */ - u8 *pCell, /* Pointer to the cell text. */ - CellInfo *pInfo /* Fill in this structure */ -){ - u8 *pIter; /* For scanning through pCell */ - u32 nPayload; /* Number of bytes of cell payload */ - - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - assert( pPage->leaf==0 || pPage->leaf==1 ); - assert( pPage->intKeyLeaf==0 ); - pIter = pCell + pPage->childPtrSize; - nPayload = *pIter; - if( nPayload>=0x80 ){ - u8 *pEnd = &pIter[8]; - nPayload &= 0x7f; - do{ - nPayload = (nPayload<<7) | (*++pIter & 0x7f); - }while( *(pIter)>=0x80 && pIter<pEnd ); - } - pIter++; - pInfo->nKey = nPayload; - pInfo->nPayload = nPayload; - pInfo->pPayload = pIter; - testcase( nPayload==pPage->maxLocal ); - testcase( nPayload==pPage->maxLocal+1 ); - if( nPayload<=pPage->maxLocal ){ - /* This is the (easy) common case where the entire payload fits - ** on the local page. No overflow is required. - */ - pInfo->nSize = nPayload + (u16)(pIter - pCell); - if( pInfo->nSize<4 ) pInfo->nSize = 4; - pInfo->nLocal = (u16)nPayload; - }else{ - btreeParseCellAdjustSizeForOverflow(pPage, pCell, pInfo); - } -} -static void btreeParseCell( - MemPage *pPage, /* Page containing the cell */ - int iCell, /* The cell index. First cell is 0 */ - CellInfo *pInfo /* Fill in this structure */ -){ - pPage->xParseCell(pPage, findCell(pPage, iCell), pInfo); -} - -/* -** The following routines are implementations of the MemPage.xCellSize -** method. -** -** Compute the total number of bytes that a Cell needs in the cell -** data area of the btree-page. The return number includes the cell -** data header and the local payload, but not any overflow page or -** the space used by the cell pointer. -** -** cellSizePtrNoPayload() => table internal nodes -** cellSizePtr() => all index nodes & table leaf nodes -*/ -static u16 cellSizePtr(MemPage *pPage, u8 *pCell){ - u8 *pIter = pCell + pPage->childPtrSize; /* For looping over bytes of pCell */ - u8 *pEnd; /* End mark for a varint */ - u32 nSize; /* Size value to return */ - -#ifdef SQLITE_DEBUG - /* The value returned by this function should always be the same as - ** the (CellInfo.nSize) value found by doing a full parse of the - ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of - ** this function verifies that this invariant is not violated. */ - CellInfo debuginfo; - pPage->xParseCell(pPage, pCell, &debuginfo); -#endif - - nSize = *pIter; - if( nSize>=0x80 ){ - pEnd = &pIter[8]; - nSize &= 0x7f; - do{ - nSize = (nSize<<7) | (*++pIter & 0x7f); - }while( *(pIter)>=0x80 && pIter<pEnd ); - } - pIter++; - if( pPage->intKey ){ - /* pIter now points at the 64-bit integer key value, a variable length - ** integer. The following block moves pIter to point at the first byte - ** past the end of the key value. */ - pEnd = &pIter[9]; - while( (*pIter++)&0x80 && pIter<pEnd ); - } - testcase( nSize==pPage->maxLocal ); - testcase( nSize==pPage->maxLocal+1 ); - if( nSize<=pPage->maxLocal ){ - nSize += (u32)(pIter - pCell); - if( nSize<4 ) nSize = 4; - }else{ - int minLocal = pPage->minLocal; - nSize = minLocal + (nSize - minLocal) % (pPage->pBt->usableSize - 4); - testcase( nSize==pPage->maxLocal ); - testcase( nSize==pPage->maxLocal+1 ); - if( nSize>pPage->maxLocal ){ - nSize = minLocal; - } - nSize += 4 + (u16)(pIter - pCell); - } - assert( nSize==debuginfo.nSize || CORRUPT_DB ); - return (u16)nSize; -} -static u16 cellSizePtrNoPayload(MemPage *pPage, u8 *pCell){ - u8 *pIter = pCell + 4; /* For looping over bytes of pCell */ - u8 *pEnd; /* End mark for a varint */ - -#ifdef SQLITE_DEBUG - /* The value returned by this function should always be the same as - ** the (CellInfo.nSize) value found by doing a full parse of the - ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of - ** this function verifies that this invariant is not violated. */ - CellInfo debuginfo; - pPage->xParseCell(pPage, pCell, &debuginfo); -#else - UNUSED_PARAMETER(pPage); -#endif - - assert( pPage->childPtrSize==4 ); - pEnd = pIter + 9; - while( (*pIter++)&0x80 && pIter<pEnd ); - assert( debuginfo.nSize==(u16)(pIter - pCell) || CORRUPT_DB ); - return (u16)(pIter - pCell); -} - - -#ifdef SQLITE_DEBUG -/* This variation on cellSizePtr() is used inside of assert() statements -** only. */ -static u16 cellSize(MemPage *pPage, int iCell){ - return pPage->xCellSize(pPage, findCell(pPage, iCell)); -} -#endif - -#ifndef SQLITE_OMIT_AUTOVACUUM -/* -** If the cell pCell, part of page pPage contains a pointer -** to an overflow page, insert an entry into the pointer-map -** for the overflow page. -*/ -static void ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell, int *pRC){ - CellInfo info; - if( *pRC ) return; - assert( pCell!=0 ); - pPage->xParseCell(pPage, pCell, &info); - if( info.nLocal<info.nPayload ){ - Pgno ovfl = get4byte(&pCell[info.nSize-4]); - ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno, pRC); - } -} -#endif - - -/* -** Defragment the page given. This routine reorganizes cells within the -** page so that there are no free-blocks on the free-block list. -** -** Parameter nMaxFrag is the maximum amount of fragmented space that may be -** present in the page after this routine returns. -** -** EVIDENCE-OF: R-44582-60138 SQLite may from time to time reorganize a -** b-tree page so that there are no freeblocks or fragment bytes, all -** unused bytes are contained in the unallocated space region, and all -** cells are packed tightly at the end of the page. -*/ -static int defragmentPage(MemPage *pPage, int nMaxFrag){ - int i; /* Loop counter */ - int pc; /* Address of the i-th cell */ - int hdr; /* Offset to the page header */ - int size; /* Size of a cell */ - int usableSize; /* Number of usable bytes on a page */ - int cellOffset; /* Offset to the cell pointer array */ - int cbrk; /* Offset to the cell content area */ - int nCell; /* Number of cells on the page */ - unsigned char *data; /* The page data */ - unsigned char *temp; /* Temp area for cell content */ - unsigned char *src; /* Source of content */ - int iCellFirst; /* First allowable cell index */ - int iCellLast; /* Last possible cell index */ - - assert( sqlite3PagerIswriteable(pPage->pDbPage) ); - assert( pPage->pBt!=0 ); - assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE ); - assert( pPage->nOverflow==0 ); - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - temp = 0; - src = data = pPage->aData; - hdr = pPage->hdrOffset; - cellOffset = pPage->cellOffset; - nCell = pPage->nCell; - assert( nCell==get2byte(&data[hdr+3]) ); - iCellFirst = cellOffset + 2*nCell; - usableSize = pPage->pBt->usableSize; - - /* This block handles pages with two or fewer free blocks and nMaxFrag - ** or fewer fragmented bytes. In this case it is faster to move the - ** two (or one) blocks of cells using memmove() and add the required - ** offsets to each pointer in the cell-pointer array than it is to - ** reconstruct the entire page. */ - if( (int)data[hdr+7]<=nMaxFrag ){ - int iFree = get2byte(&data[hdr+1]); - if( iFree ){ - int iFree2 = get2byte(&data[iFree]); - - /* pageFindSlot() has already verified that free blocks are sorted - ** in order of offset within the page, and that no block extends - ** past the end of the page. Provided the two free slots do not - ** overlap, this guarantees that the memmove() calls below will not - ** overwrite the usableSize byte buffer, even if the database page - ** is corrupt. */ - assert( iFree2==0 || iFree2>iFree ); - assert( iFree+get2byte(&data[iFree+2]) <= usableSize ); - assert( iFree2==0 || iFree2+get2byte(&data[iFree2+2]) <= usableSize ); - - if( 0==iFree2 || (data[iFree2]==0 && data[iFree2+1]==0) ){ - u8 *pEnd = &data[cellOffset + nCell*2]; - u8 *pAddr; - int sz2 = 0; - int sz = get2byte(&data[iFree+2]); - int top = get2byte(&data[hdr+5]); - if( top>=iFree ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - if( iFree2 ){ - assert( iFree+sz<=iFree2 ); /* Verified by pageFindSlot() */ - sz2 = get2byte(&data[iFree2+2]); - assert( iFree+sz+sz2+iFree2-(iFree+sz) <= usableSize ); - memmove(&data[iFree+sz+sz2], &data[iFree+sz], iFree2-(iFree+sz)); - sz += sz2; - } - cbrk = top+sz; - assert( cbrk+(iFree-top) <= usableSize ); - memmove(&data[cbrk], &data[top], iFree-top); - for(pAddr=&data[cellOffset]; pAddr<pEnd; pAddr+=2){ - pc = get2byte(pAddr); - if( pc<iFree ){ put2byte(pAddr, pc+sz); } - else if( pc<iFree2 ){ put2byte(pAddr, pc+sz2); } - } - goto defragment_out; - } - } - } - - cbrk = usableSize; - iCellLast = usableSize - 4; - for(i=0; i<nCell; i++){ - u8 *pAddr; /* The i-th cell pointer */ - pAddr = &data[cellOffset + i*2]; - pc = get2byte(pAddr); - testcase( pc==iCellFirst ); - testcase( pc==iCellLast ); - /* These conditions have already been verified in btreeInitPage() - ** if PRAGMA cell_size_check=ON. - */ - if( pc<iCellFirst || pc>iCellLast ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - assert( pc>=iCellFirst && pc<=iCellLast ); - size = pPage->xCellSize(pPage, &src[pc]); - cbrk -= size; - if( cbrk<iCellFirst || pc+size>usableSize ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - assert( cbrk+size<=usableSize && cbrk>=iCellFirst ); - testcase( cbrk+size==usableSize ); - testcase( pc+size==usableSize ); - put2byte(pAddr, cbrk); - if( temp==0 ){ - int x; - if( cbrk==pc ) continue; - temp = sqlite3PagerTempSpace(pPage->pBt->pPager); - x = get2byte(&data[hdr+5]); - memcpy(&temp[x], &data[x], (cbrk+size) - x); - src = temp; - } - memcpy(&data[cbrk], &src[pc], size); - } - data[hdr+7] = 0; - - defragment_out: - if( data[hdr+7]+cbrk-iCellFirst!=pPage->nFree ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - assert( cbrk>=iCellFirst ); - put2byte(&data[hdr+5], cbrk); - data[hdr+1] = 0; - data[hdr+2] = 0; - memset(&data[iCellFirst], 0, cbrk-iCellFirst); - assert( sqlite3PagerIswriteable(pPage->pDbPage) ); - return SQLITE_OK; -} - -/* -** Search the free-list on page pPg for space to store a cell nByte bytes in -** size. If one can be found, return a pointer to the space and remove it -** from the free-list. -** -** If no suitable space can be found on the free-list, return NULL. -** -** This function may detect corruption within pPg. If corruption is -** detected then *pRc is set to SQLITE_CORRUPT and NULL is returned. -** -** Slots on the free list that are between 1 and 3 bytes larger than nByte -** will be ignored if adding the extra space to the fragmentation count -** causes the fragmentation count to exceed 60. -*/ -static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){ - const int hdr = pPg->hdrOffset; - u8 * const aData = pPg->aData; - int iAddr = hdr + 1; - int pc = get2byte(&aData[iAddr]); - int x; - int usableSize = pPg->pBt->usableSize; - int size; /* Size of the free slot */ - - assert( pc>0 ); - while( pc<=usableSize-4 ){ - /* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each - ** freeblock form a big-endian integer which is the size of the freeblock - ** in bytes, including the 4-byte header. */ - size = get2byte(&aData[pc+2]); - if( (x = size - nByte)>=0 ){ - testcase( x==4 ); - testcase( x==3 ); - if( size+pc > usableSize ){ - *pRc = SQLITE_CORRUPT_PAGE(pPg); - return 0; - }else if( x<4 ){ - /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total - ** number of bytes in fragments may not exceed 60. */ - if( aData[hdr+7]>57 ) return 0; - - /* Remove the slot from the free-list. Update the number of - ** fragmented bytes within the page. */ - memcpy(&aData[iAddr], &aData[pc], 2); - aData[hdr+7] += (u8)x; - }else{ - /* The slot remains on the free-list. Reduce its size to account - ** for the portion used by the new allocation. */ - put2byte(&aData[pc+2], x); - } - return &aData[pc + x]; - } - iAddr = pc; - pc = get2byte(&aData[pc]); - if( pc<iAddr+size ) break; - } - if( pc ){ - *pRc = SQLITE_CORRUPT_PAGE(pPg); - } - - return 0; -} - -/* -** Allocate nByte bytes of space from within the B-Tree page passed -** as the first argument. Write into *pIdx the index into pPage->aData[] -** of the first byte of allocated space. Return either SQLITE_OK or -** an error code (usually SQLITE_CORRUPT). -** -** The caller guarantees that there is sufficient space to make the -** allocation. This routine might need to defragment in order to bring -** all the space together, however. This routine will avoid using -** the first two bytes past the cell pointer area since presumably this -** allocation is being made in order to insert a new cell, so we will -** also end up needing a new cell pointer. -*/ -static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){ - const int hdr = pPage->hdrOffset; /* Local cache of pPage->hdrOffset */ - u8 * const data = pPage->aData; /* Local cache of pPage->aData */ - int top; /* First byte of cell content area */ - int rc = SQLITE_OK; /* Integer return code */ - int gap; /* First byte of gap between cell pointers and cell content */ - - assert( sqlite3PagerIswriteable(pPage->pDbPage) ); - assert( pPage->pBt ); - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - assert( nByte>=0 ); /* Minimum cell size is 4 */ - assert( pPage->nFree>=nByte ); - assert( pPage->nOverflow==0 ); - assert( nByte < (int)(pPage->pBt->usableSize-8) ); - - assert( pPage->cellOffset == hdr + 12 - 4*pPage->leaf ); - gap = pPage->cellOffset + 2*pPage->nCell; - assert( gap<=65536 ); - /* EVIDENCE-OF: R-29356-02391 If the database uses a 65536-byte page size - ** and the reserved space is zero (the usual value for reserved space) - ** then the cell content offset of an empty page wants to be 65536. - ** However, that integer is too large to be stored in a 2-byte unsigned - ** integer, so a value of 0 is used in its place. */ - top = get2byte(&data[hdr+5]); - assert( top<=(int)pPage->pBt->usableSize ); /* Prevent by getAndInitPage() */ - if( gap>top ){ - if( top==0 && pPage->pBt->usableSize==65536 ){ - top = 65536; - }else{ - return SQLITE_CORRUPT_PAGE(pPage); - } - } - - /* If there is enough space between gap and top for one more cell pointer - ** array entry offset, and if the freelist is not empty, then search the - ** freelist looking for a free slot big enough to satisfy the request. - */ - testcase( gap+2==top ); - testcase( gap+1==top ); - testcase( gap==top ); - if( (data[hdr+2] || data[hdr+1]) && gap+2<=top ){ - u8 *pSpace = pageFindSlot(pPage, nByte, &rc); - if( pSpace ){ - assert( pSpace>=data && (pSpace - data)<65536 ); - *pIdx = (int)(pSpace - data); - return SQLITE_OK; - }else if( rc ){ - return rc; - } - } - - /* The request could not be fulfilled using a freelist slot. Check - ** to see if defragmentation is necessary. - */ - testcase( gap+2+nByte==top ); - if( gap+2+nByte>top ){ - assert( pPage->nCell>0 || CORRUPT_DB ); - rc = defragmentPage(pPage, MIN(4, pPage->nFree - (2+nByte))); - if( rc ) return rc; - top = get2byteNotZero(&data[hdr+5]); - assert( gap+2+nByte<=top ); - } - - - /* Allocate memory from the gap in between the cell pointer array - ** and the cell content area. The btreeInitPage() call has already - ** validated the freelist. Given that the freelist is valid, there - ** is no way that the allocation can extend off the end of the page. - ** The assert() below verifies the previous sentence. - */ - top -= nByte; - put2byte(&data[hdr+5], top); - assert( top+nByte <= (int)pPage->pBt->usableSize ); - *pIdx = top; - return SQLITE_OK; -} - -/* -** Return a section of the pPage->aData to the freelist. -** The first byte of the new free block is pPage->aData[iStart] -** and the size of the block is iSize bytes. -** -** Adjacent freeblocks are coalesced. -** -** Note that even though the freeblock list was checked by btreeInitPage(), -** that routine will not detect overlap between cells or freeblocks. Nor -** does it detect cells or freeblocks that encrouch into the reserved bytes -** at the end of the page. So do additional corruption checks inside this -** routine and return SQLITE_CORRUPT if any problems are found. -*/ -static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){ - u16 iPtr; /* Address of ptr to next freeblock */ - u16 iFreeBlk; /* Address of the next freeblock */ - u8 hdr; /* Page header size. 0 or 100 */ - u8 nFrag = 0; /* Reduction in fragmentation */ - u16 iOrigSize = iSize; /* Original value of iSize */ - u16 x; /* Offset to cell content area */ - u32 iEnd = iStart + iSize; /* First byte past the iStart buffer */ - unsigned char *data = pPage->aData; /* Page content */ - - assert( pPage->pBt!=0 ); - assert( sqlite3PagerIswriteable(pPage->pDbPage) ); - assert( CORRUPT_DB || iStart>=pPage->hdrOffset+6+pPage->childPtrSize ); - assert( CORRUPT_DB || iEnd <= pPage->pBt->usableSize ); - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - assert( iSize>=4 ); /* Minimum cell size is 4 */ - assert( iStart<=pPage->pBt->usableSize-4 ); - - /* The list of freeblocks must be in ascending order. Find the - ** spot on the list where iStart should be inserted. - */ - hdr = pPage->hdrOffset; - iPtr = hdr + 1; - if( data[iPtr+1]==0 && data[iPtr]==0 ){ - iFreeBlk = 0; /* Shortcut for the case when the freelist is empty */ - }else{ - while( (iFreeBlk = get2byte(&data[iPtr]))<iStart ){ - if( iFreeBlk<iPtr+4 ){ - if( iFreeBlk==0 ) break; - return SQLITE_CORRUPT_PAGE(pPage); - } - iPtr = iFreeBlk; - } - if( iFreeBlk>pPage->pBt->usableSize-4 ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - assert( iFreeBlk>iPtr || iFreeBlk==0 ); - - /* At this point: - ** iFreeBlk: First freeblock after iStart, or zero if none - ** iPtr: The address of a pointer to iFreeBlk - ** - ** Check to see if iFreeBlk should be coalesced onto the end of iStart. - */ - if( iFreeBlk && iEnd+3>=iFreeBlk ){ - nFrag = iFreeBlk - iEnd; - if( iEnd>iFreeBlk ) return SQLITE_CORRUPT_PAGE(pPage); - iEnd = iFreeBlk + get2byte(&data[iFreeBlk+2]); - if( iEnd > pPage->pBt->usableSize ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - iSize = iEnd - iStart; - iFreeBlk = get2byte(&data[iFreeBlk]); - } - - /* If iPtr is another freeblock (that is, if iPtr is not the freelist - ** pointer in the page header) then check to see if iStart should be - ** coalesced onto the end of iPtr. - */ - if( iPtr>hdr+1 ){ - int iPtrEnd = iPtr + get2byte(&data[iPtr+2]); - if( iPtrEnd+3>=iStart ){ - if( iPtrEnd>iStart ) return SQLITE_CORRUPT_PAGE(pPage); - nFrag += iStart - iPtrEnd; - iSize = iEnd - iPtr; - iStart = iPtr; - } - } - if( nFrag>data[hdr+7] ) return SQLITE_CORRUPT_PAGE(pPage); - data[hdr+7] -= nFrag; - } - x = get2byte(&data[hdr+5]); - if( iStart<=x ){ - /* The new freeblock is at the beginning of the cell content area, - ** so just extend the cell content area rather than create another - ** freelist entry */ - if( iStart<x || iPtr!=hdr+1 ) return SQLITE_CORRUPT_PAGE(pPage); - put2byte(&data[hdr+1], iFreeBlk); - put2byte(&data[hdr+5], iEnd); - }else{ - /* Insert the new freeblock into the freelist */ - put2byte(&data[iPtr], iStart); - } - if( pPage->pBt->btsFlags & BTS_FAST_SECURE ){ - /* Overwrite deleted information with zeros when the secure_delete - ** option is enabled */ - memset(&data[iStart], 0, iSize); - } - put2byte(&data[iStart], iFreeBlk); - put2byte(&data[iStart+2], iSize); - pPage->nFree += iOrigSize; - return SQLITE_OK; -} - -/* -** Decode the flags byte (the first byte of the header) for a page -** and initialize fields of the MemPage structure accordingly. -** -** Only the following combinations are supported. Anything different -** indicates a corrupt database files: -** -** PTF_ZERODATA -** PTF_ZERODATA | PTF_LEAF -** PTF_LEAFDATA | PTF_INTKEY -** PTF_LEAFDATA | PTF_INTKEY | PTF_LEAF -*/ -static int decodeFlags(MemPage *pPage, int flagByte){ - BtShared *pBt; /* A copy of pPage->pBt */ - - assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) ); - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - pPage->leaf = (u8)(flagByte>>3); assert( PTF_LEAF == 1<<3 ); - flagByte &= ~PTF_LEAF; - pPage->childPtrSize = 4-4*pPage->leaf; - pPage->xCellSize = cellSizePtr; - pBt = pPage->pBt; - if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){ - /* EVIDENCE-OF: R-07291-35328 A value of 5 (0x05) means the page is an - ** interior table b-tree page. */ - assert( (PTF_LEAFDATA|PTF_INTKEY)==5 ); - /* EVIDENCE-OF: R-26900-09176 A value of 13 (0x0d) means the page is a - ** leaf table b-tree page. */ - assert( (PTF_LEAFDATA|PTF_INTKEY|PTF_LEAF)==13 ); - pPage->intKey = 1; - if( pPage->leaf ){ - pPage->intKeyLeaf = 1; - pPage->xParseCell = btreeParseCellPtr; - }else{ - pPage->intKeyLeaf = 0; - pPage->xCellSize = cellSizePtrNoPayload; - pPage->xParseCell = btreeParseCellPtrNoPayload; - } - pPage->maxLocal = pBt->maxLeaf; - pPage->minLocal = pBt->minLeaf; - }else if( flagByte==PTF_ZERODATA ){ - /* EVIDENCE-OF: R-43316-37308 A value of 2 (0x02) means the page is an - ** interior index b-tree page. */ - assert( (PTF_ZERODATA)==2 ); - /* EVIDENCE-OF: R-59615-42828 A value of 10 (0x0a) means the page is a - ** leaf index b-tree page. */ - assert( (PTF_ZERODATA|PTF_LEAF)==10 ); - pPage->intKey = 0; - pPage->intKeyLeaf = 0; - pPage->xParseCell = btreeParseCellPtrIndex; - pPage->maxLocal = pBt->maxLocal; - pPage->minLocal = pBt->minLocal; - }else{ - /* EVIDENCE-OF: R-47608-56469 Any other value for the b-tree page type is - ** an error. */ - return SQLITE_CORRUPT_PAGE(pPage); - } - pPage->max1bytePayload = pBt->max1bytePayload; - return SQLITE_OK; -} - -/* -** Initialize the auxiliary information for a disk block. -** -** Return SQLITE_OK on success. If we see that the page does -** not contain a well-formed database page, then return -** SQLITE_CORRUPT. Note that a return of SQLITE_OK does not -** guarantee that the page is well-formed. It only shows that -** we failed to detect any corruption. -*/ -static int btreeInitPage(MemPage *pPage){ - int pc; /* Address of a freeblock within pPage->aData[] */ - u8 hdr; /* Offset to beginning of page header */ - u8 *data; /* Equal to pPage->aData */ - BtShared *pBt; /* The main btree structure */ - int usableSize; /* Amount of usable space on each page */ - u16 cellOffset; /* Offset from start of page to first cell pointer */ - int nFree; /* Number of unused bytes on the page */ - int top; /* First byte of the cell content area */ - int iCellFirst; /* First allowable cell or freeblock offset */ - int iCellLast; /* Last possible cell or freeblock offset */ - - assert( pPage->pBt!=0 ); - assert( pPage->pBt->db!=0 ); - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) ); - assert( pPage == sqlite3PagerGetExtra(pPage->pDbPage) ); - assert( pPage->aData == sqlite3PagerGetData(pPage->pDbPage) ); - assert( pPage->isInit==0 ); - - pBt = pPage->pBt; - hdr = pPage->hdrOffset; - data = pPage->aData; - /* EVIDENCE-OF: R-28594-02890 The one-byte flag at offset 0 indicating - ** the b-tree page type. */ - if( decodeFlags(pPage, data[hdr]) ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - assert( pBt->pageSize>=512 && pBt->pageSize<=65536 ); - pPage->maskPage = (u16)(pBt->pageSize - 1); - pPage->nOverflow = 0; - usableSize = pBt->usableSize; - pPage->cellOffset = cellOffset = hdr + 8 + pPage->childPtrSize; - pPage->aDataEnd = &data[usableSize]; - pPage->aCellIdx = &data[cellOffset]; - pPage->aDataOfst = &data[pPage->childPtrSize]; - /* EVIDENCE-OF: R-58015-48175 The two-byte integer at offset 5 designates - ** the start of the cell content area. A zero value for this integer is - ** interpreted as 65536. */ - top = get2byteNotZero(&data[hdr+5]); - /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the - ** number of cells on the page. */ - pPage->nCell = get2byte(&data[hdr+3]); - if( pPage->nCell>MX_CELL(pBt) ){ - /* To many cells for a single page. The page must be corrupt */ - return SQLITE_CORRUPT_PAGE(pPage); - } - testcase( pPage->nCell==MX_CELL(pBt) ); - /* EVIDENCE-OF: R-24089-57979 If a page contains no cells (which is only - ** possible for a root page of a table that contains no rows) then the - ** offset to the cell content area will equal the page size minus the - ** bytes of reserved space. */ - assert( pPage->nCell>0 || top==usableSize || CORRUPT_DB ); - - /* A malformed database page might cause us to read past the end - ** of page when parsing a cell. - ** - ** The following block of code checks early to see if a cell extends - ** past the end of a page boundary and causes SQLITE_CORRUPT to be - ** returned if it does. - */ - iCellFirst = cellOffset + 2*pPage->nCell; - iCellLast = usableSize - 4; - if( pBt->db->flags & SQLITE_CellSizeCk ){ - int i; /* Index into the cell pointer array */ - int sz; /* Size of a cell */ - - if( !pPage->leaf ) iCellLast--; - for(i=0; i<pPage->nCell; i++){ - pc = get2byteAligned(&data[cellOffset+i*2]); - testcase( pc==iCellFirst ); - testcase( pc==iCellLast ); - if( pc<iCellFirst || pc>iCellLast ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - sz = pPage->xCellSize(pPage, &data[pc]); - testcase( pc+sz==usableSize ); - if( pc+sz>usableSize ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - } - if( !pPage->leaf ) iCellLast++; - } - - /* Compute the total free space on the page - ** EVIDENCE-OF: R-23588-34450 The two-byte integer at offset 1 gives the - ** start of the first freeblock on the page, or is zero if there are no - ** freeblocks. */ - pc = get2byte(&data[hdr+1]); - nFree = data[hdr+7] + top; /* Init nFree to non-freeblock free space */ - if( pc>0 ){ - u32 next, size; - if( pc<iCellFirst ){ - /* EVIDENCE-OF: R-55530-52930 In a well-formed b-tree page, there will - ** always be at least one cell before the first freeblock. - */ - return SQLITE_CORRUPT_PAGE(pPage); - } - while( 1 ){ - if( pc>iCellLast ){ - /* Freeblock off the end of the page */ - return SQLITE_CORRUPT_PAGE(pPage); - } - next = get2byte(&data[pc]); - size = get2byte(&data[pc+2]); - nFree = nFree + size; - if( next<=pc+size+3 ) break; - pc = next; - } - if( next>0 ){ - /* Freeblock not in ascending order */ - return SQLITE_CORRUPT_PAGE(pPage); - } - if( pc+size>(unsigned int)usableSize ){ - /* Last freeblock extends past page end */ - return SQLITE_CORRUPT_PAGE(pPage); - } - } - - /* At this point, nFree contains the sum of the offset to the start - ** of the cell-content area plus the number of free bytes within - ** the cell-content area. If this is greater than the usable-size - ** of the page, then the page must be corrupted. This check also - ** serves to verify that the offset to the start of the cell-content - ** area, according to the page header, lies within the page. - */ - if( nFree>usableSize ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - pPage->nFree = (u16)(nFree - iCellFirst); - pPage->isInit = 1; - return SQLITE_OK; -} - -/* -** Set up a raw page so that it looks like a database page holding -** no entries. -*/ -static void zeroPage(MemPage *pPage, int flags){ - unsigned char *data = pPage->aData; - BtShared *pBt = pPage->pBt; - u8 hdr = pPage->hdrOffset; - u16 first; - - assert( sqlite3PagerPagenumber(pPage->pDbPage)==pPage->pgno ); - assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage ); - assert( sqlite3PagerGetData(pPage->pDbPage) == data ); - assert( sqlite3PagerIswriteable(pPage->pDbPage) ); - assert( sqlite3_mutex_held(pBt->mutex) ); - if( pBt->btsFlags & BTS_FAST_SECURE ){ - memset(&data[hdr], 0, pBt->usableSize - hdr); - } - data[hdr] = (char)flags; - first = hdr + ((flags&PTF_LEAF)==0 ? 12 : 8); - memset(&data[hdr+1], 0, 4); - data[hdr+7] = 0; - put2byte(&data[hdr+5], pBt->usableSize); - pPage->nFree = (u16)(pBt->usableSize - first); - decodeFlags(pPage, flags); - pPage->cellOffset = first; - pPage->aDataEnd = &data[pBt->usableSize]; - pPage->aCellIdx = &data[first]; - pPage->aDataOfst = &data[pPage->childPtrSize]; - pPage->nOverflow = 0; - assert( pBt->pageSize>=512 && pBt->pageSize<=65536 ); - pPage->maskPage = (u16)(pBt->pageSize - 1); - pPage->nCell = 0; - pPage->isInit = 1; -} - - -/* -** Convert a DbPage obtained from the pager into a MemPage used by -** the btree layer. -*/ -static MemPage *btreePageFromDbPage(DbPage *pDbPage, Pgno pgno, BtShared *pBt){ - MemPage *pPage = (MemPage*)sqlite3PagerGetExtra(pDbPage); - if( pgno!=pPage->pgno ){ - pPage->aData = sqlite3PagerGetData(pDbPage); - pPage->pDbPage = pDbPage; - pPage->pBt = pBt; - pPage->pgno = pgno; - pPage->hdrOffset = pgno==1 ? 100 : 0; - } - assert( pPage->aData==sqlite3PagerGetData(pDbPage) ); - return pPage; -} - -/* -** Get a page from the pager. Initialize the MemPage.pBt and -** MemPage.aData elements if needed. See also: btreeGetUnusedPage(). -** -** If the PAGER_GET_NOCONTENT flag is set, it means that we do not care -** about the content of the page at this time. So do not go to the disk -** to fetch the content. Just fill in the content with zeros for now. -** If in the future we call sqlite3PagerWrite() on this page, that -** means we have started to be concerned about content and the disk -** read should occur at that point. -*/ -static int btreeGetPage( - BtShared *pBt, /* The btree */ - Pgno pgno, /* Number of the page to fetch */ - MemPage **ppPage, /* Return the page in this parameter */ - int flags /* PAGER_GET_NOCONTENT or PAGER_GET_READONLY */ -){ - int rc; - DbPage *pDbPage; - - assert( flags==0 || flags==PAGER_GET_NOCONTENT || flags==PAGER_GET_READONLY ); - assert( sqlite3_mutex_held(pBt->mutex) ); - rc = sqlite3PagerGet(pBt->pPager, pgno, (DbPage**)&pDbPage, flags); - if( rc ) return rc; - *ppPage = btreePageFromDbPage(pDbPage, pgno, pBt); - return SQLITE_OK; -} - -/* -** Retrieve a page from the pager cache. If the requested page is not -** already in the pager cache return NULL. Initialize the MemPage.pBt and -** MemPage.aData elements if needed. -*/ -static MemPage *btreePageLookup(BtShared *pBt, Pgno pgno){ - DbPage *pDbPage; - assert( sqlite3_mutex_held(pBt->mutex) ); - pDbPage = sqlite3PagerLookup(pBt->pPager, pgno); - if( pDbPage ){ - return btreePageFromDbPage(pDbPage, pgno, pBt); - } - return 0; -} - -/* -** Return the size of the database file in pages. If there is any kind of -** error, return ((unsigned int)-1). -*/ -static Pgno btreePagecount(BtShared *pBt){ - return pBt->nPage; -} -u32 sqlite3BtreeLastPage(Btree *p){ - assert( sqlite3BtreeHoldsMutex(p) ); - assert( ((p->pBt->nPage)&0x80000000)==0 ); - return btreePagecount(p->pBt); -} - -/* -** Get a page from the pager and initialize it. -** -** If pCur!=0 then the page is being fetched as part of a moveToChild() -** call. Do additional sanity checking on the page in this case. -** And if the fetch fails, this routine must decrement pCur->iPage. -** -** The page is fetched as read-write unless pCur is not NULL and is -** a read-only cursor. -** -** If an error occurs, then *ppPage is undefined. It -** may remain unchanged, or it may be set to an invalid value. -*/ -static int getAndInitPage( - BtShared *pBt, /* The database file */ - Pgno pgno, /* Number of the page to get */ - MemPage **ppPage, /* Write the page pointer here */ - BtCursor *pCur, /* Cursor to receive the page, or NULL */ - int bReadOnly /* True for a read-only page */ -){ - int rc; - DbPage *pDbPage; - assert( sqlite3_mutex_held(pBt->mutex) ); - assert( pCur==0 || ppPage==&pCur->pPage ); - assert( pCur==0 || bReadOnly==pCur->curPagerFlags ); - assert( pCur==0 || pCur->iPage>0 ); - - if( pgno>btreePagecount(pBt) ){ - rc = SQLITE_CORRUPT_BKPT; - goto getAndInitPage_error; - } - rc = sqlite3PagerGet(pBt->pPager, pgno, (DbPage**)&pDbPage, bReadOnly); - if( rc ){ - goto getAndInitPage_error; - } - *ppPage = (MemPage*)sqlite3PagerGetExtra(pDbPage); - if( (*ppPage)->isInit==0 ){ - btreePageFromDbPage(pDbPage, pgno, pBt); - rc = btreeInitPage(*ppPage); - if( rc!=SQLITE_OK ){ - releasePage(*ppPage); - goto getAndInitPage_error; - } - } - assert( (*ppPage)->pgno==pgno ); - assert( (*ppPage)->aData==sqlite3PagerGetData(pDbPage) ); - - /* If obtaining a child page for a cursor, we must verify that the page is - ** compatible with the root page. */ - if( pCur && ((*ppPage)->nCell<1 || (*ppPage)->intKey!=pCur->curIntKey) ){ - rc = SQLITE_CORRUPT_PGNO(pgno); - releasePage(*ppPage); - goto getAndInitPage_error; - } - return SQLITE_OK; - -getAndInitPage_error: - if( pCur ){ - pCur->iPage--; - pCur->pPage = pCur->apPage[pCur->iPage]; - } - testcase( pgno==0 ); - assert( pgno!=0 || rc==SQLITE_CORRUPT ); - return rc; -} - -/* -** Release a MemPage. This should be called once for each prior -** call to btreeGetPage. -** -** Page1 is a special case and must be released using releasePageOne(). -*/ -static void releasePageNotNull(MemPage *pPage){ - assert( pPage->aData ); - assert( pPage->pBt ); - assert( pPage->pDbPage!=0 ); - assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage ); - assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData ); - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - sqlite3PagerUnrefNotNull(pPage->pDbPage); -} -static void releasePage(MemPage *pPage){ - if( pPage ) releasePageNotNull(pPage); -} -static void releasePageOne(MemPage *pPage){ - assert( pPage!=0 ); - assert( pPage->aData ); - assert( pPage->pBt ); - assert( pPage->pDbPage!=0 ); - assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage ); - assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData ); - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - sqlite3PagerUnrefPageOne(pPage->pDbPage); -} - -/* -** Get an unused page. -** -** This works just like btreeGetPage() with the addition: -** -** * If the page is already in use for some other purpose, immediately -** release it and return an SQLITE_CURRUPT error. -** * Make sure the isInit flag is clear -*/ -static int btreeGetUnusedPage( - BtShared *pBt, /* The btree */ - Pgno pgno, /* Number of the page to fetch */ - MemPage **ppPage, /* Return the page in this parameter */ - int flags /* PAGER_GET_NOCONTENT or PAGER_GET_READONLY */ -){ - int rc = btreeGetPage(pBt, pgno, ppPage, flags); - if( rc==SQLITE_OK ){ - if( sqlite3PagerPageRefcount((*ppPage)->pDbPage)>1 ){ - releasePage(*ppPage); - *ppPage = 0; - return SQLITE_CORRUPT_BKPT; - } - (*ppPage)->isInit = 0; - }else{ - *ppPage = 0; - } - return rc; -} - - -/* -** During a rollback, when the pager reloads information into the cache -** so that the cache is restored to its original state at the start of -** the transaction, for each page restored this routine is called. -** -** This routine needs to reset the extra data section at the end of the -** page to agree with the restored data. -*/ -static void pageReinit(DbPage *pData){ - MemPage *pPage; - pPage = (MemPage *)sqlite3PagerGetExtra(pData); - assert( sqlite3PagerPageRefcount(pData)>0 ); - if( pPage->isInit ){ - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - pPage->isInit = 0; - if( sqlite3PagerPageRefcount(pData)>1 ){ - /* pPage might not be a btree page; it might be an overflow page - ** or ptrmap page or a free page. In those cases, the following - ** call to btreeInitPage() will likely return SQLITE_CORRUPT. - ** But no harm is done by this. And it is very important that - ** btreeInitPage() be called on every btree page so we make - ** the call for every page that comes in for re-initing. */ - btreeInitPage(pPage); - } - } -} - -/* -** Invoke the busy handler for a btree. -*/ -static int btreeInvokeBusyHandler(void *pArg){ - BtShared *pBt = (BtShared*)pArg; - assert( pBt->db ); - assert( sqlite3_mutex_held(pBt->db->mutex) ); - return sqlite3InvokeBusyHandler(&pBt->db->busyHandler, - sqlite3PagerFile(pBt->pPager)); -} - -/* -** Open a database file. -** -** zFilename is the name of the database file. If zFilename is NULL -** then an ephemeral database is created. The ephemeral database might -** be exclusively in memory, or it might use a disk-based memory cache. -** Either way, the ephemeral database will be automatically deleted -** when sqlite3BtreeClose() is called. -** -** If zFilename is ":memory:" then an in-memory database is created -** that is automatically destroyed when it is closed. -** -** The "flags" parameter is a bitmask that might contain bits like -** BTREE_OMIT_JOURNAL and/or BTREE_MEMORY. -** -** If the database is already opened in the same database connection -** and we are in shared cache mode, then the open will fail with an -** SQLITE_CONSTRAINT error. We cannot allow two or more BtShared -** objects in the same database connection since doing so will lead -** to problems with locking. -*/ -int sqlite3BtreeOpen( - sqlite3_vfs *pVfs, /* VFS to use for this b-tree */ - const char *zFilename, /* Name of the file containing the BTree database */ - sqlite3 *db, /* Associated database handle */ - Btree **ppBtree, /* Pointer to new Btree object written here */ - int flags, /* Options */ - int vfsFlags /* Flags passed through to sqlite3_vfs.xOpen() */ -){ - BtShared *pBt = 0; /* Shared part of btree structure */ - Btree *p; /* Handle to return */ - sqlite3_mutex *mutexOpen = 0; /* Prevents a race condition. Ticket #3537 */ - int rc = SQLITE_OK; /* Result code from this function */ - u8 nReserve; /* Byte of unused space on each page */ - unsigned char zDbHeader[100]; /* Database header content */ - - /* True if opening an ephemeral, temporary database */ - const int isTempDb = zFilename==0 || zFilename[0]==0; - - /* Set the variable isMemdb to true for an in-memory database, or - ** false for a file-based database. - */ -#ifdef SQLITE_OMIT_MEMORYDB - const int isMemdb = 0; -#else - const int isMemdb = (zFilename && strcmp(zFilename, ":memory:")==0) - || (isTempDb && sqlite3TempInMemory(db)) - || (vfsFlags & SQLITE_OPEN_MEMORY)!=0; -#endif - - assert( db!=0 ); - assert( pVfs!=0 ); - assert( sqlite3_mutex_held(db->mutex) ); - assert( (flags&0xff)==flags ); /* flags fit in 8 bits */ - - /* Only a BTREE_SINGLE database can be BTREE_UNORDERED */ - assert( (flags & BTREE_UNORDERED)==0 || (flags & BTREE_SINGLE)!=0 ); - - /* A BTREE_SINGLE database is always a temporary and/or ephemeral */ - assert( (flags & BTREE_SINGLE)==0 || isTempDb ); - - if( isMemdb ){ - flags |= BTREE_MEMORY; - } - if( (vfsFlags & SQLITE_OPEN_MAIN_DB)!=0 && (isMemdb || isTempDb) ){ - vfsFlags = (vfsFlags & ~SQLITE_OPEN_MAIN_DB) | SQLITE_OPEN_TEMP_DB; - } - p = sqlite3MallocZero(sizeof(Btree)); - if( !p ){ - return SQLITE_NOMEM_BKPT; - } - p->inTrans = TRANS_NONE; - p->db = db; -#ifndef SQLITE_OMIT_SHARED_CACHE - p->lock.pBtree = p; - p->lock.iTable = 1; -#endif - -#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO) - /* - ** If this Btree is a candidate for shared cache, try to find an - ** existing BtShared object that we can share with - */ - if( isTempDb==0 && (isMemdb==0 || (vfsFlags&SQLITE_OPEN_URI)!=0) ){ - if( vfsFlags & SQLITE_OPEN_SHAREDCACHE ){ - int nFilename = sqlite3Strlen30(zFilename)+1; - int nFullPathname = pVfs->mxPathname+1; - char *zFullPathname = sqlite3Malloc(MAX(nFullPathname,nFilename)); - MUTEX_LOGIC( sqlite3_mutex *mutexShared; ) - - p->sharable = 1; - if( !zFullPathname ){ - sqlite3_free(p); - return SQLITE_NOMEM_BKPT; - } - if( isMemdb ){ - memcpy(zFullPathname, zFilename, nFilename); - }else{ - rc = sqlite3OsFullPathname(pVfs, zFilename, - nFullPathname, zFullPathname); - if( rc ){ - sqlite3_free(zFullPathname); - sqlite3_free(p); - return rc; - } - } -#if SQLITE_THREADSAFE - mutexOpen = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_OPEN); - sqlite3_mutex_enter(mutexOpen); - mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); - sqlite3_mutex_enter(mutexShared); -#endif - for(pBt=GLOBAL(BtShared*,sqlite3SharedCacheList); pBt; pBt=pBt->pNext){ - assert( pBt->nRef>0 ); - if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager, 0)) - && sqlite3PagerVfs(pBt->pPager)==pVfs ){ - int iDb; - for(iDb=db->nDb-1; iDb>=0; iDb--){ - Btree *pExisting = db->aDb[iDb].pBt; - if( pExisting && pExisting->pBt==pBt ){ - sqlite3_mutex_leave(mutexShared); - sqlite3_mutex_leave(mutexOpen); - sqlite3_free(zFullPathname); - sqlite3_free(p); - return SQLITE_CONSTRAINT; - } - } - p->pBt = pBt; - pBt->nRef++; - break; - } - } - sqlite3_mutex_leave(mutexShared); - sqlite3_free(zFullPathname); - } -#ifdef SQLITE_DEBUG - else{ - /* In debug mode, we mark all persistent databases as sharable - ** even when they are not. This exercises the locking code and - ** gives more opportunity for asserts(sqlite3_mutex_held()) - ** statements to find locking problems. - */ - p->sharable = 1; - } -#endif - } -#endif - if( pBt==0 ){ - /* - ** The following asserts make sure that structures used by the btree are - ** the right size. This is to guard against size changes that result - ** when compiling on a different architecture. - */ - assert( sizeof(i64)==8 ); - assert( sizeof(u64)==8 ); - assert( sizeof(u32)==4 ); - assert( sizeof(u16)==2 ); - assert( sizeof(Pgno)==4 ); - - pBt = sqlite3MallocZero( sizeof(*pBt) ); - if( pBt==0 ){ - rc = SQLITE_NOMEM_BKPT; - goto btree_open_out; - } - rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename, - sizeof(MemPage), flags, vfsFlags, pageReinit); - if( rc==SQLITE_OK ){ - sqlite3PagerSetMmapLimit(pBt->pPager, db->szMmap); - rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader); - } - if( rc!=SQLITE_OK ){ - goto btree_open_out; - } - pBt->openFlags = (u8)flags; - pBt->db = db; - sqlite3PagerSetBusyHandler(pBt->pPager, btreeInvokeBusyHandler, pBt); - p->pBt = pBt; - - pBt->pCursor = 0; - pBt->pPage1 = 0; - if( sqlite3PagerIsreadonly(pBt->pPager) ) pBt->btsFlags |= BTS_READ_ONLY; -#if defined(SQLITE_SECURE_DELETE) - pBt->btsFlags |= BTS_SECURE_DELETE; -#elif defined(SQLITE_FAST_SECURE_DELETE) - pBt->btsFlags |= BTS_OVERWRITE; -#endif - /* EVIDENCE-OF: R-51873-39618 The page size for a database file is - ** determined by the 2-byte integer located at an offset of 16 bytes from - ** the beginning of the database file. */ - pBt->pageSize = (zDbHeader[16]<<8) | (zDbHeader[17]<<16); - if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE - || ((pBt->pageSize-1)&pBt->pageSize)!=0 ){ - pBt->pageSize = 0; -#ifndef SQLITE_OMIT_AUTOVACUUM - /* If the magic name ":memory:" will create an in-memory database, then - ** leave the autoVacuum mode at 0 (do not auto-vacuum), even if - ** SQLITE_DEFAULT_AUTOVACUUM is true. On the other hand, if - ** SQLITE_OMIT_MEMORYDB has been defined, then ":memory:" is just a - ** regular file-name. In this case the auto-vacuum applies as per normal. - */ - if( zFilename && !isMemdb ){ - pBt->autoVacuum = (SQLITE_DEFAULT_AUTOVACUUM ? 1 : 0); - pBt->incrVacuum = (SQLITE_DEFAULT_AUTOVACUUM==2 ? 1 : 0); - } -#endif - nReserve = 0; - }else{ - /* EVIDENCE-OF: R-37497-42412 The size of the reserved region is - ** determined by the one-byte unsigned integer found at an offset of 20 - ** into the database file header. */ - nReserve = zDbHeader[20]; - pBt->btsFlags |= BTS_PAGESIZE_FIXED; -#ifndef SQLITE_OMIT_AUTOVACUUM - pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0); - pBt->incrVacuum = (get4byte(&zDbHeader[36 + 7*4])?1:0); -#endif - } - rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize, nReserve); - if( rc ) goto btree_open_out; - pBt->usableSize = pBt->pageSize - nReserve; - assert( (pBt->pageSize & 7)==0 ); /* 8-byte alignment of pageSize */ - -#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO) - /* Add the new BtShared object to the linked list sharable BtShareds. - */ - pBt->nRef = 1; - if( p->sharable ){ - MUTEX_LOGIC( sqlite3_mutex *mutexShared; ) - MUTEX_LOGIC( mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);) - if( SQLITE_THREADSAFE && sqlite3GlobalConfig.bCoreMutex ){ - pBt->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_FAST); - if( pBt->mutex==0 ){ - rc = SQLITE_NOMEM_BKPT; - goto btree_open_out; - } - } - sqlite3_mutex_enter(mutexShared); - pBt->pNext = GLOBAL(BtShared*,sqlite3SharedCacheList); - GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt; - sqlite3_mutex_leave(mutexShared); - } -#endif - } - -#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO) - /* If the new Btree uses a sharable pBtShared, then link the new - ** Btree into the list of all sharable Btrees for the same connection. - ** The list is kept in ascending order by pBt address. - */ - if( p->sharable ){ - int i; - Btree *pSib; - for(i=0; i<db->nDb; i++){ - if( (pSib = db->aDb[i].pBt)!=0 && pSib->sharable ){ - while( pSib->pPrev ){ pSib = pSib->pPrev; } - if( (uptr)p->pBt<(uptr)pSib->pBt ){ - p->pNext = pSib; - p->pPrev = 0; - pSib->pPrev = p; - }else{ - while( pSib->pNext && (uptr)pSib->pNext->pBt<(uptr)p->pBt ){ - pSib = pSib->pNext; - } - p->pNext = pSib->pNext; - p->pPrev = pSib; - if( p->pNext ){ - p->pNext->pPrev = p; - } - pSib->pNext = p; - } - break; - } - } - } -#endif - *ppBtree = p; - -btree_open_out: - if( rc!=SQLITE_OK ){ - if( pBt && pBt->pPager ){ - sqlite3PagerClose(pBt->pPager, 0); - } - sqlite3_free(pBt); - sqlite3_free(p); - *ppBtree = 0; - }else{ - sqlite3_file *pFile; - - /* If the B-Tree was successfully opened, set the pager-cache size to the - ** default value. Except, when opening on an existing shared pager-cache, - ** do not change the pager-cache size. - */ - if( sqlite3BtreeSchema(p, 0, 0)==0 ){ - sqlite3PagerSetCachesize(p->pBt->pPager, SQLITE_DEFAULT_CACHE_SIZE); - } - - pFile = sqlite3PagerFile(pBt->pPager); - if( pFile->pMethods ){ - sqlite3OsFileControlHint(pFile, SQLITE_FCNTL_PDB, (void*)&pBt->db); - } - } - if( mutexOpen ){ - assert( sqlite3_mutex_held(mutexOpen) ); - sqlite3_mutex_leave(mutexOpen); - } - assert( rc!=SQLITE_OK || sqlite3BtreeConnectionCount(*ppBtree)>0 ); - return rc; -} - -/* -** Decrement the BtShared.nRef counter. When it reaches zero, -** remove the BtShared structure from the sharing list. Return -** true if the BtShared.nRef counter reaches zero and return -** false if it is still positive. -*/ -static int removeFromSharingList(BtShared *pBt){ -#ifndef SQLITE_OMIT_SHARED_CACHE - MUTEX_LOGIC( sqlite3_mutex *pMaster; ) - BtShared *pList; - int removed = 0; - - assert( sqlite3_mutex_notheld(pBt->mutex) ); - MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); ) - sqlite3_mutex_enter(pMaster); - pBt->nRef--; - if( pBt->nRef<=0 ){ - if( GLOBAL(BtShared*,sqlite3SharedCacheList)==pBt ){ - GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt->pNext; - }else{ - pList = GLOBAL(BtShared*,sqlite3SharedCacheList); - while( ALWAYS(pList) && pList->pNext!=pBt ){ - pList=pList->pNext; - } - if( ALWAYS(pList) ){ - pList->pNext = pBt->pNext; - } - } - if( SQLITE_THREADSAFE ){ - sqlite3_mutex_free(pBt->mutex); - } - removed = 1; - } - sqlite3_mutex_leave(pMaster); - return removed; -#else - return 1; -#endif -} - -/* -** Make sure pBt->pTmpSpace points to an allocation of -** MX_CELL_SIZE(pBt) bytes with a 4-byte prefix for a left-child -** pointer. -*/ -static void allocateTempSpace(BtShared *pBt){ - if( !pBt->pTmpSpace ){ - pBt->pTmpSpace = sqlite3PageMalloc( pBt->pageSize ); - - /* One of the uses of pBt->pTmpSpace is to format cells before - ** inserting them into a leaf page (function fillInCell()). If - ** a cell is less than 4 bytes in size, it is rounded up to 4 bytes - ** by the various routines that manipulate binary cells. Which - ** can mean that fillInCell() only initializes the first 2 or 3 - ** bytes of pTmpSpace, but that the first 4 bytes are copied from - ** it into a database page. This is not actually a problem, but it - ** does cause a valgrind error when the 1 or 2 bytes of unitialized - ** data is passed to system call write(). So to avoid this error, - ** zero the first 4 bytes of temp space here. - ** - ** Also: Provide four bytes of initialized space before the - ** beginning of pTmpSpace as an area available to prepend the - ** left-child pointer to the beginning of a cell. - */ - if( pBt->pTmpSpace ){ - memset(pBt->pTmpSpace, 0, 8); - pBt->pTmpSpace += 4; - } - } -} - -/* -** Free the pBt->pTmpSpace allocation -*/ -static void freeTempSpace(BtShared *pBt){ - if( pBt->pTmpSpace ){ - pBt->pTmpSpace -= 4; - sqlite3PageFree(pBt->pTmpSpace); - pBt->pTmpSpace = 0; - } -} - -/* -** Close an open database and invalidate all cursors. -*/ -int sqlite3BtreeClose(Btree *p){ - BtShared *pBt = p->pBt; - BtCursor *pCur; - - /* Close all cursors opened via this handle. */ - assert( sqlite3_mutex_held(p->db->mutex) ); - sqlite3BtreeEnter(p); - pCur = pBt->pCursor; - while( pCur ){ - BtCursor *pTmp = pCur; - pCur = pCur->pNext; - if( pTmp->pBtree==p ){ - sqlite3BtreeCloseCursor(pTmp); - } - } - - /* Rollback any active transaction and free the handle structure. - ** The call to sqlite3BtreeRollback() drops any table-locks held by - ** this handle. - */ - sqlite3BtreeRollback(p, SQLITE_OK, 0); - sqlite3BtreeLeave(p); - - /* If there are still other outstanding references to the shared-btree - ** structure, return now. The remainder of this procedure cleans - ** up the shared-btree. - */ - assert( p->wantToLock==0 && p->locked==0 ); - if( !p->sharable || removeFromSharingList(pBt) ){ - /* The pBt is no longer on the sharing list, so we can access - ** it without having to hold the mutex. - ** - ** Clean out and delete the BtShared object. - */ - assert( !pBt->pCursor ); - sqlite3PagerClose(pBt->pPager, p->db); - if( pBt->xFreeSchema && pBt->pSchema ){ - pBt->xFreeSchema(pBt->pSchema); - } - sqlite3DbFree(0, pBt->pSchema); - freeTempSpace(pBt); - sqlite3_free(pBt); - } - -#ifndef SQLITE_OMIT_SHARED_CACHE - assert( p->wantToLock==0 ); - assert( p->locked==0 ); - if( p->pPrev ) p->pPrev->pNext = p->pNext; - if( p->pNext ) p->pNext->pPrev = p->pPrev; -#endif - - sqlite3_free(p); - return SQLITE_OK; -} - -/* -** Change the "soft" limit on the number of pages in the cache. -** Unused and unmodified pages will be recycled when the number of -** pages in the cache exceeds this soft limit. But the size of the -** cache is allowed to grow larger than this limit if it contains -** dirty pages or pages still in active use. -*/ -int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){ - BtShared *pBt = p->pBt; - assert( sqlite3_mutex_held(p->db->mutex) ); - sqlite3BtreeEnter(p); - sqlite3PagerSetCachesize(pBt->pPager, mxPage); - sqlite3BtreeLeave(p); - return SQLITE_OK; -} - -/* -** Change the "spill" limit on the number of pages in the cache. -** If the number of pages exceeds this limit during a write transaction, -** the pager might attempt to "spill" pages to the journal early in -** order to free up memory. -** -** The value returned is the current spill size. If zero is passed -** as an argument, no changes are made to the spill size setting, so -** using mxPage of 0 is a way to query the current spill size. -*/ -int sqlite3BtreeSetSpillSize(Btree *p, int mxPage){ - BtShared *pBt = p->pBt; - int res; - assert( sqlite3_mutex_held(p->db->mutex) ); - sqlite3BtreeEnter(p); - res = sqlite3PagerSetSpillsize(pBt->pPager, mxPage); - sqlite3BtreeLeave(p); - return res; -} - -#if SQLITE_MAX_MMAP_SIZE>0 -/* -** Change the limit on the amount of the database file that may be -** memory mapped. -*/ -int sqlite3BtreeSetMmapLimit(Btree *p, sqlite3_int64 szMmap){ - BtShared *pBt = p->pBt; - assert( sqlite3_mutex_held(p->db->mutex) ); - sqlite3BtreeEnter(p); - sqlite3PagerSetMmapLimit(pBt->pPager, szMmap); - sqlite3BtreeLeave(p); - return SQLITE_OK; -} -#endif /* SQLITE_MAX_MMAP_SIZE>0 */ - -/* -** Change the way data is synced to disk in order to increase or decrease -** how well the database resists damage due to OS crashes and power -** failures. Level 1 is the same as asynchronous (no syncs() occur and -** there is a high probability of damage) Level 2 is the default. There -** is a very low but non-zero probability of damage. Level 3 reduces the -** probability of damage to near zero but with a write performance reduction. -*/ -#ifndef SQLITE_OMIT_PAGER_PRAGMAS -int sqlite3BtreeSetPagerFlags( - Btree *p, /* The btree to set the safety level on */ - unsigned pgFlags /* Various PAGER_* flags */ -){ - BtShared *pBt = p->pBt; - assert( sqlite3_mutex_held(p->db->mutex) ); - sqlite3BtreeEnter(p); - sqlite3PagerSetFlags(pBt->pPager, pgFlags); - sqlite3BtreeLeave(p); - return SQLITE_OK; -} -#endif - -/* -** Change the default pages size and the number of reserved bytes per page. -** Or, if the page size has already been fixed, return SQLITE_READONLY -** without changing anything. -** -** The page size must be a power of 2 between 512 and 65536. If the page -** size supplied does not meet this constraint then the page size is not -** changed. -** -** Page sizes are constrained to be a power of two so that the region -** of the database file used for locking (beginning at PENDING_BYTE, -** the first byte past the 1GB boundary, 0x40000000) needs to occur -** at the beginning of a page. -** -** If parameter nReserve is less than zero, then the number of reserved -** bytes per page is left unchanged. -** -** If the iFix!=0 then the BTS_PAGESIZE_FIXED flag is set so that the page size -** and autovacuum mode can no longer be changed. -*/ -int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve, int iFix){ - int rc = SQLITE_OK; - BtShared *pBt = p->pBt; - assert( nReserve>=-1 && nReserve<=255 ); - sqlite3BtreeEnter(p); -#if SQLITE_HAS_CODEC - if( nReserve>pBt->optimalReserve ) pBt->optimalReserve = (u8)nReserve; -#endif - if( pBt->btsFlags & BTS_PAGESIZE_FIXED ){ - sqlite3BtreeLeave(p); - return SQLITE_READONLY; - } - if( nReserve<0 ){ - nReserve = pBt->pageSize - pBt->usableSize; - } - assert( nReserve>=0 && nReserve<=255 ); - if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE && - ((pageSize-1)&pageSize)==0 ){ - assert( (pageSize & 7)==0 ); - assert( !pBt->pCursor ); - pBt->pageSize = (u32)pageSize; - freeTempSpace(pBt); - } - rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize, nReserve); - pBt->usableSize = pBt->pageSize - (u16)nReserve; - if( iFix ) pBt->btsFlags |= BTS_PAGESIZE_FIXED; - sqlite3BtreeLeave(p); - return rc; -} - -/* -** Return the currently defined page size -*/ -int sqlite3BtreeGetPageSize(Btree *p){ - return p->pBt->pageSize; -} - -/* -** This function is similar to sqlite3BtreeGetReserve(), except that it -** may only be called if it is guaranteed that the b-tree mutex is already -** held. -** -** This is useful in one special case in the backup API code where it is -** known that the shared b-tree mutex is held, but the mutex on the -** database handle that owns *p is not. In this case if sqlite3BtreeEnter() -** were to be called, it might collide with some other operation on the -** database handle that owns *p, causing undefined behavior. -*/ -int sqlite3BtreeGetReserveNoMutex(Btree *p){ - int n; - assert( sqlite3_mutex_held(p->pBt->mutex) ); - n = p->pBt->pageSize - p->pBt->usableSize; - return n; -} - -/* -** Return the number of bytes of space at the end of every page that -** are intentually left unused. This is the "reserved" space that is -** sometimes used by extensions. -** -** If SQLITE_HAS_MUTEX is defined then the number returned is the -** greater of the current reserved space and the maximum requested -** reserve space. -*/ -int sqlite3BtreeGetOptimalReserve(Btree *p){ - int n; - sqlite3BtreeEnter(p); - n = sqlite3BtreeGetReserveNoMutex(p); -#ifdef SQLITE_HAS_CODEC - if( n<p->pBt->optimalReserve ) n = p->pBt->optimalReserve; -#endif - sqlite3BtreeLeave(p); - return n; -} - - -/* -** Set the maximum page count for a database if mxPage is positive. -** No changes are made if mxPage is 0 or negative. -** Regardless of the value of mxPage, return the maximum page count. -*/ -int sqlite3BtreeMaxPageCount(Btree *p, int mxPage){ - int n; - sqlite3BtreeEnter(p); - n = sqlite3PagerMaxPageCount(p->pBt->pPager, mxPage); - sqlite3BtreeLeave(p); - return n; -} - -/* -** Change the values for the BTS_SECURE_DELETE and BTS_OVERWRITE flags: -** -** newFlag==0 Both BTS_SECURE_DELETE and BTS_OVERWRITE are cleared -** newFlag==1 BTS_SECURE_DELETE set and BTS_OVERWRITE is cleared -** newFlag==2 BTS_SECURE_DELETE cleared and BTS_OVERWRITE is set -** newFlag==(-1) No changes -** -** This routine acts as a query if newFlag is less than zero -** -** With BTS_OVERWRITE set, deleted content is overwritten by zeros, but -** freelist leaf pages are not written back to the database. Thus in-page -** deleted content is cleared, but freelist deleted content is not. -** -** With BTS_SECURE_DELETE, operation is like BTS_OVERWRITE with the addition -** that freelist leaf pages are written back into the database, increasing -** the amount of disk I/O. -*/ -int sqlite3BtreeSecureDelete(Btree *p, int newFlag){ - int b; - if( p==0 ) return 0; - sqlite3BtreeEnter(p); - assert( BTS_OVERWRITE==BTS_SECURE_DELETE*2 ); - assert( BTS_FAST_SECURE==(BTS_OVERWRITE|BTS_SECURE_DELETE) ); - if( newFlag>=0 ){ - p->pBt->btsFlags &= ~BTS_FAST_SECURE; - p->pBt->btsFlags |= BTS_SECURE_DELETE*newFlag; - } - b = (p->pBt->btsFlags & BTS_FAST_SECURE)/BTS_SECURE_DELETE; - sqlite3BtreeLeave(p); - return b; -} - -/* -** Change the 'auto-vacuum' property of the database. If the 'autoVacuum' -** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it -** is disabled. The default value for the auto-vacuum property is -** determined by the SQLITE_DEFAULT_AUTOVACUUM macro. -*/ -int sqlite3BtreeSetAutoVacuum(Btree *p, int autoVacuum){ -#ifdef SQLITE_OMIT_AUTOVACUUM - return SQLITE_READONLY; -#else - BtShared *pBt = p->pBt; - int rc = SQLITE_OK; - u8 av = (u8)autoVacuum; - - sqlite3BtreeEnter(p); - if( (pBt->btsFlags & BTS_PAGESIZE_FIXED)!=0 && (av ?1:0)!=pBt->autoVacuum ){ - rc = SQLITE_READONLY; - }else{ - pBt->autoVacuum = av ?1:0; - pBt->incrVacuum = av==2 ?1:0; - } - sqlite3BtreeLeave(p); - return rc; -#endif -} - -/* -** Return the value of the 'auto-vacuum' property. If auto-vacuum is -** enabled 1 is returned. Otherwise 0. -*/ -int sqlite3BtreeGetAutoVacuum(Btree *p){ -#ifdef SQLITE_OMIT_AUTOVACUUM - return BTREE_AUTOVACUUM_NONE; -#else - int rc; - sqlite3BtreeEnter(p); - rc = ( - (!p->pBt->autoVacuum)?BTREE_AUTOVACUUM_NONE: - (!p->pBt->incrVacuum)?BTREE_AUTOVACUUM_FULL: - BTREE_AUTOVACUUM_INCR - ); - sqlite3BtreeLeave(p); - return rc; -#endif -} - -/* -** If the user has not set the safety-level for this database connection -** using "PRAGMA synchronous", and if the safety-level is not already -** set to the value passed to this function as the second parameter, -** set it so. -*/ -#if SQLITE_DEFAULT_SYNCHRONOUS!=SQLITE_DEFAULT_WAL_SYNCHRONOUS \ - && !defined(SQLITE_OMIT_WAL) -static void setDefaultSyncFlag(BtShared *pBt, u8 safety_level){ - sqlite3 *db; - Db *pDb; - if( (db=pBt->db)!=0 && (pDb=db->aDb)!=0 ){ - while( pDb->pBt==0 || pDb->pBt->pBt!=pBt ){ pDb++; } - if( pDb->bSyncSet==0 - && pDb->safety_level!=safety_level - && pDb!=&db->aDb[1] - ){ - pDb->safety_level = safety_level; - sqlite3PagerSetFlags(pBt->pPager, - pDb->safety_level | (db->flags & PAGER_FLAGS_MASK)); - } - } -} -#else -# define setDefaultSyncFlag(pBt,safety_level) -#endif - -/* Forward declaration */ -static int newDatabase(BtShared*); - - -/* -** Get a reference to pPage1 of the database file. This will -** also acquire a readlock on that file. -** -** SQLITE_OK is returned on success. If the file is not a -** well-formed database file, then SQLITE_CORRUPT is returned. -** SQLITE_BUSY is returned if the database is locked. SQLITE_NOMEM -** is returned if we run out of memory. -*/ -static int lockBtree(BtShared *pBt){ - int rc; /* Result code from subfunctions */ - MemPage *pPage1; /* Page 1 of the database file */ - int nPage; /* Number of pages in the database */ - int nPageFile = 0; /* Number of pages in the database file */ - int nPageHeader; /* Number of pages in the database according to hdr */ - - assert( sqlite3_mutex_held(pBt->mutex) ); - assert( pBt->pPage1==0 ); - rc = sqlite3PagerSharedLock(pBt->pPager); - if( rc!=SQLITE_OK ) return rc; - rc = btreeGetPage(pBt, 1, &pPage1, 0); - if( rc!=SQLITE_OK ) return rc; - - /* Do some checking to help insure the file we opened really is - ** a valid database file. - */ - nPage = nPageHeader = get4byte(28+(u8*)pPage1->aData); - sqlite3PagerPagecount(pBt->pPager, &nPageFile); - if( nPage==0 || memcmp(24+(u8*)pPage1->aData, 92+(u8*)pPage1->aData,4)!=0 ){ - nPage = nPageFile; - } - if( (pBt->db->flags & SQLITE_ResetDatabase)!=0 ){ - nPage = 0; - } - if( nPage>0 ){ - u32 pageSize; - u32 usableSize; - u8 *page1 = pPage1->aData; - rc = SQLITE_NOTADB; - /* EVIDENCE-OF: R-43737-39999 Every valid SQLite database file begins - ** with the following 16 bytes (in hex): 53 51 4c 69 74 65 20 66 6f 72 6d - ** 61 74 20 33 00. */ - if( memcmp(page1, zMagicHeader, 16)!=0 ){ - goto page1_init_failed; - } - -#ifdef SQLITE_OMIT_WAL - if( page1[18]>1 ){ - pBt->btsFlags |= BTS_READ_ONLY; - } - if( page1[19]>1 ){ - goto page1_init_failed; - } -#else - if( page1[18]>2 ){ - pBt->btsFlags |= BTS_READ_ONLY; - } - if( page1[19]>2 ){ - goto page1_init_failed; - } - - /* If the write version is set to 2, this database should be accessed - ** in WAL mode. If the log is not already open, open it now. Then - ** return SQLITE_OK and return without populating BtShared.pPage1. - ** The caller detects this and calls this function again. This is - ** required as the version of page 1 currently in the page1 buffer - ** may not be the latest version - there may be a newer one in the log - ** file. - */ - if( page1[19]==2 && (pBt->btsFlags & BTS_NO_WAL)==0 ){ - int isOpen = 0; - rc = sqlite3PagerOpenWal(pBt->pPager, &isOpen); - if( rc!=SQLITE_OK ){ - goto page1_init_failed; - }else{ - setDefaultSyncFlag(pBt, SQLITE_DEFAULT_WAL_SYNCHRONOUS+1); - if( isOpen==0 ){ - releasePageOne(pPage1); - return SQLITE_OK; - } - } - rc = SQLITE_NOTADB; - }else{ - setDefaultSyncFlag(pBt, SQLITE_DEFAULT_SYNCHRONOUS+1); - } -#endif - - /* EVIDENCE-OF: R-15465-20813 The maximum and minimum embedded payload - ** fractions and the leaf payload fraction values must be 64, 32, and 32. - ** - ** The original design allowed these amounts to vary, but as of - ** version 3.6.0, we require them to be fixed. - */ - if( memcmp(&page1[21], "\100\040\040",3)!=0 ){ - goto page1_init_failed; - } - /* EVIDENCE-OF: R-51873-39618 The page size for a database file is - ** determined by the 2-byte integer located at an offset of 16 bytes from - ** the beginning of the database file. */ - pageSize = (page1[16]<<8) | (page1[17]<<16); - /* EVIDENCE-OF: R-25008-21688 The size of a page is a power of two - ** between 512 and 65536 inclusive. */ - if( ((pageSize-1)&pageSize)!=0 - || pageSize>SQLITE_MAX_PAGE_SIZE - || pageSize<=256 - ){ - goto page1_init_failed; - } - assert( (pageSize & 7)==0 ); - /* EVIDENCE-OF: R-59310-51205 The "reserved space" size in the 1-byte - ** integer at offset 20 is the number of bytes of space at the end of - ** each page to reserve for extensions. - ** - ** EVIDENCE-OF: R-37497-42412 The size of the reserved region is - ** determined by the one-byte unsigned integer found at an offset of 20 - ** into the database file header. */ - usableSize = pageSize - page1[20]; - if( (u32)pageSize!=pBt->pageSize ){ - /* After reading the first page of the database assuming a page size - ** of BtShared.pageSize, we have discovered that the page-size is - ** actually pageSize. Unlock the database, leave pBt->pPage1 at - ** zero and return SQLITE_OK. The caller will call this function - ** again with the correct page-size. - */ - releasePageOne(pPage1); - pBt->usableSize = usableSize; - pBt->pageSize = pageSize; - freeTempSpace(pBt); - rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize, - pageSize-usableSize); - return rc; - } - if( (pBt->db->flags & SQLITE_WriteSchema)==0 && nPage>nPageFile ){ - rc = SQLITE_CORRUPT_BKPT; - goto page1_init_failed; - } - /* EVIDENCE-OF: R-28312-64704 However, the usable size is not allowed to - ** be less than 480. In other words, if the page size is 512, then the - ** reserved space size cannot exceed 32. */ - if( usableSize<480 ){ - goto page1_init_failed; - } - pBt->pageSize = pageSize; - pBt->usableSize = usableSize; -#ifndef SQLITE_OMIT_AUTOVACUUM - pBt->autoVacuum = (get4byte(&page1[36 + 4*4])?1:0); - pBt->incrVacuum = (get4byte(&page1[36 + 7*4])?1:0); -#endif - } - - /* maxLocal is the maximum amount of payload to store locally for - ** a cell. Make sure it is small enough so that at least minFanout - ** cells can will fit on one page. We assume a 10-byte page header. - ** Besides the payload, the cell must store: - ** 2-byte pointer to the cell - ** 4-byte child pointer - ** 9-byte nKey value - ** 4-byte nData value - ** 4-byte overflow page pointer - ** So a cell consists of a 2-byte pointer, a header which is as much as - ** 17 bytes long, 0 to N bytes of payload, and an optional 4 byte overflow - ** page pointer. - */ - pBt->maxLocal = (u16)((pBt->usableSize-12)*64/255 - 23); - pBt->minLocal = (u16)((pBt->usableSize-12)*32/255 - 23); - pBt->maxLeaf = (u16)(pBt->usableSize - 35); - pBt->minLeaf = (u16)((pBt->usableSize-12)*32/255 - 23); - if( pBt->maxLocal>127 ){ - pBt->max1bytePayload = 127; - }else{ - pBt->max1bytePayload = (u8)pBt->maxLocal; - } - assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) ); - pBt->pPage1 = pPage1; - pBt->nPage = nPage; - return SQLITE_OK; - -page1_init_failed: - releasePageOne(pPage1); - pBt->pPage1 = 0; - return rc; -} - -#ifndef NDEBUG -/* -** Return the number of cursors open on pBt. This is for use -** in assert() expressions, so it is only compiled if NDEBUG is not -** defined. -** -** Only write cursors are counted if wrOnly is true. If wrOnly is -** false then all cursors are counted. -** -** For the purposes of this routine, a cursor is any cursor that -** is capable of reading or writing to the database. Cursors that -** have been tripped into the CURSOR_FAULT state are not counted. -*/ -static int countValidCursors(BtShared *pBt, int wrOnly){ - BtCursor *pCur; - int r = 0; - for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){ - if( (wrOnly==0 || (pCur->curFlags & BTCF_WriteFlag)!=0) - && pCur->eState!=CURSOR_FAULT ) r++; - } - return r; -} -#endif - -/* -** If there are no outstanding cursors and we are not in the middle -** of a transaction but there is a read lock on the database, then -** this routine unrefs the first page of the database file which -** has the effect of releasing the read lock. -** -** If there is a transaction in progress, this routine is a no-op. -*/ -static void unlockBtreeIfUnused(BtShared *pBt){ - assert( sqlite3_mutex_held(pBt->mutex) ); - assert( countValidCursors(pBt,0)==0 || pBt->inTransaction>TRANS_NONE ); - if( pBt->inTransaction==TRANS_NONE && pBt->pPage1!=0 ){ - MemPage *pPage1 = pBt->pPage1; - assert( pPage1->aData ); - assert( sqlite3PagerRefcount(pBt->pPager)==1 ); - pBt->pPage1 = 0; - releasePageOne(pPage1); - } -} - -/* -** If pBt points to an empty file then convert that empty file -** into a new empty database by initializing the first page of -** the database. -*/ -static int newDatabase(BtShared *pBt){ - MemPage *pP1; - unsigned char *data; - int rc; - - assert( sqlite3_mutex_held(pBt->mutex) ); - if( pBt->nPage>0 ){ - return SQLITE_OK; - } - pP1 = pBt->pPage1; - assert( pP1!=0 ); - data = pP1->aData; - rc = sqlite3PagerWrite(pP1->pDbPage); - if( rc ) return rc; - memcpy(data, zMagicHeader, sizeof(zMagicHeader)); - assert( sizeof(zMagicHeader)==16 ); - data[16] = (u8)((pBt->pageSize>>8)&0xff); - data[17] = (u8)((pBt->pageSize>>16)&0xff); - data[18] = 1; - data[19] = 1; - assert( pBt->usableSize<=pBt->pageSize && pBt->usableSize+255>=pBt->pageSize); - data[20] = (u8)(pBt->pageSize - pBt->usableSize); - data[21] = 64; - data[22] = 32; - data[23] = 32; - memset(&data[24], 0, 100-24); - zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA ); - pBt->btsFlags |= BTS_PAGESIZE_FIXED; -#ifndef SQLITE_OMIT_AUTOVACUUM - assert( pBt->autoVacuum==1 || pBt->autoVacuum==0 ); - assert( pBt->incrVacuum==1 || pBt->incrVacuum==0 ); - put4byte(&data[36 + 4*4], pBt->autoVacuum); - put4byte(&data[36 + 7*4], pBt->incrVacuum); -#endif - pBt->nPage = 1; - data[31] = 1; - return SQLITE_OK; -} - -/* -** Initialize the first page of the database file (creating a database -** consisting of a single page and no schema objects). Return SQLITE_OK -** if successful, or an SQLite error code otherwise. -*/ -int sqlite3BtreeNewDb(Btree *p){ - int rc; - sqlite3BtreeEnter(p); - p->pBt->nPage = 0; - rc = newDatabase(p->pBt); - sqlite3BtreeLeave(p); - return rc; -} - -/* -** Attempt to start a new transaction. A write-transaction -** is started if the second argument is nonzero, otherwise a read- -** transaction. If the second argument is 2 or more and exclusive -** transaction is started, meaning that no other process is allowed -** to access the database. A preexisting transaction may not be -** upgraded to exclusive by calling this routine a second time - the -** exclusivity flag only works for a new transaction. -** -** A write-transaction must be started before attempting any -** changes to the database. None of the following routines -** will work unless a transaction is started first: -** -** sqlite3BtreeCreateTable() -** sqlite3BtreeCreateIndex() -** sqlite3BtreeClearTable() -** sqlite3BtreeDropTable() -** sqlite3BtreeInsert() -** sqlite3BtreeDelete() -** sqlite3BtreeUpdateMeta() -** -** If an initial attempt to acquire the lock fails because of lock contention -** and the database was previously unlocked, then invoke the busy handler -** if there is one. But if there was previously a read-lock, do not -** invoke the busy handler - just return SQLITE_BUSY. SQLITE_BUSY is -** returned when there is already a read-lock in order to avoid a deadlock. -** -** Suppose there are two processes A and B. A has a read lock and B has -** a reserved lock. B tries to promote to exclusive but is blocked because -** of A's read lock. A tries to promote to reserved but is blocked by B. -** One or the other of the two processes must give way or there can be -** no progress. By returning SQLITE_BUSY and not invoking the busy callback -** when A already has a read lock, we encourage A to give up and let B -** proceed. -*/ -int sqlite3BtreeBeginTrans(Btree *p, int wrflag){ - BtShared *pBt = p->pBt; - int rc = SQLITE_OK; - - sqlite3BtreeEnter(p); - btreeIntegrity(p); - - /* If the btree is already in a write-transaction, or it - ** is already in a read-transaction and a read-transaction - ** is requested, this is a no-op. - */ - if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){ - goto trans_begun; - } - assert( pBt->inTransaction==TRANS_WRITE || IfNotOmitAV(pBt->bDoTruncate)==0 ); - - /* Write transactions are not possible on a read-only database */ - if( (pBt->btsFlags & BTS_READ_ONLY)!=0 && wrflag ){ - rc = SQLITE_READONLY; - goto trans_begun; - } - -#ifndef SQLITE_OMIT_SHARED_CACHE - { - sqlite3 *pBlock = 0; - /* If another database handle has already opened a write transaction - ** on this shared-btree structure and a second write transaction is - ** requested, return SQLITE_LOCKED. - */ - if( (wrflag && pBt->inTransaction==TRANS_WRITE) - || (pBt->btsFlags & BTS_PENDING)!=0 - ){ - pBlock = pBt->pWriter->db; - }else if( wrflag>1 ){ - BtLock *pIter; - for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){ - if( pIter->pBtree!=p ){ - pBlock = pIter->pBtree->db; - break; - } - } - } - if( pBlock ){ - sqlite3ConnectionBlocked(p->db, pBlock); - rc = SQLITE_LOCKED_SHAREDCACHE; - goto trans_begun; - } - } -#endif - - /* Any read-only or read-write transaction implies a read-lock on - ** page 1. So if some other shared-cache client already has a write-lock - ** on page 1, the transaction cannot be opened. */ - rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK); - if( SQLITE_OK!=rc ) goto trans_begun; - - pBt->btsFlags &= ~BTS_INITIALLY_EMPTY; - if( pBt->nPage==0 ) pBt->btsFlags |= BTS_INITIALLY_EMPTY; - do { - /* Call lockBtree() until either pBt->pPage1 is populated or - ** lockBtree() returns something other than SQLITE_OK. lockBtree() - ** may return SQLITE_OK but leave pBt->pPage1 set to 0 if after - ** reading page 1 it discovers that the page-size of the database - ** file is not pBt->pageSize. In this case lockBtree() will update - ** pBt->pageSize to the page-size of the file on disk. - */ - while( pBt->pPage1==0 && SQLITE_OK==(rc = lockBtree(pBt)) ); - - if( rc==SQLITE_OK && wrflag ){ - if( (pBt->btsFlags & BTS_READ_ONLY)!=0 ){ - rc = SQLITE_READONLY; - }else{ - rc = sqlite3PagerBegin(pBt->pPager,wrflag>1,sqlite3TempInMemory(p->db)); - if( rc==SQLITE_OK ){ - rc = newDatabase(pBt); - } - } - } - - if( rc!=SQLITE_OK ){ - unlockBtreeIfUnused(pBt); - } - }while( (rc&0xFF)==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE && - btreeInvokeBusyHandler(pBt) ); - sqlite3PagerResetLockTimeout(pBt->pPager); - - if( rc==SQLITE_OK ){ - if( p->inTrans==TRANS_NONE ){ - pBt->nTransaction++; -#ifndef SQLITE_OMIT_SHARED_CACHE - if( p->sharable ){ - assert( p->lock.pBtree==p && p->lock.iTable==1 ); - p->lock.eLock = READ_LOCK; - p->lock.pNext = pBt->pLock; - pBt->pLock = &p->lock; - } -#endif - } - p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ); - if( p->inTrans>pBt->inTransaction ){ - pBt->inTransaction = p->inTrans; - } - if( wrflag ){ - MemPage *pPage1 = pBt->pPage1; -#ifndef SQLITE_OMIT_SHARED_CACHE - assert( !pBt->pWriter ); - pBt->pWriter = p; - pBt->btsFlags &= ~BTS_EXCLUSIVE; - if( wrflag>1 ) pBt->btsFlags |= BTS_EXCLUSIVE; -#endif - - /* If the db-size header field is incorrect (as it may be if an old - ** client has been writing the database file), update it now. Doing - ** this sooner rather than later means the database size can safely - ** re-read the database size from page 1 if a savepoint or transaction - ** rollback occurs within the transaction. - */ - if( pBt->nPage!=get4byte(&pPage1->aData[28]) ){ - rc = sqlite3PagerWrite(pPage1->pDbPage); - if( rc==SQLITE_OK ){ - put4byte(&pPage1->aData[28], pBt->nPage); - } - } - } - } - - -trans_begun: - if( rc==SQLITE_OK && wrflag ){ - /* This call makes sure that the pager has the correct number of - ** open savepoints. If the second parameter is greater than 0 and - ** the sub-journal is not already open, then it will be opened here. - */ - rc = sqlite3PagerOpenSavepoint(pBt->pPager, p->db->nSavepoint); - } - - btreeIntegrity(p); - sqlite3BtreeLeave(p); - return rc; -} - -#ifndef SQLITE_OMIT_AUTOVACUUM - -/* -** Set the pointer-map entries for all children of page pPage. Also, if -** pPage contains cells that point to overflow pages, set the pointer -** map entries for the overflow pages as well. -*/ -static int setChildPtrmaps(MemPage *pPage){ - int i; /* Counter variable */ - int nCell; /* Number of cells in page pPage */ - int rc; /* Return code */ - BtShared *pBt = pPage->pBt; - Pgno pgno = pPage->pgno; - - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - rc = pPage->isInit ? SQLITE_OK : btreeInitPage(pPage); - if( rc!=SQLITE_OK ) return rc; - nCell = pPage->nCell; - - for(i=0; i<nCell; i++){ - u8 *pCell = findCell(pPage, i); - - ptrmapPutOvflPtr(pPage, pCell, &rc); - - if( !pPage->leaf ){ - Pgno childPgno = get4byte(pCell); - ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno, &rc); - } - } - - if( !pPage->leaf ){ - Pgno childPgno = get4byte(&pPage->aData[pPage->hdrOffset+8]); - ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno, &rc); - } - - return rc; -} - -/* -** Somewhere on pPage is a pointer to page iFrom. Modify this pointer so -** that it points to iTo. Parameter eType describes the type of pointer to -** be modified, as follows: -** -** PTRMAP_BTREE: pPage is a btree-page. The pointer points at a child -** page of pPage. -** -** PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow -** page pointed to by one of the cells on pPage. -** -** PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next -** overflow page in the list. -*/ -static int modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){ - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - assert( sqlite3PagerIswriteable(pPage->pDbPage) ); - if( eType==PTRMAP_OVERFLOW2 ){ - /* The pointer is always the first 4 bytes of the page in this case. */ - if( get4byte(pPage->aData)!=iFrom ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - put4byte(pPage->aData, iTo); - }else{ - int i; - int nCell; - int rc; - - rc = pPage->isInit ? SQLITE_OK : btreeInitPage(pPage); - if( rc ) return rc; - nCell = pPage->nCell; - - for(i=0; i<nCell; i++){ - u8 *pCell = findCell(pPage, i); - if( eType==PTRMAP_OVERFLOW1 ){ - CellInfo info; - pPage->xParseCell(pPage, pCell, &info); - if( info.nLocal<info.nPayload ){ - if( pCell+info.nSize > pPage->aData+pPage->pBt->usableSize ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - if( iFrom==get4byte(pCell+info.nSize-4) ){ - put4byte(pCell+info.nSize-4, iTo); - break; - } - } - }else{ - if( get4byte(pCell)==iFrom ){ - put4byte(pCell, iTo); - break; - } - } - } - - if( i==nCell ){ - if( eType!=PTRMAP_BTREE || - get4byte(&pPage->aData[pPage->hdrOffset+8])!=iFrom ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - put4byte(&pPage->aData[pPage->hdrOffset+8], iTo); - } - } - return SQLITE_OK; -} - - -/* -** Move the open database page pDbPage to location iFreePage in the -** database. The pDbPage reference remains valid. -** -** The isCommit flag indicates that there is no need to remember that -** the journal needs to be sync()ed before database page pDbPage->pgno -** can be written to. The caller has already promised not to write to that -** page. -*/ -static int relocatePage( - BtShared *pBt, /* Btree */ - MemPage *pDbPage, /* Open page to move */ - u8 eType, /* Pointer map 'type' entry for pDbPage */ - Pgno iPtrPage, /* Pointer map 'page-no' entry for pDbPage */ - Pgno iFreePage, /* The location to move pDbPage to */ - int isCommit /* isCommit flag passed to sqlite3PagerMovepage */ -){ - MemPage *pPtrPage; /* The page that contains a pointer to pDbPage */ - Pgno iDbPage = pDbPage->pgno; - Pager *pPager = pBt->pPager; - int rc; - - assert( eType==PTRMAP_OVERFLOW2 || eType==PTRMAP_OVERFLOW1 || - eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE ); - assert( sqlite3_mutex_held(pBt->mutex) ); - assert( pDbPage->pBt==pBt ); - - /* Move page iDbPage from its current location to page number iFreePage */ - TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n", - iDbPage, iFreePage, iPtrPage, eType)); - rc = sqlite3PagerMovepage(pPager, pDbPage->pDbPage, iFreePage, isCommit); - if( rc!=SQLITE_OK ){ - return rc; - } - pDbPage->pgno = iFreePage; - - /* If pDbPage was a btree-page, then it may have child pages and/or cells - ** that point to overflow pages. The pointer map entries for all these - ** pages need to be changed. - ** - ** If pDbPage is an overflow page, then the first 4 bytes may store a - ** pointer to a subsequent overflow page. If this is the case, then - ** the pointer map needs to be updated for the subsequent overflow page. - */ - if( eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE ){ - rc = setChildPtrmaps(pDbPage); - if( rc!=SQLITE_OK ){ - return rc; - } - }else{ - Pgno nextOvfl = get4byte(pDbPage->aData); - if( nextOvfl!=0 ){ - ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage, &rc); - if( rc!=SQLITE_OK ){ - return rc; - } - } - } - - /* Fix the database pointer on page iPtrPage that pointed at iDbPage so - ** that it points at iFreePage. Also fix the pointer map entry for - ** iPtrPage. - */ - if( eType!=PTRMAP_ROOTPAGE ){ - rc = btreeGetPage(pBt, iPtrPage, &pPtrPage, 0); - if( rc!=SQLITE_OK ){ - return rc; - } - rc = sqlite3PagerWrite(pPtrPage->pDbPage); - if( rc!=SQLITE_OK ){ - releasePage(pPtrPage); - return rc; - } - rc = modifyPagePointer(pPtrPage, iDbPage, iFreePage, eType); - releasePage(pPtrPage); - if( rc==SQLITE_OK ){ - ptrmapPut(pBt, iFreePage, eType, iPtrPage, &rc); - } - } - return rc; -} - -/* Forward declaration required by incrVacuumStep(). */ -static int allocateBtreePage(BtShared *, MemPage **, Pgno *, Pgno, u8); - -/* -** Perform a single step of an incremental-vacuum. If successful, return -** SQLITE_OK. If there is no work to do (and therefore no point in -** calling this function again), return SQLITE_DONE. Or, if an error -** occurs, return some other error code. -** -** More specifically, this function attempts to re-organize the database so -** that the last page of the file currently in use is no longer in use. -** -** Parameter nFin is the number of pages that this database would contain -** were this function called until it returns SQLITE_DONE. -** -** If the bCommit parameter is non-zero, this function assumes that the -** caller will keep calling incrVacuumStep() until it returns SQLITE_DONE -** or an error. bCommit is passed true for an auto-vacuum-on-commit -** operation, or false for an incremental vacuum. -*/ -static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg, int bCommit){ - Pgno nFreeList; /* Number of pages still on the free-list */ - int rc; - - assert( sqlite3_mutex_held(pBt->mutex) ); - assert( iLastPg>nFin ); - - if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){ - u8 eType; - Pgno iPtrPage; - - nFreeList = get4byte(&pBt->pPage1->aData[36]); - if( nFreeList==0 ){ - return SQLITE_DONE; - } - - rc = ptrmapGet(pBt, iLastPg, &eType, &iPtrPage); - if( rc!=SQLITE_OK ){ - return rc; - } - if( eType==PTRMAP_ROOTPAGE ){ - return SQLITE_CORRUPT_BKPT; - } - - if( eType==PTRMAP_FREEPAGE ){ - if( bCommit==0 ){ - /* Remove the page from the files free-list. This is not required - ** if bCommit is non-zero. In that case, the free-list will be - ** truncated to zero after this function returns, so it doesn't - ** matter if it still contains some garbage entries. - */ - Pgno iFreePg; - MemPage *pFreePg; - rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iLastPg, BTALLOC_EXACT); - if( rc!=SQLITE_OK ){ - return rc; - } - assert( iFreePg==iLastPg ); - releasePage(pFreePg); - } - } else { - Pgno iFreePg; /* Index of free page to move pLastPg to */ - MemPage *pLastPg; - u8 eMode = BTALLOC_ANY; /* Mode parameter for allocateBtreePage() */ - Pgno iNear = 0; /* nearby parameter for allocateBtreePage() */ - - rc = btreeGetPage(pBt, iLastPg, &pLastPg, 0); - if( rc!=SQLITE_OK ){ - return rc; - } - - /* If bCommit is zero, this loop runs exactly once and page pLastPg - ** is swapped with the first free page pulled off the free list. - ** - ** On the other hand, if bCommit is greater than zero, then keep - ** looping until a free-page located within the first nFin pages - ** of the file is found. - */ - if( bCommit==0 ){ - eMode = BTALLOC_LE; - iNear = nFin; - } - do { - MemPage *pFreePg; - rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iNear, eMode); - if( rc!=SQLITE_OK ){ - releasePage(pLastPg); - return rc; - } - releasePage(pFreePg); - }while( bCommit && iFreePg>nFin ); - assert( iFreePg<iLastPg ); - - rc = relocatePage(pBt, pLastPg, eType, iPtrPage, iFreePg, bCommit); - releasePage(pLastPg); - if( rc!=SQLITE_OK ){ - return rc; - } - } - } - - if( bCommit==0 ){ - do { - iLastPg--; - }while( iLastPg==PENDING_BYTE_PAGE(pBt) || PTRMAP_ISPAGE(pBt, iLastPg) ); - pBt->bDoTruncate = 1; - pBt->nPage = iLastPg; - } - return SQLITE_OK; -} - -/* -** The database opened by the first argument is an auto-vacuum database -** nOrig pages in size containing nFree free pages. Return the expected -** size of the database in pages following an auto-vacuum operation. -*/ -static Pgno finalDbSize(BtShared *pBt, Pgno nOrig, Pgno nFree){ - int nEntry; /* Number of entries on one ptrmap page */ - Pgno nPtrmap; /* Number of PtrMap pages to be freed */ - Pgno nFin; /* Return value */ - - nEntry = pBt->usableSize/5; - nPtrmap = (nFree-nOrig+PTRMAP_PAGENO(pBt, nOrig)+nEntry)/nEntry; - nFin = nOrig - nFree - nPtrmap; - if( nOrig>PENDING_BYTE_PAGE(pBt) && nFin<PENDING_BYTE_PAGE(pBt) ){ - nFin--; - } - while( PTRMAP_ISPAGE(pBt, nFin) || nFin==PENDING_BYTE_PAGE(pBt) ){ - nFin--; - } - - return nFin; -} - -/* -** A write-transaction must be opened before calling this function. -** It performs a single unit of work towards an incremental vacuum. -** -** If the incremental vacuum is finished after this function has run, -** SQLITE_DONE is returned. If it is not finished, but no error occurred, -** SQLITE_OK is returned. Otherwise an SQLite error code. -*/ -int sqlite3BtreeIncrVacuum(Btree *p){ - int rc; - BtShared *pBt = p->pBt; - - sqlite3BtreeEnter(p); - assert( pBt->inTransaction==TRANS_WRITE && p->inTrans==TRANS_WRITE ); - if( !pBt->autoVacuum ){ - rc = SQLITE_DONE; - }else{ - Pgno nOrig = btreePagecount(pBt); - Pgno nFree = get4byte(&pBt->pPage1->aData[36]); - Pgno nFin = finalDbSize(pBt, nOrig, nFree); - - if( nOrig<nFin ){ - rc = SQLITE_CORRUPT_BKPT; - }else if( nFree>0 ){ - rc = saveAllCursors(pBt, 0, 0); - if( rc==SQLITE_OK ){ - invalidateAllOverflowCache(pBt); - rc = incrVacuumStep(pBt, nFin, nOrig, 0); - } - if( rc==SQLITE_OK ){ - rc = sqlite3PagerWrite(pBt->pPage1->pDbPage); - put4byte(&pBt->pPage1->aData[28], pBt->nPage); - } - }else{ - rc = SQLITE_DONE; - } - } - sqlite3BtreeLeave(p); - return rc; -} - -/* -** This routine is called prior to sqlite3PagerCommit when a transaction -** is committed for an auto-vacuum database. -** -** If SQLITE_OK is returned, then *pnTrunc is set to the number of pages -** the database file should be truncated to during the commit process. -** i.e. the database has been reorganized so that only the first *pnTrunc -** pages are in use. -*/ -static int autoVacuumCommit(BtShared *pBt){ - int rc = SQLITE_OK; - Pager *pPager = pBt->pPager; - VVA_ONLY( int nRef = sqlite3PagerRefcount(pPager); ) - - assert( sqlite3_mutex_held(pBt->mutex) ); - invalidateAllOverflowCache(pBt); - assert(pBt->autoVacuum); - if( !pBt->incrVacuum ){ - Pgno nFin; /* Number of pages in database after autovacuuming */ - Pgno nFree; /* Number of pages on the freelist initially */ - Pgno iFree; /* The next page to be freed */ - Pgno nOrig; /* Database size before freeing */ - - nOrig = btreePagecount(pBt); - if( PTRMAP_ISPAGE(pBt, nOrig) || nOrig==PENDING_BYTE_PAGE(pBt) ){ - /* It is not possible to create a database for which the final page - ** is either a pointer-map page or the pending-byte page. If one - ** is encountered, this indicates corruption. - */ - return SQLITE_CORRUPT_BKPT; - } - - nFree = get4byte(&pBt->pPage1->aData[36]); - nFin = finalDbSize(pBt, nOrig, nFree); - if( nFin>nOrig ) return SQLITE_CORRUPT_BKPT; - if( nFin<nOrig ){ - rc = saveAllCursors(pBt, 0, 0); - } - for(iFree=nOrig; iFree>nFin && rc==SQLITE_OK; iFree--){ - rc = incrVacuumStep(pBt, nFin, iFree, 1); - } - if( (rc==SQLITE_DONE || rc==SQLITE_OK) && nFree>0 ){ - rc = sqlite3PagerWrite(pBt->pPage1->pDbPage); - put4byte(&pBt->pPage1->aData[32], 0); - put4byte(&pBt->pPage1->aData[36], 0); - put4byte(&pBt->pPage1->aData[28], nFin); - pBt->bDoTruncate = 1; - pBt->nPage = nFin; - } - if( rc!=SQLITE_OK ){ - sqlite3PagerRollback(pPager); - } - } - - assert( nRef>=sqlite3PagerRefcount(pPager) ); - return rc; -} - -#else /* ifndef SQLITE_OMIT_AUTOVACUUM */ -# define setChildPtrmaps(x) SQLITE_OK -#endif - -/* -** This routine does the first phase of a two-phase commit. This routine -** causes a rollback journal to be created (if it does not already exist) -** and populated with enough information so that if a power loss occurs -** the database can be restored to its original state by playing back -** the journal. Then the contents of the journal are flushed out to -** the disk. After the journal is safely on oxide, the changes to the -** database are written into the database file and flushed to oxide. -** At the end of this call, the rollback journal still exists on the -** disk and we are still holding all locks, so the transaction has not -** committed. See sqlite3BtreeCommitPhaseTwo() for the second phase of the -** commit process. -** -** This call is a no-op if no write-transaction is currently active on pBt. -** -** Otherwise, sync the database file for the btree pBt. zMaster points to -** the name of a master journal file that should be written into the -** individual journal file, or is NULL, indicating no master journal file -** (single database transaction). -** -** When this is called, the master journal should already have been -** created, populated with this journal pointer and synced to disk. -** -** Once this is routine has returned, the only thing required to commit -** the write-transaction for this database file is to delete the journal. -*/ -int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zMaster){ - int rc = SQLITE_OK; - if( p->inTrans==TRANS_WRITE ){ - BtShared *pBt = p->pBt; - sqlite3BtreeEnter(p); -#ifndef SQLITE_OMIT_AUTOVACUUM - if( pBt->autoVacuum ){ - rc = autoVacuumCommit(pBt); - if( rc!=SQLITE_OK ){ - sqlite3BtreeLeave(p); - return rc; - } - } - if( pBt->bDoTruncate ){ - sqlite3PagerTruncateImage(pBt->pPager, pBt->nPage); - } -#endif - rc = sqlite3PagerCommitPhaseOne(pBt->pPager, zMaster, 0); - sqlite3BtreeLeave(p); - } - return rc; -} - -/* -** This function is called from both BtreeCommitPhaseTwo() and BtreeRollback() -** at the conclusion of a transaction. -*/ -static void btreeEndTransaction(Btree *p){ - BtShared *pBt = p->pBt; - sqlite3 *db = p->db; - assert( sqlite3BtreeHoldsMutex(p) ); - -#ifndef SQLITE_OMIT_AUTOVACUUM - pBt->bDoTruncate = 0; -#endif - if( p->inTrans>TRANS_NONE && db->nVdbeRead>1 ){ - /* If there are other active statements that belong to this database - ** handle, downgrade to a read-only transaction. The other statements - ** may still be reading from the database. */ - downgradeAllSharedCacheTableLocks(p); - p->inTrans = TRANS_READ; - }else{ - /* If the handle had any kind of transaction open, decrement the - ** transaction count of the shared btree. If the transaction count - ** reaches 0, set the shared state to TRANS_NONE. The unlockBtreeIfUnused() - ** call below will unlock the pager. */ - if( p->inTrans!=TRANS_NONE ){ - clearAllSharedCacheTableLocks(p); - pBt->nTransaction--; - if( 0==pBt->nTransaction ){ - pBt->inTransaction = TRANS_NONE; - } - } - - /* Set the current transaction state to TRANS_NONE and unlock the - ** pager if this call closed the only read or write transaction. */ - p->inTrans = TRANS_NONE; - unlockBtreeIfUnused(pBt); - } - - btreeIntegrity(p); -} - -/* -** Commit the transaction currently in progress. -** -** This routine implements the second phase of a 2-phase commit. The -** sqlite3BtreeCommitPhaseOne() routine does the first phase and should -** be invoked prior to calling this routine. The sqlite3BtreeCommitPhaseOne() -** routine did all the work of writing information out to disk and flushing the -** contents so that they are written onto the disk platter. All this -** routine has to do is delete or truncate or zero the header in the -** the rollback journal (which causes the transaction to commit) and -** drop locks. -** -** Normally, if an error occurs while the pager layer is attempting to -** finalize the underlying journal file, this function returns an error and -** the upper layer will attempt a rollback. However, if the second argument -** is non-zero then this b-tree transaction is part of a multi-file -** transaction. In this case, the transaction has already been committed -** (by deleting a master journal file) and the caller will ignore this -** functions return code. So, even if an error occurs in the pager layer, -** reset the b-tree objects internal state to indicate that the write -** transaction has been closed. This is quite safe, as the pager will have -** transitioned to the error state. -** -** This will release the write lock on the database file. If there -** are no active cursors, it also releases the read lock. -*/ -int sqlite3BtreeCommitPhaseTwo(Btree *p, int bCleanup){ - - if( p->inTrans==TRANS_NONE ) return SQLITE_OK; - sqlite3BtreeEnter(p); - btreeIntegrity(p); - - /* If the handle has a write-transaction open, commit the shared-btrees - ** transaction and set the shared state to TRANS_READ. - */ - if( p->inTrans==TRANS_WRITE ){ - int rc; - BtShared *pBt = p->pBt; - assert( pBt->inTransaction==TRANS_WRITE ); - assert( pBt->nTransaction>0 ); - rc = sqlite3PagerCommitPhaseTwo(pBt->pPager); - if( rc!=SQLITE_OK && bCleanup==0 ){ - sqlite3BtreeLeave(p); - return rc; - } - p->iDataVersion--; /* Compensate for pPager->iDataVersion++; */ - pBt->inTransaction = TRANS_READ; - btreeClearHasContent(pBt); - } - - btreeEndTransaction(p); - sqlite3BtreeLeave(p); - return SQLITE_OK; -} - -/* -** Do both phases of a commit. -*/ -int sqlite3BtreeCommit(Btree *p){ - int rc; - sqlite3BtreeEnter(p); - rc = sqlite3BtreeCommitPhaseOne(p, 0); - if( rc==SQLITE_OK ){ - rc = sqlite3BtreeCommitPhaseTwo(p, 0); - } - sqlite3BtreeLeave(p); - return rc; -} - -/* -** This routine sets the state to CURSOR_FAULT and the error -** code to errCode for every cursor on any BtShared that pBtree -** references. Or if the writeOnly flag is set to 1, then only -** trip write cursors and leave read cursors unchanged. -** -** Every cursor is a candidate to be tripped, including cursors -** that belong to other database connections that happen to be -** sharing the cache with pBtree. -** -** This routine gets called when a rollback occurs. If the writeOnly -** flag is true, then only write-cursors need be tripped - read-only -** cursors save their current positions so that they may continue -** following the rollback. Or, if writeOnly is false, all cursors are -** tripped. In general, writeOnly is false if the transaction being -** rolled back modified the database schema. In this case b-tree root -** pages may be moved or deleted from the database altogether, making -** it unsafe for read cursors to continue. -** -** If the writeOnly flag is true and an error is encountered while -** saving the current position of a read-only cursor, all cursors, -** including all read-cursors are tripped. -** -** SQLITE_OK is returned if successful, or if an error occurs while -** saving a cursor position, an SQLite error code. -*/ -int sqlite3BtreeTripAllCursors(Btree *pBtree, int errCode, int writeOnly){ - BtCursor *p; - int rc = SQLITE_OK; - - assert( (writeOnly==0 || writeOnly==1) && BTCF_WriteFlag==1 ); - if( pBtree ){ - sqlite3BtreeEnter(pBtree); - for(p=pBtree->pBt->pCursor; p; p=p->pNext){ - if( writeOnly && (p->curFlags & BTCF_WriteFlag)==0 ){ - if( p->eState==CURSOR_VALID || p->eState==CURSOR_SKIPNEXT ){ - rc = saveCursorPosition(p); - if( rc!=SQLITE_OK ){ - (void)sqlite3BtreeTripAllCursors(pBtree, rc, 0); - break; - } - } - }else{ - sqlite3BtreeClearCursor(p); - p->eState = CURSOR_FAULT; - p->skipNext = errCode; - } - btreeReleaseAllCursorPages(p); - } - sqlite3BtreeLeave(pBtree); - } - return rc; -} - -/* -** Rollback the transaction in progress. -** -** If tripCode is not SQLITE_OK then cursors will be invalidated (tripped). -** Only write cursors are tripped if writeOnly is true but all cursors are -** tripped if writeOnly is false. Any attempt to use -** a tripped cursor will result in an error. -** -** This will release the write lock on the database file. If there -** are no active cursors, it also releases the read lock. -*/ -int sqlite3BtreeRollback(Btree *p, int tripCode, int writeOnly){ - int rc; - BtShared *pBt = p->pBt; - MemPage *pPage1; - - assert( writeOnly==1 || writeOnly==0 ); - assert( tripCode==SQLITE_ABORT_ROLLBACK || tripCode==SQLITE_OK ); - sqlite3BtreeEnter(p); - if( tripCode==SQLITE_OK ){ - rc = tripCode = saveAllCursors(pBt, 0, 0); - if( rc ) writeOnly = 0; - }else{ - rc = SQLITE_OK; - } - if( tripCode ){ - int rc2 = sqlite3BtreeTripAllCursors(p, tripCode, writeOnly); - assert( rc==SQLITE_OK || (writeOnly==0 && rc2==SQLITE_OK) ); - if( rc2!=SQLITE_OK ) rc = rc2; - } - btreeIntegrity(p); - - if( p->inTrans==TRANS_WRITE ){ - int rc2; - - assert( TRANS_WRITE==pBt->inTransaction ); - rc2 = sqlite3PagerRollback(pBt->pPager); - if( rc2!=SQLITE_OK ){ - rc = rc2; - } - - /* The rollback may have destroyed the pPage1->aData value. So - ** call btreeGetPage() on page 1 again to make - ** sure pPage1->aData is set correctly. */ - if( btreeGetPage(pBt, 1, &pPage1, 0)==SQLITE_OK ){ - int nPage = get4byte(28+(u8*)pPage1->aData); - testcase( nPage==0 ); - if( nPage==0 ) sqlite3PagerPagecount(pBt->pPager, &nPage); - testcase( pBt->nPage!=nPage ); - pBt->nPage = nPage; - releasePageOne(pPage1); - } - assert( countValidCursors(pBt, 1)==0 ); - pBt->inTransaction = TRANS_READ; - btreeClearHasContent(pBt); - } - - btreeEndTransaction(p); - sqlite3BtreeLeave(p); - return rc; -} - -/* -** Start a statement subtransaction. The subtransaction can be rolled -** back independently of the main transaction. You must start a transaction -** before starting a subtransaction. The subtransaction is ended automatically -** if the main transaction commits or rolls back. -** -** Statement subtransactions are used around individual SQL statements -** that are contained within a BEGIN...COMMIT block. If a constraint -** error occurs within the statement, the effect of that one statement -** can be rolled back without having to rollback the entire transaction. -** -** A statement sub-transaction is implemented as an anonymous savepoint. The -** value passed as the second parameter is the total number of savepoints, -** including the new anonymous savepoint, open on the B-Tree. i.e. if there -** are no active savepoints and no other statement-transactions open, -** iStatement is 1. This anonymous savepoint can be released or rolled back -** using the sqlite3BtreeSavepoint() function. -*/ -int sqlite3BtreeBeginStmt(Btree *p, int iStatement){ - int rc; - BtShared *pBt = p->pBt; - sqlite3BtreeEnter(p); - assert( p->inTrans==TRANS_WRITE ); - assert( (pBt->btsFlags & BTS_READ_ONLY)==0 ); - assert( iStatement>0 ); - assert( iStatement>p->db->nSavepoint ); - assert( pBt->inTransaction==TRANS_WRITE ); - /* At the pager level, a statement transaction is a savepoint with - ** an index greater than all savepoints created explicitly using - ** SQL statements. It is illegal to open, release or rollback any - ** such savepoints while the statement transaction savepoint is active. - */ - rc = sqlite3PagerOpenSavepoint(pBt->pPager, iStatement); - sqlite3BtreeLeave(p); - return rc; -} - -/* -** The second argument to this function, op, is always SAVEPOINT_ROLLBACK -** or SAVEPOINT_RELEASE. This function either releases or rolls back the -** savepoint identified by parameter iSavepoint, depending on the value -** of op. -** -** Normally, iSavepoint is greater than or equal to zero. However, if op is -** SAVEPOINT_ROLLBACK, then iSavepoint may also be -1. In this case the -** contents of the entire transaction are rolled back. This is different -** from a normal transaction rollback, as no locks are released and the -** transaction remains open. -*/ -int sqlite3BtreeSavepoint(Btree *p, int op, int iSavepoint){ - int rc = SQLITE_OK; - if( p && p->inTrans==TRANS_WRITE ){ - BtShared *pBt = p->pBt; - assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK ); - assert( iSavepoint>=0 || (iSavepoint==-1 && op==SAVEPOINT_ROLLBACK) ); - sqlite3BtreeEnter(p); - if( op==SAVEPOINT_ROLLBACK ){ - rc = saveAllCursors(pBt, 0, 0); - } - if( rc==SQLITE_OK ){ - rc = sqlite3PagerSavepoint(pBt->pPager, op, iSavepoint); - } - if( rc==SQLITE_OK ){ - if( iSavepoint<0 && (pBt->btsFlags & BTS_INITIALLY_EMPTY)!=0 ){ - pBt->nPage = 0; - } - rc = newDatabase(pBt); - pBt->nPage = get4byte(28 + pBt->pPage1->aData); - - /* The database size was written into the offset 28 of the header - ** when the transaction started, so we know that the value at offset - ** 28 is nonzero. */ - assert( pBt->nPage>0 ); - } - sqlite3BtreeLeave(p); - } - return rc; -} - -/* -** Create a new cursor for the BTree whose root is on the page -** iTable. If a read-only cursor is requested, it is assumed that -** the caller already has at least a read-only transaction open -** on the database already. If a write-cursor is requested, then -** the caller is assumed to have an open write transaction. -** -** If the BTREE_WRCSR bit of wrFlag is clear, then the cursor can only -** be used for reading. If the BTREE_WRCSR bit is set, then the cursor -** can be used for reading or for writing if other conditions for writing -** are also met. These are the conditions that must be met in order -** for writing to be allowed: -** -** 1: The cursor must have been opened with wrFlag containing BTREE_WRCSR -** -** 2: Other database connections that share the same pager cache -** but which are not in the READ_UNCOMMITTED state may not have -** cursors open with wrFlag==0 on the same table. Otherwise -** the changes made by this write cursor would be visible to -** the read cursors in the other database connection. -** -** 3: The database must be writable (not on read-only media) -** -** 4: There must be an active transaction. -** -** The BTREE_FORDELETE bit of wrFlag may optionally be set if BTREE_WRCSR -** is set. If FORDELETE is set, that is a hint to the implementation that -** this cursor will only be used to seek to and delete entries of an index -** as part of a larger DELETE statement. The FORDELETE hint is not used by -** this implementation. But in a hypothetical alternative storage engine -** in which index entries are automatically deleted when corresponding table -** rows are deleted, the FORDELETE flag is a hint that all SEEK and DELETE -** operations on this cursor can be no-ops and all READ operations can -** return a null row (2-bytes: 0x01 0x00). -** -** No checking is done to make sure that page iTable really is the -** root page of a b-tree. If it is not, then the cursor acquired -** will not work correctly. -** -** It is assumed that the sqlite3BtreeCursorZero() has been called -** on pCur to initialize the memory space prior to invoking this routine. -*/ -static int btreeCursor( - Btree *p, /* The btree */ - int iTable, /* Root page of table to open */ - int wrFlag, /* 1 to write. 0 read-only */ - struct KeyInfo *pKeyInfo, /* First arg to comparison function */ - BtCursor *pCur /* Space for new cursor */ -){ - BtShared *pBt = p->pBt; /* Shared b-tree handle */ - BtCursor *pX; /* Looping over other all cursors */ - - assert( sqlite3BtreeHoldsMutex(p) ); - assert( wrFlag==0 - || wrFlag==BTREE_WRCSR - || wrFlag==(BTREE_WRCSR|BTREE_FORDELETE) - ); - - /* The following assert statements verify that if this is a sharable - ** b-tree database, the connection is holding the required table locks, - ** and that no other connection has any open cursor that conflicts with - ** this lock. */ - assert( hasSharedCacheTableLock(p, iTable, pKeyInfo!=0, (wrFlag?2:1)) ); - assert( wrFlag==0 || !hasReadConflicts(p, iTable) ); - - /* Assert that the caller has opened the required transaction. */ - assert( p->inTrans>TRANS_NONE ); - assert( wrFlag==0 || p->inTrans==TRANS_WRITE ); - assert( pBt->pPage1 && pBt->pPage1->aData ); - assert( wrFlag==0 || (pBt->btsFlags & BTS_READ_ONLY)==0 ); - - if( wrFlag ){ - allocateTempSpace(pBt); - if( pBt->pTmpSpace==0 ) return SQLITE_NOMEM_BKPT; - } - if( iTable==1 && btreePagecount(pBt)==0 ){ - assert( wrFlag==0 ); - iTable = 0; - } - - /* Now that no other errors can occur, finish filling in the BtCursor - ** variables and link the cursor into the BtShared list. */ - pCur->pgnoRoot = (Pgno)iTable; - pCur->iPage = -1; - pCur->pKeyInfo = pKeyInfo; - pCur->pBtree = p; - pCur->pBt = pBt; - pCur->curFlags = wrFlag ? BTCF_WriteFlag : 0; - pCur->curPagerFlags = wrFlag ? 0 : PAGER_GET_READONLY; - /* If there are two or more cursors on the same btree, then all such - ** cursors *must* have the BTCF_Multiple flag set. */ - for(pX=pBt->pCursor; pX; pX=pX->pNext){ - if( pX->pgnoRoot==(Pgno)iTable ){ - pX->curFlags |= BTCF_Multiple; - pCur->curFlags |= BTCF_Multiple; - } - } - pCur->pNext = pBt->pCursor; - pBt->pCursor = pCur; - pCur->eState = CURSOR_INVALID; - return SQLITE_OK; -} -int sqlite3BtreeCursor( - Btree *p, /* The btree */ - int iTable, /* Root page of table to open */ - int wrFlag, /* 1 to write. 0 read-only */ - struct KeyInfo *pKeyInfo, /* First arg to xCompare() */ - BtCursor *pCur /* Write new cursor here */ -){ - int rc; - if( iTable<1 ){ - rc = SQLITE_CORRUPT_BKPT; - }else{ - sqlite3BtreeEnter(p); - rc = btreeCursor(p, iTable, wrFlag, pKeyInfo, pCur); - sqlite3BtreeLeave(p); - } - return rc; -} - -/* -** Return the size of a BtCursor object in bytes. -** -** This interfaces is needed so that users of cursors can preallocate -** sufficient storage to hold a cursor. The BtCursor object is opaque -** to users so they cannot do the sizeof() themselves - they must call -** this routine. -*/ -int sqlite3BtreeCursorSize(void){ - return ROUND8(sizeof(BtCursor)); -} - -/* -** Initialize memory that will be converted into a BtCursor object. -** -** The simple approach here would be to memset() the entire object -** to zero. But it turns out that the apPage[] and aiIdx[] arrays -** do not need to be zeroed and they are large, so we can save a lot -** of run-time by skipping the initialization of those elements. -*/ -void sqlite3BtreeCursorZero(BtCursor *p){ - memset(p, 0, offsetof(BtCursor, BTCURSOR_FIRST_UNINIT)); -} - -/* -** Close a cursor. The read lock on the database file is released -** when the last cursor is closed. -*/ -int sqlite3BtreeCloseCursor(BtCursor *pCur){ - Btree *pBtree = pCur->pBtree; - if( pBtree ){ - BtShared *pBt = pCur->pBt; - sqlite3BtreeEnter(pBtree); - assert( pBt->pCursor!=0 ); - if( pBt->pCursor==pCur ){ - pBt->pCursor = pCur->pNext; - }else{ - BtCursor *pPrev = pBt->pCursor; - do{ - if( pPrev->pNext==pCur ){ - pPrev->pNext = pCur->pNext; - break; - } - pPrev = pPrev->pNext; - }while( ALWAYS(pPrev) ); - } - btreeReleaseAllCursorPages(pCur); - unlockBtreeIfUnused(pBt); - sqlite3_free(pCur->aOverflow); - sqlite3_free(pCur->pKey); - sqlite3BtreeLeave(pBtree); - } - return SQLITE_OK; -} - -/* -** Make sure the BtCursor* given in the argument has a valid -** BtCursor.info structure. If it is not already valid, call -** btreeParseCell() to fill it in. -** -** BtCursor.info is a cache of the information in the current cell. -** Using this cache reduces the number of calls to btreeParseCell(). -*/ -#ifndef NDEBUG - static int cellInfoEqual(CellInfo *a, CellInfo *b){ - if( a->nKey!=b->nKey ) return 0; - if( a->pPayload!=b->pPayload ) return 0; - if( a->nPayload!=b->nPayload ) return 0; - if( a->nLocal!=b->nLocal ) return 0; - if( a->nSize!=b->nSize ) return 0; - return 1; - } - static void assertCellInfo(BtCursor *pCur){ - CellInfo info; - memset(&info, 0, sizeof(info)); - btreeParseCell(pCur->pPage, pCur->ix, &info); - assert( CORRUPT_DB || cellInfoEqual(&info, &pCur->info) ); - } -#else - #define assertCellInfo(x) -#endif -static SQLITE_NOINLINE void getCellInfo(BtCursor *pCur){ - if( pCur->info.nSize==0 ){ - pCur->curFlags |= BTCF_ValidNKey; - btreeParseCell(pCur->pPage,pCur->ix,&pCur->info); - }else{ - assertCellInfo(pCur); - } -} - -#ifndef NDEBUG /* The next routine used only within assert() statements */ -/* -** Return true if the given BtCursor is valid. A valid cursor is one -** that is currently pointing to a row in a (non-empty) table. -** This is a verification routine is used only within assert() statements. -*/ -int sqlite3BtreeCursorIsValid(BtCursor *pCur){ - return pCur && pCur->eState==CURSOR_VALID; -} -#endif /* NDEBUG */ -int sqlite3BtreeCursorIsValidNN(BtCursor *pCur){ - assert( pCur!=0 ); - return pCur->eState==CURSOR_VALID; -} - -/* -** Return the value of the integer key or "rowid" for a table btree. -** This routine is only valid for a cursor that is pointing into a -** ordinary table btree. If the cursor points to an index btree or -** is invalid, the result of this routine is undefined. -*/ -i64 sqlite3BtreeIntegerKey(BtCursor *pCur){ - assert( cursorHoldsMutex(pCur) ); - assert( pCur->eState==CURSOR_VALID ); - assert( pCur->curIntKey ); - getCellInfo(pCur); - return pCur->info.nKey; -} - -#ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC -/* -** Return the offset into the database file for the start of the -** payload to which the cursor is pointing. -*/ -i64 sqlite3BtreeOffset(BtCursor *pCur){ - assert( cursorHoldsMutex(pCur) ); - assert( pCur->eState==CURSOR_VALID ); - getCellInfo(pCur); - return (i64)pCur->pBt->pageSize*((i64)pCur->pPage->pgno - 1) + - (i64)(pCur->info.pPayload - pCur->pPage->aData); -} -#endif /* SQLITE_ENABLE_OFFSET_SQL_FUNC */ - -/* -** Return the number of bytes of payload for the entry that pCur is -** currently pointing to. For table btrees, this will be the amount -** of data. For index btrees, this will be the size of the key. -** -** The caller must guarantee that the cursor is pointing to a non-NULL -** valid entry. In other words, the calling procedure must guarantee -** that the cursor has Cursor.eState==CURSOR_VALID. -*/ -u32 sqlite3BtreePayloadSize(BtCursor *pCur){ - assert( cursorHoldsMutex(pCur) ); - assert( pCur->eState==CURSOR_VALID ); - getCellInfo(pCur); - return pCur->info.nPayload; -} - -/* -** Given the page number of an overflow page in the database (parameter -** ovfl), this function finds the page number of the next page in the -** linked list of overflow pages. If possible, it uses the auto-vacuum -** pointer-map data instead of reading the content of page ovfl to do so. -** -** If an error occurs an SQLite error code is returned. Otherwise: -** -** The page number of the next overflow page in the linked list is -** written to *pPgnoNext. If page ovfl is the last page in its linked -** list, *pPgnoNext is set to zero. -** -** If ppPage is not NULL, and a reference to the MemPage object corresponding -** to page number pOvfl was obtained, then *ppPage is set to point to that -** reference. It is the responsibility of the caller to call releasePage() -** on *ppPage to free the reference. In no reference was obtained (because -** the pointer-map was used to obtain the value for *pPgnoNext), then -** *ppPage is set to zero. -*/ -static int getOverflowPage( - BtShared *pBt, /* The database file */ - Pgno ovfl, /* Current overflow page number */ - MemPage **ppPage, /* OUT: MemPage handle (may be NULL) */ - Pgno *pPgnoNext /* OUT: Next overflow page number */ -){ - Pgno next = 0; - MemPage *pPage = 0; - int rc = SQLITE_OK; - - assert( sqlite3_mutex_held(pBt->mutex) ); - assert(pPgnoNext); - -#ifndef SQLITE_OMIT_AUTOVACUUM - /* Try to find the next page in the overflow list using the - ** autovacuum pointer-map pages. Guess that the next page in - ** the overflow list is page number (ovfl+1). If that guess turns - ** out to be wrong, fall back to loading the data of page - ** number ovfl to determine the next page number. - */ - if( pBt->autoVacuum ){ - Pgno pgno; - Pgno iGuess = ovfl+1; - u8 eType; - - while( PTRMAP_ISPAGE(pBt, iGuess) || iGuess==PENDING_BYTE_PAGE(pBt) ){ - iGuess++; - } - - if( iGuess<=btreePagecount(pBt) ){ - rc = ptrmapGet(pBt, iGuess, &eType, &pgno); - if( rc==SQLITE_OK && eType==PTRMAP_OVERFLOW2 && pgno==ovfl ){ - next = iGuess; - rc = SQLITE_DONE; - } - } - } -#endif - - assert( next==0 || rc==SQLITE_DONE ); - if( rc==SQLITE_OK ){ - rc = btreeGetPage(pBt, ovfl, &pPage, (ppPage==0) ? PAGER_GET_READONLY : 0); - assert( rc==SQLITE_OK || pPage==0 ); - if( rc==SQLITE_OK ){ - next = get4byte(pPage->aData); - } - } - - *pPgnoNext = next; - if( ppPage ){ - *ppPage = pPage; - }else{ - releasePage(pPage); - } - return (rc==SQLITE_DONE ? SQLITE_OK : rc); -} - -/* -** Copy data from a buffer to a page, or from a page to a buffer. -** -** pPayload is a pointer to data stored on database page pDbPage. -** If argument eOp is false, then nByte bytes of data are copied -** from pPayload to the buffer pointed at by pBuf. If eOp is true, -** then sqlite3PagerWrite() is called on pDbPage and nByte bytes -** of data are copied from the buffer pBuf to pPayload. -** -** SQLITE_OK is returned on success, otherwise an error code. -*/ -static int copyPayload( - void *pPayload, /* Pointer to page data */ - void *pBuf, /* Pointer to buffer */ - int nByte, /* Number of bytes to copy */ - int eOp, /* 0 -> copy from page, 1 -> copy to page */ - DbPage *pDbPage /* Page containing pPayload */ -){ - if( eOp ){ - /* Copy data from buffer to page (a write operation) */ - int rc = sqlite3PagerWrite(pDbPage); - if( rc!=SQLITE_OK ){ - return rc; - } - memcpy(pPayload, pBuf, nByte); - }else{ - /* Copy data from page to buffer (a read operation) */ - memcpy(pBuf, pPayload, nByte); - } - return SQLITE_OK; -} - -/* -** This function is used to read or overwrite payload information -** for the entry that the pCur cursor is pointing to. The eOp -** argument is interpreted as follows: -** -** 0: The operation is a read. Populate the overflow cache. -** 1: The operation is a write. Populate the overflow cache. -** -** A total of "amt" bytes are read or written beginning at "offset". -** Data is read to or from the buffer pBuf. -** -** The content being read or written might appear on the main page -** or be scattered out on multiple overflow pages. -** -** If the current cursor entry uses one or more overflow pages -** this function may allocate space for and lazily populate -** the overflow page-list cache array (BtCursor.aOverflow). -** Subsequent calls use this cache to make seeking to the supplied offset -** more efficient. -** -** Once an overflow page-list cache has been allocated, it must be -** invalidated if some other cursor writes to the same table, or if -** the cursor is moved to a different row. Additionally, in auto-vacuum -** mode, the following events may invalidate an overflow page-list cache. -** -** * An incremental vacuum, -** * A commit in auto_vacuum="full" mode, -** * Creating a table (may require moving an overflow page). -*/ -static int accessPayload( - BtCursor *pCur, /* Cursor pointing to entry to read from */ - u32 offset, /* Begin reading this far into payload */ - u32 amt, /* Read this many bytes */ - unsigned char *pBuf, /* Write the bytes into this buffer */ - int eOp /* zero to read. non-zero to write. */ -){ - unsigned char *aPayload; - int rc = SQLITE_OK; - int iIdx = 0; - MemPage *pPage = pCur->pPage; /* Btree page of current entry */ - BtShared *pBt = pCur->pBt; /* Btree this cursor belongs to */ -#ifdef SQLITE_DIRECT_OVERFLOW_READ - unsigned char * const pBufStart = pBuf; /* Start of original out buffer */ -#endif - - assert( pPage ); - assert( eOp==0 || eOp==1 ); - assert( pCur->eState==CURSOR_VALID ); - assert( pCur->ix<pPage->nCell ); - assert( cursorHoldsMutex(pCur) ); - - getCellInfo(pCur); - aPayload = pCur->info.pPayload; - assert( offset+amt <= pCur->info.nPayload ); - - assert( aPayload > pPage->aData ); - if( (uptr)(aPayload - pPage->aData) > (pBt->usableSize - pCur->info.nLocal) ){ - /* Trying to read or write past the end of the data is an error. The - ** conditional above is really: - ** &aPayload[pCur->info.nLocal] > &pPage->aData[pBt->usableSize] - ** but is recast into its current form to avoid integer overflow problems - */ - return SQLITE_CORRUPT_PAGE(pPage); - } - - /* Check if data must be read/written to/from the btree page itself. */ - if( offset<pCur->info.nLocal ){ - int a = amt; - if( a+offset>pCur->info.nLocal ){ - a = pCur->info.nLocal - offset; - } - rc = copyPayload(&aPayload[offset], pBuf, a, eOp, pPage->pDbPage); - offset = 0; - pBuf += a; - amt -= a; - }else{ - offset -= pCur->info.nLocal; - } - - - if( rc==SQLITE_OK && amt>0 ){ - const u32 ovflSize = pBt->usableSize - 4; /* Bytes content per ovfl page */ - Pgno nextPage; - - nextPage = get4byte(&aPayload[pCur->info.nLocal]); - - /* If the BtCursor.aOverflow[] has not been allocated, allocate it now. - ** - ** The aOverflow[] array is sized at one entry for each overflow page - ** in the overflow chain. The page number of the first overflow page is - ** stored in aOverflow[0], etc. A value of 0 in the aOverflow[] array - ** means "not yet known" (the cache is lazily populated). - */ - if( (pCur->curFlags & BTCF_ValidOvfl)==0 ){ - int nOvfl = (pCur->info.nPayload-pCur->info.nLocal+ovflSize-1)/ovflSize; - if( pCur->aOverflow==0 - || nOvfl*(int)sizeof(Pgno) > sqlite3MallocSize(pCur->aOverflow) - ){ - Pgno *aNew = (Pgno*)sqlite3Realloc( - pCur->aOverflow, nOvfl*2*sizeof(Pgno) - ); - if( aNew==0 ){ - return SQLITE_NOMEM_BKPT; - }else{ - pCur->aOverflow = aNew; - } - } - memset(pCur->aOverflow, 0, nOvfl*sizeof(Pgno)); - pCur->curFlags |= BTCF_ValidOvfl; - }else{ - /* If the overflow page-list cache has been allocated and the - ** entry for the first required overflow page is valid, skip - ** directly to it. - */ - if( pCur->aOverflow[offset/ovflSize] ){ - iIdx = (offset/ovflSize); - nextPage = pCur->aOverflow[iIdx]; - offset = (offset%ovflSize); - } - } - - assert( rc==SQLITE_OK && amt>0 ); - while( nextPage ){ - /* If required, populate the overflow page-list cache. */ - assert( pCur->aOverflow[iIdx]==0 - || pCur->aOverflow[iIdx]==nextPage - || CORRUPT_DB ); - pCur->aOverflow[iIdx] = nextPage; - - if( offset>=ovflSize ){ - /* The only reason to read this page is to obtain the page - ** number for the next page in the overflow chain. The page - ** data is not required. So first try to lookup the overflow - ** page-list cache, if any, then fall back to the getOverflowPage() - ** function. - */ - assert( pCur->curFlags & BTCF_ValidOvfl ); - assert( pCur->pBtree->db==pBt->db ); - if( pCur->aOverflow[iIdx+1] ){ - nextPage = pCur->aOverflow[iIdx+1]; - }else{ - rc = getOverflowPage(pBt, nextPage, 0, &nextPage); - } - offset -= ovflSize; - }else{ - /* Need to read this page properly. It contains some of the - ** range of data that is being read (eOp==0) or written (eOp!=0). - */ -#ifdef SQLITE_DIRECT_OVERFLOW_READ - sqlite3_file *fd; /* File from which to do direct overflow read */ -#endif - int a = amt; - if( a + offset > ovflSize ){ - a = ovflSize - offset; - } - -#ifdef SQLITE_DIRECT_OVERFLOW_READ - /* If all the following are true: - ** - ** 1) this is a read operation, and - ** 2) data is required from the start of this overflow page, and - ** 3) there is no open write-transaction, and - ** 4) the database is file-backed, and - ** 5) the page is not in the WAL file - ** 6) at least 4 bytes have already been read into the output buffer - ** - ** then data can be read directly from the database file into the - ** output buffer, bypassing the page-cache altogether. This speeds - ** up loading large records that span many overflow pages. - */ - if( eOp==0 /* (1) */ - && offset==0 /* (2) */ - && pBt->inTransaction==TRANS_READ /* (3) */ - && (fd = sqlite3PagerFile(pBt->pPager))->pMethods /* (4) */ - && 0==sqlite3PagerUseWal(pBt->pPager, nextPage) /* (5) */ - && &pBuf[-4]>=pBufStart /* (6) */ - ){ - u8 aSave[4]; - u8 *aWrite = &pBuf[-4]; - assert( aWrite>=pBufStart ); /* due to (6) */ - memcpy(aSave, aWrite, 4); - rc = sqlite3OsRead(fd, aWrite, a+4, (i64)pBt->pageSize*(nextPage-1)); - nextPage = get4byte(aWrite); - memcpy(aWrite, aSave, 4); - }else -#endif - - { - DbPage *pDbPage; - rc = sqlite3PagerGet(pBt->pPager, nextPage, &pDbPage, - (eOp==0 ? PAGER_GET_READONLY : 0) - ); - if( rc==SQLITE_OK ){ - aPayload = sqlite3PagerGetData(pDbPage); - nextPage = get4byte(aPayload); - rc = copyPayload(&aPayload[offset+4], pBuf, a, eOp, pDbPage); - sqlite3PagerUnref(pDbPage); - offset = 0; - } - } - amt -= a; - if( amt==0 ) return rc; - pBuf += a; - } - if( rc ) break; - iIdx++; - } - } - - if( rc==SQLITE_OK && amt>0 ){ - /* Overflow chain ends prematurely */ - return SQLITE_CORRUPT_PAGE(pPage); - } - return rc; -} - -/* -** Read part of the payload for the row at which that cursor pCur is currently -** pointing. "amt" bytes will be transferred into pBuf[]. The transfer -** begins at "offset". -** -** pCur can be pointing to either a table or an index b-tree. -** If pointing to a table btree, then the content section is read. If -** pCur is pointing to an index b-tree then the key section is read. -** -** For sqlite3BtreePayload(), the caller must ensure that pCur is pointing -** to a valid row in the table. For sqlite3BtreePayloadChecked(), the -** cursor might be invalid or might need to be restored before being read. -** -** Return SQLITE_OK on success or an error code if anything goes -** wrong. An error is returned if "offset+amt" is larger than -** the available payload. -*/ -int sqlite3BtreePayload(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){ - assert( cursorHoldsMutex(pCur) ); - assert( pCur->eState==CURSOR_VALID ); - assert( pCur->iPage>=0 && pCur->pPage ); - assert( pCur->ix<pCur->pPage->nCell ); - return accessPayload(pCur, offset, amt, (unsigned char*)pBuf, 0); -} - -/* -** This variant of sqlite3BtreePayload() works even if the cursor has not -** in the CURSOR_VALID state. It is only used by the sqlite3_blob_read() -** interface. -*/ -#ifndef SQLITE_OMIT_INCRBLOB -static SQLITE_NOINLINE int accessPayloadChecked( - BtCursor *pCur, - u32 offset, - u32 amt, - void *pBuf -){ - int rc; - if ( pCur->eState==CURSOR_INVALID ){ - return SQLITE_ABORT; - } - assert( cursorOwnsBtShared(pCur) ); - rc = btreeRestoreCursorPosition(pCur); - return rc ? rc : accessPayload(pCur, offset, amt, pBuf, 0); -} -int sqlite3BtreePayloadChecked(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){ - if( pCur->eState==CURSOR_VALID ){ - assert( cursorOwnsBtShared(pCur) ); - return accessPayload(pCur, offset, amt, pBuf, 0); - }else{ - return accessPayloadChecked(pCur, offset, amt, pBuf); - } -} -#endif /* SQLITE_OMIT_INCRBLOB */ - -/* -** Return a pointer to payload information from the entry that the -** pCur cursor is pointing to. The pointer is to the beginning of -** the key if index btrees (pPage->intKey==0) and is the data for -** table btrees (pPage->intKey==1). The number of bytes of available -** key/data is written into *pAmt. If *pAmt==0, then the value -** returned will not be a valid pointer. -** -** This routine is an optimization. It is common for the entire key -** and data to fit on the local page and for there to be no overflow -** pages. When that is so, this routine can be used to access the -** key and data without making a copy. If the key and/or data spills -** onto overflow pages, then accessPayload() must be used to reassemble -** the key/data and copy it into a preallocated buffer. -** -** The pointer returned by this routine looks directly into the cached -** page of the database. The data might change or move the next time -** any btree routine is called. -*/ -static const void *fetchPayload( - BtCursor *pCur, /* Cursor pointing to entry to read from */ - u32 *pAmt /* Write the number of available bytes here */ -){ - int amt; - assert( pCur!=0 && pCur->iPage>=0 && pCur->pPage); - assert( pCur->eState==CURSOR_VALID ); - assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) ); - assert( cursorOwnsBtShared(pCur) ); - assert( pCur->ix<pCur->pPage->nCell ); - assert( pCur->info.nSize>0 ); - assert( pCur->info.pPayload>pCur->pPage->aData || CORRUPT_DB ); - assert( pCur->info.pPayload<pCur->pPage->aDataEnd ||CORRUPT_DB); - amt = pCur->info.nLocal; - if( amt>(int)(pCur->pPage->aDataEnd - pCur->info.pPayload) ){ - /* There is too little space on the page for the expected amount - ** of local content. Database must be corrupt. */ - assert( CORRUPT_DB ); - amt = MAX(0, (int)(pCur->pPage->aDataEnd - pCur->info.pPayload)); - } - *pAmt = (u32)amt; - return (void*)pCur->info.pPayload; -} - - -/* -** For the entry that cursor pCur is point to, return as -** many bytes of the key or data as are available on the local -** b-tree page. Write the number of available bytes into *pAmt. -** -** The pointer returned is ephemeral. The key/data may move -** or be destroyed on the next call to any Btree routine, -** including calls from other threads against the same cache. -** Hence, a mutex on the BtShared should be held prior to calling -** this routine. -** -** These routines is used to get quick access to key and data -** in the common case where no overflow pages are used. -*/ -const void *sqlite3BtreePayloadFetch(BtCursor *pCur, u32 *pAmt){ - return fetchPayload(pCur, pAmt); -} - - -/* -** Move the cursor down to a new child page. The newPgno argument is the -** page number of the child page to move to. -** -** This function returns SQLITE_CORRUPT if the page-header flags field of -** the new child page does not match the flags field of the parent (i.e. -** if an intkey page appears to be the parent of a non-intkey page, or -** vice-versa). -*/ -static int moveToChild(BtCursor *pCur, u32 newPgno){ - BtShared *pBt = pCur->pBt; - - assert( cursorOwnsBtShared(pCur) ); - assert( pCur->eState==CURSOR_VALID ); - assert( pCur->iPage<BTCURSOR_MAX_DEPTH ); - assert( pCur->iPage>=0 ); - if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){ - return SQLITE_CORRUPT_BKPT; - } - pCur->info.nSize = 0; - pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl); - pCur->aiIdx[pCur->iPage] = pCur->ix; - pCur->apPage[pCur->iPage] = pCur->pPage; - pCur->ix = 0; - pCur->iPage++; - return getAndInitPage(pBt, newPgno, &pCur->pPage, pCur, pCur->curPagerFlags); -} - -#ifdef SQLITE_DEBUG -/* -** Page pParent is an internal (non-leaf) tree page. This function -** asserts that page number iChild is the left-child if the iIdx'th -** cell in page pParent. Or, if iIdx is equal to the total number of -** cells in pParent, that page number iChild is the right-child of -** the page. -*/ -static void assertParentIndex(MemPage *pParent, int iIdx, Pgno iChild){ - if( CORRUPT_DB ) return; /* The conditions tested below might not be true - ** in a corrupt database */ - assert( iIdx<=pParent->nCell ); - if( iIdx==pParent->nCell ){ - assert( get4byte(&pParent->aData[pParent->hdrOffset+8])==iChild ); - }else{ - assert( get4byte(findCell(pParent, iIdx))==iChild ); - } -} -#else -# define assertParentIndex(x,y,z) -#endif - -/* -** Move the cursor up to the parent page. -** -** pCur->idx is set to the cell index that contains the pointer -** to the page we are coming from. If we are coming from the -** right-most child page then pCur->idx is set to one more than -** the largest cell index. -*/ -static void moveToParent(BtCursor *pCur){ - MemPage *pLeaf; - assert( cursorOwnsBtShared(pCur) ); - assert( pCur->eState==CURSOR_VALID ); - assert( pCur->iPage>0 ); - assert( pCur->pPage ); - assertParentIndex( - pCur->apPage[pCur->iPage-1], - pCur->aiIdx[pCur->iPage-1], - pCur->pPage->pgno - ); - testcase( pCur->aiIdx[pCur->iPage-1] > pCur->apPage[pCur->iPage-1]->nCell ); - pCur->info.nSize = 0; - pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl); - pCur->ix = pCur->aiIdx[pCur->iPage-1]; - pLeaf = pCur->pPage; - pCur->pPage = pCur->apPage[--pCur->iPage]; - releasePageNotNull(pLeaf); -} - -/* -** Move the cursor to point to the root page of its b-tree structure. -** -** If the table has a virtual root page, then the cursor is moved to point -** to the virtual root page instead of the actual root page. A table has a -** virtual root page when the actual root page contains no cells and a -** single child page. This can only happen with the table rooted at page 1. -** -** If the b-tree structure is empty, the cursor state is set to -** CURSOR_INVALID and this routine returns SQLITE_EMPTY. Otherwise, -** the cursor is set to point to the first cell located on the root -** (or virtual root) page and the cursor state is set to CURSOR_VALID. -** -** If this function returns successfully, it may be assumed that the -** page-header flags indicate that the [virtual] root-page is the expected -** kind of b-tree page (i.e. if when opening the cursor the caller did not -** specify a KeyInfo structure the flags byte is set to 0x05 or 0x0D, -** indicating a table b-tree, or if the caller did specify a KeyInfo -** structure the flags byte is set to 0x02 or 0x0A, indicating an index -** b-tree). -*/ -static int moveToRoot(BtCursor *pCur){ - MemPage *pRoot; - int rc = SQLITE_OK; - - assert( cursorOwnsBtShared(pCur) ); - assert( CURSOR_INVALID < CURSOR_REQUIRESEEK ); - assert( CURSOR_VALID < CURSOR_REQUIRESEEK ); - assert( CURSOR_FAULT > CURSOR_REQUIRESEEK ); - assert( pCur->eState < CURSOR_REQUIRESEEK || pCur->iPage<0 ); - assert( pCur->pgnoRoot>0 || pCur->iPage<0 ); - - if( pCur->iPage>=0 ){ - if( pCur->iPage ){ - releasePageNotNull(pCur->pPage); - while( --pCur->iPage ){ - releasePageNotNull(pCur->apPage[pCur->iPage]); - } - pCur->pPage = pCur->apPage[0]; - goto skip_init; - } - }else if( pCur->pgnoRoot==0 ){ - pCur->eState = CURSOR_INVALID; - return SQLITE_EMPTY; - }else{ - assert( pCur->iPage==(-1) ); - if( pCur->eState>=CURSOR_REQUIRESEEK ){ - if( pCur->eState==CURSOR_FAULT ){ - assert( pCur->skipNext!=SQLITE_OK ); - return pCur->skipNext; - } - sqlite3BtreeClearCursor(pCur); - } - rc = getAndInitPage(pCur->pBtree->pBt, pCur->pgnoRoot, &pCur->pPage, - 0, pCur->curPagerFlags); - if( rc!=SQLITE_OK ){ - pCur->eState = CURSOR_INVALID; - return rc; - } - pCur->iPage = 0; - pCur->curIntKey = pCur->pPage->intKey; - } - pRoot = pCur->pPage; - assert( pRoot->pgno==pCur->pgnoRoot ); - - /* If pCur->pKeyInfo is not NULL, then the caller that opened this cursor - ** expected to open it on an index b-tree. Otherwise, if pKeyInfo is - ** NULL, the caller expects a table b-tree. If this is not the case, - ** return an SQLITE_CORRUPT error. - ** - ** Earlier versions of SQLite assumed that this test could not fail - ** if the root page was already loaded when this function was called (i.e. - ** if pCur->iPage>=0). But this is not so if the database is corrupted - ** in such a way that page pRoot is linked into a second b-tree table - ** (or the freelist). */ - assert( pRoot->intKey==1 || pRoot->intKey==0 ); - if( pRoot->isInit==0 || (pCur->pKeyInfo==0)!=pRoot->intKey ){ - return SQLITE_CORRUPT_PAGE(pCur->pPage); - } - -skip_init: - pCur->ix = 0; - pCur->info.nSize = 0; - pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidNKey|BTCF_ValidOvfl); - - pRoot = pCur->pPage; - if( pRoot->nCell>0 ){ - pCur->eState = CURSOR_VALID; - }else if( !pRoot->leaf ){ - Pgno subpage; - if( pRoot->pgno!=1 ) return SQLITE_CORRUPT_BKPT; - subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]); - pCur->eState = CURSOR_VALID; - rc = moveToChild(pCur, subpage); - }else{ - pCur->eState = CURSOR_INVALID; - rc = SQLITE_EMPTY; - } - return rc; -} - -/* -** Move the cursor down to the left-most leaf entry beneath the -** entry to which it is currently pointing. -** -** The left-most leaf is the one with the smallest key - the first -** in ascending order. -*/ -static int moveToLeftmost(BtCursor *pCur){ - Pgno pgno; - int rc = SQLITE_OK; - MemPage *pPage; - - assert( cursorOwnsBtShared(pCur) ); - assert( pCur->eState==CURSOR_VALID ); - while( rc==SQLITE_OK && !(pPage = pCur->pPage)->leaf ){ - assert( pCur->ix<pPage->nCell ); - pgno = get4byte(findCell(pPage, pCur->ix)); - rc = moveToChild(pCur, pgno); - } - return rc; -} - -/* -** Move the cursor down to the right-most leaf entry beneath the -** page to which it is currently pointing. Notice the difference -** between moveToLeftmost() and moveToRightmost(). moveToLeftmost() -** finds the left-most entry beneath the *entry* whereas moveToRightmost() -** finds the right-most entry beneath the *page*. -** -** The right-most entry is the one with the largest key - the last -** key in ascending order. -*/ -static int moveToRightmost(BtCursor *pCur){ - Pgno pgno; - int rc = SQLITE_OK; - MemPage *pPage = 0; - - assert( cursorOwnsBtShared(pCur) ); - assert( pCur->eState==CURSOR_VALID ); - while( !(pPage = pCur->pPage)->leaf ){ - pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]); - pCur->ix = pPage->nCell; - rc = moveToChild(pCur, pgno); - if( rc ) return rc; - } - pCur->ix = pPage->nCell-1; - assert( pCur->info.nSize==0 ); - assert( (pCur->curFlags & BTCF_ValidNKey)==0 ); - return SQLITE_OK; -} - -/* Move the cursor to the first entry in the table. Return SQLITE_OK -** on success. Set *pRes to 0 if the cursor actually points to something -** or set *pRes to 1 if the table is empty. -*/ -int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){ - int rc; - - assert( cursorOwnsBtShared(pCur) ); - assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) ); - rc = moveToRoot(pCur); - if( rc==SQLITE_OK ){ - assert( pCur->pPage->nCell>0 ); - *pRes = 0; - rc = moveToLeftmost(pCur); - }else if( rc==SQLITE_EMPTY ){ - assert( pCur->pgnoRoot==0 || pCur->pPage->nCell==0 ); - *pRes = 1; - rc = SQLITE_OK; - } - return rc; -} - -/* Move the cursor to the last entry in the table. Return SQLITE_OK -** on success. Set *pRes to 0 if the cursor actually points to something -** or set *pRes to 1 if the table is empty. -*/ -int sqlite3BtreeLast(BtCursor *pCur, int *pRes){ - int rc; - - assert( cursorOwnsBtShared(pCur) ); - assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) ); - - /* If the cursor already points to the last entry, this is a no-op. */ - if( CURSOR_VALID==pCur->eState && (pCur->curFlags & BTCF_AtLast)!=0 ){ -#ifdef SQLITE_DEBUG - /* This block serves to assert() that the cursor really does point - ** to the last entry in the b-tree. */ - int ii; - for(ii=0; ii<pCur->iPage; ii++){ - assert( pCur->aiIdx[ii]==pCur->apPage[ii]->nCell ); - } - assert( pCur->ix==pCur->pPage->nCell-1 ); - assert( pCur->pPage->leaf ); -#endif - return SQLITE_OK; - } - - rc = moveToRoot(pCur); - if( rc==SQLITE_OK ){ - assert( pCur->eState==CURSOR_VALID ); - *pRes = 0; - rc = moveToRightmost(pCur); - if( rc==SQLITE_OK ){ - pCur->curFlags |= BTCF_AtLast; - }else{ - pCur->curFlags &= ~BTCF_AtLast; - } - }else if( rc==SQLITE_EMPTY ){ - assert( pCur->pgnoRoot==0 || pCur->pPage->nCell==0 ); - *pRes = 1; - rc = SQLITE_OK; - } - return rc; -} - -/* Move the cursor so that it points to an entry near the key -** specified by pIdxKey or intKey. Return a success code. -** -** For INTKEY tables, the intKey parameter is used. pIdxKey -** must be NULL. For index tables, pIdxKey is used and intKey -** is ignored. -** -** If an exact match is not found, then the cursor is always -** left pointing at a leaf page which would hold the entry if it -** were present. The cursor might point to an entry that comes -** before or after the key. -** -** An integer is written into *pRes which is the result of -** comparing the key with the entry to which the cursor is -** pointing. The meaning of the integer written into -** *pRes is as follows: -** -** *pRes<0 The cursor is left pointing at an entry that -** is smaller than intKey/pIdxKey or if the table is empty -** and the cursor is therefore left point to nothing. -** -** *pRes==0 The cursor is left pointing at an entry that -** exactly matches intKey/pIdxKey. -** -** *pRes>0 The cursor is left pointing at an entry that -** is larger than intKey/pIdxKey. -** -** For index tables, the pIdxKey->eqSeen field is set to 1 if there -** exists an entry in the table that exactly matches pIdxKey. -*/ -int sqlite3BtreeMovetoUnpacked( - BtCursor *pCur, /* The cursor to be moved */ - UnpackedRecord *pIdxKey, /* Unpacked index key */ - i64 intKey, /* The table key */ - int biasRight, /* If true, bias the search to the high end */ - int *pRes /* Write search results here */ -){ - int rc; - RecordCompare xRecordCompare; - - assert( cursorOwnsBtShared(pCur) ); - assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) ); - assert( pRes ); - assert( (pIdxKey==0)==(pCur->pKeyInfo==0) ); - assert( pCur->eState!=CURSOR_VALID || (pIdxKey==0)==(pCur->curIntKey!=0) ); - - /* If the cursor is already positioned at the point we are trying - ** to move to, then just return without doing any work */ - if( pIdxKey==0 - && pCur->eState==CURSOR_VALID && (pCur->curFlags & BTCF_ValidNKey)!=0 - ){ - if( pCur->info.nKey==intKey ){ - *pRes = 0; - return SQLITE_OK; - } - if( pCur->info.nKey<intKey ){ - if( (pCur->curFlags & BTCF_AtLast)!=0 ){ - *pRes = -1; - return SQLITE_OK; - } - /* If the requested key is one more than the previous key, then - ** try to get there using sqlite3BtreeNext() rather than a full - ** binary search. This is an optimization only. The correct answer - ** is still obtained without this case, only a little more slowely */ - if( pCur->info.nKey+1==intKey && !pCur->skipNext ){ - *pRes = 0; - rc = sqlite3BtreeNext(pCur, 0); - if( rc==SQLITE_OK ){ - getCellInfo(pCur); - if( pCur->info.nKey==intKey ){ - return SQLITE_OK; - } - }else if( rc==SQLITE_DONE ){ - rc = SQLITE_OK; - }else{ - return rc; - } - } - } - } - - if( pIdxKey ){ - xRecordCompare = sqlite3VdbeFindCompare(pIdxKey); - pIdxKey->errCode = 0; - assert( pIdxKey->default_rc==1 - || pIdxKey->default_rc==0 - || pIdxKey->default_rc==-1 - ); - }else{ - xRecordCompare = 0; /* All keys are integers */ - } - - rc = moveToRoot(pCur); - if( rc ){ - if( rc==SQLITE_EMPTY ){ - assert( pCur->pgnoRoot==0 || pCur->pPage->nCell==0 ); - *pRes = -1; - return SQLITE_OK; - } - return rc; - } - assert( pCur->pPage ); - assert( pCur->pPage->isInit ); - assert( pCur->eState==CURSOR_VALID ); - assert( pCur->pPage->nCell > 0 ); - assert( pCur->iPage==0 || pCur->apPage[0]->intKey==pCur->curIntKey ); - assert( pCur->curIntKey || pIdxKey ); - for(;;){ - int lwr, upr, idx, c; - Pgno chldPg; - MemPage *pPage = pCur->pPage; - u8 *pCell; /* Pointer to current cell in pPage */ - - /* pPage->nCell must be greater than zero. If this is the root-page - ** the cursor would have been INVALID above and this for(;;) loop - ** not run. If this is not the root-page, then the moveToChild() routine - ** would have already detected db corruption. Similarly, pPage must - ** be the right kind (index or table) of b-tree page. Otherwise - ** a moveToChild() or moveToRoot() call would have detected corruption. */ - assert( pPage->nCell>0 ); - assert( pPage->intKey==(pIdxKey==0) ); - lwr = 0; - upr = pPage->nCell-1; - assert( biasRight==0 || biasRight==1 ); - idx = upr>>(1-biasRight); /* idx = biasRight ? upr : (lwr+upr)/2; */ - pCur->ix = (u16)idx; - if( xRecordCompare==0 ){ - for(;;){ - i64 nCellKey; - pCell = findCellPastPtr(pPage, idx); - if( pPage->intKeyLeaf ){ - while( 0x80 <= *(pCell++) ){ - if( pCell>=pPage->aDataEnd ){ - return SQLITE_CORRUPT_PAGE(pPage); - } - } - } - getVarint(pCell, (u64*)&nCellKey); - if( nCellKey<intKey ){ - lwr = idx+1; - if( lwr>upr ){ c = -1; break; } - }else if( nCellKey>intKey ){ - upr = idx-1; - if( lwr>upr ){ c = +1; break; } - }else{ - assert( nCellKey==intKey ); - pCur->ix = (u16)idx; - if( !pPage->leaf ){ - lwr = idx; - goto moveto_next_layer; - }else{ - pCur->curFlags |= BTCF_ValidNKey; - pCur->info.nKey = nCellKey; - pCur->info.nSize = 0; - *pRes = 0; - return SQLITE_OK; - } - } - assert( lwr+upr>=0 ); - idx = (lwr+upr)>>1; /* idx = (lwr+upr)/2; */ - } - }else{ - for(;;){ - int nCell; /* Size of the pCell cell in bytes */ - pCell = findCellPastPtr(pPage, idx); - - /* The maximum supported page-size is 65536 bytes. This means that - ** the maximum number of record bytes stored on an index B-Tree - ** page is less than 16384 bytes and may be stored as a 2-byte - ** varint. This information is used to attempt to avoid parsing - ** the entire cell by checking for the cases where the record is - ** stored entirely within the b-tree page by inspecting the first - ** 2 bytes of the cell. - */ - nCell = pCell[0]; - if( nCell<=pPage->max1bytePayload ){ - /* This branch runs if the record-size field of the cell is a - ** single byte varint and the record fits entirely on the main - ** b-tree page. */ - testcase( pCell+nCell+1==pPage->aDataEnd ); - c = xRecordCompare(nCell, (void*)&pCell[1], pIdxKey); - }else if( !(pCell[1] & 0x80) - && (nCell = ((nCell&0x7f)<<7) + pCell[1])<=pPage->maxLocal - ){ - /* The record-size field is a 2 byte varint and the record - ** fits entirely on the main b-tree page. */ - testcase( pCell+nCell+2==pPage->aDataEnd ); - c = xRecordCompare(nCell, (void*)&pCell[2], pIdxKey); - }else{ - /* The record flows over onto one or more overflow pages. In - ** this case the whole cell needs to be parsed, a buffer allocated - ** and accessPayload() used to retrieve the record into the - ** buffer before VdbeRecordCompare() can be called. - ** - ** If the record is corrupt, the xRecordCompare routine may read - ** up to two varints past the end of the buffer. An extra 18 - ** bytes of padding is allocated at the end of the buffer in - ** case this happens. */ - void *pCellKey; - u8 * const pCellBody = pCell - pPage->childPtrSize; - pPage->xParseCell(pPage, pCellBody, &pCur->info); - nCell = (int)pCur->info.nKey; - testcase( nCell<0 ); /* True if key size is 2^32 or more */ - testcase( nCell==0 ); /* Invalid key size: 0x80 0x80 0x00 */ - testcase( nCell==1 ); /* Invalid key size: 0x80 0x80 0x01 */ - testcase( nCell==2 ); /* Minimum legal index key size */ - if( nCell<2 ){ - rc = SQLITE_CORRUPT_PAGE(pPage); - goto moveto_finish; - } - pCellKey = sqlite3Malloc( nCell+18 ); - if( pCellKey==0 ){ - rc = SQLITE_NOMEM_BKPT; - goto moveto_finish; - } - pCur->ix = (u16)idx; - rc = accessPayload(pCur, 0, nCell, (unsigned char*)pCellKey, 0); - pCur->curFlags &= ~BTCF_ValidOvfl; - if( rc ){ - sqlite3_free(pCellKey); - goto moveto_finish; - } - c = xRecordCompare(nCell, pCellKey, pIdxKey); - sqlite3_free(pCellKey); - } - assert( - (pIdxKey->errCode!=SQLITE_CORRUPT || c==0) - && (pIdxKey->errCode!=SQLITE_NOMEM || pCur->pBtree->db->mallocFailed) - ); - if( c<0 ){ - lwr = idx+1; - }else if( c>0 ){ - upr = idx-1; - }else{ - assert( c==0 ); - *pRes = 0; - rc = SQLITE_OK; - pCur->ix = (u16)idx; - if( pIdxKey->errCode ) rc = SQLITE_CORRUPT_BKPT; - goto moveto_finish; - } - if( lwr>upr ) break; - assert( lwr+upr>=0 ); - idx = (lwr+upr)>>1; /* idx = (lwr+upr)/2 */ - } - } - assert( lwr==upr+1 || (pPage->intKey && !pPage->leaf) ); - assert( pPage->isInit ); - if( pPage->leaf ){ - assert( pCur->ix<pCur->pPage->nCell ); - pCur->ix = (u16)idx; - *pRes = c; - rc = SQLITE_OK; - goto moveto_finish; - } -moveto_next_layer: - if( lwr>=pPage->nCell ){ - chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]); - }else{ - chldPg = get4byte(findCell(pPage, lwr)); - } - pCur->ix = (u16)lwr; - rc = moveToChild(pCur, chldPg); - if( rc ) break; - } -moveto_finish: - pCur->info.nSize = 0; - assert( (pCur->curFlags & BTCF_ValidOvfl)==0 ); - return rc; -} - - -/* -** Return TRUE if the cursor is not pointing at an entry of the table. -** -** TRUE will be returned after a call to sqlite3BtreeNext() moves -** past the last entry in the table or sqlite3BtreePrev() moves past -** the first entry. TRUE is also returned if the table is empty. -*/ -int sqlite3BtreeEof(BtCursor *pCur){ - /* TODO: What if the cursor is in CURSOR_REQUIRESEEK but all table entries - ** have been deleted? This API will need to change to return an error code - ** as well as the boolean result value. - */ - return (CURSOR_VALID!=pCur->eState); -} - -/* -** Return an estimate for the number of rows in the table that pCur is -** pointing to. Return a negative number if no estimate is currently -** available. -*/ -i64 sqlite3BtreeRowCountEst(BtCursor *pCur){ - i64 n; - u8 i; - - assert( cursorOwnsBtShared(pCur) ); - assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) ); - - /* Currently this interface is only called by the OP_IfSmaller - ** opcode, and it that case the cursor will always be valid and - ** will always point to a leaf node. */ - if( NEVER(pCur->eState!=CURSOR_VALID) ) return -1; - if( NEVER(pCur->pPage->leaf==0) ) return -1; - - n = pCur->pPage->nCell; - for(i=0; i<pCur->iPage; i++){ - n *= pCur->apPage[i]->nCell; - } - return n; -} - -/* -** Advance the cursor to the next entry in the database. -** Return value: -** -** SQLITE_OK success -** SQLITE_DONE cursor is already pointing at the last element -** otherwise some kind of error occurred -** -** The main entry point is sqlite3BtreeNext(). That routine is optimized -** for the common case of merely incrementing the cell counter BtCursor.aiIdx -** to the next cell on the current page. The (slower) btreeNext() helper -** routine is called when it is necessary to move to a different page or -** to restore the cursor. -** -** If bit 0x01 of the F argument in sqlite3BtreeNext(C,F) is 1, then the -** cursor corresponds to an SQL index and this routine could have been -** skipped if the SQL index had been a unique index. The F argument -** is a hint to the implement. SQLite btree implementation does not use -** this hint, but COMDB2 does. -*/ -static SQLITE_NOINLINE int btreeNext(BtCursor *pCur){ - int rc; - int idx; - MemPage *pPage; - - assert( cursorOwnsBtShared(pCur) ); - assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID ); - if( pCur->eState!=CURSOR_VALID ){ - assert( (pCur->curFlags & BTCF_ValidOvfl)==0 ); - rc = restoreCursorPosition(pCur); - if( rc!=SQLITE_OK ){ - return rc; - } - if( CURSOR_INVALID==pCur->eState ){ - return SQLITE_DONE; - } - if( pCur->skipNext ){ - assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_SKIPNEXT ); - pCur->eState = CURSOR_VALID; - if( pCur->skipNext>0 ){ - pCur->skipNext = 0; - return SQLITE_OK; - } - pCur->skipNext = 0; - } - } - - pPage = pCur->pPage; - idx = ++pCur->ix; - assert( pPage->isInit ); - - /* If the database file is corrupt, it is possible for the value of idx - ** to be invalid here. This can only occur if a second cursor modifies - ** the page while cursor pCur is holding a reference to it. Which can - ** only happen if the database is corrupt in such a way as to link the - ** page into more than one b-tree structure. */ - testcase( idx>pPage->nCell ); - - if( idx>=pPage->nCell ){ - if( !pPage->leaf ){ - rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8])); - if( rc ) return rc; - return moveToLeftmost(pCur); - } - do{ - if( pCur->iPage==0 ){ - pCur->eState = CURSOR_INVALID; - return SQLITE_DONE; - } - moveToParent(pCur); - pPage = pCur->pPage; - }while( pCur->ix>=pPage->nCell ); - if( pPage->intKey ){ - return sqlite3BtreeNext(pCur, 0); - }else{ - return SQLITE_OK; - } - } - if( pPage->leaf ){ - return SQLITE_OK; - }else{ - return moveToLeftmost(pCur); - } -} -int sqlite3BtreeNext(BtCursor *pCur, int flags){ - MemPage *pPage; - UNUSED_PARAMETER( flags ); /* Used in COMDB2 but not native SQLite */ - assert( cursorOwnsBtShared(pCur) ); - assert( flags==0 || flags==1 ); - assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID ); - pCur->info.nSize = 0; - pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl); - if( pCur->eState!=CURSOR_VALID ) return btreeNext(pCur); - pPage = pCur->pPage; - if( (++pCur->ix)>=pPage->nCell ){ - pCur->ix--; - return btreeNext(pCur); - } - if( pPage->leaf ){ - return SQLITE_OK; - }else{ - return moveToLeftmost(pCur); - } -} - -/* -** Step the cursor to the back to the previous entry in the database. -** Return values: -** -** SQLITE_OK success -** SQLITE_DONE the cursor is already on the first element of the table -** otherwise some kind of error occurred -** -** The main entry point is sqlite3BtreePrevious(). That routine is optimized -** for the common case of merely decrementing the cell counter BtCursor.aiIdx -** to the previous cell on the current page. The (slower) btreePrevious() -** helper routine is called when it is necessary to move to a different page -** or to restore the cursor. -** -** If bit 0x01 of the F argument to sqlite3BtreePrevious(C,F) is 1, then -** the cursor corresponds to an SQL index and this routine could have been -** skipped if the SQL index had been a unique index. The F argument is a -** hint to the implement. The native SQLite btree implementation does not -** use this hint, but COMDB2 does. -*/ -static SQLITE_NOINLINE int btreePrevious(BtCursor *pCur){ - int rc; - MemPage *pPage; - - assert( cursorOwnsBtShared(pCur) ); - assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID ); - assert( (pCur->curFlags & (BTCF_AtLast|BTCF_ValidOvfl|BTCF_ValidNKey))==0 ); - assert( pCur->info.nSize==0 ); - if( pCur->eState!=CURSOR_VALID ){ - rc = restoreCursorPosition(pCur); - if( rc!=SQLITE_OK ){ - return rc; - } - if( CURSOR_INVALID==pCur->eState ){ - return SQLITE_DONE; - } - if( pCur->skipNext ){ - assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_SKIPNEXT ); - pCur->eState = CURSOR_VALID; - if( pCur->skipNext<0 ){ - pCur->skipNext = 0; - return SQLITE_OK; - } - pCur->skipNext = 0; - } - } - - pPage = pCur->pPage; - assert( pPage->isInit ); - if( !pPage->leaf ){ - int idx = pCur->ix; - rc = moveToChild(pCur, get4byte(findCell(pPage, idx))); - if( rc ) return rc; - rc = moveToRightmost(pCur); - }else{ - while( pCur->ix==0 ){ - if( pCur->iPage==0 ){ - pCur->eState = CURSOR_INVALID; - return SQLITE_DONE; - } - moveToParent(pCur); - } - assert( pCur->info.nSize==0 ); - assert( (pCur->curFlags & (BTCF_ValidOvfl))==0 ); - - pCur->ix--; - pPage = pCur->pPage; - if( pPage->intKey && !pPage->leaf ){ - rc = sqlite3BtreePrevious(pCur, 0); - }else{ - rc = SQLITE_OK; - } - } - return rc; -} -int sqlite3BtreePrevious(BtCursor *pCur, int flags){ - assert( cursorOwnsBtShared(pCur) ); - assert( flags==0 || flags==1 ); - assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID ); - UNUSED_PARAMETER( flags ); /* Used in COMDB2 but not native SQLite */ - pCur->curFlags &= ~(BTCF_AtLast|BTCF_ValidOvfl|BTCF_ValidNKey); - pCur->info.nSize = 0; - if( pCur->eState!=CURSOR_VALID - || pCur->ix==0 - || pCur->pPage->leaf==0 - ){ - return btreePrevious(pCur); - } - pCur->ix--; - return SQLITE_OK; -} - -/* -** Allocate a new page from the database file. -** -** The new page is marked as dirty. (In other words, sqlite3PagerWrite() -** has already been called on the new page.) The new page has also -** been referenced and the calling routine is responsible for calling -** sqlite3PagerUnref() on the new page when it is done. -** -** SQLITE_OK is returned on success. Any other return value indicates -** an error. *ppPage is set to NULL in the event of an error. -** -** If the "nearby" parameter is not 0, then an effort is made to -** locate a page close to the page number "nearby". This can be used in an -** attempt to keep related pages close to each other in the database file, -** which in turn can make database access faster. -** -** If the eMode parameter is BTALLOC_EXACT and the nearby page exists -** anywhere on the free-list, then it is guaranteed to be returned. If -** eMode is BTALLOC_LT then the page returned will be less than or equal -** to nearby if any such page exists. If eMode is BTALLOC_ANY then there -** are no restrictions on which page is returned. -*/ -static int allocateBtreePage( - BtShared *pBt, /* The btree */ - MemPage **ppPage, /* Store pointer to the allocated page here */ - Pgno *pPgno, /* Store the page number here */ - Pgno nearby, /* Search for a page near this one */ - u8 eMode /* BTALLOC_EXACT, BTALLOC_LT, or BTALLOC_ANY */ -){ - MemPage *pPage1; - int rc; - u32 n; /* Number of pages on the freelist */ - u32 k; /* Number of leaves on the trunk of the freelist */ - MemPage *pTrunk = 0; - MemPage *pPrevTrunk = 0; - Pgno mxPage; /* Total size of the database file */ - - assert( sqlite3_mutex_held(pBt->mutex) ); - assert( eMode==BTALLOC_ANY || (nearby>0 && IfNotOmitAV(pBt->autoVacuum)) ); - pPage1 = pBt->pPage1; - mxPage = btreePagecount(pBt); - /* EVIDENCE-OF: R-05119-02637 The 4-byte big-endian integer at offset 36 - ** stores stores the total number of pages on the freelist. */ - n = get4byte(&pPage1->aData[36]); - testcase( n==mxPage-1 ); - if( n>=mxPage ){ - return SQLITE_CORRUPT_BKPT; - } - if( n>0 ){ - /* There are pages on the freelist. Reuse one of those pages. */ - Pgno iTrunk; - u8 searchList = 0; /* If the free-list must be searched for 'nearby' */ - u32 nSearch = 0; /* Count of the number of search attempts */ - - /* If eMode==BTALLOC_EXACT and a query of the pointer-map - ** shows that the page 'nearby' is somewhere on the free-list, then - ** the entire-list will be searched for that page. - */ -#ifndef SQLITE_OMIT_AUTOVACUUM - if( eMode==BTALLOC_EXACT ){ - if( nearby<=mxPage ){ - u8 eType; - assert( nearby>0 ); - assert( pBt->autoVacuum ); - rc = ptrmapGet(pBt, nearby, &eType, 0); - if( rc ) return rc; - if( eType==PTRMAP_FREEPAGE ){ - searchList = 1; - } - } - }else if( eMode==BTALLOC_LE ){ - searchList = 1; - } -#endif - - /* Decrement the free-list count by 1. Set iTrunk to the index of the - ** first free-list trunk page. iPrevTrunk is initially 1. - */ - rc = sqlite3PagerWrite(pPage1->pDbPage); - if( rc ) return rc; - put4byte(&pPage1->aData[36], n-1); - - /* The code within this loop is run only once if the 'searchList' variable - ** is not true. Otherwise, it runs once for each trunk-page on the - ** free-list until the page 'nearby' is located (eMode==BTALLOC_EXACT) - ** or until a page less than 'nearby' is located (eMode==BTALLOC_LT) - */ - do { - pPrevTrunk = pTrunk; - if( pPrevTrunk ){ - /* EVIDENCE-OF: R-01506-11053 The first integer on a freelist trunk page - ** is the page number of the next freelist trunk page in the list or - ** zero if this is the last freelist trunk page. */ - iTrunk = get4byte(&pPrevTrunk->aData[0]); - }else{ - /* EVIDENCE-OF: R-59841-13798 The 4-byte big-endian integer at offset 32 - ** stores the page number of the first page of the freelist, or zero if - ** the freelist is empty. */ - iTrunk = get4byte(&pPage1->aData[32]); - } - testcase( iTrunk==mxPage ); - if( iTrunk>mxPage || nSearch++ > n ){ - rc = SQLITE_CORRUPT_PGNO(pPrevTrunk ? pPrevTrunk->pgno : 1); - }else{ - rc = btreeGetUnusedPage(pBt, iTrunk, &pTrunk, 0); - } - if( rc ){ - pTrunk = 0; - goto end_allocate_page; - } - assert( pTrunk!=0 ); - assert( pTrunk->aData!=0 ); - /* EVIDENCE-OF: R-13523-04394 The second integer on a freelist trunk page - ** is the number of leaf page pointers to follow. */ - k = get4byte(&pTrunk->aData[4]); - if( k==0 && !searchList ){ - /* The trunk has no leaves and the list is not being searched. - ** So extract the trunk page itself and use it as the newly - ** allocated page */ - assert( pPrevTrunk==0 ); - rc = sqlite3PagerWrite(pTrunk->pDbPage); - if( rc ){ - goto end_allocate_page; - } - *pPgno = iTrunk; - memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4); - *ppPage = pTrunk; - pTrunk = 0; - TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1)); - }else if( k>(u32)(pBt->usableSize/4 - 2) ){ - /* Value of k is out of range. Database corruption */ - rc = SQLITE_CORRUPT_PGNO(iTrunk); - goto end_allocate_page; -#ifndef SQLITE_OMIT_AUTOVACUUM - }else if( searchList - && (nearby==iTrunk || (iTrunk<nearby && eMode==BTALLOC_LE)) - ){ - /* The list is being searched and this trunk page is the page - ** to allocate, regardless of whether it has leaves. - */ - *pPgno = iTrunk; - *ppPage = pTrunk; - searchList = 0; - rc = sqlite3PagerWrite(pTrunk->pDbPage); - if( rc ){ - goto end_allocate_page; - } - if( k==0 ){ - if( !pPrevTrunk ){ - memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4); - }else{ - rc = sqlite3PagerWrite(pPrevTrunk->pDbPage); - if( rc!=SQLITE_OK ){ - goto end_allocate_page; - } - memcpy(&pPrevTrunk->aData[0], &pTrunk->aData[0], 4); - } - }else{ - /* The trunk page is required by the caller but it contains - ** pointers to free-list leaves. The first leaf becomes a trunk - ** page in this case. - */ - MemPage *pNewTrunk; - Pgno iNewTrunk = get4byte(&pTrunk->aData[8]); - if( iNewTrunk>mxPage ){ - rc = SQLITE_CORRUPT_PGNO(iTrunk); - goto end_allocate_page; - } - testcase( iNewTrunk==mxPage ); - rc = btreeGetUnusedPage(pBt, iNewTrunk, &pNewTrunk, 0); - if( rc!=SQLITE_OK ){ - goto end_allocate_page; - } - rc = sqlite3PagerWrite(pNewTrunk->pDbPage); - if( rc!=SQLITE_OK ){ - releasePage(pNewTrunk); - goto end_allocate_page; - } - memcpy(&pNewTrunk->aData[0], &pTrunk->aData[0], 4); - put4byte(&pNewTrunk->aData[4], k-1); - memcpy(&pNewTrunk->aData[8], &pTrunk->aData[12], (k-1)*4); - releasePage(pNewTrunk); - if( !pPrevTrunk ){ - assert( sqlite3PagerIswriteable(pPage1->pDbPage) ); - put4byte(&pPage1->aData[32], iNewTrunk); - }else{ - rc = sqlite3PagerWrite(pPrevTrunk->pDbPage); - if( rc ){ - goto end_allocate_page; - } - put4byte(&pPrevTrunk->aData[0], iNewTrunk); - } - } - pTrunk = 0; - TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1)); -#endif - }else if( k>0 ){ - /* Extract a leaf from the trunk */ - u32 closest; - Pgno iPage; - unsigned char *aData = pTrunk->aData; - if( nearby>0 ){ - u32 i; - closest = 0; - if( eMode==BTALLOC_LE ){ - for(i=0; i<k; i++){ - iPage = get4byte(&aData[8+i*4]); - if( iPage<=nearby ){ - closest = i; - break; - } - } - }else{ - int dist; - dist = sqlite3AbsInt32(get4byte(&aData[8]) - nearby); - for(i=1; i<k; i++){ - int d2 = sqlite3AbsInt32(get4byte(&aData[8+i*4]) - nearby); - if( d2<dist ){ - closest = i; - dist = d2; - } - } - } - }else{ - closest = 0; - } - - iPage = get4byte(&aData[8+closest*4]); - testcase( iPage==mxPage ); - if( iPage>mxPage ){ - rc = SQLITE_CORRUPT_PGNO(iTrunk); - goto end_allocate_page; - } - testcase( iPage==mxPage ); - if( !searchList - || (iPage==nearby || (iPage<nearby && eMode==BTALLOC_LE)) - ){ - int noContent; - *pPgno = iPage; - TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d" - ": %d more free pages\n", - *pPgno, closest+1, k, pTrunk->pgno, n-1)); - rc = sqlite3PagerWrite(pTrunk->pDbPage); - if( rc ) goto end_allocate_page; - if( closest<k-1 ){ - memcpy(&aData[8+closest*4], &aData[4+k*4], 4); - } - put4byte(&aData[4], k-1); - noContent = !btreeGetHasContent(pBt, *pPgno)? PAGER_GET_NOCONTENT : 0; - rc = btreeGetUnusedPage(pBt, *pPgno, ppPage, noContent); - if( rc==SQLITE_OK ){ - rc = sqlite3PagerWrite((*ppPage)->pDbPage); - if( rc!=SQLITE_OK ){ - releasePage(*ppPage); - *ppPage = 0; - } - } - searchList = 0; - } - } - releasePage(pPrevTrunk); - pPrevTrunk = 0; - }while( searchList ); - }else{ - /* There are no pages on the freelist, so append a new page to the - ** database image. - ** - ** Normally, new pages allocated by this block can be requested from the - ** pager layer with the 'no-content' flag set. This prevents the pager - ** from trying to read the pages content from disk. However, if the - ** current transaction has already run one or more incremental-vacuum - ** steps, then the page we are about to allocate may contain content - ** that is required in the event of a rollback. In this case, do - ** not set the no-content flag. This causes the pager to load and journal - ** the current page content before overwriting it. - ** - ** Note that the pager will not actually attempt to load or journal - ** content for any page that really does lie past the end of the database - ** file on disk. So the effects of disabling the no-content optimization - ** here are confined to those pages that lie between the end of the - ** database image and the end of the database file. - */ - int bNoContent = (0==IfNotOmitAV(pBt->bDoTruncate))? PAGER_GET_NOCONTENT:0; - - rc = sqlite3PagerWrite(pBt->pPage1->pDbPage); - if( rc ) return rc; - pBt->nPage++; - if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ) pBt->nPage++; - -#ifndef SQLITE_OMIT_AUTOVACUUM - if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, pBt->nPage) ){ - /* If *pPgno refers to a pointer-map page, allocate two new pages - ** at the end of the file instead of one. The first allocated page - ** becomes a new pointer-map page, the second is used by the caller. - */ - MemPage *pPg = 0; - TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", pBt->nPage)); - assert( pBt->nPage!=PENDING_BYTE_PAGE(pBt) ); - rc = btreeGetUnusedPage(pBt, pBt->nPage, &pPg, bNoContent); - if( rc==SQLITE_OK ){ - rc = sqlite3PagerWrite(pPg->pDbPage); - releasePage(pPg); - } - if( rc ) return rc; - pBt->nPage++; - if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ){ pBt->nPage++; } - } -#endif - put4byte(28 + (u8*)pBt->pPage1->aData, pBt->nPage); - *pPgno = pBt->nPage; - - assert( *pPgno!=PENDING_BYTE_PAGE(pBt) ); - rc = btreeGetUnusedPage(pBt, *pPgno, ppPage, bNoContent); - if( rc ) return rc; - rc = sqlite3PagerWrite((*ppPage)->pDbPage); - if( rc!=SQLITE_OK ){ - releasePage(*ppPage); - *ppPage = 0; - } - TRACE(("ALLOCATE: %d from end of file\n", *pPgno)); - } - - assert( *pPgno!=PENDING_BYTE_PAGE(pBt) ); - -end_allocate_page: - releasePage(pTrunk); - releasePage(pPrevTrunk); - assert( rc!=SQLITE_OK || sqlite3PagerPageRefcount((*ppPage)->pDbPage)<=1 ); - assert( rc!=SQLITE_OK || (*ppPage)->isInit==0 ); - return rc; -} - -/* -** This function is used to add page iPage to the database file free-list. -** It is assumed that the page is not already a part of the free-list. -** -** The value passed as the second argument to this function is optional. -** If the caller happens to have a pointer to the MemPage object -** corresponding to page iPage handy, it may pass it as the second value. -** Otherwise, it may pass NULL. -** -** If a pointer to a MemPage object is passed as the second argument, -** its reference count is not altered by this function. -*/ -static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){ - MemPage *pTrunk = 0; /* Free-list trunk page */ - Pgno iTrunk = 0; /* Page number of free-list trunk page */ - MemPage *pPage1 = pBt->pPage1; /* Local reference to page 1 */ - MemPage *pPage; /* Page being freed. May be NULL. */ - int rc; /* Return Code */ - int nFree; /* Initial number of pages on free-list */ - - assert( sqlite3_mutex_held(pBt->mutex) ); - assert( CORRUPT_DB || iPage>1 ); - assert( !pMemPage || pMemPage->pgno==iPage ); - - if( iPage<2 ) return SQLITE_CORRUPT_BKPT; - if( pMemPage ){ - pPage = pMemPage; - sqlite3PagerRef(pPage->pDbPage); - }else{ - pPage = btreePageLookup(pBt, iPage); - } - - /* Increment the free page count on pPage1 */ - rc = sqlite3PagerWrite(pPage1->pDbPage); - if( rc ) goto freepage_out; - nFree = get4byte(&pPage1->aData[36]); - put4byte(&pPage1->aData[36], nFree+1); - - if( pBt->btsFlags & BTS_SECURE_DELETE ){ - /* If the secure_delete option is enabled, then - ** always fully overwrite deleted information with zeros. - */ - if( (!pPage && ((rc = btreeGetPage(pBt, iPage, &pPage, 0))!=0) ) - || ((rc = sqlite3PagerWrite(pPage->pDbPage))!=0) - ){ - goto freepage_out; - } - memset(pPage->aData, 0, pPage->pBt->pageSize); - } - - /* If the database supports auto-vacuum, write an entry in the pointer-map - ** to indicate that the page is free. - */ - if( ISAUTOVACUUM ){ - ptrmapPut(pBt, iPage, PTRMAP_FREEPAGE, 0, &rc); - if( rc ) goto freepage_out; - } - - /* Now manipulate the actual database free-list structure. There are two - ** possibilities. If the free-list is currently empty, or if the first - ** trunk page in the free-list is full, then this page will become a - ** new free-list trunk page. Otherwise, it will become a leaf of the - ** first trunk page in the current free-list. This block tests if it - ** is possible to add the page as a new free-list leaf. - */ - if( nFree!=0 ){ - u32 nLeaf; /* Initial number of leaf cells on trunk page */ - - iTrunk = get4byte(&pPage1->aData[32]); - rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0); - if( rc!=SQLITE_OK ){ - goto freepage_out; - } - - nLeaf = get4byte(&pTrunk->aData[4]); - assert( pBt->usableSize>32 ); - if( nLeaf > (u32)pBt->usableSize/4 - 2 ){ - rc = SQLITE_CORRUPT_BKPT; - goto freepage_out; - } - if( nLeaf < (u32)pBt->usableSize/4 - 8 ){ - /* In this case there is room on the trunk page to insert the page - ** being freed as a new leaf. - ** - ** Note that the trunk page is not really full until it contains - ** usableSize/4 - 2 entries, not usableSize/4 - 8 entries as we have - ** coded. But due to a coding error in versions of SQLite prior to - ** 3.6.0, databases with freelist trunk pages holding more than - ** usableSize/4 - 8 entries will be reported as corrupt. In order - ** to maintain backwards compatibility with older versions of SQLite, - ** we will continue to restrict the number of entries to usableSize/4 - 8 - ** for now. At some point in the future (once everyone has upgraded - ** to 3.6.0 or later) we should consider fixing the conditional above - ** to read "usableSize/4-2" instead of "usableSize/4-8". - ** - ** EVIDENCE-OF: R-19920-11576 However, newer versions of SQLite still - ** avoid using the last six entries in the freelist trunk page array in - ** order that database files created by newer versions of SQLite can be - ** read by older versions of SQLite. - */ - rc = sqlite3PagerWrite(pTrunk->pDbPage); - if( rc==SQLITE_OK ){ - put4byte(&pTrunk->aData[4], nLeaf+1); - put4byte(&pTrunk->aData[8+nLeaf*4], iPage); - if( pPage && (pBt->btsFlags & BTS_SECURE_DELETE)==0 ){ - sqlite3PagerDontWrite(pPage->pDbPage); - } - rc = btreeSetHasContent(pBt, iPage); - } - TRACE(("FREE-PAGE: %d leaf on trunk page %d\n",pPage->pgno,pTrunk->pgno)); - goto freepage_out; - } - } - - /* If control flows to this point, then it was not possible to add the - ** the page being freed as a leaf page of the first trunk in the free-list. - ** Possibly because the free-list is empty, or possibly because the - ** first trunk in the free-list is full. Either way, the page being freed - ** will become the new first trunk page in the free-list. - */ - if( pPage==0 && SQLITE_OK!=(rc = btreeGetPage(pBt, iPage, &pPage, 0)) ){ - goto freepage_out; - } - rc = sqlite3PagerWrite(pPage->pDbPage); - if( rc!=SQLITE_OK ){ - goto freepage_out; - } - put4byte(pPage->aData, iTrunk); - put4byte(&pPage->aData[4], 0); - put4byte(&pPage1->aData[32], iPage); - TRACE(("FREE-PAGE: %d new trunk page replacing %d\n", pPage->pgno, iTrunk)); - -freepage_out: - if( pPage ){ - pPage->isInit = 0; - } - releasePage(pPage); - releasePage(pTrunk); - return rc; -} -static void freePage(MemPage *pPage, int *pRC){ - if( (*pRC)==SQLITE_OK ){ - *pRC = freePage2(pPage->pBt, pPage, pPage->pgno); - } -} - -/* -** Free any overflow pages associated with the given Cell. Store -** size information about the cell in pInfo. -*/ -static int clearCell( - MemPage *pPage, /* The page that contains the Cell */ - unsigned char *pCell, /* First byte of the Cell */ - CellInfo *pInfo /* Size information about the cell */ -){ - BtShared *pBt; - Pgno ovflPgno; - int rc; - int nOvfl; - u32 ovflPageSize; - - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - pPage->xParseCell(pPage, pCell, pInfo); - if( pInfo->nLocal==pInfo->nPayload ){ - return SQLITE_OK; /* No overflow pages. Return without doing anything */ - } - testcase( pCell + pInfo->nSize == pPage->aDataEnd ); - testcase( pCell + (pInfo->nSize-1) == pPage->aDataEnd ); - if( pCell + pInfo->nSize > pPage->aDataEnd ){ - /* Cell extends past end of page */ - return SQLITE_CORRUPT_PAGE(pPage); - } - ovflPgno = get4byte(pCell + pInfo->nSize - 4); - pBt = pPage->pBt; - assert( pBt->usableSize > 4 ); - ovflPageSize = pBt->usableSize - 4; - nOvfl = (pInfo->nPayload - pInfo->nLocal + ovflPageSize - 1)/ovflPageSize; - assert( nOvfl>0 || - (CORRUPT_DB && (pInfo->nPayload + ovflPageSize)<ovflPageSize) - ); - while( nOvfl-- ){ - Pgno iNext = 0; - MemPage *pOvfl = 0; - if( ovflPgno<2 || ovflPgno>btreePagecount(pBt) ){ - /* 0 is not a legal page number and page 1 cannot be an - ** overflow page. Therefore if ovflPgno<2 or past the end of the - ** file the database must be corrupt. */ - return SQLITE_CORRUPT_BKPT; - } - if( nOvfl ){ - rc = getOverflowPage(pBt, ovflPgno, &pOvfl, &iNext); - if( rc ) return rc; - } - - if( ( pOvfl || ((pOvfl = btreePageLookup(pBt, ovflPgno))!=0) ) - && sqlite3PagerPageRefcount(pOvfl->pDbPage)!=1 - ){ - /* There is no reason any cursor should have an outstanding reference - ** to an overflow page belonging to a cell that is being deleted/updated. - ** So if there exists more than one reference to this page, then it - ** must not really be an overflow page and the database must be corrupt. - ** It is helpful to detect this before calling freePage2(), as - ** freePage2() may zero the page contents if secure-delete mode is - ** enabled. If this 'overflow' page happens to be a page that the - ** caller is iterating through or using in some other way, this - ** can be problematic. - */ - rc = SQLITE_CORRUPT_BKPT; - }else{ - rc = freePage2(pBt, pOvfl, ovflPgno); - } - - if( pOvfl ){ - sqlite3PagerUnref(pOvfl->pDbPage); - } - if( rc ) return rc; - ovflPgno = iNext; - } - return SQLITE_OK; -} - -/* -** Create the byte sequence used to represent a cell on page pPage -** and write that byte sequence into pCell[]. Overflow pages are -** allocated and filled in as necessary. The calling procedure -** is responsible for making sure sufficient space has been allocated -** for pCell[]. -** -** Note that pCell does not necessary need to point to the pPage->aData -** area. pCell might point to some temporary storage. The cell will -** be constructed in this temporary area then copied into pPage->aData -** later. -*/ -static int fillInCell( - MemPage *pPage, /* The page that contains the cell */ - unsigned char *pCell, /* Complete text of the cell */ - const BtreePayload *pX, /* Payload with which to construct the cell */ - int *pnSize /* Write cell size here */ -){ - int nPayload; - const u8 *pSrc; - int nSrc, n, rc, mn; - int spaceLeft; - MemPage *pToRelease; - unsigned char *pPrior; - unsigned char *pPayload; - BtShared *pBt; - Pgno pgnoOvfl; - int nHeader; - - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - - /* pPage is not necessarily writeable since pCell might be auxiliary - ** buffer space that is separate from the pPage buffer area */ - assert( pCell<pPage->aData || pCell>=&pPage->aData[pPage->pBt->pageSize] - || sqlite3PagerIswriteable(pPage->pDbPage) ); - - /* Fill in the header. */ - nHeader = pPage->childPtrSize; - if( pPage->intKey ){ - nPayload = pX->nData + pX->nZero; - pSrc = pX->pData; - nSrc = pX->nData; - assert( pPage->intKeyLeaf ); /* fillInCell() only called for leaves */ - nHeader += putVarint32(&pCell[nHeader], nPayload); - nHeader += putVarint(&pCell[nHeader], *(u64*)&pX->nKey); - }else{ - assert( pX->nKey<=0x7fffffff && pX->pKey!=0 ); - nSrc = nPayload = (int)pX->nKey; - pSrc = pX->pKey; - nHeader += putVarint32(&pCell[nHeader], nPayload); - } - - /* Fill in the payload */ - pPayload = &pCell[nHeader]; - if( nPayload<=pPage->maxLocal ){ - /* This is the common case where everything fits on the btree page - ** and no overflow pages are required. */ - n = nHeader + nPayload; - testcase( n==3 ); - testcase( n==4 ); - if( n<4 ) n = 4; - *pnSize = n; - assert( nSrc<=nPayload ); - testcase( nSrc<nPayload ); - memcpy(pPayload, pSrc, nSrc); - memset(pPayload+nSrc, 0, nPayload-nSrc); - return SQLITE_OK; - } - - /* If we reach this point, it means that some of the content will need - ** to spill onto overflow pages. - */ - mn = pPage->minLocal; - n = mn + (nPayload - mn) % (pPage->pBt->usableSize - 4); - testcase( n==pPage->maxLocal ); - testcase( n==pPage->maxLocal+1 ); - if( n > pPage->maxLocal ) n = mn; - spaceLeft = n; - *pnSize = n + nHeader + 4; - pPrior = &pCell[nHeader+n]; - pToRelease = 0; - pgnoOvfl = 0; - pBt = pPage->pBt; - - /* At this point variables should be set as follows: - ** - ** nPayload Total payload size in bytes - ** pPayload Begin writing payload here - ** spaceLeft Space available at pPayload. If nPayload>spaceLeft, - ** that means content must spill into overflow pages. - ** *pnSize Size of the local cell (not counting overflow pages) - ** pPrior Where to write the pgno of the first overflow page - ** - ** Use a call to btreeParseCellPtr() to verify that the values above - ** were computed correctly. - */ -#ifdef SQLITE_DEBUG - { - CellInfo info; - pPage->xParseCell(pPage, pCell, &info); - assert( nHeader==(int)(info.pPayload - pCell) ); - assert( info.nKey==pX->nKey ); - assert( *pnSize == info.nSize ); - assert( spaceLeft == info.nLocal ); - } -#endif - - /* Write the payload into the local Cell and any extra into overflow pages */ - while( 1 ){ - n = nPayload; - if( n>spaceLeft ) n = spaceLeft; - - /* If pToRelease is not zero than pPayload points into the data area - ** of pToRelease. Make sure pToRelease is still writeable. */ - assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) ); - - /* If pPayload is part of the data area of pPage, then make sure pPage - ** is still writeable */ - assert( pPayload<pPage->aData || pPayload>=&pPage->aData[pBt->pageSize] - || sqlite3PagerIswriteable(pPage->pDbPage) ); - - if( nSrc>=n ){ - memcpy(pPayload, pSrc, n); - }else if( nSrc>0 ){ - n = nSrc; - memcpy(pPayload, pSrc, n); - }else{ - memset(pPayload, 0, n); - } - nPayload -= n; - if( nPayload<=0 ) break; - pPayload += n; - pSrc += n; - nSrc -= n; - spaceLeft -= n; - if( spaceLeft==0 ){ - MemPage *pOvfl = 0; -#ifndef SQLITE_OMIT_AUTOVACUUM - Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */ - if( pBt->autoVacuum ){ - do{ - pgnoOvfl++; - } while( - PTRMAP_ISPAGE(pBt, pgnoOvfl) || pgnoOvfl==PENDING_BYTE_PAGE(pBt) - ); - } -#endif - rc = allocateBtreePage(pBt, &pOvfl, &pgnoOvfl, pgnoOvfl, 0); -#ifndef SQLITE_OMIT_AUTOVACUUM - /* If the database supports auto-vacuum, and the second or subsequent - ** overflow page is being allocated, add an entry to the pointer-map - ** for that page now. - ** - ** If this is the first overflow page, then write a partial entry - ** to the pointer-map. If we write nothing to this pointer-map slot, - ** then the optimistic overflow chain processing in clearCell() - ** may misinterpret the uninitialized values and delete the - ** wrong pages from the database. - */ - if( pBt->autoVacuum && rc==SQLITE_OK ){ - u8 eType = (pgnoPtrmap?PTRMAP_OVERFLOW2:PTRMAP_OVERFLOW1); - ptrmapPut(pBt, pgnoOvfl, eType, pgnoPtrmap, &rc); - if( rc ){ - releasePage(pOvfl); - } - } -#endif - if( rc ){ - releasePage(pToRelease); - return rc; - } - - /* If pToRelease is not zero than pPrior points into the data area - ** of pToRelease. Make sure pToRelease is still writeable. */ - assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) ); - - /* If pPrior is part of the data area of pPage, then make sure pPage - ** is still writeable */ - assert( pPrior<pPage->aData || pPrior>=&pPage->aData[pBt->pageSize] - || sqlite3PagerIswriteable(pPage->pDbPage) ); - - put4byte(pPrior, pgnoOvfl); - releasePage(pToRelease); - pToRelease = pOvfl; - pPrior = pOvfl->aData; - put4byte(pPrior, 0); - pPayload = &pOvfl->aData[4]; - spaceLeft = pBt->usableSize - 4; - } - } - releasePage(pToRelease); - return SQLITE_OK; -} - -/* -** Remove the i-th cell from pPage. This routine effects pPage only. -** The cell content is not freed or deallocated. It is assumed that -** the cell content has been copied someplace else. This routine just -** removes the reference to the cell from pPage. -** -** "sz" must be the number of bytes in the cell. -*/ -static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){ - u32 pc; /* Offset to cell content of cell being deleted */ - u8 *data; /* pPage->aData */ - u8 *ptr; /* Used to move bytes around within data[] */ - int rc; /* The return code */ - int hdr; /* Beginning of the header. 0 most pages. 100 page 1 */ - - if( *pRC ) return; - assert( idx>=0 && idx<pPage->nCell ); - assert( CORRUPT_DB || sz==cellSize(pPage, idx) ); - assert( sqlite3PagerIswriteable(pPage->pDbPage) ); - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - data = pPage->aData; - ptr = &pPage->aCellIdx[2*idx]; - pc = get2byte(ptr); - hdr = pPage->hdrOffset; - testcase( pc==get2byte(&data[hdr+5]) ); - testcase( pc+sz==pPage->pBt->usableSize ); - if( pc+sz > pPage->pBt->usableSize ){ - *pRC = SQLITE_CORRUPT_BKPT; - return; - } - rc = freeSpace(pPage, pc, sz); - if( rc ){ - *pRC = rc; - return; - } - pPage->nCell--; - if( pPage->nCell==0 ){ - memset(&data[hdr+1], 0, 4); - data[hdr+7] = 0; - put2byte(&data[hdr+5], pPage->pBt->usableSize); - pPage->nFree = pPage->pBt->usableSize - pPage->hdrOffset - - pPage->childPtrSize - 8; - }else{ - memmove(ptr, ptr+2, 2*(pPage->nCell - idx)); - put2byte(&data[hdr+3], pPage->nCell); - pPage->nFree += 2; - } -} - -/* -** Insert a new cell on pPage at cell index "i". pCell points to the -** content of the cell. -** -** If the cell content will fit on the page, then put it there. If it -** will not fit, then make a copy of the cell content into pTemp if -** pTemp is not null. Regardless of pTemp, allocate a new entry -** in pPage->apOvfl[] and make it point to the cell content (either -** in pTemp or the original pCell) and also record its index. -** Allocating a new entry in pPage->aCell[] implies that -** pPage->nOverflow is incremented. -** -** *pRC must be SQLITE_OK when this routine is called. -*/ -static void insertCell( - MemPage *pPage, /* Page into which we are copying */ - int i, /* New cell becomes the i-th cell of the page */ - u8 *pCell, /* Content of the new cell */ - int sz, /* Bytes of content in pCell */ - u8 *pTemp, /* Temp storage space for pCell, if needed */ - Pgno iChild, /* If non-zero, replace first 4 bytes with this value */ - int *pRC /* Read and write return code from here */ -){ - int idx = 0; /* Where to write new cell content in data[] */ - int j; /* Loop counter */ - u8 *data; /* The content of the whole page */ - u8 *pIns; /* The point in pPage->aCellIdx[] where no cell inserted */ - - assert( *pRC==SQLITE_OK ); - assert( i>=0 && i<=pPage->nCell+pPage->nOverflow ); - assert( MX_CELL(pPage->pBt)<=10921 ); - assert( pPage->nCell<=MX_CELL(pPage->pBt) || CORRUPT_DB ); - assert( pPage->nOverflow<=ArraySize(pPage->apOvfl) ); - assert( ArraySize(pPage->apOvfl)==ArraySize(pPage->aiOvfl) ); - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - /* The cell should normally be sized correctly. However, when moving a - ** malformed cell from a leaf page to an interior page, if the cell size - ** wanted to be less than 4 but got rounded up to 4 on the leaf, then size - ** might be less than 8 (leaf-size + pointer) on the interior node. Hence - ** the term after the || in the following assert(). */ - assert( sz==pPage->xCellSize(pPage, pCell) || (sz==8 && iChild>0) ); - if( pPage->nOverflow || sz+2>pPage->nFree ){ - if( pTemp ){ - memcpy(pTemp, pCell, sz); - pCell = pTemp; - } - if( iChild ){ - put4byte(pCell, iChild); - } - j = pPage->nOverflow++; - /* Comparison against ArraySize-1 since we hold back one extra slot - ** as a contingency. In other words, never need more than 3 overflow - ** slots but 4 are allocated, just to be safe. */ - assert( j < ArraySize(pPage->apOvfl)-1 ); - pPage->apOvfl[j] = pCell; - pPage->aiOvfl[j] = (u16)i; - - /* When multiple overflows occur, they are always sequential and in - ** sorted order. This invariants arise because multiple overflows can - ** only occur when inserting divider cells into the parent page during - ** balancing, and the dividers are adjacent and sorted. - */ - assert( j==0 || pPage->aiOvfl[j-1]<(u16)i ); /* Overflows in sorted order */ - assert( j==0 || i==pPage->aiOvfl[j-1]+1 ); /* Overflows are sequential */ - }else{ - int rc = sqlite3PagerWrite(pPage->pDbPage); - if( rc!=SQLITE_OK ){ - *pRC = rc; - return; - } - assert( sqlite3PagerIswriteable(pPage->pDbPage) ); - data = pPage->aData; - assert( &data[pPage->cellOffset]==pPage->aCellIdx ); - rc = allocateSpace(pPage, sz, &idx); - if( rc ){ *pRC = rc; return; } - /* The allocateSpace() routine guarantees the following properties - ** if it returns successfully */ - assert( idx >= 0 ); - assert( idx >= pPage->cellOffset+2*pPage->nCell+2 || CORRUPT_DB ); - assert( idx+sz <= (int)pPage->pBt->usableSize ); - pPage->nFree -= (u16)(2 + sz); - memcpy(&data[idx], pCell, sz); - if( iChild ){ - put4byte(&data[idx], iChild); - } - pIns = pPage->aCellIdx + i*2; - memmove(pIns+2, pIns, 2*(pPage->nCell - i)); - put2byte(pIns, idx); - pPage->nCell++; - /* increment the cell count */ - if( (++data[pPage->hdrOffset+4])==0 ) data[pPage->hdrOffset+3]++; - assert( get2byte(&data[pPage->hdrOffset+3])==pPage->nCell ); -#ifndef SQLITE_OMIT_AUTOVACUUM - if( pPage->pBt->autoVacuum ){ - /* The cell may contain a pointer to an overflow page. If so, write - ** the entry for the overflow page into the pointer map. - */ - ptrmapPutOvflPtr(pPage, pCell, pRC); - } -#endif - } -} - -/* -** A CellArray object contains a cache of pointers and sizes for a -** consecutive sequence of cells that might be held on multiple pages. -*/ -typedef struct CellArray CellArray; -struct CellArray { - int nCell; /* Number of cells in apCell[] */ - MemPage *pRef; /* Reference page */ - u8 **apCell; /* All cells begin balanced */ - u16 *szCell; /* Local size of all cells in apCell[] */ -}; - -/* -** Make sure the cell sizes at idx, idx+1, ..., idx+N-1 have been -** computed. -*/ -static void populateCellCache(CellArray *p, int idx, int N){ - assert( idx>=0 && idx+N<=p->nCell ); - while( N>0 ){ - assert( p->apCell[idx]!=0 ); - if( p->szCell[idx]==0 ){ - p->szCell[idx] = p->pRef->xCellSize(p->pRef, p->apCell[idx]); - }else{ - assert( CORRUPT_DB || - p->szCell[idx]==p->pRef->xCellSize(p->pRef, p->apCell[idx]) ); - } - idx++; - N--; - } -} - -/* -** Return the size of the Nth element of the cell array -*/ -static SQLITE_NOINLINE u16 computeCellSize(CellArray *p, int N){ - assert( N>=0 && N<p->nCell ); - assert( p->szCell[N]==0 ); - p->szCell[N] = p->pRef->xCellSize(p->pRef, p->apCell[N]); - return p->szCell[N]; -} -static u16 cachedCellSize(CellArray *p, int N){ - assert( N>=0 && N<p->nCell ); - if( p->szCell[N] ) return p->szCell[N]; - return computeCellSize(p, N); -} - -/* -** Array apCell[] contains pointers to nCell b-tree page cells. The -** szCell[] array contains the size in bytes of each cell. This function -** replaces the current contents of page pPg with the contents of the cell -** array. -** -** Some of the cells in apCell[] may currently be stored in pPg. This -** function works around problems caused by this by making a copy of any -** such cells before overwriting the page data. -** -** The MemPage.nFree field is invalidated by this function. It is the -** responsibility of the caller to set it correctly. -*/ -static int rebuildPage( - MemPage *pPg, /* Edit this page */ - int nCell, /* Final number of cells on page */ - u8 **apCell, /* Array of cells */ - u16 *szCell /* Array of cell sizes */ -){ - const int hdr = pPg->hdrOffset; /* Offset of header on pPg */ - u8 * const aData = pPg->aData; /* Pointer to data for pPg */ - const int usableSize = pPg->pBt->usableSize; - u8 * const pEnd = &aData[usableSize]; - int i; - u8 *pCellptr = pPg->aCellIdx; - u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager); - u8 *pData; - - i = get2byte(&aData[hdr+5]); - memcpy(&pTmp[i], &aData[i], usableSize - i); - - pData = pEnd; - for(i=0; i<nCell; i++){ - u8 *pCell = apCell[i]; - if( SQLITE_WITHIN(pCell,aData,pEnd) ){ - pCell = &pTmp[pCell - aData]; - } - pData -= szCell[i]; - put2byte(pCellptr, (pData - aData)); - pCellptr += 2; - if( pData < pCellptr ) return SQLITE_CORRUPT_BKPT; - memcpy(pData, pCell, szCell[i]); - assert( szCell[i]==pPg->xCellSize(pPg, pCell) || CORRUPT_DB ); - testcase( szCell[i]!=pPg->xCellSize(pPg,pCell) ); - } - - /* The pPg->nFree field is now set incorrectly. The caller will fix it. */ - pPg->nCell = nCell; - pPg->nOverflow = 0; - - put2byte(&aData[hdr+1], 0); - put2byte(&aData[hdr+3], pPg->nCell); - put2byte(&aData[hdr+5], pData - aData); - aData[hdr+7] = 0x00; - return SQLITE_OK; -} - -/* -** Array apCell[] contains nCell pointers to b-tree cells. Array szCell -** contains the size in bytes of each such cell. This function attempts to -** add the cells stored in the array to page pPg. If it cannot (because -** the page needs to be defragmented before the cells will fit), non-zero -** is returned. Otherwise, if the cells are added successfully, zero is -** returned. -** -** Argument pCellptr points to the first entry in the cell-pointer array -** (part of page pPg) to populate. After cell apCell[0] is written to the -** page body, a 16-bit offset is written to pCellptr. And so on, for each -** cell in the array. It is the responsibility of the caller to ensure -** that it is safe to overwrite this part of the cell-pointer array. -** -** When this function is called, *ppData points to the start of the -** content area on page pPg. If the size of the content area is extended, -** *ppData is updated to point to the new start of the content area -** before returning. -** -** Finally, argument pBegin points to the byte immediately following the -** end of the space required by this page for the cell-pointer area (for -** all cells - not just those inserted by the current call). If the content -** area must be extended to before this point in order to accomodate all -** cells in apCell[], then the cells do not fit and non-zero is returned. -*/ -static int pageInsertArray( - MemPage *pPg, /* Page to add cells to */ - u8 *pBegin, /* End of cell-pointer array */ - u8 **ppData, /* IN/OUT: Page content -area pointer */ - u8 *pCellptr, /* Pointer to cell-pointer area */ - int iFirst, /* Index of first cell to add */ - int nCell, /* Number of cells to add to pPg */ - CellArray *pCArray /* Array of cells */ -){ - int i; - u8 *aData = pPg->aData; - u8 *pData = *ppData; - int iEnd = iFirst + nCell; - assert( CORRUPT_DB || pPg->hdrOffset==0 ); /* Never called on page 1 */ - for(i=iFirst; i<iEnd; i++){ - int sz, rc; - u8 *pSlot; - sz = cachedCellSize(pCArray, i); - if( (aData[1]==0 && aData[2]==0) || (pSlot = pageFindSlot(pPg,sz,&rc))==0 ){ - if( (pData - pBegin)<sz ) return 1; - pData -= sz; - pSlot = pData; - } - /* pSlot and pCArray->apCell[i] will never overlap on a well-formed - ** database. But they might for a corrupt database. Hence use memmove() - ** since memcpy() sends SIGABORT with overlapping buffers on OpenBSD */ - assert( (pSlot+sz)<=pCArray->apCell[i] - || pSlot>=(pCArray->apCell[i]+sz) - || CORRUPT_DB ); - memmove(pSlot, pCArray->apCell[i], sz); - put2byte(pCellptr, (pSlot - aData)); - pCellptr += 2; - } - *ppData = pData; - return 0; -} - -/* -** Array apCell[] contains nCell pointers to b-tree cells. Array szCell -** contains the size in bytes of each such cell. This function adds the -** space associated with each cell in the array that is currently stored -** within the body of pPg to the pPg free-list. The cell-pointers and other -** fields of the page are not updated. -** -** This function returns the total number of cells added to the free-list. -*/ -static int pageFreeArray( - MemPage *pPg, /* Page to edit */ - int iFirst, /* First cell to delete */ - int nCell, /* Cells to delete */ - CellArray *pCArray /* Array of cells */ -){ - u8 * const aData = pPg->aData; - u8 * const pEnd = &aData[pPg->pBt->usableSize]; - u8 * const pStart = &aData[pPg->hdrOffset + 8 + pPg->childPtrSize]; - int nRet = 0; - int i; - int iEnd = iFirst + nCell; - u8 *pFree = 0; - int szFree = 0; - - for(i=iFirst; i<iEnd; i++){ - u8 *pCell = pCArray->apCell[i]; - if( SQLITE_WITHIN(pCell, pStart, pEnd) ){ - int sz; - /* No need to use cachedCellSize() here. The sizes of all cells that - ** are to be freed have already been computing while deciding which - ** cells need freeing */ - sz = pCArray->szCell[i]; assert( sz>0 ); - if( pFree!=(pCell + sz) ){ - if( pFree ){ - assert( pFree>aData && (pFree - aData)<65536 ); - freeSpace(pPg, (u16)(pFree - aData), szFree); - } - pFree = pCell; - szFree = sz; - if( pFree+sz>pEnd ) return 0; - }else{ - pFree = pCell; - szFree += sz; - } - nRet++; - } - } - if( pFree ){ - assert( pFree>aData && (pFree - aData)<65536 ); - freeSpace(pPg, (u16)(pFree - aData), szFree); - } - return nRet; -} - -/* -** apCell[] and szCell[] contains pointers to and sizes of all cells in the -** pages being balanced. The current page, pPg, has pPg->nCell cells starting -** with apCell[iOld]. After balancing, this page should hold nNew cells -** starting at apCell[iNew]. -** -** This routine makes the necessary adjustments to pPg so that it contains -** the correct cells after being balanced. -** -** The pPg->nFree field is invalid when this function returns. It is the -** responsibility of the caller to set it correctly. -*/ -static int editPage( - MemPage *pPg, /* Edit this page */ - int iOld, /* Index of first cell currently on page */ - int iNew, /* Index of new first cell on page */ - int nNew, /* Final number of cells on page */ - CellArray *pCArray /* Array of cells and sizes */ -){ - u8 * const aData = pPg->aData; - const int hdr = pPg->hdrOffset; - u8 *pBegin = &pPg->aCellIdx[nNew * 2]; - int nCell = pPg->nCell; /* Cells stored on pPg */ - u8 *pData; - u8 *pCellptr; - int i; - int iOldEnd = iOld + pPg->nCell + pPg->nOverflow; - int iNewEnd = iNew + nNew; - -#ifdef SQLITE_DEBUG - u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager); - memcpy(pTmp, aData, pPg->pBt->usableSize); -#endif - - /* Remove cells from the start and end of the page */ - if( iOld<iNew ){ - int nShift = pageFreeArray(pPg, iOld, iNew-iOld, pCArray); - memmove(pPg->aCellIdx, &pPg->aCellIdx[nShift*2], nCell*2); - nCell -= nShift; - } - if( iNewEnd < iOldEnd ){ - nCell -= pageFreeArray(pPg, iNewEnd, iOldEnd - iNewEnd, pCArray); - } - - pData = &aData[get2byteNotZero(&aData[hdr+5])]; - if( pData<pBegin ) goto editpage_fail; - - /* Add cells to the start of the page */ - if( iNew<iOld ){ - int nAdd = MIN(nNew,iOld-iNew); - assert( (iOld-iNew)<nNew || nCell==0 || CORRUPT_DB ); - pCellptr = pPg->aCellIdx; - memmove(&pCellptr[nAdd*2], pCellptr, nCell*2); - if( pageInsertArray( - pPg, pBegin, &pData, pCellptr, - iNew, nAdd, pCArray - ) ) goto editpage_fail; - nCell += nAdd; - } - - /* Add any overflow cells */ - for(i=0; i<pPg->nOverflow; i++){ - int iCell = (iOld + pPg->aiOvfl[i]) - iNew; - if( iCell>=0 && iCell<nNew ){ - pCellptr = &pPg->aCellIdx[iCell * 2]; - memmove(&pCellptr[2], pCellptr, (nCell - iCell) * 2); - nCell++; - if( pageInsertArray( - pPg, pBegin, &pData, pCellptr, - iCell+iNew, 1, pCArray - ) ) goto editpage_fail; - } - } - - /* Append cells to the end of the page */ - pCellptr = &pPg->aCellIdx[nCell*2]; - if( pageInsertArray( - pPg, pBegin, &pData, pCellptr, - iNew+nCell, nNew-nCell, pCArray - ) ) goto editpage_fail; - - pPg->nCell = nNew; - pPg->nOverflow = 0; - - put2byte(&aData[hdr+3], pPg->nCell); - put2byte(&aData[hdr+5], pData - aData); - -#ifdef SQLITE_DEBUG - for(i=0; i<nNew && !CORRUPT_DB; i++){ - u8 *pCell = pCArray->apCell[i+iNew]; - int iOff = get2byteAligned(&pPg->aCellIdx[i*2]); - if( SQLITE_WITHIN(pCell, aData, &aData[pPg->pBt->usableSize]) ){ - pCell = &pTmp[pCell - aData]; - } - assert( 0==memcmp(pCell, &aData[iOff], - pCArray->pRef->xCellSize(pCArray->pRef, pCArray->apCell[i+iNew])) ); - } -#endif - - return SQLITE_OK; - editpage_fail: - /* Unable to edit this page. Rebuild it from scratch instead. */ - populateCellCache(pCArray, iNew, nNew); - return rebuildPage(pPg, nNew, &pCArray->apCell[iNew], &pCArray->szCell[iNew]); -} - -/* -** The following parameters determine how many adjacent pages get involved -** in a balancing operation. NN is the number of neighbors on either side -** of the page that participate in the balancing operation. NB is the -** total number of pages that participate, including the target page and -** NN neighbors on either side. -** -** The minimum value of NN is 1 (of course). Increasing NN above 1 -** (to 2 or 3) gives a modest improvement in SELECT and DELETE performance -** in exchange for a larger degradation in INSERT and UPDATE performance. -** The value of NN appears to give the best results overall. -*/ -#define NN 1 /* Number of neighbors on either side of pPage */ -#define NB (NN*2+1) /* Total pages involved in the balance */ - - -#ifndef SQLITE_OMIT_QUICKBALANCE -/* -** This version of balance() handles the common special case where -** a new entry is being inserted on the extreme right-end of the -** tree, in other words, when the new entry will become the largest -** entry in the tree. -** -** Instead of trying to balance the 3 right-most leaf pages, just add -** a new page to the right-hand side and put the one new entry in -** that page. This leaves the right side of the tree somewhat -** unbalanced. But odds are that we will be inserting new entries -** at the end soon afterwards so the nearly empty page will quickly -** fill up. On average. -** -** pPage is the leaf page which is the right-most page in the tree. -** pParent is its parent. pPage must have a single overflow entry -** which is also the right-most entry on the page. -** -** The pSpace buffer is used to store a temporary copy of the divider -** cell that will be inserted into pParent. Such a cell consists of a 4 -** byte page number followed by a variable length integer. In other -** words, at most 13 bytes. Hence the pSpace buffer must be at -** least 13 bytes in size. -*/ -static int balance_quick(MemPage *pParent, MemPage *pPage, u8 *pSpace){ - BtShared *const pBt = pPage->pBt; /* B-Tree Database */ - MemPage *pNew; /* Newly allocated page */ - int rc; /* Return Code */ - Pgno pgnoNew; /* Page number of pNew */ - - assert( sqlite3_mutex_held(pPage->pBt->mutex) ); - assert( sqlite3PagerIswriteable(pParent->pDbPage) ); - assert( pPage->nOverflow==1 ); - - /* This error condition is now caught prior to reaching this function */ - if( NEVER(pPage->nCell==0) ) return SQLITE_CORRUPT_BKPT; - - /* Allocate a new page. This page will become the right-sibling of - ** pPage. Make the parent page writable, so that the new divider cell - ** may be inserted. If both these operations are successful, proceed. - */ - rc = allocateBtreePage(pBt, &pNew, &pgnoNew, 0, 0); - - if( rc==SQLITE_OK ){ - - u8 *pOut = &pSpace[4]; - u8 *pCell = pPage->apOvfl[0]; - u16 szCell = pPage->xCellSize(pPage, pCell); - u8 *pStop; - - assert( sqlite3PagerIswriteable(pNew->pDbPage) ); - assert( pPage->aData[0]==(PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF) ); - zeroPage(pNew, PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF); - rc = rebuildPage(pNew, 1, &pCell, &szCell); - if( NEVER(rc) ) return rc; - pNew->nFree = pBt->usableSize - pNew->cellOffset - 2 - szCell; - - /* If this is an auto-vacuum database, update the pointer map - ** with entries for the new page, and any pointer from the - ** cell on the page to an overflow page. If either of these - ** operations fails, the return code is set, but the contents - ** of the parent page are still manipulated by thh code below. - ** That is Ok, at this point the parent page is guaranteed to - ** be marked as dirty. Returning an error code will cause a - ** rollback, undoing any changes made to the parent page. - */ - if( ISAUTOVACUUM ){ - ptrmapPut(pBt, pgnoNew, PTRMAP_BTREE, pParent->pgno, &rc); - if( szCell>pNew->minLocal ){ - ptrmapPutOvflPtr(pNew, pCell, &rc); - } - } - - /* Create a divider cell to insert into pParent. The divider cell - ** consists of a 4-byte page number (the page number of pPage) and - ** a variable length key value (which must be the same value as the - ** largest key on pPage). - ** - ** To find the largest key value on pPage, first find the right-most - ** cell on pPage. The first two fields of this cell are the - ** record-length (a variable length integer at most 32-bits in size) - ** and the key value (a variable length integer, may have any value). - ** The first of the while(...) loops below skips over the record-length - ** field. The second while(...) loop copies the key value from the - ** cell on pPage into the pSpace buffer. - */ - pCell = findCell(pPage, pPage->nCell-1); - pStop = &pCell[9]; - while( (*(pCell++)&0x80) && pCell<pStop ); - pStop = &pCell[9]; - while( ((*(pOut++) = *(pCell++))&0x80) && pCell<pStop ); - - /* Insert the new divider cell into pParent. */ - if( rc==SQLITE_OK ){ - insertCell(pParent, pParent->nCell, pSpace, (int)(pOut-pSpace), - 0, pPage->pgno, &rc); - } - - /* Set the right-child pointer of pParent to point to the new page. */ - put4byte(&pParent->aData[pParent->hdrOffset+8], pgnoNew); - - /* Release the reference to the new page. */ - releasePage(pNew); - } - - return rc; -} -#endif /* SQLITE_OMIT_QUICKBALANCE */ - -#if 0 -/* -** This function does not contribute anything to the operation of SQLite. -** it is sometimes activated temporarily while debugging code responsible -** for setting pointer-map entries. -*/ -static int ptrmapCheckPages(MemPage **apPage, int nPage){ - int i, j; - for(i=0; i<nPage; i++){ - Pgno n; - u8 e; - MemPage *pPage = apPage[i]; - BtShared *pBt = pPage->pBt; - assert( pPage->isInit ); - - for(j=0; j<pPage->nCell; j++){ - CellInfo info; - u8 *z; - - z = findCell(pPage, j); - pPage->xParseCell(pPage, z, &info); - if( info.nLocal<info.nPayload ){ - Pgno ovfl = get4byte(&z[info.nSize-4]); - ptrmapGet(pBt, ovfl, &e, &n); - assert( n==pPage->pgno && e==PTRMAP_OVERFLOW1 ); - } - if( !pPage->leaf ){ - Pgno child = get4byte(z); - ptrmapGet(pBt, child, &e, &n); - assert( n==pPage->pgno && e==PTRMAP_BTREE ); - } - } - if( !pPage->leaf ){ - Pgno child = get4byte(&pPage->aData[pPage->hdrOffset+8]); - ptrmapGet(pBt, child, &e, &n); - assert( n==pPage->pgno && e==PTRMAP_BTREE ); - } - } - return 1; -} -#endif - -/* -** This function is used to copy the contents of the b-tree node stored -** on page pFrom to page pTo. If page pFrom was not a leaf page, then -** the pointer-map entries for each child page are updated so that the -** parent page stored in the pointer map is page pTo. If pFrom contained -** any cells with overflow page pointers, then the corresponding pointer -** map entries are also updated so that the parent page is page pTo. -** -** If pFrom is currently carrying any overflow cells (entries in the -** MemPage.apOvfl[] array), they are not copied to pTo. -** -** Before returning, page pTo is reinitialized using btreeInitPage(). -** -** The performance of this function is not critical. It is only used by -** the balance_shallower() and balance_deeper() procedures, neither of -** which are called often under normal circumstances. -*/ -static void copyNodeContent(MemPage *pFrom, MemPage *pTo, int *pRC){ - if( (*pRC)==SQLITE_OK ){ - BtShared * const pBt = pFrom->pBt; - u8 * const aFrom = pFrom->aData; - u8 * const aTo = pTo->aData; - int const iFromHdr = pFrom->hdrOffset; - int const iToHdr = ((pTo->pgno==1) ? 100 : 0); - int rc; - int iData; - - - assert( pFrom->isInit ); - assert( pFrom->nFree>=iToHdr ); - assert( get2byte(&aFrom[iFromHdr+5]) <= (int)pBt->usableSize ); - - /* Copy the b-tree node content from page pFrom to page pTo. */ - iData = get2byte(&aFrom[iFromHdr+5]); - memcpy(&aTo[iData], &aFrom[iData], pBt->usableSize-iData); - memcpy(&aTo[iToHdr], &aFrom[iFromHdr], pFrom->cellOffset + 2*pFrom->nCell); - - /* Reinitialize page pTo so that the contents of the MemPage structure - ** match the new data. The initialization of pTo can actually fail under - ** fairly obscure circumstances, even though it is a copy of initialized - ** page pFrom. - */ - pTo->isInit = 0; - rc = btreeInitPage(pTo); - if( rc!=SQLITE_OK ){ - *pRC = rc; - return; - } - - /* If this is an auto-vacuum database, update the pointer-map entries - ** for any b-tree or overflow pages that pTo now contains the pointers to. - */ - if( ISAUTOVACUUM ){ - *pRC = setChildPtrmaps(pTo); - } - } -} - -/* -** This routine redistributes cells on the iParentIdx'th child of pParent -** (hereafter "the page") and up to 2 siblings so that all pages have about the -** same amount of free space. Usually a single sibling on either side of the -** page are used in the balancing, though both siblings might come from one -** side if the page is the first or last child of its parent. If the page -** has fewer than 2 siblings (something which can only happen if the page -** is a root page or a child of a root page) then all available siblings -** participate in the balancing. -** -** The number of siblings of the page might be increased or decreased by -** one or two in an effort to keep pages nearly full but not over full. -** -** Note that when this routine is called, some of the cells on the page -** might not actually be stored in MemPage.aData[]. This can happen -** if the page is overfull. This routine ensures that all cells allocated -** to the page and its siblings fit into MemPage.aData[] before returning. -** -** In the course of balancing the page and its siblings, cells may be -** inserted into or removed from the parent page (pParent). Doing so -** may cause the parent page to become overfull or underfull. If this -** happens, it is the responsibility of the caller to invoke the correct -** balancing routine to fix this problem (see the balance() routine). -** -** If this routine fails for any reason, it might leave the database -** in a corrupted state. So if this routine fails, the database should -** be rolled back. -** -** The third argument to this function, aOvflSpace, is a pointer to a -** buffer big enough to hold one page. If while inserting cells into the parent -** page (pParent) the parent page becomes overfull, this buffer is -** used to store the parent's overflow cells. Because this function inserts -** a maximum of four divider cells into the parent page, and the maximum -** size of a cell stored within an internal node is always less than 1/4 -** of the page-size, the aOvflSpace[] buffer is guaranteed to be large -** enough for all overflow cells. -** -** If aOvflSpace is set to a null pointer, this function returns -** SQLITE_NOMEM. -*/ -static int balance_nonroot( - MemPage *pParent, /* Parent page of siblings being balanced */ - int iParentIdx, /* Index of "the page" in pParent */ - u8 *aOvflSpace, /* page-size bytes of space for parent ovfl */ - int isRoot, /* True if pParent is a root-page */ - int bBulk /* True if this call is part of a bulk load */ -){ - BtShared *pBt; /* The whole database */ - int nMaxCells = 0; /* Allocated size of apCell, szCell, aFrom. */ - int nNew = 0; /* Number of pages in apNew[] */ - int nOld; /* Number of pages in apOld[] */ - int i, j, k; /* Loop counters */ - int nxDiv; /* Next divider slot in pParent->aCell[] */ - int rc = SQLITE_OK; /* The return code */ - u16 leafCorrection; /* 4 if pPage is a leaf. 0 if not */ - int leafData; /* True if pPage is a leaf of a LEAFDATA tree */ - int usableSpace; /* Bytes in pPage beyond the header */ - int pageFlags; /* Value of pPage->aData[0] */ - int iSpace1 = 0; /* First unused byte of aSpace1[] */ - int iOvflSpace = 0; /* First unused byte of aOvflSpace[] */ - int szScratch; /* Size of scratch memory requested */ - MemPage *apOld[NB]; /* pPage and up to two siblings */ - MemPage *apNew[NB+2]; /* pPage and up to NB siblings after balancing */ - u8 *pRight; /* Location in parent of right-sibling pointer */ - u8 *apDiv[NB-1]; /* Divider cells in pParent */ - int cntNew[NB+2]; /* Index in b.paCell[] of cell after i-th page */ - int cntOld[NB+2]; /* Old index in b.apCell[] */ - int szNew[NB+2]; /* Combined size of cells placed on i-th page */ - u8 *aSpace1; /* Space for copies of dividers cells */ - Pgno pgno; /* Temp var to store a page number in */ - u8 abDone[NB+2]; /* True after i'th new page is populated */ - Pgno aPgno[NB+2]; /* Page numbers of new pages before shuffling */ - Pgno aPgOrder[NB+2]; /* Copy of aPgno[] used for sorting pages */ - u16 aPgFlags[NB+2]; /* flags field of new pages before shuffling */ - CellArray b; /* Parsed information on cells being balanced */ - - memset(abDone, 0, sizeof(abDone)); - b.nCell = 0; - b.apCell = 0; - pBt = pParent->pBt; - assert( sqlite3_mutex_held(pBt->mutex) ); - assert( sqlite3PagerIswriteable(pParent->pDbPage) ); - -#if 0 - TRACE(("BALANCE: begin page %d child of %d\n", pPage->pgno, pParent->pgno)); -#endif - - /* At this point pParent may have at most one overflow cell. And if - ** this overflow cell is present, it must be the cell with - ** index iParentIdx. This scenario comes about when this function - ** is called (indirectly) from sqlite3BtreeDelete(). - */ - assert( pParent->nOverflow==0 || pParent->nOverflow==1 ); - assert( pParent->nOverflow==0 || pParent->aiOvfl[0]==iParentIdx ); - - if( !aOvflSpace ){ - return SQLITE_NOMEM_BKPT; - } - - /* Find the sibling pages to balance. Also locate the cells in pParent - ** that divide the siblings. An attempt is made to find NN siblings on - ** either side of pPage. More siblings are taken from one side, however, - ** if there are fewer than NN siblings on the other side. If pParent - ** has NB or fewer children then all children of pParent are taken. - ** - ** This loop also drops the divider cells from the parent page. This - ** way, the remainder of the function does not have to deal with any - ** overflow cells in the parent page, since if any existed they will - ** have already been removed. - */ - i = pParent->nOverflow + pParent->nCell; - if( i<2 ){ - nxDiv = 0; - }else{ - assert( bBulk==0 || bBulk==1 ); - if( iParentIdx==0 ){ - nxDiv = 0; - }else if( iParentIdx==i ){ - nxDiv = i-2+bBulk; - }else{ - nxDiv = iParentIdx-1; - } - i = 2-bBulk; - } - nOld = i+1; - if( (i+nxDiv-pParent->nOverflow)==pParent->nCell ){ - pRight = &pParent->aData[pParent->hdrOffset+8]; - }else{ - pRight = findCell(pParent, i+nxDiv-pParent->nOverflow); - } - pgno = get4byte(pRight); - while( 1 ){ - rc = getAndInitPage(pBt, pgno, &apOld[i], 0, 0); - if( rc ){ - memset(apOld, 0, (i+1)*sizeof(MemPage*)); - goto balance_cleanup; - } - nMaxCells += 1+apOld[i]->nCell+apOld[i]->nOverflow; - if( (i--)==0 ) break; - - if( pParent->nOverflow && i+nxDiv==pParent->aiOvfl[0] ){ - apDiv[i] = pParent->apOvfl[0]; - pgno = get4byte(apDiv[i]); - szNew[i] = pParent->xCellSize(pParent, apDiv[i]); - pParent->nOverflow = 0; - }else{ - apDiv[i] = findCell(pParent, i+nxDiv-pParent->nOverflow); - pgno = get4byte(apDiv[i]); - szNew[i] = pParent->xCellSize(pParent, apDiv[i]); - - /* Drop the cell from the parent page. apDiv[i] still points to - ** the cell within the parent, even though it has been dropped. - ** This is safe because dropping a cell only overwrites the first - ** four bytes of it, and this function does not need the first - ** four bytes of the divider cell. So the pointer is safe to use - ** later on. - ** - ** But not if we are in secure-delete mode. In secure-delete mode, - ** the dropCell() routine will overwrite the entire cell with zeroes. - ** In this case, temporarily copy the cell into the aOvflSpace[] - ** buffer. It will be copied out again as soon as the aSpace[] buffer - ** is allocated. */ - if( pBt->btsFlags & BTS_FAST_SECURE ){ - int iOff; - - iOff = SQLITE_PTR_TO_INT(apDiv[i]) - SQLITE_PTR_TO_INT(pParent->aData); - if( (iOff+szNew[i])>(int)pBt->usableSize ){ - rc = SQLITE_CORRUPT_BKPT; - memset(apOld, 0, (i+1)*sizeof(MemPage*)); - goto balance_cleanup; - }else{ - memcpy(&aOvflSpace[iOff], apDiv[i], szNew[i]); - apDiv[i] = &aOvflSpace[apDiv[i]-pParent->aData]; - } - } - dropCell(pParent, i+nxDiv-pParent->nOverflow, szNew[i], &rc); - } - } - - /* Make nMaxCells a multiple of 4 in order to preserve 8-byte - ** alignment */ - nMaxCells = (nMaxCells + 3)&~3; - - /* - ** Allocate space for memory structures - */ - szScratch = - nMaxCells*sizeof(u8*) /* b.apCell */ - + nMaxCells*sizeof(u16) /* b.szCell */ - + pBt->pageSize; /* aSpace1 */ - - assert( szScratch<=6*(int)pBt->pageSize ); - b.apCell = sqlite3StackAllocRaw(0, szScratch ); - if( b.apCell==0 ){ - rc = SQLITE_NOMEM_BKPT; - goto balance_cleanup; - } - b.szCell = (u16*)&b.apCell[nMaxCells]; - aSpace1 = (u8*)&b.szCell[nMaxCells]; - assert( EIGHT_BYTE_ALIGNMENT(aSpace1) ); - - /* - ** Load pointers to all cells on sibling pages and the divider cells - ** into the local b.apCell[] array. Make copies of the divider cells - ** into space obtained from aSpace1[]. The divider cells have already - ** been removed from pParent. - ** - ** If the siblings are on leaf pages, then the child pointers of the - ** divider cells are stripped from the cells before they are copied - ** into aSpace1[]. In this way, all cells in b.apCell[] are without - ** child pointers. If siblings are not leaves, then all cell in - ** b.apCell[] include child pointers. Either way, all cells in b.apCell[] - ** are alike. - ** - ** leafCorrection: 4 if pPage is a leaf. 0 if pPage is not a leaf. - ** leafData: 1 if pPage holds key+data and pParent holds only keys. - */ - b.pRef = apOld[0]; - leafCorrection = b.pRef->leaf*4; - leafData = b.pRef->intKeyLeaf; - for(i=0; i<nOld; i++){ - MemPage *pOld = apOld[i]; - int limit = pOld->nCell; - u8 *aData = pOld->aData; - u16 maskPage = pOld->maskPage; - u8 *piCell = aData + pOld->cellOffset; - u8 *piEnd; - - /* Verify that all sibling pages are of the same "type" (table-leaf, - ** table-interior, index-leaf, or index-interior). - */ - if( pOld->aData[0]!=apOld[0]->aData[0] ){ - rc = SQLITE_CORRUPT_BKPT; - goto balance_cleanup; - } - - /* Load b.apCell[] with pointers to all cells in pOld. If pOld - ** contains overflow cells, include them in the b.apCell[] array - ** in the correct spot. - ** - ** Note that when there are multiple overflow cells, it is always the - ** case that they are sequential and adjacent. This invariant arises - ** because multiple overflows can only occurs when inserting divider - ** cells into a parent on a prior balance, and divider cells are always - ** adjacent and are inserted in order. There is an assert() tagged - ** with "NOTE 1" in the overflow cell insertion loop to prove this - ** invariant. - ** - ** This must be done in advance. Once the balance starts, the cell - ** offset section of the btree page will be overwritten and we will no - ** long be able to find the cells if a pointer to each cell is not saved - ** first. - */ - memset(&b.szCell[b.nCell], 0, sizeof(b.szCell[0])*(limit+pOld->nOverflow)); - if( pOld->nOverflow>0 ){ - limit = pOld->aiOvfl[0]; - for(j=0; j<limit; j++){ - b.apCell[b.nCell] = aData + (maskPage & get2byteAligned(piCell)); - piCell += 2; - b.nCell++; - } - for(k=0; k<pOld->nOverflow; k++){ - assert( k==0 || pOld->aiOvfl[k-1]+1==pOld->aiOvfl[k] );/* NOTE 1 */ - b.apCell[b.nCell] = pOld->apOvfl[k]; - b.nCell++; - } - } - piEnd = aData + pOld->cellOffset + 2*pOld->nCell; - while( piCell<piEnd ){ - assert( b.nCell<nMaxCells ); - b.apCell[b.nCell] = aData + (maskPage & get2byteAligned(piCell)); - piCell += 2; - b.nCell++; - } - - cntOld[i] = b.nCell; - if( i<nOld-1 && !leafData){ - u16 sz = (u16)szNew[i]; - u8 *pTemp; - assert( b.nCell<nMaxCells ); - b.szCell[b.nCell] = sz; - pTemp = &aSpace1[iSpace1]; - iSpace1 += sz; - assert( sz<=pBt->maxLocal+23 ); - assert( iSpace1 <= (int)pBt->pageSize ); - memcpy(pTemp, apDiv[i], sz); - b.apCell[b.nCell] = pTemp+leafCorrection; - assert( leafCorrection==0 || leafCorrection==4 ); - b.szCell[b.nCell] = b.szCell[b.nCell] - leafCorrection; - if( !pOld->leaf ){ - assert( leafCorrection==0 ); - assert( pOld->hdrOffset==0 ); - /* The right pointer of the child page pOld becomes the left - ** pointer of the divider cell */ - memcpy(b.apCell[b.nCell], &pOld->aData[8], 4); - }else{ - assert( leafCorrection==4 ); - while( b.szCell[b.nCell]<4 ){ - /* Do not allow any cells smaller than 4 bytes. If a smaller cell - ** does exist, pad it with 0x00 bytes. */ - assert( b.szCell[b.nCell]==3 || CORRUPT_DB ); - assert( b.apCell[b.nCell]==&aSpace1[iSpace1-3] || CORRUPT_DB ); - aSpace1[iSpace1++] = 0x00; - b.szCell[b.nCell]++; - } - } - b.nCell++; - } - } - - /* - ** Figure out the number of pages needed to hold all b.nCell cells. - ** Store this number in "k". Also compute szNew[] which is the total - ** size of all cells on the i-th page and cntNew[] which is the index - ** in b.apCell[] of the cell that divides page i from page i+1. - ** cntNew[k] should equal b.nCell. - ** - ** Values computed by this block: - ** - ** k: The total number of sibling pages - ** szNew[i]: Spaced used on the i-th sibling page. - ** cntNew[i]: Index in b.apCell[] and b.szCell[] for the first cell to - ** the right of the i-th sibling page. - ** usableSpace: Number of bytes of space available on each sibling. - ** - */ - usableSpace = pBt->usableSize - 12 + leafCorrection; - for(i=0; i<nOld; i++){ - MemPage *p = apOld[i]; - szNew[i] = usableSpace - p->nFree; - for(j=0; j<p->nOverflow; j++){ - szNew[i] += 2 + p->xCellSize(p, p->apOvfl[j]); - } - cntNew[i] = cntOld[i]; - } - k = nOld; - for(i=0; i<k; i++){ - int sz; - while( szNew[i]>usableSpace ){ - if( i+1>=k ){ - k = i+2; - if( k>NB+2 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; } - szNew[k-1] = 0; - cntNew[k-1] = b.nCell; - } - sz = 2 + cachedCellSize(&b, cntNew[i]-1); - szNew[i] -= sz; - if( !leafData ){ - if( cntNew[i]<b.nCell ){ - sz = 2 + cachedCellSize(&b, cntNew[i]); - }else{ - sz = 0; - } - } - szNew[i+1] += sz; - cntNew[i]--; - } - while( cntNew[i]<b.nCell ){ - sz = 2 + cachedCellSize(&b, cntNew[i]); - if( szNew[i]+sz>usableSpace ) break; - szNew[i] += sz; - cntNew[i]++; - if( !leafData ){ - if( cntNew[i]<b.nCell ){ - sz = 2 + cachedCellSize(&b, cntNew[i]); - }else{ - sz = 0; - } - } - szNew[i+1] -= sz; - } - if( cntNew[i]>=b.nCell ){ - k = i+1; - }else if( cntNew[i] <= (i>0 ? cntNew[i-1] : 0) ){ - rc = SQLITE_CORRUPT_BKPT; - goto balance_cleanup; - } - } - - /* - ** The packing computed by the previous block is biased toward the siblings - ** on the left side (siblings with smaller keys). The left siblings are - ** always nearly full, while the right-most sibling might be nearly empty. - ** The next block of code attempts to adjust the packing of siblings to - ** get a better balance. - ** - ** This adjustment is more than an optimization. The packing above might - ** be so out of balance as to be illegal. For example, the right-most - ** sibling might be completely empty. This adjustment is not optional. - */ - for(i=k-1; i>0; i--){ - int szRight = szNew[i]; /* Size of sibling on the right */ - int szLeft = szNew[i-1]; /* Size of sibling on the left */ - int r; /* Index of right-most cell in left sibling */ - int d; /* Index of first cell to the left of right sibling */ - - r = cntNew[i-1] - 1; - d = r + 1 - leafData; - (void)cachedCellSize(&b, d); - do{ - assert( d<nMaxCells ); - assert( r<nMaxCells ); - (void)cachedCellSize(&b, r); - if( szRight!=0 - && (bBulk || szRight+b.szCell[d]+2 > szLeft-(b.szCell[r]+(i==k-1?0:2)))){ - break; - } - szRight += b.szCell[d] + 2; - szLeft -= b.szCell[r] + 2; - cntNew[i-1] = r; - r--; - d--; - }while( r>=0 ); - szNew[i] = szRight; - szNew[i-1] = szLeft; - if( cntNew[i-1] <= (i>1 ? cntNew[i-2] : 0) ){ - rc = SQLITE_CORRUPT_BKPT; - goto balance_cleanup; - } - } - - /* Sanity check: For a non-corrupt database file one of the follwing - ** must be true: - ** (1) We found one or more cells (cntNew[0])>0), or - ** (2) pPage is a virtual root page. A virtual root page is when - ** the real root page is page 1 and we are the only child of - ** that page. - */ - assert( cntNew[0]>0 || (pParent->pgno==1 && pParent->nCell==0) || CORRUPT_DB); - TRACE(("BALANCE: old: %d(nc=%d) %d(nc=%d) %d(nc=%d)\n", - apOld[0]->pgno, apOld[0]->nCell, - nOld>=2 ? apOld[1]->pgno : 0, nOld>=2 ? apOld[1]->nCell : 0, - nOld>=3 ? apOld[2]->pgno : 0, nOld>=3 ? apOld[2]->nCell : 0 - )); - - /* - ** Allocate k new pages. Reuse old pages where possible. - */ - pageFlags = apOld[0]->aData[0]; - for(i=0; i<k; i++){ - MemPage *pNew; - if( i<nOld ){ - pNew = apNew[i] = apOld[i]; - apOld[i] = 0; - rc = sqlite3PagerWrite(pNew->pDbPage); - nNew++; - if( rc ) goto balance_cleanup; - }else{ - assert( i>0 ); - rc = allocateBtreePage(pBt, &pNew, &pgno, (bBulk ? 1 : pgno), 0); - if( rc ) goto balance_cleanup; - zeroPage(pNew, pageFlags); - apNew[i] = pNew; - nNew++; - cntOld[i] = b.nCell; - - /* Set the pointer-map entry for the new sibling page. */ - if( ISAUTOVACUUM ){ - ptrmapPut(pBt, pNew->pgno, PTRMAP_BTREE, pParent->pgno, &rc); - if( rc!=SQLITE_OK ){ - goto balance_cleanup; - } - } - } - } - - /* - ** Reassign page numbers so that the new pages are in ascending order. - ** This helps to keep entries in the disk file in order so that a scan - ** of the table is closer to a linear scan through the file. That in turn - ** helps the operating system to deliver pages from the disk more rapidly. - ** - ** An O(n^2) insertion sort algorithm is used, but since n is never more - ** than (NB+2) (a small constant), that should not be a problem. - ** - ** When NB==3, this one optimization makes the database about 25% faster - ** for large insertions and deletions. - */ - for(i=0; i<nNew; i++){ - aPgOrder[i] = aPgno[i] = apNew[i]->pgno; - aPgFlags[i] = apNew[i]->pDbPage->flags; - for(j=0; j<i; j++){ - if( aPgno[j]==aPgno[i] ){ - /* This branch is taken if the set of sibling pages somehow contains - ** duplicate entries. This can happen if the database is corrupt. - ** It would be simpler to detect this as part of the loop below, but - ** we do the detection here in order to avoid populating the pager - ** cache with two separate objects associated with the same - ** page number. */ - assert( CORRUPT_DB ); - rc = SQLITE_CORRUPT_BKPT; - goto balance_cleanup; - } - } - } - for(i=0; i<nNew; i++){ - int iBest = 0; /* aPgno[] index of page number to use */ - for(j=1; j<nNew; j++){ - if( aPgOrder[j]<aPgOrder[iBest] ) iBest = j; - } - pgno = aPgOrder[iBest]; - aPgOrder[iBest] = 0xffffffff; - if( iBest!=i ){ - if( iBest>i ){ - sqlite3PagerRekey(apNew[iBest]->pDbPage, pBt->nPage+iBest+1, 0); - } - sqlite3PagerRekey(apNew[i]->pDbPage, pgno, aPgFlags[iBest]); - apNew[i]->pgno = pgno; - } - } - - TRACE(("BALANCE: new: %d(%d nc=%d) %d(%d nc=%d) %d(%d nc=%d) " - "%d(%d nc=%d) %d(%d nc=%d)\n", - apNew[0]->pgno, szNew[0], cntNew[0], - nNew>=2 ? apNew[1]->pgno : 0, nNew>=2 ? szNew[1] : 0, - nNew>=2 ? cntNew[1] - cntNew[0] - !leafData : 0, - nNew>=3 ? apNew[2]->pgno : 0, nNew>=3 ? szNew[2] : 0, - nNew>=3 ? cntNew[2] - cntNew[1] - !leafData : 0, - nNew>=4 ? apNew[3]->pgno : 0, nNew>=4 ? szNew[3] : 0, - nNew>=4 ? cntNew[3] - cntNew[2] - !leafData : 0, - nNew>=5 ? apNew[4]->pgno : 0, nNew>=5 ? szNew[4] : 0, - nNew>=5 ? cntNew[4] - cntNew[3] - !leafData : 0 - )); - - assert( sqlite3PagerIswriteable(pParent->pDbPage) ); - put4byte(pRight, apNew[nNew-1]->pgno); - - /* If the sibling pages are not leaves, ensure that the right-child pointer - ** of the right-most new sibling page is set to the value that was - ** originally in the same field of the right-most old sibling page. */ - if( (pageFlags & PTF_LEAF)==0 && nOld!=nNew ){ - MemPage *pOld = (nNew>nOld ? apNew : apOld)[nOld-1]; - memcpy(&apNew[nNew-1]->aData[8], &pOld->aData[8], 4); - } - - /* Make any required updates to pointer map entries associated with - ** cells stored on sibling pages following the balance operation. Pointer - ** map entries associated with divider cells are set by the insertCell() - ** routine. The associated pointer map entries are: - ** - ** a) if the cell contains a reference to an overflow chain, the - ** entry associated with the first page in the overflow chain, and - ** - ** b) if the sibling pages are not leaves, the child page associated - ** with the cell. - ** - ** If the sibling pages are not leaves, then the pointer map entry - ** associated with the right-child of each sibling may also need to be - ** updated. This happens below, after the sibling pages have been - ** populated, not here. - */ - if( ISAUTOVACUUM ){ - MemPage *pNew = apNew[0]; - u8 *aOld = pNew->aData; - int cntOldNext = pNew->nCell + pNew->nOverflow; - int usableSize = pBt->usableSize; - int iNew = 0; - int iOld = 0; - - for(i=0; i<b.nCell; i++){ - u8 *pCell = b.apCell[i]; - if( i==cntOldNext ){ - MemPage *pOld = (++iOld)<nNew ? apNew[iOld] : apOld[iOld]; - cntOldNext += pOld->nCell + pOld->nOverflow + !leafData; - aOld = pOld->aData; - } - if( i==cntNew[iNew] ){ - pNew = apNew[++iNew]; - if( !leafData ) continue; - } - - /* Cell pCell is destined for new sibling page pNew. Originally, it - ** was either part of sibling page iOld (possibly an overflow cell), - ** or else the divider cell to the left of sibling page iOld. So, - ** if sibling page iOld had the same page number as pNew, and if - ** pCell really was a part of sibling page iOld (not a divider or - ** overflow cell), we can skip updating the pointer map entries. */ - if( iOld>=nNew - || pNew->pgno!=aPgno[iOld] - || !SQLITE_WITHIN(pCell,aOld,&aOld[usableSize]) - ){ - if( !leafCorrection ){ - ptrmapPut(pBt, get4byte(pCell), PTRMAP_BTREE, pNew->pgno, &rc); - } - if( cachedCellSize(&b,i)>pNew->minLocal ){ - ptrmapPutOvflPtr(pNew, pCell, &rc); - } - if( rc ) goto balance_cleanup; - } - } - } - - /* Insert new divider cells into pParent. */ - for(i=0; i<nNew-1; i++){ - u8 *pCell; - u8 *pTemp; - int sz; - MemPage *pNew = apNew[i]; - j = cntNew[i]; - - assert( j<nMaxCells ); - assert( b.apCell[j]!=0 ); - pCell = b.apCell[j]; - sz = b.szCell[j] + leafCorrection; - pTemp = &aOvflSpace[iOvflSpace]; - if( !pNew->leaf ){ - memcpy(&pNew->aData[8], pCell, 4); - }else if( leafData ){ - /* If the tree is a leaf-data tree, and the siblings are leaves, - ** then there is no divider cell in b.apCell[]. Instead, the divider - ** cell consists of the integer key for the right-most cell of - ** the sibling-page assembled above only. - */ - CellInfo info; - j--; - pNew->xParseCell(pNew, b.apCell[j], &info); - pCell = pTemp; - sz = 4 + putVarint(&pCell[4], info.nKey); - pTemp = 0; - }else{ - pCell -= 4; - /* Obscure case for non-leaf-data trees: If the cell at pCell was - ** previously stored on a leaf node, and its reported size was 4 - ** bytes, then it may actually be smaller than this - ** (see btreeParseCellPtr(), 4 bytes is the minimum size of - ** any cell). But it is important to pass the correct size to - ** insertCell(), so reparse the cell now. - ** - ** This can only happen for b-trees used to evaluate "IN (SELECT ...)" - ** and WITHOUT ROWID tables with exactly one column which is the - ** primary key. - */ - if( b.szCell[j]==4 ){ - assert(leafCorrection==4); - sz = pParent->xCellSize(pParent, pCell); - } - } - iOvflSpace += sz; - assert( sz<=pBt->maxLocal+23 ); - assert( iOvflSpace <= (int)pBt->pageSize ); - insertCell(pParent, nxDiv+i, pCell, sz, pTemp, pNew->pgno, &rc); - if( rc!=SQLITE_OK ) goto balance_cleanup; - assert( sqlite3PagerIswriteable(pParent->pDbPage) ); - } - - /* Now update the actual sibling pages. The order in which they are updated - ** is important, as this code needs to avoid disrupting any page from which - ** cells may still to be read. In practice, this means: - ** - ** (1) If cells are moving left (from apNew[iPg] to apNew[iPg-1]) - ** then it is not safe to update page apNew[iPg] until after - ** the left-hand sibling apNew[iPg-1] has been updated. - ** - ** (2) If cells are moving right (from apNew[iPg] to apNew[iPg+1]) - ** then it is not safe to update page apNew[iPg] until after - ** the right-hand sibling apNew[iPg+1] has been updated. - ** - ** If neither of the above apply, the page is safe to update. - ** - ** The iPg value in the following loop starts at nNew-1 goes down - ** to 0, then back up to nNew-1 again, thus making two passes over - ** the pages. On the initial downward pass, only condition (1) above - ** needs to be tested because (2) will always be true from the previous - ** step. On the upward pass, both conditions are always true, so the - ** upwards pass simply processes pages that were missed on the downward - ** pass. - */ - for(i=1-nNew; i<nNew; i++){ - int iPg = i<0 ? -i : i; - assert( iPg>=0 && iPg<nNew ); - if( abDone[iPg] ) continue; /* Skip pages already processed */ - if( i>=0 /* On the upwards pass, or... */ - || cntOld[iPg-1]>=cntNew[iPg-1] /* Condition (1) is true */ - ){ - int iNew; - int iOld; - int nNewCell; - - /* Verify condition (1): If cells are moving left, update iPg - ** only after iPg-1 has already been updated. */ - assert( iPg==0 || cntOld[iPg-1]>=cntNew[iPg-1] || abDone[iPg-1] ); - - /* Verify condition (2): If cells are moving right, update iPg - ** only after iPg+1 has already been updated. */ - assert( cntNew[iPg]>=cntOld[iPg] || abDone[iPg+1] ); - - if( iPg==0 ){ - iNew = iOld = 0; - nNewCell = cntNew[0]; - }else{ - iOld = iPg<nOld ? (cntOld[iPg-1] + !leafData) : b.nCell; - iNew = cntNew[iPg-1] + !leafData; - nNewCell = cntNew[iPg] - iNew; - } - - rc = editPage(apNew[iPg], iOld, iNew, nNewCell, &b); - if( rc ) goto balance_cleanup; - abDone[iPg]++; - apNew[iPg]->nFree = usableSpace-szNew[iPg]; - assert( apNew[iPg]->nOverflow==0 ); - assert( apNew[iPg]->nCell==nNewCell ); - } - } - - /* All pages have been processed exactly once */ - assert( memcmp(abDone, "\01\01\01\01\01", nNew)==0 ); - - assert( nOld>0 ); - assert( nNew>0 ); - - if( isRoot && pParent->nCell==0 && pParent->hdrOffset<=apNew[0]->nFree ){ - /* The root page of the b-tree now contains no cells. The only sibling - ** page is the right-child of the parent. Copy the contents of the - ** child page into the parent, decreasing the overall height of the - ** b-tree structure by one. This is described as the "balance-shallower" - ** sub-algorithm in some documentation. - ** - ** If this is an auto-vacuum database, the call to copyNodeContent() - ** sets all pointer-map entries corresponding to database image pages - ** for which the pointer is stored within the content being copied. - ** - ** It is critical that the child page be defragmented before being - ** copied into the parent, because if the parent is page 1 then it will - ** by smaller than the child due to the database header, and so all the - ** free space needs to be up front. - */ - assert( nNew==1 || CORRUPT_DB ); - rc = defragmentPage(apNew[0], -1); - testcase( rc!=SQLITE_OK ); - assert( apNew[0]->nFree == - (get2byte(&apNew[0]->aData[5])-apNew[0]->cellOffset-apNew[0]->nCell*2) - || rc!=SQLITE_OK - ); - copyNodeContent(apNew[0], pParent, &rc); - freePage(apNew[0], &rc); - }else if( ISAUTOVACUUM && !leafCorrection ){ - /* Fix the pointer map entries associated with the right-child of each - ** sibling page. All other pointer map entries have already been taken - ** care of. */ - for(i=0; i<nNew; i++){ - u32 key = get4byte(&apNew[i]->aData[8]); - ptrmapPut(pBt, key, PTRMAP_BTREE, apNew[i]->pgno, &rc); - } - } - - assert( pParent->isInit ); - TRACE(("BALANCE: finished: old=%d new=%d cells=%d\n", - nOld, nNew, b.nCell)); - - /* Free any old pages that were not reused as new pages. - */ - for(i=nNew; i<nOld; i++){ - freePage(apOld[i], &rc); - } - -#if 0 - if( ISAUTOVACUUM && rc==SQLITE_OK && apNew[0]->isInit ){ - /* The ptrmapCheckPages() contains assert() statements that verify that - ** all pointer map pages are set correctly. This is helpful while - ** debugging. This is usually disabled because a corrupt database may - ** cause an assert() statement to fail. */ - ptrmapCheckPages(apNew, nNew); - ptrmapCheckPages(&pParent, 1); - } -#endif - - /* - ** Cleanup before returning. - */ -balance_cleanup: - sqlite3StackFree(0, b.apCell); - for(i=0; i<nOld; i++){ - releasePage(apOld[i]); - } - for(i=0; i<nNew; i++){ - releasePage(apNew[i]); - } - - return rc; -} - - -/* -** This function is called when the root page of a b-tree structure is -** overfull (has one or more overflow pages). -** -** A new child page is allocated and the contents of the current root -** page, including overflow cells, are copied into the child. The root -** page is then overwritten to make it an empty page with the right-child -** pointer pointing to the new page. -** -** Before returning, all pointer-map entries corresponding to pages -** that the new child-page now contains pointers to are updated. The -** entry corresponding to the new right-child pointer of the root -** page is also updated. -** -** If successful, *ppChild is set to contain a reference to the child -** page and SQLITE_OK is returned. In this case the caller is required -** to call releasePage() on *ppChild exactly once. If an error occurs, -** an error code is returned and *ppChild is set to 0. -*/ -static int balance_deeper(MemPage *pRoot, MemPage **ppChild){ - int rc; /* Return value from subprocedures */ - MemPage *pChild = 0; /* Pointer to a new child page */ - Pgno pgnoChild = 0; /* Page number of the new child page */ - BtShared *pBt = pRoot->pBt; /* The BTree */ - - assert( pRoot->nOverflow>0 ); - assert( sqlite3_mutex_held(pBt->mutex) ); - - /* Make pRoot, the root page of the b-tree, writable. Allocate a new - ** page that will become the new right-child of pPage. Copy the contents - ** of the node stored on pRoot into the new child page. - */ - rc = sqlite3PagerWrite(pRoot->pDbPage); - if( rc==SQLITE_OK ){ - rc = allocateBtreePage(pBt,&pChild,&pgnoChild,pRoot->pgno,0); - copyNodeContent(pRoot, pChild, &rc); - if( ISAUTOVACUUM ){ - ptrmapPut(pBt, pgnoChild, PTRMAP_BTREE, pRoot->pgno, &rc); - } - } - if( rc ){ - *ppChild = 0; - releasePage(pChild); - return rc; - } - assert( sqlite3PagerIswriteable(pChild->pDbPage) ); - assert( sqlite3PagerIswriteable(pRoot->pDbPage) ); - assert( pChild->nCell==pRoot->nCell ); - - TRACE(("BALANCE: copy root %d into %d\n", pRoot->pgno, pChild->pgno)); - - /* Copy the overflow cells from pRoot to pChild */ - memcpy(pChild->aiOvfl, pRoot->aiOvfl, - pRoot->nOverflow*sizeof(pRoot->aiOvfl[0])); - memcpy(pChild->apOvfl, pRoot->apOvfl, - pRoot->nOverflow*sizeof(pRoot->apOvfl[0])); - pChild->nOverflow = pRoot->nOverflow; - - /* Zero the contents of pRoot. Then install pChild as the right-child. */ - zeroPage(pRoot, pChild->aData[0] & ~PTF_LEAF); - put4byte(&pRoot->aData[pRoot->hdrOffset+8], pgnoChild); - - *ppChild = pChild; - return SQLITE_OK; -} - -/* -** The page that pCur currently points to has just been modified in -** some way. This function figures out if this modification means the -** tree needs to be balanced, and if so calls the appropriate balancing -** routine. Balancing routines are: -** -** balance_quick() -** balance_deeper() -** balance_nonroot() -*/ -static int balance(BtCursor *pCur){ - int rc = SQLITE_OK; - const int nMin = pCur->pBt->usableSize * 2 / 3; - u8 aBalanceQuickSpace[13]; - u8 *pFree = 0; - - VVA_ONLY( int balance_quick_called = 0 ); - VVA_ONLY( int balance_deeper_called = 0 ); - - do { - int iPage = pCur->iPage; - MemPage *pPage = pCur->pPage; - - if( iPage==0 ){ - if( pPage->nOverflow ){ - /* The root page of the b-tree is overfull. In this case call the - ** balance_deeper() function to create a new child for the root-page - ** and copy the current contents of the root-page to it. The - ** next iteration of the do-loop will balance the child page. - */ - assert( balance_deeper_called==0 ); - VVA_ONLY( balance_deeper_called++ ); - rc = balance_deeper(pPage, &pCur->apPage[1]); - if( rc==SQLITE_OK ){ - pCur->iPage = 1; - pCur->ix = 0; - pCur->aiIdx[0] = 0; - pCur->apPage[0] = pPage; - pCur->pPage = pCur->apPage[1]; - assert( pCur->pPage->nOverflow ); - } - }else{ - break; - } - }else if( pPage->nOverflow==0 && pPage->nFree<=nMin ){ - break; - }else{ - MemPage * const pParent = pCur->apPage[iPage-1]; - int const iIdx = pCur->aiIdx[iPage-1]; - - rc = sqlite3PagerWrite(pParent->pDbPage); - if( rc==SQLITE_OK ){ -#ifndef SQLITE_OMIT_QUICKBALANCE - if( pPage->intKeyLeaf - && pPage->nOverflow==1 - && pPage->aiOvfl[0]==pPage->nCell - && pParent->pgno!=1 - && pParent->nCell==iIdx - ){ - /* Call balance_quick() to create a new sibling of pPage on which - ** to store the overflow cell. balance_quick() inserts a new cell - ** into pParent, which may cause pParent overflow. If this - ** happens, the next iteration of the do-loop will balance pParent - ** use either balance_nonroot() or balance_deeper(). Until this - ** happens, the overflow cell is stored in the aBalanceQuickSpace[] - ** buffer. - ** - ** The purpose of the following assert() is to check that only a - ** single call to balance_quick() is made for each call to this - ** function. If this were not verified, a subtle bug involving reuse - ** of the aBalanceQuickSpace[] might sneak in. - */ - assert( balance_quick_called==0 ); - VVA_ONLY( balance_quick_called++ ); - rc = balance_quick(pParent, pPage, aBalanceQuickSpace); - }else -#endif - { - /* In this case, call balance_nonroot() to redistribute cells - ** between pPage and up to 2 of its sibling pages. This involves - ** modifying the contents of pParent, which may cause pParent to - ** become overfull or underfull. The next iteration of the do-loop - ** will balance the parent page to correct this. - ** - ** If the parent page becomes overfull, the overflow cell or cells - ** are stored in the pSpace buffer allocated immediately below. - ** A subsequent iteration of the do-loop will deal with this by - ** calling balance_nonroot() (balance_deeper() may be called first, - ** but it doesn't deal with overflow cells - just moves them to a - ** different page). Once this subsequent call to balance_nonroot() - ** has completed, it is safe to release the pSpace buffer used by - ** the previous call, as the overflow cell data will have been - ** copied either into the body of a database page or into the new - ** pSpace buffer passed to the latter call to balance_nonroot(). - */ - u8 *pSpace = sqlite3PageMalloc(pCur->pBt->pageSize); - rc = balance_nonroot(pParent, iIdx, pSpace, iPage==1, - pCur->hints&BTREE_BULKLOAD); - if( pFree ){ - /* If pFree is not NULL, it points to the pSpace buffer used - ** by a previous call to balance_nonroot(). Its contents are - ** now stored either on real database pages or within the - ** new pSpace buffer, so it may be safely freed here. */ - sqlite3PageFree(pFree); - } - - /* The pSpace buffer will be freed after the next call to - ** balance_nonroot(), or just before this function returns, whichever - ** comes first. */ - pFree = pSpace; - } - } - - pPage->nOverflow = 0; - - /* The next iteration of the do-loop balances the parent page. */ - releasePage(pPage); - pCur->iPage--; - assert( pCur->iPage>=0 ); - pCur->pPage = pCur->apPage[pCur->iPage]; - } - }while( rc==SQLITE_OK ); - - if( pFree ){ - sqlite3PageFree(pFree); - } - return rc; -} - -/* Overwrite content from pX into pDest. Only do the write if the -** content is different from what is already there. -*/ -static int btreeOverwriteContent( - MemPage *pPage, /* MemPage on which writing will occur */ - u8 *pDest, /* Pointer to the place to start writing */ - const BtreePayload *pX, /* Source of data to write */ - int iOffset, /* Offset of first byte to write */ - int iAmt /* Number of bytes to be written */ -){ - int nData = pX->nData - iOffset; - if( nData<=0 ){ - /* Overwritting with zeros */ - int i; - for(i=0; i<iAmt && pDest[i]==0; i++){} - if( i<iAmt ){ - int rc = sqlite3PagerWrite(pPage->pDbPage); - if( rc ) return rc; - memset(pDest + i, 0, iAmt - i); - } - }else{ - if( nData<iAmt ){ - /* Mixed read data and zeros at the end. Make a recursive call - ** to write the zeros then fall through to write the real data */ - int rc = btreeOverwriteContent(pPage, pDest+nData, pX, iOffset+nData, - iAmt-nData); - if( rc ) return rc; - iAmt = nData; - } - if( memcmp(pDest, ((u8*)pX->pData) + iOffset, iAmt)!=0 ){ - int rc = sqlite3PagerWrite(pPage->pDbPage); - if( rc ) return rc; - memcpy(pDest, ((u8*)pX->pData) + iOffset, iAmt); - } - } - return SQLITE_OK; -} - -/* -** Overwrite the cell that cursor pCur is pointing to with fresh content -** contained in pX. -*/ -static int btreeOverwriteCell(BtCursor *pCur, const BtreePayload *pX){ - int iOffset; /* Next byte of pX->pData to write */ - int nTotal = pX->nData + pX->nZero; /* Total bytes of to write */ - int rc; /* Return code */ - MemPage *pPage = pCur->pPage; /* Page being written */ - BtShared *pBt; /* Btree */ - Pgno ovflPgno; /* Next overflow page to write */ - u32 ovflPageSize; /* Size to write on overflow page */ - - if( pCur->info.pPayload + pCur->info.nLocal > pPage->aDataEnd ){ - return SQLITE_CORRUPT_BKPT; - } - /* Overwrite the local portion first */ - rc = btreeOverwriteContent(pPage, pCur->info.pPayload, pX, - 0, pCur->info.nLocal); - if( rc ) return rc; - if( pCur->info.nLocal==nTotal ) return SQLITE_OK; - - /* Now overwrite the overflow pages */ - iOffset = pCur->info.nLocal; - assert( nTotal>=0 ); - assert( iOffset>=0 ); - ovflPgno = get4byte(pCur->info.pPayload + iOffset); - pBt = pPage->pBt; - ovflPageSize = pBt->usableSize - 4; - do{ - rc = btreeGetPage(pBt, ovflPgno, &pPage, 0); - if( rc ) return rc; - if( sqlite3PagerPageRefcount(pPage->pDbPage)!=1 ){ - rc = SQLITE_CORRUPT_BKPT; - }else{ - if( iOffset+ovflPageSize<(u32)nTotal ){ - ovflPgno = get4byte(pPage->aData); - }else{ - ovflPageSize = nTotal - iOffset; - } - rc = btreeOverwriteContent(pPage, pPage->aData+4, pX, - iOffset, ovflPageSize); - } - sqlite3PagerUnref(pPage->pDbPage); - if( rc ) return rc; - iOffset += ovflPageSize; - }while( iOffset<nTotal ); - return SQLITE_OK; -} - - -/* -** Insert a new record into the BTree. The content of the new record -** is described by the pX object. The pCur cursor is used only to -** define what table the record should be inserted into, and is left -** pointing at a random location. -** -** For a table btree (used for rowid tables), only the pX.nKey value of -** the key is used. The pX.pKey value must be NULL. The pX.nKey is the -** rowid or INTEGER PRIMARY KEY of the row. The pX.nData,pData,nZero fields -** hold the content of the row. -** -** For an index btree (used for indexes and WITHOUT ROWID tables), the -** key is an arbitrary byte sequence stored in pX.pKey,nKey. The -** pX.pData,nData,nZero fields must be zero. -** -** If the seekResult parameter is non-zero, then a successful call to -** MovetoUnpacked() to seek cursor pCur to (pKey,nKey) has already -** been performed. In other words, if seekResult!=0 then the cursor -** is currently pointing to a cell that will be adjacent to the cell -** to be inserted. If seekResult<0 then pCur points to a cell that is -** smaller then (pKey,nKey). If seekResult>0 then pCur points to a cell -** that is larger than (pKey,nKey). -** -** If seekResult==0, that means pCur is pointing at some unknown location. -** In that case, this routine must seek the cursor to the correct insertion -** point for (pKey,nKey) before doing the insertion. For index btrees, -** if pX->nMem is non-zero, then pX->aMem contains pointers to the unpacked -** key values and pX->aMem can be used instead of pX->pKey to avoid having -** to decode the key. -*/ -int sqlite3BtreeInsert( - BtCursor *pCur, /* Insert data into the table of this cursor */ - const BtreePayload *pX, /* Content of the row to be inserted */ - int flags, /* True if this is likely an append */ - int seekResult /* Result of prior MovetoUnpacked() call */ -){ - int rc; - int loc = seekResult; /* -1: before desired location +1: after */ - int szNew = 0; - int idx; - MemPage *pPage; - Btree *p = pCur->pBtree; - BtShared *pBt = p->pBt; - unsigned char *oldCell; - unsigned char *newCell = 0; - - assert( (flags & (BTREE_SAVEPOSITION|BTREE_APPEND))==flags ); - - if( pCur->eState==CURSOR_FAULT ){ - assert( pCur->skipNext!=SQLITE_OK ); - return pCur->skipNext; - } - - assert( cursorOwnsBtShared(pCur) ); - assert( (pCur->curFlags & BTCF_WriteFlag)!=0 - && pBt->inTransaction==TRANS_WRITE - && (pBt->btsFlags & BTS_READ_ONLY)==0 ); - assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) ); - - /* Assert that the caller has been consistent. If this cursor was opened - ** expecting an index b-tree, then the caller should be inserting blob - ** keys with no associated data. If the cursor was opened expecting an - ** intkey table, the caller should be inserting integer keys with a - ** blob of associated data. */ - assert( (pX->pKey==0)==(pCur->pKeyInfo==0) ); - - /* Save the positions of any other cursors open on this table. - ** - ** In some cases, the call to btreeMoveto() below is a no-op. For - ** example, when inserting data into a table with auto-generated integer - ** keys, the VDBE layer invokes sqlite3BtreeLast() to figure out the - ** integer key to use. It then calls this function to actually insert the - ** data into the intkey B-Tree. In this case btreeMoveto() recognizes - ** that the cursor is already where it needs to be and returns without - ** doing any work. To avoid thwarting these optimizations, it is important - ** not to clear the cursor here. - */ - if( pCur->curFlags & BTCF_Multiple ){ - rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur); - if( rc ) return rc; - } - - if( pCur->pKeyInfo==0 ){ - assert( pX->pKey==0 ); - /* If this is an insert into a table b-tree, invalidate any incrblob - ** cursors open on the row being replaced */ - invalidateIncrblobCursors(p, pCur->pgnoRoot, pX->nKey, 0); - - /* If BTREE_SAVEPOSITION is set, the cursor must already be pointing - ** to a row with the same key as the new entry being inserted. - */ -#ifdef SQLITE_DEBUG - if( flags & BTREE_SAVEPOSITION ){ - assert( pCur->curFlags & BTCF_ValidNKey ); - assert( pX->nKey==pCur->info.nKey ); - assert( pCur->info.nSize!=0 ); - assert( loc==0 ); - } -#endif - - /* On the other hand, BTREE_SAVEPOSITION==0 does not imply - ** that the cursor is not pointing to a row to be overwritten. - ** So do a complete check. - */ - if( (pCur->curFlags&BTCF_ValidNKey)!=0 && pX->nKey==pCur->info.nKey ){ - /* The cursor is pointing to the entry that is to be - ** overwritten */ - assert( pX->nData>=0 && pX->nZero>=0 ); - if( pCur->info.nSize!=0 - && pCur->info.nPayload==(u32)pX->nData+pX->nZero - ){ - /* New entry is the same size as the old. Do an overwrite */ - return btreeOverwriteCell(pCur, pX); - } - assert( loc==0 ); - }else if( loc==0 ){ - /* The cursor is *not* pointing to the cell to be overwritten, nor - ** to an adjacent cell. Move the cursor so that it is pointing either - ** to the cell to be overwritten or an adjacent cell. - */ - rc = sqlite3BtreeMovetoUnpacked(pCur, 0, pX->nKey, flags!=0, &loc); - if( rc ) return rc; - } - }else{ - /* This is an index or a WITHOUT ROWID table */ - - /* If BTREE_SAVEPOSITION is set, the cursor must already be pointing - ** to a row with the same key as the new entry being inserted. - */ - assert( (flags & BTREE_SAVEPOSITION)==0 || loc==0 ); - - /* If the cursor is not already pointing either to the cell to be - ** overwritten, or if a new cell is being inserted, if the cursor is - ** not pointing to an immediately adjacent cell, then move the cursor - ** so that it does. - */ - if( loc==0 && (flags & BTREE_SAVEPOSITION)==0 ){ - if( pX->nMem ){ - UnpackedRecord r; - r.pKeyInfo = pCur->pKeyInfo; - r.aMem = pX->aMem; - r.nField = pX->nMem; - r.default_rc = 0; - r.errCode = 0; - r.r1 = 0; - r.r2 = 0; - r.eqSeen = 0; - rc = sqlite3BtreeMovetoUnpacked(pCur, &r, 0, flags!=0, &loc); - }else{ - rc = btreeMoveto(pCur, pX->pKey, pX->nKey, flags!=0, &loc); - } - if( rc ) return rc; - } - - /* If the cursor is currently pointing to an entry to be overwritten - ** and the new content is the same as as the old, then use the - ** overwrite optimization. - */ - if( loc==0 ){ - getCellInfo(pCur); - if( pCur->info.nKey==pX->nKey ){ - BtreePayload x2; - x2.pData = pX->pKey; - x2.nData = pX->nKey; - x2.nZero = 0; - return btreeOverwriteCell(pCur, &x2); - } - } - - } - assert( pCur->eState==CURSOR_VALID || (pCur->eState==CURSOR_INVALID && loc) ); - - pPage = pCur->pPage; - assert( pPage->intKey || pX->nKey>=0 ); - assert( pPage->leaf || !pPage->intKey ); - - TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n", - pCur->pgnoRoot, pX->nKey, pX->nData, pPage->pgno, - loc==0 ? "overwrite" : "new entry")); - assert( pPage->isInit ); - newCell = pBt->pTmpSpace; - assert( newCell!=0 ); - rc = fillInCell(pPage, newCell, pX, &szNew); - if( rc ) goto end_insert; - assert( szNew==pPage->xCellSize(pPage, newCell) ); - assert( szNew <= MX_CELL_SIZE(pBt) ); - idx = pCur->ix; - if( loc==0 ){ - CellInfo info; - assert( idx<pPage->nCell ); - rc = sqlite3PagerWrite(pPage->pDbPage); - if( rc ){ - goto end_insert; - } - oldCell = findCell(pPage, idx); - if( !pPage->leaf ){ - memcpy(newCell, oldCell, 4); - } - rc = clearCell(pPage, oldCell, &info); - if( info.nSize==szNew && info.nLocal==info.nPayload - && (!ISAUTOVACUUM || szNew<pPage->minLocal) - ){ - /* Overwrite the old cell with the new if they are the same size. - ** We could also try to do this if the old cell is smaller, then add - ** the leftover space to the free list. But experiments show that - ** doing that is no faster then skipping this optimization and just - ** calling dropCell() and insertCell(). - ** - ** This optimization cannot be used on an autovacuum database if the - ** new entry uses overflow pages, as the insertCell() call below is - ** necessary to add the PTRMAP_OVERFLOW1 pointer-map entry. */ - assert( rc==SQLITE_OK ); /* clearCell never fails when nLocal==nPayload */ - if( oldCell+szNew > pPage->aDataEnd ) return SQLITE_CORRUPT_BKPT; - memcpy(oldCell, newCell, szNew); - return SQLITE_OK; - } - dropCell(pPage, idx, info.nSize, &rc); - if( rc ) goto end_insert; - }else if( loc<0 && pPage->nCell>0 ){ - assert( pPage->leaf ); - idx = ++pCur->ix; - pCur->curFlags &= ~BTCF_ValidNKey; - }else{ - assert( pPage->leaf ); - } - insertCell(pPage, idx, newCell, szNew, 0, 0, &rc); - assert( pPage->nOverflow==0 || rc==SQLITE_OK ); - assert( rc!=SQLITE_OK || pPage->nCell>0 || pPage->nOverflow>0 ); - - /* If no error has occurred and pPage has an overflow cell, call balance() - ** to redistribute the cells within the tree. Since balance() may move - ** the cursor, zero the BtCursor.info.nSize and BTCF_ValidNKey - ** variables. - ** - ** Previous versions of SQLite called moveToRoot() to move the cursor - ** back to the root page as balance() used to invalidate the contents - ** of BtCursor.apPage[] and BtCursor.aiIdx[]. Instead of doing that, - ** set the cursor state to "invalid". This makes common insert operations - ** slightly faster. - ** - ** There is a subtle but important optimization here too. When inserting - ** multiple records into an intkey b-tree using a single cursor (as can - ** happen while processing an "INSERT INTO ... SELECT" statement), it - ** is advantageous to leave the cursor pointing to the last entry in - ** the b-tree if possible. If the cursor is left pointing to the last - ** entry in the table, and the next row inserted has an integer key - ** larger than the largest existing key, it is possible to insert the - ** row without seeking the cursor. This can be a big performance boost. - */ - pCur->info.nSize = 0; - if( pPage->nOverflow ){ - assert( rc==SQLITE_OK ); - pCur->curFlags &= ~(BTCF_ValidNKey); - rc = balance(pCur); - - /* Must make sure nOverflow is reset to zero even if the balance() - ** fails. Internal data structure corruption will result otherwise. - ** Also, set the cursor state to invalid. This stops saveCursorPosition() - ** from trying to save the current position of the cursor. */ - pCur->pPage->nOverflow = 0; - pCur->eState = CURSOR_INVALID; - if( (flags & BTREE_SAVEPOSITION) && rc==SQLITE_OK ){ - btreeReleaseAllCursorPages(pCur); - if( pCur->pKeyInfo ){ - assert( pCur->pKey==0 ); - pCur->pKey = sqlite3Malloc( pX->nKey ); - if( pCur->pKey==0 ){ - rc = SQLITE_NOMEM; - }else{ - memcpy(pCur->pKey, pX->pKey, pX->nKey); - } - } - pCur->eState = CURSOR_REQUIRESEEK; - pCur->nKey = pX->nKey; - } - } - assert( pCur->iPage<0 || pCur->pPage->nOverflow==0 ); - -end_insert: - return rc; -} - -/* -** Delete the entry that the cursor is pointing to. -** -** If the BTREE_SAVEPOSITION bit of the flags parameter is zero, then -** the cursor is left pointing at an arbitrary location after the delete. -** But if that bit is set, then the cursor is left in a state such that -** the next call to BtreeNext() or BtreePrev() moves it to the same row -** as it would have been on if the call to BtreeDelete() had been omitted. -** -** The BTREE_AUXDELETE bit of flags indicates that is one of several deletes -** associated with a single table entry and its indexes. Only one of those -** deletes is considered the "primary" delete. The primary delete occurs -** on a cursor that is not a BTREE_FORDELETE cursor. All but one delete -** operation on non-FORDELETE cursors is tagged with the AUXDELETE flag. -** The BTREE_AUXDELETE bit is a hint that is not used by this implementation, -** but which might be used by alternative storage engines. -*/ -int sqlite3BtreeDelete(BtCursor *pCur, u8 flags){ - Btree *p = pCur->pBtree; - BtShared *pBt = p->pBt; - int rc; /* Return code */ - MemPage *pPage; /* Page to delete cell from */ - unsigned char *pCell; /* Pointer to cell to delete */ - int iCellIdx; /* Index of cell to delete */ - int iCellDepth; /* Depth of node containing pCell */ - CellInfo info; /* Size of the cell being deleted */ - int bSkipnext = 0; /* Leaf cursor in SKIPNEXT state */ - u8 bPreserve = flags & BTREE_SAVEPOSITION; /* Keep cursor valid */ - - assert( cursorOwnsBtShared(pCur) ); - assert( pBt->inTransaction==TRANS_WRITE ); - assert( (pBt->btsFlags & BTS_READ_ONLY)==0 ); - assert( pCur->curFlags & BTCF_WriteFlag ); - assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) ); - assert( !hasReadConflicts(p, pCur->pgnoRoot) ); - assert( pCur->ix<pCur->pPage->nCell ); - assert( pCur->eState==CURSOR_VALID ); - assert( (flags & ~(BTREE_SAVEPOSITION | BTREE_AUXDELETE))==0 ); - - iCellDepth = pCur->iPage; - iCellIdx = pCur->ix; - pPage = pCur->pPage; - pCell = findCell(pPage, iCellIdx); - - /* If the bPreserve flag is set to true, then the cursor position must - ** be preserved following this delete operation. If the current delete - ** will cause a b-tree rebalance, then this is done by saving the cursor - ** key and leaving the cursor in CURSOR_REQUIRESEEK state before - ** returning. - ** - ** Or, if the current delete will not cause a rebalance, then the cursor - ** will be left in CURSOR_SKIPNEXT state pointing to the entry immediately - ** before or after the deleted entry. In this case set bSkipnext to true. */ - if( bPreserve ){ - if( !pPage->leaf - || (pPage->nFree+cellSizePtr(pPage,pCell)+2)>(int)(pBt->usableSize*2/3) - ){ - /* A b-tree rebalance will be required after deleting this entry. - ** Save the cursor key. */ - rc = saveCursorKey(pCur); - if( rc ) return rc; - }else{ - bSkipnext = 1; - } - } - - /* If the page containing the entry to delete is not a leaf page, move - ** the cursor to the largest entry in the tree that is smaller than - ** the entry being deleted. This cell will replace the cell being deleted - ** from the internal node. The 'previous' entry is used for this instead - ** of the 'next' entry, as the previous entry is always a part of the - ** sub-tree headed by the child page of the cell being deleted. This makes - ** balancing the tree following the delete operation easier. */ - if( !pPage->leaf ){ - rc = sqlite3BtreePrevious(pCur, 0); - assert( rc!=SQLITE_DONE ); - if( rc ) return rc; - } - - /* Save the positions of any other cursors open on this table before - ** making any modifications. */ - if( pCur->curFlags & BTCF_Multiple ){ - rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur); - if( rc ) return rc; - } - - /* If this is a delete operation to remove a row from a table b-tree, - ** invalidate any incrblob cursors open on the row being deleted. */ - if( pCur->pKeyInfo==0 ){ - invalidateIncrblobCursors(p, pCur->pgnoRoot, pCur->info.nKey, 0); - } - - /* Make the page containing the entry to be deleted writable. Then free any - ** overflow pages associated with the entry and finally remove the cell - ** itself from within the page. */ - rc = sqlite3PagerWrite(pPage->pDbPage); - if( rc ) return rc; - rc = clearCell(pPage, pCell, &info); - dropCell(pPage, iCellIdx, info.nSize, &rc); - if( rc ) return rc; - - /* If the cell deleted was not located on a leaf page, then the cursor - ** is currently pointing to the largest entry in the sub-tree headed - ** by the child-page of the cell that was just deleted from an internal - ** node. The cell from the leaf node needs to be moved to the internal - ** node to replace the deleted cell. */ - if( !pPage->leaf ){ - MemPage *pLeaf = pCur->pPage; - int nCell; - Pgno n; - unsigned char *pTmp; - - if( iCellDepth<pCur->iPage-1 ){ - n = pCur->apPage[iCellDepth+1]->pgno; - }else{ - n = pCur->pPage->pgno; - } - pCell = findCell(pLeaf, pLeaf->nCell-1); - if( pCell<&pLeaf->aData[4] ) return SQLITE_CORRUPT_BKPT; - nCell = pLeaf->xCellSize(pLeaf, pCell); - assert( MX_CELL_SIZE(pBt) >= nCell ); - pTmp = pBt->pTmpSpace; - assert( pTmp!=0 ); - rc = sqlite3PagerWrite(pLeaf->pDbPage); - if( rc==SQLITE_OK ){ - insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc); - } - dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc); - if( rc ) return rc; - } - - /* Balance the tree. If the entry deleted was located on a leaf page, - ** then the cursor still points to that page. In this case the first - ** call to balance() repairs the tree, and the if(...) condition is - ** never true. - ** - ** Otherwise, if the entry deleted was on an internal node page, then - ** pCur is pointing to the leaf page from which a cell was removed to - ** replace the cell deleted from the internal node. This is slightly - ** tricky as the leaf node may be underfull, and the internal node may - ** be either under or overfull. In this case run the balancing algorithm - ** on the leaf node first. If the balance proceeds far enough up the - ** tree that we can be sure that any problem in the internal node has - ** been corrected, so be it. Otherwise, after balancing the leaf node, - ** walk the cursor up the tree to the internal node and balance it as - ** well. */ - rc = balance(pCur); - if( rc==SQLITE_OK && pCur->iPage>iCellDepth ){ - releasePageNotNull(pCur->pPage); - pCur->iPage--; - while( pCur->iPage>iCellDepth ){ - releasePage(pCur->apPage[pCur->iPage--]); - } - pCur->pPage = pCur->apPage[pCur->iPage]; - rc = balance(pCur); - } - - if( rc==SQLITE_OK ){ - if( bSkipnext ){ - assert( bPreserve && (pCur->iPage==iCellDepth || CORRUPT_DB) ); - assert( pPage==pCur->pPage || CORRUPT_DB ); - assert( (pPage->nCell>0 || CORRUPT_DB) && iCellIdx<=pPage->nCell ); - pCur->eState = CURSOR_SKIPNEXT; - if( iCellIdx>=pPage->nCell ){ - pCur->skipNext = -1; - pCur->ix = pPage->nCell-1; - }else{ - pCur->skipNext = 1; - } - }else{ - rc = moveToRoot(pCur); - if( bPreserve ){ - btreeReleaseAllCursorPages(pCur); - pCur->eState = CURSOR_REQUIRESEEK; - } - if( rc==SQLITE_EMPTY ) rc = SQLITE_OK; - } - } - return rc; -} - -/* -** Create a new BTree table. Write into *piTable the page -** number for the root page of the new table. -** -** The type of type is determined by the flags parameter. Only the -** following values of flags are currently in use. Other values for -** flags might not work: -** -** BTREE_INTKEY|BTREE_LEAFDATA Used for SQL tables with rowid keys -** BTREE_ZERODATA Used for SQL indices -*/ -static int btreeCreateTable(Btree *p, int *piTable, int createTabFlags){ - BtShared *pBt = p->pBt; - MemPage *pRoot; - Pgno pgnoRoot; - int rc; - int ptfFlags; /* Page-type flage for the root page of new table */ - - assert( sqlite3BtreeHoldsMutex(p) ); - assert( pBt->inTransaction==TRANS_WRITE ); - assert( (pBt->btsFlags & BTS_READ_ONLY)==0 ); - -#ifdef SQLITE_OMIT_AUTOVACUUM - rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0); - if( rc ){ - return rc; - } -#else - if( pBt->autoVacuum ){ - Pgno pgnoMove; /* Move a page here to make room for the root-page */ - MemPage *pPageMove; /* The page to move to. */ - - /* Creating a new table may probably require moving an existing database - ** to make room for the new tables root page. In case this page turns - ** out to be an overflow page, delete all overflow page-map caches - ** held by open cursors. - */ - invalidateAllOverflowCache(pBt); - - /* Read the value of meta[3] from the database to determine where the - ** root page of the new table should go. meta[3] is the largest root-page - ** created so far, so the new root-page is (meta[3]+1). - */ - sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &pgnoRoot); - pgnoRoot++; - - /* The new root-page may not be allocated on a pointer-map page, or the - ** PENDING_BYTE page. - */ - while( pgnoRoot==PTRMAP_PAGENO(pBt, pgnoRoot) || - pgnoRoot==PENDING_BYTE_PAGE(pBt) ){ - pgnoRoot++; - } - assert( pgnoRoot>=3 || CORRUPT_DB ); - testcase( pgnoRoot<3 ); - - /* Allocate a page. The page that currently resides at pgnoRoot will - ** be moved to the allocated page (unless the allocated page happens - ** to reside at pgnoRoot). - */ - rc = allocateBtreePage(pBt, &pPageMove, &pgnoMove, pgnoRoot, BTALLOC_EXACT); - if( rc!=SQLITE_OK ){ - return rc; - } - - if( pgnoMove!=pgnoRoot ){ - /* pgnoRoot is the page that will be used for the root-page of - ** the new table (assuming an error did not occur). But we were - ** allocated pgnoMove. If required (i.e. if it was not allocated - ** by extending the file), the current page at position pgnoMove - ** is already journaled. - */ - u8 eType = 0; - Pgno iPtrPage = 0; - - /* Save the positions of any open cursors. This is required in - ** case they are holding a reference to an xFetch reference - ** corresponding to page pgnoRoot. */ - rc = saveAllCursors(pBt, 0, 0); - releasePage(pPageMove); - if( rc!=SQLITE_OK ){ - return rc; - } - - /* Move the page currently at pgnoRoot to pgnoMove. */ - rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0); - if( rc!=SQLITE_OK ){ - return rc; - } - rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage); - if( eType==PTRMAP_ROOTPAGE || eType==PTRMAP_FREEPAGE ){ - rc = SQLITE_CORRUPT_BKPT; - } - if( rc!=SQLITE_OK ){ - releasePage(pRoot); - return rc; - } - assert( eType!=PTRMAP_ROOTPAGE ); - assert( eType!=PTRMAP_FREEPAGE ); - rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove, 0); - releasePage(pRoot); - - /* Obtain the page at pgnoRoot */ - if( rc!=SQLITE_OK ){ - return rc; - } - rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0); - if( rc!=SQLITE_OK ){ - return rc; - } - rc = sqlite3PagerWrite(pRoot->pDbPage); - if( rc!=SQLITE_OK ){ - releasePage(pRoot); - return rc; - } - }else{ - pRoot = pPageMove; - } - - /* Update the pointer-map and meta-data with the new root-page number. */ - ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0, &rc); - if( rc ){ - releasePage(pRoot); - return rc; - } - - /* When the new root page was allocated, page 1 was made writable in - ** order either to increase the database filesize, or to decrement the - ** freelist count. Hence, the sqlite3BtreeUpdateMeta() call cannot fail. - */ - assert( sqlite3PagerIswriteable(pBt->pPage1->pDbPage) ); - rc = sqlite3BtreeUpdateMeta(p, 4, pgnoRoot); - if( NEVER(rc) ){ - releasePage(pRoot); - return rc; - } - - }else{ - rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0); - if( rc ) return rc; - } -#endif - assert( sqlite3PagerIswriteable(pRoot->pDbPage) ); - if( createTabFlags & BTREE_INTKEY ){ - ptfFlags = PTF_INTKEY | PTF_LEAFDATA | PTF_LEAF; - }else{ - ptfFlags = PTF_ZERODATA | PTF_LEAF; - } - zeroPage(pRoot, ptfFlags); - sqlite3PagerUnref(pRoot->pDbPage); - assert( (pBt->openFlags & BTREE_SINGLE)==0 || pgnoRoot==2 ); - *piTable = (int)pgnoRoot; - return SQLITE_OK; -} -int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){ - int rc; - sqlite3BtreeEnter(p); - rc = btreeCreateTable(p, piTable, flags); - sqlite3BtreeLeave(p); - return rc; -} - -/* -** Erase the given database page and all its children. Return -** the page to the freelist. -*/ -static int clearDatabasePage( - BtShared *pBt, /* The BTree that contains the table */ - Pgno pgno, /* Page number to clear */ - int freePageFlag, /* Deallocate page if true */ - int *pnChange /* Add number of Cells freed to this counter */ -){ - MemPage *pPage; - int rc; - unsigned char *pCell; - int i; - int hdr; - CellInfo info; - - assert( sqlite3_mutex_held(pBt->mutex) ); - if( pgno>btreePagecount(pBt) ){ - return SQLITE_CORRUPT_BKPT; - } - rc = getAndInitPage(pBt, pgno, &pPage, 0, 0); - if( rc ) return rc; - if( pPage->bBusy ){ - rc = SQLITE_CORRUPT_BKPT; - goto cleardatabasepage_out; - } - pPage->bBusy = 1; - hdr = pPage->hdrOffset; - for(i=0; i<pPage->nCell; i++){ - pCell = findCell(pPage, i); - if( !pPage->leaf ){ - rc = clearDatabasePage(pBt, get4byte(pCell), 1, pnChange); - if( rc ) goto cleardatabasepage_out; - } - rc = clearCell(pPage, pCell, &info); - if( rc ) goto cleardatabasepage_out; - } - if( !pPage->leaf ){ - rc = clearDatabasePage(pBt, get4byte(&pPage->aData[hdr+8]), 1, pnChange); - if( rc ) goto cleardatabasepage_out; - }else if( pnChange ){ - assert( pPage->intKey || CORRUPT_DB ); - testcase( !pPage->intKey ); - *pnChange += pPage->nCell; - } - if( freePageFlag ){ - freePage(pPage, &rc); - }else if( (rc = sqlite3PagerWrite(pPage->pDbPage))==0 ){ - zeroPage(pPage, pPage->aData[hdr] | PTF_LEAF); - } - -cleardatabasepage_out: - pPage->bBusy = 0; - releasePage(pPage); - return rc; -} - -/* -** Delete all information from a single table in the database. iTable is -** the page number of the root of the table. After this routine returns, -** the root page is empty, but still exists. -** -** This routine will fail with SQLITE_LOCKED if there are any open -** read cursors on the table. Open write cursors are moved to the -** root of the table. -** -** If pnChange is not NULL, then table iTable must be an intkey table. The -** integer value pointed to by pnChange is incremented by the number of -** entries in the table. -*/ -int sqlite3BtreeClearTable(Btree *p, int iTable, int *pnChange){ - int rc; - BtShared *pBt = p->pBt; - sqlite3BtreeEnter(p); - assert( p->inTrans==TRANS_WRITE ); - - rc = saveAllCursors(pBt, (Pgno)iTable, 0); - - if( SQLITE_OK==rc ){ - /* Invalidate all incrblob cursors open on table iTable (assuming iTable - ** is the root of a table b-tree - if it is not, the following call is - ** a no-op). */ - invalidateIncrblobCursors(p, (Pgno)iTable, 0, 1); - rc = clearDatabasePage(pBt, (Pgno)iTable, 0, pnChange); - } - sqlite3BtreeLeave(p); - return rc; -} - -/* -** Delete all information from the single table that pCur is open on. -** -** This routine only work for pCur on an ephemeral table. -*/ -int sqlite3BtreeClearTableOfCursor(BtCursor *pCur){ - return sqlite3BtreeClearTable(pCur->pBtree, pCur->pgnoRoot, 0); -} - -/* -** Erase all information in a table and add the root of the table to -** the freelist. Except, the root of the principle table (the one on -** page 1) is never added to the freelist. -** -** This routine will fail with SQLITE_LOCKED if there are any open -** cursors on the table. -** -** If AUTOVACUUM is enabled and the page at iTable is not the last -** root page in the database file, then the last root page -** in the database file is moved into the slot formerly occupied by -** iTable and that last slot formerly occupied by the last root page -** is added to the freelist instead of iTable. In this say, all -** root pages are kept at the beginning of the database file, which -** is necessary for AUTOVACUUM to work right. *piMoved is set to the -** page number that used to be the last root page in the file before -** the move. If no page gets moved, *piMoved is set to 0. -** The last root page is recorded in meta[3] and the value of -** meta[3] is updated by this procedure. -*/ -static int btreeDropTable(Btree *p, Pgno iTable, int *piMoved){ - int rc; - MemPage *pPage = 0; - BtShared *pBt = p->pBt; - - assert( sqlite3BtreeHoldsMutex(p) ); - assert( p->inTrans==TRANS_WRITE ); - assert( iTable>=2 ); - - rc = btreeGetPage(pBt, (Pgno)iTable, &pPage, 0); - if( rc ) return rc; - rc = sqlite3BtreeClearTable(p, iTable, 0); - if( rc ){ - releasePage(pPage); - return rc; - } - - *piMoved = 0; - -#ifdef SQLITE_OMIT_AUTOVACUUM - freePage(pPage, &rc); - releasePage(pPage); -#else - if( pBt->autoVacuum ){ - Pgno maxRootPgno; - sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &maxRootPgno); - - if( iTable==maxRootPgno ){ - /* If the table being dropped is the table with the largest root-page - ** number in the database, put the root page on the free list. - */ - freePage(pPage, &rc); - releasePage(pPage); - if( rc!=SQLITE_OK ){ - return rc; - } - }else{ - /* The table being dropped does not have the largest root-page - ** number in the database. So move the page that does into the - ** gap left by the deleted root-page. - */ - MemPage *pMove; - releasePage(pPage); - rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0); - if( rc!=SQLITE_OK ){ - return rc; - } - rc = relocatePage(pBt, pMove, PTRMAP_ROOTPAGE, 0, iTable, 0); - releasePage(pMove); - if( rc!=SQLITE_OK ){ - return rc; - } - pMove = 0; - rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0); - freePage(pMove, &rc); - releasePage(pMove); - if( rc!=SQLITE_OK ){ - return rc; - } - *piMoved = maxRootPgno; - } - - /* Set the new 'max-root-page' value in the database header. This - ** is the old value less one, less one more if that happens to - ** be a root-page number, less one again if that is the - ** PENDING_BYTE_PAGE. - */ - maxRootPgno--; - while( maxRootPgno==PENDING_BYTE_PAGE(pBt) - || PTRMAP_ISPAGE(pBt, maxRootPgno) ){ - maxRootPgno--; - } - assert( maxRootPgno!=PENDING_BYTE_PAGE(pBt) ); - - rc = sqlite3BtreeUpdateMeta(p, 4, maxRootPgno); - }else{ - freePage(pPage, &rc); - releasePage(pPage); - } -#endif - return rc; -} -int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){ - int rc; - sqlite3BtreeEnter(p); - rc = btreeDropTable(p, iTable, piMoved); - sqlite3BtreeLeave(p); - return rc; -} - - -/* -** This function may only be called if the b-tree connection already -** has a read or write transaction open on the database. -** -** Read the meta-information out of a database file. Meta[0] -** is the number of free pages currently in the database. Meta[1] -** through meta[15] are available for use by higher layers. Meta[0] -** is read-only, the others are read/write. -** -** The schema layer numbers meta values differently. At the schema -** layer (and the SetCookie and ReadCookie opcodes) the number of -** free pages is not visible. So Cookie[0] is the same as Meta[1]. -** -** This routine treats Meta[BTREE_DATA_VERSION] as a special case. Instead -** of reading the value out of the header, it instead loads the "DataVersion" -** from the pager. The BTREE_DATA_VERSION value is not actually stored in the -** database file. It is a number computed by the pager. But its access -** pattern is the same as header meta values, and so it is convenient to -** read it from this routine. -*/ -void sqlite3BtreeGetMeta(Btree *p, int idx, u32 *pMeta){ - BtShared *pBt = p->pBt; - - sqlite3BtreeEnter(p); - assert( p->inTrans>TRANS_NONE ); - assert( SQLITE_OK==querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK) ); - assert( pBt->pPage1 ); - assert( idx>=0 && idx<=15 ); - - if( idx==BTREE_DATA_VERSION ){ - *pMeta = sqlite3PagerDataVersion(pBt->pPager) + p->iDataVersion; - }else{ - *pMeta = get4byte(&pBt->pPage1->aData[36 + idx*4]); - } - - /* If auto-vacuum is disabled in this build and this is an auto-vacuum - ** database, mark the database as read-only. */ -#ifdef SQLITE_OMIT_AUTOVACUUM - if( idx==BTREE_LARGEST_ROOT_PAGE && *pMeta>0 ){ - pBt->btsFlags |= BTS_READ_ONLY; - } -#endif - - sqlite3BtreeLeave(p); -} - -/* -** Write meta-information back into the database. Meta[0] is -** read-only and may not be written. -*/ -int sqlite3BtreeUpdateMeta(Btree *p, int idx, u32 iMeta){ - BtShared *pBt = p->pBt; - unsigned char *pP1; - int rc; - assert( idx>=1 && idx<=15 ); - sqlite3BtreeEnter(p); - assert( p->inTrans==TRANS_WRITE ); - assert( pBt->pPage1!=0 ); - pP1 = pBt->pPage1->aData; - rc = sqlite3PagerWrite(pBt->pPage1->pDbPage); - if( rc==SQLITE_OK ){ - put4byte(&pP1[36 + idx*4], iMeta); -#ifndef SQLITE_OMIT_AUTOVACUUM - if( idx==BTREE_INCR_VACUUM ){ - assert( pBt->autoVacuum || iMeta==0 ); - assert( iMeta==0 || iMeta==1 ); - pBt->incrVacuum = (u8)iMeta; - } -#endif - } - sqlite3BtreeLeave(p); - return rc; -} - -#ifndef SQLITE_OMIT_BTREECOUNT -/* -** The first argument, pCur, is a cursor opened on some b-tree. Count the -** number of entries in the b-tree and write the result to *pnEntry. -** -** SQLITE_OK is returned if the operation is successfully executed. -** Otherwise, if an error is encountered (i.e. an IO error or database -** corruption) an SQLite error code is returned. -*/ -int sqlite3BtreeCount(BtCursor *pCur, i64 *pnEntry){ - i64 nEntry = 0; /* Value to return in *pnEntry */ - int rc; /* Return code */ - - rc = moveToRoot(pCur); - if( rc==SQLITE_EMPTY ){ - *pnEntry = 0; - return SQLITE_OK; - } - - /* Unless an error occurs, the following loop runs one iteration for each - ** page in the B-Tree structure (not including overflow pages). - */ - while( rc==SQLITE_OK ){ - int iIdx; /* Index of child node in parent */ - MemPage *pPage; /* Current page of the b-tree */ - - /* If this is a leaf page or the tree is not an int-key tree, then - ** this page contains countable entries. Increment the entry counter - ** accordingly. - */ - pPage = pCur->pPage; - if( pPage->leaf || !pPage->intKey ){ - nEntry += pPage->nCell; - } - - /* pPage is a leaf node. This loop navigates the cursor so that it - ** points to the first interior cell that it points to the parent of - ** the next page in the tree that has not yet been visited. The - ** pCur->aiIdx[pCur->iPage] value is set to the index of the parent cell - ** of the page, or to the number of cells in the page if the next page - ** to visit is the right-child of its parent. - ** - ** If all pages in the tree have been visited, return SQLITE_OK to the - ** caller. - */ - if( pPage->leaf ){ - do { - if( pCur->iPage==0 ){ - /* All pages of the b-tree have been visited. Return successfully. */ - *pnEntry = nEntry; - return moveToRoot(pCur); - } - moveToParent(pCur); - }while ( pCur->ix>=pCur->pPage->nCell ); - - pCur->ix++; - pPage = pCur->pPage; - } - - /* Descend to the child node of the cell that the cursor currently - ** points at. This is the right-child if (iIdx==pPage->nCell). - */ - iIdx = pCur->ix; - if( iIdx==pPage->nCell ){ - rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8])); - }else{ - rc = moveToChild(pCur, get4byte(findCell(pPage, iIdx))); - } - } - - /* An error has occurred. Return an error code. */ - return rc; -} -#endif - -/* -** Return the pager associated with a BTree. This routine is used for -** testing and debugging only. -*/ -Pager *sqlite3BtreePager(Btree *p){ - return p->pBt->pPager; -} - -#ifndef SQLITE_OMIT_INTEGRITY_CHECK -/* -** Append a message to the error message string. -*/ -static void checkAppendMsg( - IntegrityCk *pCheck, - const char *zFormat, - ... -){ - va_list ap; - if( !pCheck->mxErr ) return; - pCheck->mxErr--; - pCheck->nErr++; - va_start(ap, zFormat); - if( pCheck->errMsg.nChar ){ - sqlite3_str_append(&pCheck->errMsg, "\n", 1); - } - if( pCheck->zPfx ){ - sqlite3_str_appendf(&pCheck->errMsg, pCheck->zPfx, pCheck->v1, pCheck->v2); - } - sqlite3_str_vappendf(&pCheck->errMsg, zFormat, ap); - va_end(ap); - if( pCheck->errMsg.accError==SQLITE_NOMEM ){ - pCheck->mallocFailed = 1; - } -} -#endif /* SQLITE_OMIT_INTEGRITY_CHECK */ - -#ifndef SQLITE_OMIT_INTEGRITY_CHECK - -/* -** Return non-zero if the bit in the IntegrityCk.aPgRef[] array that -** corresponds to page iPg is already set. -*/ -static int getPageReferenced(IntegrityCk *pCheck, Pgno iPg){ - assert( iPg<=pCheck->nPage && sizeof(pCheck->aPgRef[0])==1 ); - return (pCheck->aPgRef[iPg/8] & (1 << (iPg & 0x07))); -} - -/* -** Set the bit in the IntegrityCk.aPgRef[] array that corresponds to page iPg. -*/ -static void setPageReferenced(IntegrityCk *pCheck, Pgno iPg){ - assert( iPg<=pCheck->nPage && sizeof(pCheck->aPgRef[0])==1 ); - pCheck->aPgRef[iPg/8] |= (1 << (iPg & 0x07)); -} - - -/* -** Add 1 to the reference count for page iPage. If this is the second -** reference to the page, add an error message to pCheck->zErrMsg. -** Return 1 if there are 2 or more references to the page and 0 if -** if this is the first reference to the page. -** -** Also check that the page number is in bounds. -*/ -static int checkRef(IntegrityCk *pCheck, Pgno iPage){ - if( iPage==0 ) return 1; - if( iPage>pCheck->nPage ){ - checkAppendMsg(pCheck, "invalid page number %d", iPage); - return 1; - } - if( getPageReferenced(pCheck, iPage) ){ - checkAppendMsg(pCheck, "2nd reference to page %d", iPage); - return 1; - } - setPageReferenced(pCheck, iPage); - return 0; -} - -#ifndef SQLITE_OMIT_AUTOVACUUM -/* -** Check that the entry in the pointer-map for page iChild maps to -** page iParent, pointer type ptrType. If not, append an error message -** to pCheck. -*/ -static void checkPtrmap( - IntegrityCk *pCheck, /* Integrity check context */ - Pgno iChild, /* Child page number */ - u8 eType, /* Expected pointer map type */ - Pgno iParent /* Expected pointer map parent page number */ -){ - int rc; - u8 ePtrmapType; - Pgno iPtrmapParent; - - rc = ptrmapGet(pCheck->pBt, iChild, &ePtrmapType, &iPtrmapParent); - if( rc!=SQLITE_OK ){ - if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ) pCheck->mallocFailed = 1; - checkAppendMsg(pCheck, "Failed to read ptrmap key=%d", iChild); - return; - } - - if( ePtrmapType!=eType || iPtrmapParent!=iParent ){ - checkAppendMsg(pCheck, - "Bad ptr map entry key=%d expected=(%d,%d) got=(%d,%d)", - iChild, eType, iParent, ePtrmapType, iPtrmapParent); - } -} -#endif - -/* -** Check the integrity of the freelist or of an overflow page list. -** Verify that the number of pages on the list is N. -*/ -static void checkList( - IntegrityCk *pCheck, /* Integrity checking context */ - int isFreeList, /* True for a freelist. False for overflow page list */ - int iPage, /* Page number for first page in the list */ - int N /* Expected number of pages in the list */ -){ - int i; - int expected = N; - int iFirst = iPage; - while( N-- > 0 && pCheck->mxErr ){ - DbPage *pOvflPage; - unsigned char *pOvflData; - if( iPage<1 ){ - checkAppendMsg(pCheck, - "%d of %d pages missing from overflow list starting at %d", - N+1, expected, iFirst); - break; - } - if( checkRef(pCheck, iPage) ) break; - if( sqlite3PagerGet(pCheck->pPager, (Pgno)iPage, &pOvflPage, 0) ){ - checkAppendMsg(pCheck, "failed to get page %d", iPage); - break; - } - pOvflData = (unsigned char *)sqlite3PagerGetData(pOvflPage); - if( isFreeList ){ - int n = get4byte(&pOvflData[4]); -#ifndef SQLITE_OMIT_AUTOVACUUM - if( pCheck->pBt->autoVacuum ){ - checkPtrmap(pCheck, iPage, PTRMAP_FREEPAGE, 0); - } -#endif - if( n>(int)pCheck->pBt->usableSize/4-2 ){ - checkAppendMsg(pCheck, - "freelist leaf count too big on page %d", iPage); - N--; - }else{ - for(i=0; i<n; i++){ - Pgno iFreePage = get4byte(&pOvflData[8+i*4]); -#ifndef SQLITE_OMIT_AUTOVACUUM - if( pCheck->pBt->autoVacuum ){ - checkPtrmap(pCheck, iFreePage, PTRMAP_FREEPAGE, 0); - } -#endif - checkRef(pCheck, iFreePage); - } - N -= n; - } - } -#ifndef SQLITE_OMIT_AUTOVACUUM - else{ - /* If this database supports auto-vacuum and iPage is not the last - ** page in this overflow list, check that the pointer-map entry for - ** the following page matches iPage. - */ - if( pCheck->pBt->autoVacuum && N>0 ){ - i = get4byte(pOvflData); - checkPtrmap(pCheck, i, PTRMAP_OVERFLOW2, iPage); - } - } -#endif - iPage = get4byte(pOvflData); - sqlite3PagerUnref(pOvflPage); - - if( isFreeList && N<(iPage!=0) ){ - checkAppendMsg(pCheck, "free-page count in header is too small"); - } - } -} -#endif /* SQLITE_OMIT_INTEGRITY_CHECK */ - -/* -** An implementation of a min-heap. -** -** aHeap[0] is the number of elements on the heap. aHeap[1] is the -** root element. The daughter nodes of aHeap[N] are aHeap[N*2] -** and aHeap[N*2+1]. -** -** The heap property is this: Every node is less than or equal to both -** of its daughter nodes. A consequence of the heap property is that the -** root node aHeap[1] is always the minimum value currently in the heap. -** -** The btreeHeapInsert() routine inserts an unsigned 32-bit number onto -** the heap, preserving the heap property. The btreeHeapPull() routine -** removes the root element from the heap (the minimum value in the heap) -** and then moves other nodes around as necessary to preserve the heap -** property. -** -** This heap is used for cell overlap and coverage testing. Each u32 -** entry represents the span of a cell or freeblock on a btree page. -** The upper 16 bits are the index of the first byte of a range and the -** lower 16 bits are the index of the last byte of that range. -*/ -static void btreeHeapInsert(u32 *aHeap, u32 x){ - u32 j, i = ++aHeap[0]; - aHeap[i] = x; - while( (j = i/2)>0 && aHeap[j]>aHeap[i] ){ - x = aHeap[j]; - aHeap[j] = aHeap[i]; - aHeap[i] = x; - i = j; - } -} -static int btreeHeapPull(u32 *aHeap, u32 *pOut){ - u32 j, i, x; - if( (x = aHeap[0])==0 ) return 0; - *pOut = aHeap[1]; - aHeap[1] = aHeap[x]; - aHeap[x] = 0xffffffff; - aHeap[0]--; - i = 1; - while( (j = i*2)<=aHeap[0] ){ - if( aHeap[j]>aHeap[j+1] ) j++; - if( aHeap[i]<aHeap[j] ) break; - x = aHeap[i]; - aHeap[i] = aHeap[j]; - aHeap[j] = x; - i = j; - } - return 1; -} - -#ifndef SQLITE_OMIT_INTEGRITY_CHECK -/* -** Do various sanity checks on a single page of a tree. Return -** the tree depth. Root pages return 0. Parents of root pages -** return 1, and so forth. -** -** These checks are done: -** -** 1. Make sure that cells and freeblocks do not overlap -** but combine to completely cover the page. -** 2. Make sure integer cell keys are in order. -** 3. Check the integrity of overflow pages. -** 4. Recursively call checkTreePage on all children. -** 5. Verify that the depth of all children is the same. -*/ -static int checkTreePage( - IntegrityCk *pCheck, /* Context for the sanity check */ - int iPage, /* Page number of the page to check */ - i64 *piMinKey, /* Write minimum integer primary key here */ - i64 maxKey /* Error if integer primary key greater than this */ -){ - MemPage *pPage = 0; /* The page being analyzed */ - int i; /* Loop counter */ - int rc; /* Result code from subroutine call */ - int depth = -1, d2; /* Depth of a subtree */ - int pgno; /* Page number */ - int nFrag; /* Number of fragmented bytes on the page */ - int hdr; /* Offset to the page header */ - int cellStart; /* Offset to the start of the cell pointer array */ - int nCell; /* Number of cells */ - int doCoverageCheck = 1; /* True if cell coverage checking should be done */ - int keyCanBeEqual = 1; /* True if IPK can be equal to maxKey - ** False if IPK must be strictly less than maxKey */ - u8 *data; /* Page content */ - u8 *pCell; /* Cell content */ - u8 *pCellIdx; /* Next element of the cell pointer array */ - BtShared *pBt; /* The BtShared object that owns pPage */ - u32 pc; /* Address of a cell */ - u32 usableSize; /* Usable size of the page */ - u32 contentOffset; /* Offset to the start of the cell content area */ - u32 *heap = 0; /* Min-heap used for checking cell coverage */ - u32 x, prev = 0; /* Next and previous entry on the min-heap */ - const char *saved_zPfx = pCheck->zPfx; - int saved_v1 = pCheck->v1; - int saved_v2 = pCheck->v2; - u8 savedIsInit = 0; - - /* Check that the page exists - */ - pBt = pCheck->pBt; - usableSize = pBt->usableSize; - if( iPage==0 ) return 0; - if( checkRef(pCheck, iPage) ) return 0; - pCheck->zPfx = "Page %d: "; - pCheck->v1 = iPage; - if( (rc = btreeGetPage(pBt, (Pgno)iPage, &pPage, 0))!=0 ){ - checkAppendMsg(pCheck, - "unable to get the page. error code=%d", rc); - goto end_of_check; - } - - /* Clear MemPage.isInit to make sure the corruption detection code in - ** btreeInitPage() is executed. */ - savedIsInit = pPage->isInit; - pPage->isInit = 0; - if( (rc = btreeInitPage(pPage))!=0 ){ - assert( rc==SQLITE_CORRUPT ); /* The only possible error from InitPage */ - checkAppendMsg(pCheck, - "btreeInitPage() returns error code %d", rc); - goto end_of_check; - } - data = pPage->aData; - hdr = pPage->hdrOffset; - - /* Set up for cell analysis */ - pCheck->zPfx = "On tree page %d cell %d: "; - contentOffset = get2byteNotZero(&data[hdr+5]); - assert( contentOffset<=usableSize ); /* Enforced by btreeInitPage() */ - - /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the - ** number of cells on the page. */ - nCell = get2byte(&data[hdr+3]); - assert( pPage->nCell==nCell ); - - /* EVIDENCE-OF: R-23882-45353 The cell pointer array of a b-tree page - ** immediately follows the b-tree page header. */ - cellStart = hdr + 12 - 4*pPage->leaf; - assert( pPage->aCellIdx==&data[cellStart] ); - pCellIdx = &data[cellStart + 2*(nCell-1)]; - - if( !pPage->leaf ){ - /* Analyze the right-child page of internal pages */ - pgno = get4byte(&data[hdr+8]); -#ifndef SQLITE_OMIT_AUTOVACUUM - if( pBt->autoVacuum ){ - pCheck->zPfx = "On page %d at right child: "; - checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage); - } -#endif - depth = checkTreePage(pCheck, pgno, &maxKey, maxKey); - keyCanBeEqual = 0; - }else{ - /* For leaf pages, the coverage check will occur in the same loop - ** as the other cell checks, so initialize the heap. */ - heap = pCheck->heap; - heap[0] = 0; - } - - /* EVIDENCE-OF: R-02776-14802 The cell pointer array consists of K 2-byte - ** integer offsets to the cell contents. */ - for(i=nCell-1; i>=0 && pCheck->mxErr; i--){ - CellInfo info; - - /* Check cell size */ - pCheck->v2 = i; - assert( pCellIdx==&data[cellStart + i*2] ); - pc = get2byteAligned(pCellIdx); - pCellIdx -= 2; - if( pc<contentOffset || pc>usableSize-4 ){ - checkAppendMsg(pCheck, "Offset %d out of range %d..%d", - pc, contentOffset, usableSize-4); - doCoverageCheck = 0; - continue; - } - pCell = &data[pc]; - pPage->xParseCell(pPage, pCell, &info); - if( pc+info.nSize>usableSize ){ - checkAppendMsg(pCheck, "Extends off end of page"); - doCoverageCheck = 0; - continue; - } - - /* Check for integer primary key out of range */ - if( pPage->intKey ){ - if( keyCanBeEqual ? (info.nKey > maxKey) : (info.nKey >= maxKey) ){ - checkAppendMsg(pCheck, "Rowid %lld out of order", info.nKey); - } - maxKey = info.nKey; - keyCanBeEqual = 0; /* Only the first key on the page may ==maxKey */ - } - - /* Check the content overflow list */ - if( info.nPayload>info.nLocal ){ - int nPage; /* Number of pages on the overflow chain */ - Pgno pgnoOvfl; /* First page of the overflow chain */ - assert( pc + info.nSize - 4 <= usableSize ); - nPage = (info.nPayload - info.nLocal + usableSize - 5)/(usableSize - 4); - pgnoOvfl = get4byte(&pCell[info.nSize - 4]); -#ifndef SQLITE_OMIT_AUTOVACUUM - if( pBt->autoVacuum ){ - checkPtrmap(pCheck, pgnoOvfl, PTRMAP_OVERFLOW1, iPage); - } -#endif - checkList(pCheck, 0, pgnoOvfl, nPage); - } - - if( !pPage->leaf ){ - /* Check sanity of left child page for internal pages */ - pgno = get4byte(pCell); -#ifndef SQLITE_OMIT_AUTOVACUUM - if( pBt->autoVacuum ){ - checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage); - } -#endif - d2 = checkTreePage(pCheck, pgno, &maxKey, maxKey); - keyCanBeEqual = 0; - if( d2!=depth ){ - checkAppendMsg(pCheck, "Child page depth differs"); - depth = d2; - } - }else{ - /* Populate the coverage-checking heap for leaf pages */ - btreeHeapInsert(heap, (pc<<16)|(pc+info.nSize-1)); - } - } - *piMinKey = maxKey; - - /* Check for complete coverage of the page - */ - pCheck->zPfx = 0; - if( doCoverageCheck && pCheck->mxErr>0 ){ - /* For leaf pages, the min-heap has already been initialized and the - ** cells have already been inserted. But for internal pages, that has - ** not yet been done, so do it now */ - if( !pPage->leaf ){ - heap = pCheck->heap; - heap[0] = 0; - for(i=nCell-1; i>=0; i--){ - u32 size; - pc = get2byteAligned(&data[cellStart+i*2]); - size = pPage->xCellSize(pPage, &data[pc]); - btreeHeapInsert(heap, (pc<<16)|(pc+size-1)); - } - } - /* Add the freeblocks to the min-heap - ** - ** EVIDENCE-OF: R-20690-50594 The second field of the b-tree page header - ** is the offset of the first freeblock, or zero if there are no - ** freeblocks on the page. - */ - i = get2byte(&data[hdr+1]); - while( i>0 ){ - int size, j; - assert( (u32)i<=usableSize-4 ); /* Enforced by btreeInitPage() */ - size = get2byte(&data[i+2]); - assert( (u32)(i+size)<=usableSize ); /* Enforced by btreeInitPage() */ - btreeHeapInsert(heap, (((u32)i)<<16)|(i+size-1)); - /* EVIDENCE-OF: R-58208-19414 The first 2 bytes of a freeblock are a - ** big-endian integer which is the offset in the b-tree page of the next - ** freeblock in the chain, or zero if the freeblock is the last on the - ** chain. */ - j = get2byte(&data[i]); - /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of - ** increasing offset. */ - assert( j==0 || j>i+size ); /* Enforced by btreeInitPage() */ - assert( (u32)j<=usableSize-4 ); /* Enforced by btreeInitPage() */ - i = j; - } - /* Analyze the min-heap looking for overlap between cells and/or - ** freeblocks, and counting the number of untracked bytes in nFrag. - ** - ** Each min-heap entry is of the form: (start_address<<16)|end_address. - ** There is an implied first entry the covers the page header, the cell - ** pointer index, and the gap between the cell pointer index and the start - ** of cell content. - ** - ** The loop below pulls entries from the min-heap in order and compares - ** the start_address against the previous end_address. If there is an - ** overlap, that means bytes are used multiple times. If there is a gap, - ** that gap is added to the fragmentation count. - */ - nFrag = 0; - prev = contentOffset - 1; /* Implied first min-heap entry */ - while( btreeHeapPull(heap,&x) ){ - if( (prev&0xffff)>=(x>>16) ){ - checkAppendMsg(pCheck, - "Multiple uses for byte %u of page %d", x>>16, iPage); - break; - }else{ - nFrag += (x>>16) - (prev&0xffff) - 1; - prev = x; - } - } - nFrag += usableSize - (prev&0xffff) - 1; - /* EVIDENCE-OF: R-43263-13491 The total number of bytes in all fragments - ** is stored in the fifth field of the b-tree page header. - ** EVIDENCE-OF: R-07161-27322 The one-byte integer at offset 7 gives the - ** number of fragmented free bytes within the cell content area. - */ - if( heap[0]==0 && nFrag!=data[hdr+7] ){ - checkAppendMsg(pCheck, - "Fragmentation of %d bytes reported as %d on page %d", - nFrag, data[hdr+7], iPage); - } - } - -end_of_check: - if( !doCoverageCheck ) pPage->isInit = savedIsInit; - releasePage(pPage); - pCheck->zPfx = saved_zPfx; - pCheck->v1 = saved_v1; - pCheck->v2 = saved_v2; - return depth+1; -} -#endif /* SQLITE_OMIT_INTEGRITY_CHECK */ - -#ifndef SQLITE_OMIT_INTEGRITY_CHECK -/* -** This routine does a complete check of the given BTree file. aRoot[] is -** an array of pages numbers were each page number is the root page of -** a table. nRoot is the number of entries in aRoot. -** -** A read-only or read-write transaction must be opened before calling -** this function. -** -** Write the number of error seen in *pnErr. Except for some memory -** allocation errors, an error message held in memory obtained from -** malloc is returned if *pnErr is non-zero. If *pnErr==0 then NULL is -** returned. If a memory allocation error occurs, NULL is returned. -*/ -char *sqlite3BtreeIntegrityCheck( - Btree *p, /* The btree to be checked */ - int *aRoot, /* An array of root pages numbers for individual trees */ - int nRoot, /* Number of entries in aRoot[] */ - int mxErr, /* Stop reporting errors after this many */ - int *pnErr /* Write number of errors seen to this variable */ -){ - Pgno i; - IntegrityCk sCheck; - BtShared *pBt = p->pBt; - int savedDbFlags = pBt->db->flags; - char zErr[100]; - VVA_ONLY( int nRef ); - - sqlite3BtreeEnter(p); - assert( p->inTrans>TRANS_NONE && pBt->inTransaction>TRANS_NONE ); - VVA_ONLY( nRef = sqlite3PagerRefcount(pBt->pPager) ); - assert( nRef>=0 ); - sCheck.pBt = pBt; - sCheck.pPager = pBt->pPager; - sCheck.nPage = btreePagecount(sCheck.pBt); - sCheck.mxErr = mxErr; - sCheck.nErr = 0; - sCheck.mallocFailed = 0; - sCheck.zPfx = 0; - sCheck.v1 = 0; - sCheck.v2 = 0; - sCheck.aPgRef = 0; - sCheck.heap = 0; - sqlite3StrAccumInit(&sCheck.errMsg, 0, zErr, sizeof(zErr), SQLITE_MAX_LENGTH); - sCheck.errMsg.printfFlags = SQLITE_PRINTF_INTERNAL; - if( sCheck.nPage==0 ){ - goto integrity_ck_cleanup; - } - - sCheck.aPgRef = sqlite3MallocZero((sCheck.nPage / 8)+ 1); - if( !sCheck.aPgRef ){ - sCheck.mallocFailed = 1; - goto integrity_ck_cleanup; - } - sCheck.heap = (u32*)sqlite3PageMalloc( pBt->pageSize ); - if( sCheck.heap==0 ){ - sCheck.mallocFailed = 1; - goto integrity_ck_cleanup; - } - - i = PENDING_BYTE_PAGE(pBt); - if( i<=sCheck.nPage ) setPageReferenced(&sCheck, i); - - /* Check the integrity of the freelist - */ - sCheck.zPfx = "Main freelist: "; - checkList(&sCheck, 1, get4byte(&pBt->pPage1->aData[32]), - get4byte(&pBt->pPage1->aData[36])); - sCheck.zPfx = 0; - - /* Check all the tables. - */ - testcase( pBt->db->flags & SQLITE_CellSizeCk ); - pBt->db->flags &= ~SQLITE_CellSizeCk; - for(i=0; (int)i<nRoot && sCheck.mxErr; i++){ - i64 notUsed; - if( aRoot[i]==0 ) continue; -#ifndef SQLITE_OMIT_AUTOVACUUM - if( pBt->autoVacuum && aRoot[i]>1 ){ - checkPtrmap(&sCheck, aRoot[i], PTRMAP_ROOTPAGE, 0); - } -#endif - checkTreePage(&sCheck, aRoot[i], ¬Used, LARGEST_INT64); - } - pBt->db->flags = savedDbFlags; - - /* Make sure every page in the file is referenced - */ - for(i=1; i<=sCheck.nPage && sCheck.mxErr; i++){ -#ifdef SQLITE_OMIT_AUTOVACUUM - if( getPageReferenced(&sCheck, i)==0 ){ - checkAppendMsg(&sCheck, "Page %d is never used", i); - } -#else - /* If the database supports auto-vacuum, make sure no tables contain - ** references to pointer-map pages. - */ - if( getPageReferenced(&sCheck, i)==0 && - (PTRMAP_PAGENO(pBt, i)!=i || !pBt->autoVacuum) ){ - checkAppendMsg(&sCheck, "Page %d is never used", i); - } - if( getPageReferenced(&sCheck, i)!=0 && - (PTRMAP_PAGENO(pBt, i)==i && pBt->autoVacuum) ){ - checkAppendMsg(&sCheck, "Pointer map page %d is referenced", i); - } -#endif - } - - /* Clean up and report errors. - */ -integrity_ck_cleanup: - sqlite3PageFree(sCheck.heap); - sqlite3_free(sCheck.aPgRef); - if( sCheck.mallocFailed ){ - sqlite3_str_reset(&sCheck.errMsg); - sCheck.nErr++; - } - *pnErr = sCheck.nErr; - if( sCheck.nErr==0 ) sqlite3_str_reset(&sCheck.errMsg); - /* Make sure this analysis did not leave any unref() pages. */ - assert( nRef==sqlite3PagerRefcount(pBt->pPager) ); - sqlite3BtreeLeave(p); - return sqlite3StrAccumFinish(&sCheck.errMsg); -} -#endif /* SQLITE_OMIT_INTEGRITY_CHECK */ - -/* -** Return the full pathname of the underlying database file. Return -** an empty string if the database is in-memory or a TEMP database. -** -** The pager filename is invariant as long as the pager is -** open so it is safe to access without the BtShared mutex. -*/ -const char *sqlite3BtreeGetFilename(Btree *p){ - assert( p->pBt->pPager!=0 ); - return sqlite3PagerFilename(p->pBt->pPager, 1); -} - -/* -** Return the pathname of the journal file for this database. The return -** value of this routine is the same regardless of whether the journal file -** has been created or not. -** -** The pager journal filename is invariant as long as the pager is -** open so it is safe to access without the BtShared mutex. -*/ -const char *sqlite3BtreeGetJournalname(Btree *p){ - assert( p->pBt->pPager!=0 ); - return sqlite3PagerJournalname(p->pBt->pPager); -} - -/* -** Return non-zero if a transaction is active. -*/ -int sqlite3BtreeIsInTrans(Btree *p){ - assert( p==0 || sqlite3_mutex_held(p->db->mutex) ); - return (p && (p->inTrans==TRANS_WRITE)); -} - -#ifndef SQLITE_OMIT_WAL -/* -** Run a checkpoint on the Btree passed as the first argument. -** -** Return SQLITE_LOCKED if this or any other connection has an open -** transaction on the shared-cache the argument Btree is connected to. -** -** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART. -*/ -int sqlite3BtreeCheckpoint(Btree *p, int eMode, int *pnLog, int *pnCkpt){ - int rc = SQLITE_OK; - if( p ){ - BtShared *pBt = p->pBt; - sqlite3BtreeEnter(p); - if( pBt->inTransaction!=TRANS_NONE ){ - rc = SQLITE_LOCKED; - }else{ - rc = sqlite3PagerCheckpoint(pBt->pPager, p->db, eMode, pnLog, pnCkpt); - } - sqlite3BtreeLeave(p); - } - return rc; -} -#endif - -/* -** Return non-zero if a read (or write) transaction is active. -*/ -int sqlite3BtreeIsInReadTrans(Btree *p){ - assert( p ); - assert( sqlite3_mutex_held(p->db->mutex) ); - return p->inTrans!=TRANS_NONE; -} - -int sqlite3BtreeIsInBackup(Btree *p){ - assert( p ); - assert( sqlite3_mutex_held(p->db->mutex) ); - return p->nBackup!=0; -} - -/* -** This function returns a pointer to a blob of memory associated with -** a single shared-btree. The memory is used by client code for its own -** purposes (for example, to store a high-level schema associated with -** the shared-btree). The btree layer manages reference counting issues. -** -** The first time this is called on a shared-btree, nBytes bytes of memory -** are allocated, zeroed, and returned to the caller. For each subsequent -** call the nBytes parameter is ignored and a pointer to the same blob -** of memory returned. -** -** If the nBytes parameter is 0 and the blob of memory has not yet been -** allocated, a null pointer is returned. If the blob has already been -** allocated, it is returned as normal. -** -** Just before the shared-btree is closed, the function passed as the -** xFree argument when the memory allocation was made is invoked on the -** blob of allocated memory. The xFree function should not call sqlite3_free() -** on the memory, the btree layer does that. -*/ -void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){ - BtShared *pBt = p->pBt; - sqlite3BtreeEnter(p); - if( !pBt->pSchema && nBytes ){ - pBt->pSchema = sqlite3DbMallocZero(0, nBytes); - pBt->xFreeSchema = xFree; - } - sqlite3BtreeLeave(p); - return pBt->pSchema; -} - -/* -** Return SQLITE_LOCKED_SHAREDCACHE if another user of the same shared -** btree as the argument handle holds an exclusive lock on the -** sqlite_master table. Otherwise SQLITE_OK. -*/ -int sqlite3BtreeSchemaLocked(Btree *p){ - int rc; - assert( sqlite3_mutex_held(p->db->mutex) ); - sqlite3BtreeEnter(p); - rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK); - assert( rc==SQLITE_OK || rc==SQLITE_LOCKED_SHAREDCACHE ); - sqlite3BtreeLeave(p); - return rc; -} - - -#ifndef SQLITE_OMIT_SHARED_CACHE -/* -** Obtain a lock on the table whose root page is iTab. The -** lock is a write lock if isWritelock is true or a read lock -** if it is false. -*/ -int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){ - int rc = SQLITE_OK; - assert( p->inTrans!=TRANS_NONE ); - if( p->sharable ){ - u8 lockType = READ_LOCK + isWriteLock; - assert( READ_LOCK+1==WRITE_LOCK ); - assert( isWriteLock==0 || isWriteLock==1 ); - - sqlite3BtreeEnter(p); - rc = querySharedCacheTableLock(p, iTab, lockType); - if( rc==SQLITE_OK ){ - rc = setSharedCacheTableLock(p, iTab, lockType); - } - sqlite3BtreeLeave(p); - } - return rc; -} -#endif - -#ifndef SQLITE_OMIT_INCRBLOB -/* -** Argument pCsr must be a cursor opened for writing on an -** INTKEY table currently pointing at a valid table entry. -** This function modifies the data stored as part of that entry. -** -** Only the data content may only be modified, it is not possible to -** change the length of the data stored. If this function is called with -** parameters that attempt to write past the end of the existing data, -** no modifications are made and SQLITE_CORRUPT is returned. -*/ -int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, void *z){ - int rc; - assert( cursorOwnsBtShared(pCsr) ); - assert( sqlite3_mutex_held(pCsr->pBtree->db->mutex) ); - assert( pCsr->curFlags & BTCF_Incrblob ); - - rc = restoreCursorPosition(pCsr); - if( rc!=SQLITE_OK ){ - return rc; - } - assert( pCsr->eState!=CURSOR_REQUIRESEEK ); - if( pCsr->eState!=CURSOR_VALID ){ - return SQLITE_ABORT; - } - - /* Save the positions of all other cursors open on this table. This is - ** required in case any of them are holding references to an xFetch - ** version of the b-tree page modified by the accessPayload call below. - ** - ** Note that pCsr must be open on a INTKEY table and saveCursorPosition() - ** and hence saveAllCursors() cannot fail on a BTREE_INTKEY table, hence - ** saveAllCursors can only return SQLITE_OK. - */ - VVA_ONLY(rc =) saveAllCursors(pCsr->pBt, pCsr->pgnoRoot, pCsr); - assert( rc==SQLITE_OK ); - - /* Check some assumptions: - ** (a) the cursor is open for writing, - ** (b) there is a read/write transaction open, - ** (c) the connection holds a write-lock on the table (if required), - ** (d) there are no conflicting read-locks, and - ** (e) the cursor points at a valid row of an intKey table. - */ - if( (pCsr->curFlags & BTCF_WriteFlag)==0 ){ - return SQLITE_READONLY; - } - assert( (pCsr->pBt->btsFlags & BTS_READ_ONLY)==0 - && pCsr->pBt->inTransaction==TRANS_WRITE ); - assert( hasSharedCacheTableLock(pCsr->pBtree, pCsr->pgnoRoot, 0, 2) ); - assert( !hasReadConflicts(pCsr->pBtree, pCsr->pgnoRoot) ); - assert( pCsr->pPage->intKey ); - - return accessPayload(pCsr, offset, amt, (unsigned char *)z, 1); -} - -/* -** Mark this cursor as an incremental blob cursor. -*/ -void sqlite3BtreeIncrblobCursor(BtCursor *pCur){ - pCur->curFlags |= BTCF_Incrblob; - pCur->pBtree->hasIncrblobCur = 1; -} -#endif - -/* -** Set both the "read version" (single byte at byte offset 18) and -** "write version" (single byte at byte offset 19) fields in the database -** header to iVersion. -*/ -int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){ - BtShared *pBt = pBtree->pBt; - int rc; /* Return code */ - - assert( iVersion==1 || iVersion==2 ); - - /* If setting the version fields to 1, do not automatically open the - ** WAL connection, even if the version fields are currently set to 2. - */ - pBt->btsFlags &= ~BTS_NO_WAL; - if( iVersion==1 ) pBt->btsFlags |= BTS_NO_WAL; - - rc = sqlite3BtreeBeginTrans(pBtree, 0); - if( rc==SQLITE_OK ){ - u8 *aData = pBt->pPage1->aData; - if( aData[18]!=(u8)iVersion || aData[19]!=(u8)iVersion ){ - rc = sqlite3BtreeBeginTrans(pBtree, 2); - if( rc==SQLITE_OK ){ - rc = sqlite3PagerWrite(pBt->pPage1->pDbPage); - if( rc==SQLITE_OK ){ - aData[18] = (u8)iVersion; - aData[19] = (u8)iVersion; - } - } - } - } - - pBt->btsFlags &= ~BTS_NO_WAL; - return rc; -} - -/* -** Return true if the cursor has a hint specified. This routine is -** only used from within assert() statements -*/ -int sqlite3BtreeCursorHasHint(BtCursor *pCsr, unsigned int mask){ - return (pCsr->hints & mask)!=0; -} - -/* -** Return true if the given Btree is read-only. -*/ -int sqlite3BtreeIsReadonly(Btree *p){ - return (p->pBt->btsFlags & BTS_READ_ONLY)!=0; -} - -/* -** Return the size of the header added to each page by this module. -*/ -int sqlite3HeaderSizeBtree(void){ return ROUND8(sizeof(MemPage)); } - -#if !defined(SQLITE_OMIT_SHARED_CACHE) -/* -** Return true if the Btree passed as the only argument is sharable. -*/ -int sqlite3BtreeSharable(Btree *p){ - return p->sharable; -} - -/* -** Return the number of connections to the BtShared object accessed by -** the Btree handle passed as the only argument. For private caches -** this is always 1. For shared caches it may be 1 or greater. -*/ -int sqlite3BtreeConnectionCount(Btree *p){ - testcase( p->sharable ); - return p->pBt->nRef; -} -#endif |