mirror of
https://github.com/samba-team/samba.git
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6e6374cb5b
(This used to be commit eec698254f
)
376 lines
9.5 KiB
C
376 lines
9.5 KiB
C
/*
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Unix SMB/CIFS implementation.
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Generic, persistent and shared between processes cache mechanism for use
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by various parts of the Samba code
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Copyright (C) Rafal Szczesniak 2002
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "includes.h"
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#include "system/time.h"
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#undef DBGC_CLASS
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#define DBGC_CLASS DBGC_TDB
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#define TIMEOUT_LEN 12
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#define CACHE_DATA_FMT "%12u/%s"
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static struct tdb_wrap *cache;
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/**
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* @file gencache.c
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* @brief Generic, persistent and shared between processes cache mechanism
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* for use by various parts of the Samba code
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*
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**/
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/**
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* Cache initialisation function. Opens cache tdb file or creates
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* it if does not exist.
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*
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* @return true on successful initialisation of the cache or
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* false on failure
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**/
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BOOL gencache_init(void)
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{
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char* cache_fname = NULL;
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/* skip file open if it's already opened */
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if (cache) return True;
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asprintf(&cache_fname, "%s/%s", lp_lockdir(), "gencache.tdb");
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if (cache_fname)
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DEBUG(5, ("Opening cache file at %s\n", cache_fname));
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else {
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DEBUG(0, ("Filename allocation failed.\n"));
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return False;
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}
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cache = tdb_wrap_open(NULL, cache_fname, 0, TDB_DEFAULT,
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O_RDWR|O_CREAT, 0644);
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SAFE_FREE(cache_fname);
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if (!cache) {
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DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
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return False;
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}
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return True;
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}
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/**
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* Cache shutdown function. Closes opened cache tdb file.
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*
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* @return true on successful closing the cache or
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* false on failure during cache shutdown
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**/
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BOOL gencache_shutdown(void)
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{
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if (!cache) return False;
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DEBUG(5, ("Closing cache file\n"));
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talloc_free(cache);
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return True;
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}
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/**
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* Set an entry in the cache file. If there's no such
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* one, then add it.
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*
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* @param keystr string that represents a key of this entry
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* @param value text representation value being cached
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* @param timeout time when the value is expired
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*
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* @retval true when entry is successfuly stored
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* @retval false on failure
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**/
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BOOL gencache_set(const char *keystr, const char *value, time_t timeout)
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{
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int ret;
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TDB_DATA keybuf, databuf;
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char* valstr = NULL;
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/* fail completely if get null pointers passed */
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SMB_ASSERT(keystr && value);
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if (!gencache_init()) return False;
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asprintf(&valstr, CACHE_DATA_FMT, (int)timeout, value);
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if (!valstr)
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return False;
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keybuf.dptr = strdup(keystr);
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keybuf.dsize = strlen(keystr)+1;
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databuf.dptr = strdup(valstr);
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databuf.dsize = strlen(valstr)+1;
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DEBUG(10, ("Adding cache entry with key = %s; value = %s and timeout \
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= %s (%d seconds %s)\n", keybuf.dptr, value, ctime(&timeout),
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(int)(timeout - time(NULL)), timeout > time(NULL) ? "ahead" : "in the past"));
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ret = tdb_store(cache->tdb, keybuf, databuf, 0);
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SAFE_FREE(valstr);
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SAFE_FREE(keybuf.dptr);
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SAFE_FREE(databuf.dptr);
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return ret == 0;
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}
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/**
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* Set existing entry to the cache file.
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*
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* @param keystr string that represents a key of this entry
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* @param valstr text representation value being cached
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* @param timeout time when the value is expired
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*
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* @retval true when entry is successfuly set
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* @retval false on failure
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**/
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BOOL gencache_set_only(const char *keystr, const char *valstr, time_t timeout)
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{
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int ret = -1;
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TDB_DATA keybuf, databuf;
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char *old_valstr, *datastr;
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time_t old_timeout;
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/* fail completely if get null pointers passed */
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SMB_ASSERT(keystr && valstr);
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if (!gencache_init()) return False;
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/*
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* Check whether entry exists in the cache
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* Don't verify gencache_get exit code, since the entry may be expired
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*/
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gencache_get(keystr, &old_valstr, &old_timeout);
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if (!(old_valstr && old_timeout)) return False;
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DEBUG(10, ("Setting cache entry with key = %s; old value = %s and old timeout \
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= %s\n", keystr, old_valstr, ctime(&old_timeout)));
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asprintf(&datastr, CACHE_DATA_FMT, (int)timeout, valstr);
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keybuf.dptr = strdup(keystr);
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keybuf.dsize = strlen(keystr)+1;
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databuf.dptr = strdup(datastr);
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databuf.dsize = strlen(datastr)+1;
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DEBUGADD(10, ("New value = %s, new timeout = %s (%d seconds %s)", valstr,
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ctime(&timeout), (int)(timeout - time(NULL)),
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timeout > time(NULL) ? "ahead" : "in the past"));
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ret = tdb_store(cache->tdb, keybuf, databuf, TDB_REPLACE);
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SAFE_FREE(datastr);
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SAFE_FREE(old_valstr);
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SAFE_FREE(keybuf.dptr);
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SAFE_FREE(databuf.dptr);
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return ret == 0;
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}
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/**
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* Delete one entry from the cache file.
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*
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* @param keystr string that represents a key of this entry
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*
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* @retval true upon successful deletion
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* @retval false in case of failure
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**/
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BOOL gencache_del(const char *keystr)
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{
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int ret;
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TDB_DATA keybuf;
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/* fail completely if get null pointers passed */
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SMB_ASSERT(keystr);
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if (!gencache_init()) return False;
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keybuf.dptr = strdup(keystr);
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keybuf.dsize = strlen(keystr)+1;
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DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
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ret = tdb_delete(cache->tdb, keybuf);
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SAFE_FREE(keybuf.dptr);
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return ret == 0;
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}
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/**
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* Get existing entry from the cache file.
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*
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* @param keystr string that represents a key of this entry
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* @param valstr buffer that is allocated and filled with the entry value
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* buffer's disposing must be done outside
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* @param timeout pointer to a time_t that is filled with entry's
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* timeout
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*
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* @retval true when entry is successfuly fetched
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* @retval False for failure
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**/
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BOOL gencache_get(const char *keystr, char **valstr, time_t *timeout)
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{
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TDB_DATA keybuf, databuf;
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/* fail completely if get null pointers passed */
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SMB_ASSERT(keystr);
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if (!gencache_init())
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return False;
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keybuf.dptr = strdup(keystr);
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keybuf.dsize = strlen(keystr)+1;
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databuf = tdb_fetch(cache->tdb, keybuf);
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SAFE_FREE(keybuf.dptr);
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if (databuf.dptr && databuf.dsize > TIMEOUT_LEN) {
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char* entry_buf = strndup(databuf.dptr, databuf.dsize);
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char *v;
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time_t t;
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unsigned i;
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v = malloc_array_p(char, databuf.dsize - TIMEOUT_LEN);
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SAFE_FREE(databuf.dptr);
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sscanf(entry_buf, CACHE_DATA_FMT, (int*)&i, v);
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SAFE_FREE(entry_buf);
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t = i;
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DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
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"timeout = %s\n", t > time(NULL) ? "valid" :
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"expired", keystr, v, ctime(&t)));
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if (valstr)
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*valstr = v;
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else
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SAFE_FREE(v);
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if (timeout)
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*timeout = t;
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return t > time(NULL);
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} else {
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SAFE_FREE(databuf.dptr);
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if (valstr)
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*valstr = NULL;
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if (timeout)
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timeout = NULL;
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DEBUG(10, ("Cache entry with key = %s couldn't be found\n",
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keystr));
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return False;
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}
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}
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/**
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* Iterate through all entries which key matches to specified pattern
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*
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* @param fn pointer to the function that will be supplied with each single
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* matching cache entry (key, value and timeout) as an arguments
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* @param data void pointer to an arbitrary data that is passed directly to the fn
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* function on each call
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* @param keystr_pattern pattern the existing entries' keys are matched to
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*
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**/
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void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
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void* data, const char* keystr_pattern)
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{
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TDB_LIST_NODE *node, *first_node;
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TDB_DATA databuf;
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char *keystr = NULL, *valstr = NULL, *entry = NULL;
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time_t timeout = 0;
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unsigned i;
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/* fail completely if get null pointers passed */
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SMB_ASSERT(fn && keystr_pattern);
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if (!gencache_init()) return;
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DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
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node = tdb_search_keys(cache->tdb, keystr_pattern);
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first_node = node;
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while (node) {
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/* ensure null termination of the key string */
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keystr = strndup(node->node_key.dptr, node->node_key.dsize);
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/*
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* We don't use gencache_get function, because we need to iterate through
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* all of the entries. Validity verification is up to fn routine.
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*/
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databuf = tdb_fetch(cache->tdb, node->node_key);
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if (!databuf.dptr || databuf.dsize <= TIMEOUT_LEN) {
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SAFE_FREE(databuf.dptr);
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SAFE_FREE(keystr);
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node = node->next;
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continue;
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}
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entry = strndup(databuf.dptr, databuf.dsize);
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SAFE_FREE(databuf.dptr);
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valstr = malloc_array_p(char, databuf.dsize - TIMEOUT_LEN);
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sscanf(entry, CACHE_DATA_FMT, (int*)(&i), valstr);
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timeout = i;
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DEBUG(10, ("Calling function with arguments (key = %s, value = %s, timeout = %s)\n",
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keystr, valstr, ctime(&timeout)));
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fn(keystr, valstr, timeout, data);
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SAFE_FREE(valstr);
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SAFE_FREE(entry);
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SAFE_FREE(keystr);
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node = node->next;
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}
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tdb_search_list_free(first_node);
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}
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/********************************************************************
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lock a key
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********************************************************************/
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int gencache_lock_entry( const char *key )
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{
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return tdb_lock_bystring(cache->tdb, key, 0);
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}
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/********************************************************************
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unlock a key
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********************************************************************/
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void gencache_unlock_entry( const char *key )
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{
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tdb_unlock_bystring(cache->tdb, key);
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}
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