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/*
* db_xdbm.c: common code for gdbm and ndbm backends
*
* Copyright (C) 2003-2019 Colin Watson.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif /* HAVE_CONFIG_H */
#if defined(GDBM) || defined(NDBM)
# include <stdbool.h>
# include <stdlib.h>
# include <string.h>
# include "gl_hash_map.h"
# include "gl_rbtree_list.h"
# include "gl_xlist.h"
# include "gl_xmap.h"
# include "hash-pjw-bare.h"
# include "xalloc.h"
# include "manconfig.h"
# include "cleanup.h"
# include "glcontainers.h"
# include "db_xdbm.h"
# include "mydbm.h"
static gl_map_t parent_keys;
static int datum_compare (const void *a, const void *b)
{
const datum *left = (const datum *) a;
const datum *right = (const datum *) b;
int cmp;
size_t minsize;
/* Sentinel NULL elements sort to the end. */
if (!MYDBM_DPTR (*left))
return 1;
else if (!MYDBM_DPTR (*right))
return -1;
if (MYDBM_DSIZE (*left) < MYDBM_DSIZE (*right))
minsize = MYDBM_DSIZE (*left);
else
minsize = MYDBM_DSIZE (*right);
cmp = strncmp (MYDBM_DPTR (*left), MYDBM_DPTR (*right), minsize);
if (cmp)
return cmp;
else if (MYDBM_DSIZE (*left) < MYDBM_DSIZE (*right))
return 1;
else if (MYDBM_DSIZE (*left) > MYDBM_DSIZE (*right))
return -1;
else
return 0;
}
static bool datum_equals (const void *a, const void *b)
{
return datum_compare (a, b) == 0;
}
static size_t datum_hash (const void *value)
{
const datum *d = value;
return hash_pjw_bare (MYDBM_DPTR (*d), MYDBM_DSIZE (*d));
}
static void datum_free (const void *value)
{
MYDBM_FREE_DPTR (*(datum *) value);
}
static datum empty_datum = {NULL, 0};
/* We keep a map of filenames to sorted lists of keys. Each list is stored
* using a hash-based implementation that allows lookup by name and
* traversal to the next item in O(log n) time, which is necessary for a
* reasonable ordered implementation of nextkey.
*/
datum man_xdbm_firstkey (MYDBM_FILE dbf,
man_xdbm_unsorted_firstkey unsorted_firstkey,
man_xdbm_unsorted_nextkey unsorted_nextkey)
{
gl_list_t keys;
datum *key;
/* Build the raw sorted list of keys. */
keys = gl_list_create_empty (GL_RBTREE_LIST, datum_equals, datum_hash,
datum_free, false);
key = XMALLOC (datum);
*key = unsorted_firstkey (dbf);
while (MYDBM_DPTR (*key)) {
datum *next;
gl_sortedlist_add (keys, datum_compare, key);
next = XMALLOC (datum);
*next = unsorted_nextkey (dbf, *key);
key = next;
}
if (!parent_keys) {
parent_keys = new_string_map (
GL_HASH_MAP, (gl_mapvalue_dispose_fn) gl_list_free);
push_cleanup ((cleanup_fun) gl_map_free, parent_keys, 0);
}
/* Remember this structure for use by nextkey. */
gl_map_put (parent_keys, xstrdup (dbf->name), keys);
if (gl_list_size (keys))
return copy_datum (*(datum *) gl_list_get_at (keys, 0));
else
return empty_datum;
}
datum man_xdbm_nextkey (MYDBM_FILE dbf, datum key)
{
gl_list_t keys;
gl_list_node_t node, next_node;
if (!parent_keys)
return empty_datum;
keys = (gl_list_t) gl_map_get (parent_keys, dbf->name);
if (!keys)
return empty_datum;
node = gl_sortedlist_search (keys, datum_compare, &key);
if (!node)
return empty_datum;
next_node = gl_list_next_node (keys, node);
if (!next_node)
return empty_datum;
return copy_datum (*(datum *) gl_list_node_value (keys, next_node));
}
void man_xdbm_free (MYDBM_FILE dbf, man_xdbm_raw_close raw_close)
{
if (!dbf)
return;
if (parent_keys)
gl_map_remove (parent_keys, dbf->name);
free (dbf->name);
raw_close (dbf);
free (dbf->mtime);
free (dbf);
}
#endif /* GDBM || NDBM */
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