diff options
Diffstat (limited to 'src/gdbmopen.c')
| -rw-r--r-- | src/gdbmopen.c | 475 |
1 files changed, 475 insertions, 0 deletions
diff --git a/src/gdbmopen.c b/src/gdbmopen.c new file mode 100644 index 0000000..14c687d --- /dev/null +++ b/src/gdbmopen.c @@ -0,0 +1,475 @@ +/* gdbmopen.c - Open the dbm file and initialize data structures for use. */ + +/* This file is part of GDBM, the GNU data base manager. + Copyright (C) 1990, 1991, 1993, 2007, 2011, 2013 Free Software Foundation, + Inc. + + GDBM is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3, or (at your option) + any later version. + + GDBM is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with GDBM. If not, see <http://www.gnu.org/licenses/>. */ + +/* Include system configuration before all else. */ +#include "autoconf.h" + +#include "gdbmdefs.h" + +/* Determine our native magic number and bail if we can't. */ +#if SIZEOF_OFF_T == 4 +# define GDBM_MAGIC GDBM_MAGIC32 +#elif SIZEOF_OFF_T == 8 +# define GDBM_MAGIC GDBM_MAGIC64 +#else +# error "Unsupported off_t size, contact GDBM maintainer. What crazy system is this?!?" +#endif + +/* Initialize dbm system. FILE is a pointer to the file name. If the file + has a size of zero bytes, a file initialization procedure is performed, + setting up the initial structure in the file. BLOCK_SIZE is used during + initialization to determine the size of various constructs. If the value + is less than 512, the file system blocksize is used, otherwise the value + of BLOCK_SIZE is used. BLOCK_SIZE is ignored if the file has previously + initialized. If FLAGS is set to GDBM_READ the user wants to just + read the database and any call to dbm_store or dbm_delete will fail. Many + readers can access the database at the same time. If FLAGS is set to + GDBM_WRITE, the user wants both read and write access to the database and + requires exclusive access. If FLAGS is GDBM_WRCREAT, the user wants + both read and write access to the database and if the database does not + exist, create a new one. If FLAGS is GDBM_NEWDB, the user want a + new database created, regardless of whether one existed, and wants read + and write access to the new database. Any error detected will cause a + return value of null and an approprate value will be in gdbm_errno. If + no errors occur, a pointer to the "gdbm file descriptor" will be + returned. */ + + +GDBM_FILE +gdbm_open (const char *file, int block_size, int flags, int mode, + void (*fatal_func) (const char *)) +{ + GDBM_FILE dbf; /* The record to return. */ + struct stat file_stat; /* Space for the stat information. */ + int len; /* Length of the file name. */ + off_t file_pos; /* Used with seeks. */ + int file_block_size; /* Block size to use for a new file. */ + int index; /* Used as a loop index. */ + char need_trunc; /* Used with GDBM_NEWDB and locking to avoid + truncating a file from under a reader. */ + int rc; /* temporary error code */ + int fbits = 0; /* additional bits for open(2) flags */ + + /* Initialize the gdbm_errno variable. */ + gdbm_errno = GDBM_NO_ERROR; + + /* Allocate new info structure. */ + dbf = (GDBM_FILE) malloc (sizeof (*dbf)); + if (dbf == NULL) + { + gdbm_errno = GDBM_MALLOC_ERROR; + return NULL; + } + + /* Initialize some fields for known values. This is done so gdbm_close + will work if called before allocating some structures. */ + dbf->dir = NULL; + dbf->bucket = NULL; + dbf->header = NULL; + dbf->bucket_cache = NULL; + dbf->cache_size = 0; + + dbf->memory_mapping = FALSE; + dbf->mapped_size_max = SIZE_T_MAX; + dbf->mapped_region = NULL; + dbf->mapped_size = 0; + dbf->mapped_pos = 0; + dbf->mapped_off = 0; + + /* Save name of file. */ + len = strlen (file); + dbf->name = (char *) malloc (len + 1); + if (dbf->name == NULL) + { + free (dbf); + gdbm_errno = GDBM_MALLOC_ERROR; + return NULL; + } + strcpy (dbf->name, file); + + /* Initialize the fatal error routine. */ + dbf->fatal_err = fatal_func; + + dbf->fast_write = TRUE; /* Default to setting fast_write. */ + dbf->file_locking = TRUE; /* Default to doing file locking. */ + dbf->central_free = FALSE; /* Default to not using central_free. */ + dbf->coalesce_blocks = FALSE; /* Default to not coalescing blocks. */ + + /* GDBM_FAST used to determine whether or not we set fast_write. */ + if (flags & GDBM_SYNC) + { + /* If GDBM_SYNC has been requested, don't do fast_write. */ + dbf->fast_write = FALSE; + } + if (flags & GDBM_NOLOCK) + { + dbf->file_locking = FALSE; + } + if (flags & GDBM_CLOEXEC) + { + fbits = O_CLOEXEC; + dbf->cloexec = TRUE; + } + else + dbf->cloexec = FALSE; + + /* Open the file. */ + need_trunc = FALSE; + switch (flags & GDBM_OPENMASK) + { + case GDBM_READER: + dbf->desc = open (dbf->name, O_RDONLY|fbits, 0); + break; + + case GDBM_WRITER: + dbf->desc = open (dbf->name, O_RDWR|fbits, 0); + break; + + case GDBM_NEWDB: + dbf->desc = open (dbf->name, O_RDWR|O_CREAT|fbits, mode); + need_trunc = TRUE; + break; + + default: + dbf->desc = open (dbf->name, O_RDWR|O_CREAT|fbits, mode); + break; + + } + if (dbf->desc < 0) + { + SAVE_ERRNO (free (dbf->name); + free (dbf)); + gdbm_errno = GDBM_FILE_OPEN_ERROR; + return NULL; + } + + /* Get the status of the file. */ + if (fstat (dbf->desc, &file_stat)) + { + SAVE_ERRNO (close (dbf->desc); + free (dbf->name); + free (dbf)); + gdbm_errno = GDBM_FILE_STAT_ERROR; + return NULL; + } + + /* Zero-length file can't be a reader... */ + if (((flags & GDBM_OPENMASK) == GDBM_READER) && (file_stat.st_size == 0)) + { + close (dbf->desc); + free (dbf->name); + free (dbf); + gdbm_errno = GDBM_EMPTY_DATABASE; + return NULL; + } + + /* Record the kind of user. */ + dbf->read_write = (flags & GDBM_OPENMASK); + + /* Lock the file in the appropriate way. */ + if (dbf->file_locking) + { + if (_gdbm_lock_file (dbf) == -1) + { + close (dbf->desc); + free (dbf->name); + free (dbf); + if ((flags & GDBM_OPENMASK) == GDBM_READER) + gdbm_errno = GDBM_CANT_BE_READER; + else + gdbm_errno = GDBM_CANT_BE_WRITER; + return NULL; + } + } + + /* If we do have a write lock and it was a GDBM_NEWDB, it is + now time to truncate the file. */ + if (need_trunc && file_stat.st_size != 0) + { + TRUNCATE (dbf); + fstat (dbf->desc, &file_stat); + } + + /* Decide if this is a new file or an old file. */ + if (file_stat.st_size == 0) + { + + /* This is a new file. Create an empty database. */ + + /* Start with the blocksize. */ + if (block_size < 512) + file_block_size = STATBLKSIZE; + else + file_block_size = block_size; + + /* Get space for the file header. It will be written to disk, so + make sure there's no garbage in it. */ + dbf->header = (gdbm_file_header *) calloc (1, file_block_size); + if (dbf->header == NULL) + { + gdbm_close (dbf); + gdbm_errno = GDBM_MALLOC_ERROR; + return NULL; + } + + /* Set the magic number and the block_size. */ + dbf->header->header_magic = GDBM_MAGIC; + dbf->header->block_size = file_block_size; + + /* Create the initial hash table directory. */ + dbf->header->dir_size = 8 * sizeof (off_t); + dbf->header->dir_bits = 3; + while (dbf->header->dir_size < dbf->header->block_size) + { + dbf->header->dir_size <<= 1; + dbf->header->dir_bits += 1; + } + + /* Check for correct block_size. */ + if (dbf->header->dir_size != dbf->header->block_size) + { + gdbm_close (dbf); + gdbm_errno = GDBM_BLOCK_SIZE_ERROR; + return NULL; + } + + /* Allocate the space for the directory. */ + dbf->dir = (off_t *) malloc (dbf->header->dir_size); + if (dbf->dir == NULL) + { + gdbm_close (dbf); + gdbm_errno = GDBM_MALLOC_ERROR; + return NULL; + } + dbf->header->dir = dbf->header->block_size; + + /* Create the first and only hash bucket. */ + dbf->header->bucket_elems = + (dbf->header->block_size - sizeof (hash_bucket)) + / sizeof (bucket_element) + 1; + dbf->header->bucket_size = dbf->header->block_size; + dbf->bucket = (hash_bucket *) malloc (dbf->header->bucket_size); + if (dbf->bucket == NULL) + { + gdbm_close (dbf); + gdbm_errno = GDBM_MALLOC_ERROR; + return NULL; + } + _gdbm_new_bucket (dbf, dbf->bucket, 0); + dbf->bucket->av_count = 1; + dbf->bucket->bucket_avail[0].av_adr = 3*dbf->header->block_size; + dbf->bucket->bucket_avail[0].av_size = dbf->header->block_size; + + /* Set table entries to point to hash buckets. */ + for (index = 0; index < GDBM_DIR_COUNT (dbf); index++) + dbf->dir[index] = 2*dbf->header->block_size; + + /* Initialize the active avail block. */ + dbf->header->avail.size + = ( (dbf->header->block_size - sizeof (gdbm_file_header)) + / sizeof (avail_elem)) + 1; + dbf->header->avail.count = 0; + dbf->header->avail.next_block = 0; + dbf->header->next_block = 4*dbf->header->block_size; + + /* Write initial configuration to the file. */ + /* Block 0 is the file header and active avail block. */ + rc = _gdbm_full_write (dbf, dbf->header, dbf->header->block_size); + if (rc) + { + SAVE_ERRNO (gdbm_close (dbf)); + gdbm_errno = rc; + return NULL; + } + + /* Block 1 is the initial bucket directory. */ + rc = _gdbm_full_write (dbf, dbf->dir, dbf->header->dir_size); + if (rc) + { + SAVE_ERRNO (gdbm_close (dbf)); + gdbm_errno = rc; + return NULL; + } + + /* Block 2 is the only bucket. */ + rc = _gdbm_full_write (dbf, dbf->bucket, dbf->header->bucket_size); + if (rc) + { + SAVE_ERRNO (gdbm_close (dbf)); + gdbm_errno = rc; + return NULL; + } + + /* Wait for initial configuration to be written to disk. */ + __fsync (dbf); + + free (dbf->bucket); + } + else + { + /* This is an old database. Read in the information from the file + header and initialize the hash directory. */ + + gdbm_file_header partial_header; /* For the first part of it. */ + + /* Read the partial file header. */ + rc = _gdbm_full_read (dbf, &partial_header, sizeof (gdbm_file_header)); + if (rc) + { + SAVE_ERRNO (gdbm_close (dbf)); + gdbm_errno = rc; + return NULL; + } + + /* Is the magic number good? */ + if (partial_header.header_magic != GDBM_MAGIC + && partial_header.header_magic != GDBM_OMAGIC) + { + gdbm_close (dbf); + switch (partial_header.header_magic) + { + case GDBM_OMAGIC_SWAP: + case GDBM_MAGIC32_SWAP: + case GDBM_MAGIC64_SWAP: + gdbm_errno = GDBM_BYTE_SWAPPED; + break; + case GDBM_MAGIC32: + case GDBM_MAGIC64: + gdbm_errno = GDBM_BAD_FILE_OFFSET; + break; + default: + gdbm_errno = GDBM_BAD_MAGIC_NUMBER; + } + return NULL; + } + + /* It is a good database, read the entire header. */ + dbf->header = (gdbm_file_header *) malloc (partial_header.block_size); + if (dbf->header == NULL) + { + gdbm_close (dbf); + gdbm_errno = GDBM_MALLOC_ERROR; + return NULL; + } + memcpy (dbf->header, &partial_header, sizeof (gdbm_file_header)); + rc = _gdbm_full_read (dbf, &dbf->header->avail.av_table[1], + dbf->header->block_size-sizeof (gdbm_file_header)); + if (rc) + { + SAVE_ERRNO (gdbm_close (dbf)); + gdbm_errno = rc; + return NULL; + } + + /* Allocate space for the hash table directory. */ + dbf->dir = (off_t *) malloc (dbf->header->dir_size); + if (dbf->dir == NULL) + { + gdbm_close (dbf); + gdbm_errno = GDBM_MALLOC_ERROR; + return NULL; + } + + /* Read the hash table directory. */ + file_pos = __lseek (dbf, dbf->header->dir, SEEK_SET); + if (file_pos != dbf->header->dir) + { + SAVE_ERRNO (gdbm_close (dbf)); + gdbm_errno = GDBM_FILE_SEEK_ERROR; + return NULL; + } + + rc = _gdbm_full_read (dbf, dbf->dir, dbf->header->dir_size); + if (rc) + { + SAVE_ERRNO (gdbm_close (dbf)); + gdbm_errno = rc; + return NULL; + } + + } + +#if HAVE_MMAP + if (!(flags & GDBM_NOMMAP)) + { + if (_gdbm_mapped_init (dbf) == 0) + dbf->memory_mapping = TRUE; + else + { + /* gdbm_errno should already be set. */ + close (dbf->desc); + free (dbf->name); + free (dbf); + return NULL; + } + } +#endif + + /* Finish initializing dbf. */ + dbf->last_read = -1; + dbf->bucket = NULL; + dbf->bucket_dir = 0; + dbf->cache_entry = NULL; + dbf->header_changed = FALSE; + dbf->directory_changed = FALSE; + dbf->bucket_changed = FALSE; + dbf->second_changed = FALSE; + + /* Everything is fine, return the pointer to the file + information structure. */ + return dbf; + +} + +/* Initialize the bucket cache. */ +int +_gdbm_init_cache(GDBM_FILE dbf, size_t size) +{ + int index; + + if (dbf->bucket_cache == NULL) + { + dbf->bucket_cache = (cache_elem *) malloc(sizeof(cache_elem) * size); + if(dbf->bucket_cache == NULL) + { + gdbm_errno = GDBM_MALLOC_ERROR; + return -1; + } + dbf->cache_size = size; + + for(index = 0; index < size; index++) + { + (dbf->bucket_cache[index]).ca_bucket + = (hash_bucket *) malloc (dbf->header->bucket_size); + if ((dbf->bucket_cache[index]).ca_bucket == NULL) + { + gdbm_errno = GDBM_MALLOC_ERROR; + return -1; + } + (dbf->bucket_cache[index]).ca_adr = 0; + (dbf->bucket_cache[index]).ca_changed = FALSE; + (dbf->bucket_cache[index]).ca_data.hash_val = -1; + (dbf->bucket_cache[index]).ca_data.elem_loc = -1; + (dbf->bucket_cache[index]).ca_data.dptr = NULL; + } + dbf->bucket = dbf->bucket_cache[0].ca_bucket; + dbf->cache_entry = &dbf->bucket_cache[0]; + } + return 0; +} |