diff options
author | Tom Lane <tgl@sss.pgh.pa.us> | 2005-05-31 19:10:57 +0000 |
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committer | Tom Lane <tgl@sss.pgh.pa.us> | 2005-05-31 19:10:57 +0000 |
commit | 5205024b5a61a2c6e66748df909c38976ab0895a (patch) | |
tree | b64a8455495cc1dcde399b22ce8b1b6e685c444f | |
parent | 3c6bba3072a40befa12b57ba610bdb5d6a11c607 (diff) | |
download | postgresql-5205024b5a61a2c6e66748df909c38976ab0895a.tar.gz |
Add test to WAL replay to verify that xl_prev points back to the previous
WAL record; this is necessary to be sure we recognize stale WAL records
when a WAL page was only partially written during a system crash.
-rw-r--r-- | src/backend/access/transam/xlog.c | 37 |
1 files changed, 34 insertions, 3 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index a8acf758a8..3d7b55712b 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.125.2.2 2004/08/11 04:08:00 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.125.2.3 2005/05/31 19:10:57 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -430,8 +430,8 @@ static uint32 readOff = 0; static char *readBuf = NULL; /* State information for XLOG reading */ -static XLogRecPtr ReadRecPtr; -static XLogRecPtr EndRecPtr; +static XLogRecPtr ReadRecPtr; /* start of last record read */ +static XLogRecPtr EndRecPtr; /* end+1 of last record read */ static XLogRecord *nextRecord = NULL; static StartUpID lastReadSUI; @@ -1900,6 +1900,37 @@ got_record:; RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } + if (!nextmode) + { + /* + * We can't exactly verify the prev-link, but surely it should be + * less than the record's own address. + */ + if (!XLByteLT(record->xl_prev, *RecPtr)) + { + ereport(emode, + (errmsg("record with incorrect prev-link %X/%X at %X/%X", + record->xl_prev.xlogid, record->xl_prev.xrecoff, + RecPtr->xlogid, RecPtr->xrecoff))); + goto next_record_is_invalid; + } + } + else + { + /* + * Record's prev-link should exactly match our previous location. + * This check guards against torn WAL pages where a stale but + * valid-looking WAL record starts on a sector boundary. + */ + if (!XLByteEQ(record->xl_prev, ReadRecPtr)) + { + ereport(emode, + (errmsg("record with incorrect prev-link %X/%X at %X/%X", + record->xl_prev.xlogid, record->xl_prev.xrecoff, + RecPtr->xlogid, RecPtr->xrecoff))); + goto next_record_is_invalid; + } + } /* * Compute total length of record including any appended backup |