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path: root/src/gdbmstore.c
authorJason Downs <downsj@downsj.com>2008-11-21 21:33:39 (GMT)
committer Jason Downs <downsj@downsj.com>2008-11-21 21:33:39 (GMT)
commit10fe387708ddfba6449b9abd74cfbdf67d495465 (patch) (side-by-side diff)
tree50115c0708c762940f580d081c73495bf148101a /src/gdbmstore.c
downloadgdbm-10fe387708ddfba6449b9abd74cfbdf67d495465.tar.gz
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+/* gdbmstore.c - Add a new key/data pair to the database. */
+
+/* This file is part of GDBM, the GNU data base manager.
+ Copyright (C) 1990, 1991, 1993, 2007 Free Software Foundation, Inc.
+
+ This program 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.
+
+ This program 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 this program; if not, write to the Free Software Foundation,
+ Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+/* Include system configuration before all else. */
+#include "autoconf.h"
+
+#include "gdbmdefs.h"
+#include "gdbmerrno.h"
+
+
+/* Add a new element to the database. CONTENT is keyed by KEY. The
+ file on disk is updated to reflect the structure of the new database
+ before returning from this procedure. The FLAGS define the action to
+ take when the KEY is already in the database. The value GDBM_REPLACE
+ asks that the old data be replaced by the new CONTENT. The value
+ GDBM_INSERT asks that an error be returned and no action taken. A
+ return value of 0 means no errors. A return value of -1 means that
+ the item was not stored in the data base because the caller was not an
+ official writer. A return value of 0 means that the item was not stored
+ because the argument FLAGS was GDBM_INSERT and the KEY was already in
+ the database. */
+
+int
+gdbm_store (gdbm_file_info *dbf, datum key, datum content, int flags)
+{
+ int new_hash_val; /* The new hash value. */
+ int elem_loc; /* The location in hash bucket. */
+ off_t file_adr; /* The address of new space in the file. */
+ off_t file_pos; /* The position after a lseek. */
+ int num_bytes; /* Used for error detection. */
+ off_t free_adr; /* For keeping track of a freed section. */
+ int free_size;
+ int new_size; /* Used in allocating space. */
+ char *temp; /* Used in _gdbm_findkey call. */
+
+
+ /* First check to make sure this guy is a writer. */
+ if (dbf->read_write == GDBM_READER)
+ {
+ gdbm_errno = GDBM_READER_CANT_STORE;
+ return -1;
+ }
+
+ /* Check for illegal data values. A NULL dptr field is illegal because
+ NULL dptr returned by a lookup procedure indicates an error. */
+ if ((key.dptr == NULL) || (content.dptr == NULL))
+ {
+ gdbm_errno = GDBM_ILLEGAL_DATA;
+ return -1;
+ }
+
+ /* Initialize the gdbm_errno variable. */
+ gdbm_errno = GDBM_NO_ERROR;
+
+ /* Look for the key in the file.
+ A side effect loads the correct bucket and calculates the hash value. */
+ elem_loc = _gdbm_findkey (dbf, key, &temp, &new_hash_val);
+
+ /* Initialize these. */
+ file_adr = 0;
+ new_size = key.dsize + content.dsize;
+
+ /* Did we find the item? */
+ if (elem_loc != -1)
+ {
+ if (flags == GDBM_REPLACE)
+ {
+ /* Just replace the data. */
+ free_adr = dbf->bucket->h_table[elem_loc].data_pointer;
+ free_size = dbf->bucket->h_table[elem_loc].key_size
+ + dbf->bucket->h_table[elem_loc].data_size;
+ if (free_size != new_size)
+ {
+ _gdbm_free (dbf, free_adr, free_size);
+ }
+ else
+ {
+ /* Just reuse the same address! */
+ file_adr = free_adr;
+ }
+ }
+ else
+ {
+ gdbm_errno = GDBM_CANNOT_REPLACE;
+ return 1;
+ }
+ }
+
+
+ /* Get the file address for the new space.
+ (Current bucket's free space is first place to look.) */
+ if (file_adr == 0)
+ {
+ file_adr = _gdbm_alloc (dbf, new_size);
+ }
+
+ /* If this is a new entry in the bucket, we need to do special things. */
+ if (elem_loc == -1)
+ {
+ if (dbf->bucket->count == dbf->header->bucket_elems)
+ {
+ /* Split the current bucket. */
+ _gdbm_split_bucket (dbf, new_hash_val);
+ }
+
+ /* Find space to insert into bucket and set elem_loc to that place. */
+ elem_loc = new_hash_val % dbf->header->bucket_elems;
+ while (dbf->bucket->h_table[elem_loc].hash_value != -1)
+ { elem_loc = (elem_loc + 1) % dbf->header->bucket_elems; }
+
+ /* We now have another element in the bucket. Add the new information.*/
+ dbf->bucket->count += 1;
+ dbf->bucket->h_table[elem_loc].hash_value = new_hash_val;
+ memcpy (dbf->bucket->h_table[elem_loc].key_start, key.dptr,
+ (SMALL < key.dsize ? SMALL : key.dsize));
+ }
+
+
+ /* Update current bucket data pointer and sizes. */
+ dbf->bucket->h_table[elem_loc].data_pointer = file_adr;
+ dbf->bucket->h_table[elem_loc].key_size = key.dsize;
+ dbf->bucket->h_table[elem_loc].data_size = content.dsize;
+
+ /* Write the data to the file. */
+ file_pos = __lseek (dbf, file_adr, L_SET);
+ if (file_pos != file_adr) _gdbm_fatal (dbf, "lseek error");
+ num_bytes = __write (dbf, key.dptr, key.dsize);
+ if (num_bytes != key.dsize) _gdbm_fatal (dbf, "write error");
+ num_bytes = __write (dbf, content.dptr, content.dsize);
+ if (num_bytes != content.dsize) _gdbm_fatal (dbf, "write error");
+
+ /* Current bucket has changed. */
+ dbf->cache_entry->ca_changed = TRUE;
+ dbf->bucket_changed = TRUE;
+
+ /* Write everything that is needed to the disk. */
+ _gdbm_end_update (dbf);
+ return 0;
+
+}

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