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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, by Philip A. Nelson.
Copyright (C) 1990, 1991, 1993 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 2, 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; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
You may contact the author by:
e-mail: phil@cs.wwu.edu
us-mail: Philip A. Nelson
Computer Science Department
Western Washington University
Bellingham, WA 98226
*************************************************************************/
/* 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 (dbf, key)
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. */
word_t 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_WRITER)
{
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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