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authorJason Downs <downsj@downsj.com>2008-11-21 21:33:39 +0000
committerJason Downs <downsj@downsj.com>2008-11-21 21:33:39 +0000
commit10fe387708ddfba6449b9abd74cfbdf67d495465 (patch)
tree50115c0708c762940f580d081c73495bf148101a /src/gdbmdelete.c
downloadgdbm-10fe387708ddfba6449b9abd74cfbdf67d495465.tar.gz
gdbm-10fe387708ddfba6449b9abd74cfbdf67d495465.tar.bz2
Initial revision
Diffstat (limited to 'src/gdbmdelete.c')
-rw-r--r--src/gdbmdelete.c107
1 files changed, 107 insertions, 0 deletions
diff --git a/src/gdbmdelete.c b/src/gdbmdelete.c
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+/* gdbmdelete.c - Remove the key and its associated data from 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"
+
+/* Remove the KEYed item and the KEY from the database DBF. The file on disk
+ is updated to reflect the structure of the new database before returning
+ from this procedure. */
+
+int
+gdbm_delete (gdbm_file_info *dbf, datum key)
+{
+ int elem_loc; /* The location in the current hash bucket. */
+ int last_loc; /* Last location emptied by the delete. */
+ int home; /* Home position of an item. */
+ bucket_element elem; /* The element to be deleted. */
+ char *find_data; /* Return pointer from findkey. */
+ int hash_val; /* Returned by findkey. */
+ off_t free_adr; /* Temporary stroage for address and size. */
+ int free_size;
+
+ /* First check to make sure this guy is a writer. */
+ if (dbf->read_write == GDBM_READER)
+ {
+ gdbm_errno = GDBM_READER_CANT_DELETE;
+ return -1;
+ }
+
+ /* Initialize the gdbm_errno variable. */
+ gdbm_errno = GDBM_NO_ERROR;
+
+ /* Find the item. */
+ elem_loc = _gdbm_findkey (dbf, key, &find_data, &hash_val);
+ if (elem_loc == -1)
+ {
+ gdbm_errno = GDBM_ITEM_NOT_FOUND;
+ return -1;
+ }
+
+ /* Save the element. */
+ elem = dbf->bucket->h_table[elem_loc];
+
+ /* Delete the element. */
+ dbf->bucket->h_table[elem_loc].hash_value = -1;
+ dbf->bucket->count -= 1;
+
+ /* Move other elements to guarantee that they can be found. */
+ last_loc = elem_loc;
+ elem_loc = (elem_loc + 1) % dbf->header->bucket_elems;
+ while (elem_loc != last_loc
+ && dbf->bucket->h_table[elem_loc].hash_value != -1)
+ {
+ home = dbf->bucket->h_table[elem_loc].hash_value
+ % dbf->header->bucket_elems;
+ if ( (last_loc < elem_loc && (home <= last_loc || home > elem_loc))
+ || (last_loc > elem_loc && home <= last_loc && home > elem_loc))
+
+ {
+ dbf->bucket->h_table[last_loc] = dbf->bucket->h_table[elem_loc];
+ dbf->bucket->h_table[elem_loc].hash_value = -1;
+ last_loc = elem_loc;
+ }
+ elem_loc = (elem_loc + 1) % dbf->header->bucket_elems;
+ }
+
+ /* Free the file space. */
+ free_adr = elem.data_pointer;
+ free_size = elem.key_size + elem.data_size;
+ _gdbm_free (dbf, free_adr, free_size);
+
+ /* Set the flags. */
+ dbf->bucket_changed = TRUE;
+
+ /* Clear out the data cache for the current bucket. */
+ if (dbf->cache_entry->ca_data.dptr != NULL)
+ {
+ free (dbf->cache_entry->ca_data.dptr);
+ dbf->cache_entry->ca_data.dptr = NULL;
+ }
+ dbf->cache_entry->ca_data.hash_val = -1;
+ dbf->cache_entry->ca_data.key_size = 0;
+ dbf->cache_entry->ca_data.elem_loc = -1;
+
+ /* Do the writes. */
+ _gdbm_end_update (dbf);
+ return 0;
+}

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