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/*
Unix SMB/CIFS implementation.
Generic, persistent and shared between processes cache mechanism for use
by various parts of the Samba code
Copyright (C) Rafal Szczesniak 2002
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 2 of the License, 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
#undef DBGC_CLASS
#define DBGC_CLASS DBGC_TDB
#define TIMEOUT_LEN 12
#define CACHE_DATA_FMT "%12u/%s"
#define READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
static TDB_CONTEXT *cache;
/**
* @file gencache.c
* @brief Generic, persistent and shared between processes cache mechanism
* for use by various parts of the Samba code
*
**/
/**
* Cache initialisation function. Opens cache tdb file or creates
* it if does not exist.
*
* @return true on successful initialisation of the cache or
* false on failure
**/
BOOL gencache_init(void)
{
char* cache_fname = NULL;
/* skip file open if it's already opened */
if (cache) return True;
asprintf(&cache_fname, "%s/%s", lp_lockdir(), "gencache.tdb");
if (cache_fname)
DEBUG(5, ("Opening cache file at %s\n", cache_fname));
else {
DEBUG(0, ("Filename allocation failed.\n"));
return False;
}
cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT,
O_RDWR|O_CREAT, 0644);
SAFE_FREE(cache_fname);
if (!cache) {
DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
return False;
}
return True;
}
/**
* Cache shutdown function. Closes opened cache tdb file.
*
* @return true on successful closing the cache or
* false on failure during cache shutdown
**/
BOOL gencache_shutdown(void)
{
int ret;
/* tdb_close routine returns -1 on error */
if (!cache) return False;
DEBUG(5, ("Closing cache file\n"));
ret = tdb_close(cache);
cache = NULL;
return ret != -1;
}
/**
* Set an entry in the cache file. If there's no such
* one, then add it.
*
* @param keystr string that represents a key of this entry
* @param value text representation value being cached
* @param timeout time when the value is expired
*
* @retval true when entry is successfuly stored
* @retval false on failure
**/
BOOL gencache_set(const char *keystr, const char *value, time_t timeout)
{
int ret;
TDB_DATA keybuf, databuf;
char* valstr = NULL;
/* fail completely if get null pointers passed */
SMB_ASSERT(keystr && value);
if (!gencache_init()) return False;
asprintf(&valstr, CACHE_DATA_FMT, (int)timeout, value);
if (!valstr)
return False;
keybuf.dptr = SMB_STRDUP(keystr);
keybuf.dsize = strlen(keystr)+1;
databuf.dptr = SMB_STRDUP(valstr);
databuf.dsize = strlen(valstr)+1;
DEBUG(10, ("Adding cache entry with key = %s; value = %s and timeout ="
" %s (%d seconds %s)\n", keybuf.dptr, value,ctime(&timeout),
(int)(timeout - time(NULL)),
timeout > time(NULL) ? "ahead" : "in the past"));
ret = tdb_store(cache, keybuf, databuf, 0);
SAFE_FREE(valstr);
SAFE_FREE(keybuf.dptr);
SAFE_FREE(databuf.dptr);
return ret == 0;
}
/**
* Set existing entry to the cache file.
*
* @param keystr string that represents a key of this entry
* @param valstr text representation value being cached
* @param timeout time when the value is expired
*
* @retval true when entry is successfuly set
* @retval false on failure
**/
BOOL gencache_set_only(const char *keystr, const char *valstr, time_t timeout)
{
int ret = -1;
TDB_DATA keybuf, databuf;
char *old_valstr, *datastr;
time_t old_timeout;
/* fail completely if get null pointers passed */
SMB_ASSERT(keystr && valstr);
if (!gencache_init()) return False;
/*
* Check whether entry exists in the cache
* Don't verify gencache_get exit code, since the entry may be expired
*/
gencache_get(keystr, &old_valstr, &old_timeout);
if (!(old_valstr && old_timeout)) return False;
DEBUG(10, ("Setting cache entry with key = %s; old value = %s and old timeout \
= %s\n", keystr, old_valstr, ctime(&old_timeout)));
asprintf(&datastr, CACHE_DATA_FMT, (int)timeout, valstr);
keybuf.dptr = SMB_STRDUP(keystr);
keybuf.dsize = strlen(keystr)+1;
databuf.dptr = SMB_STRDUP(datastr);
databuf.dsize = strlen(datastr)+1;
DEBUGADD(10, ("New value = %s, new timeout = %s (%d seconds %s)", valstr,
ctime(&timeout), (int)(timeout - time(NULL)),
timeout > time(NULL) ? "ahead" : "in the past"));
ret = tdb_store(cache, keybuf, databuf, TDB_REPLACE);
SAFE_FREE(datastr);
SAFE_FREE(old_valstr);
SAFE_FREE(keybuf.dptr);
SAFE_FREE(databuf.dptr);
return ret == 0;
}
/**
* Delete one entry from the cache file.
*
* @param keystr string that represents a key of this entry
*
* @retval true upon successful deletion
* @retval false in case of failure
**/
BOOL gencache_del(const char *keystr)
{
int ret;
TDB_DATA keybuf;
/* fail completely if get null pointers passed */
SMB_ASSERT(keystr);
if (!gencache_init()) return False;
keybuf.dptr = SMB_STRDUP(keystr);
keybuf.dsize = strlen(keystr)+1;
DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
ret = tdb_delete(cache, keybuf);
SAFE_FREE(keybuf.dptr);
return ret == 0;
}
/**
* Get existing entry from the cache file.
*
* @param keystr string that represents a key of this entry
* @param valstr buffer that is allocated and filled with the entry value
* buffer's disposing must be done outside
* @param timeout pointer to a time_t that is filled with entry's
* timeout
*
* @retval true when entry is successfuly fetched
* @retval False for failure
**/
BOOL gencache_get(const char *keystr, char **valstr, time_t *timeout)
{
TDB_DATA keybuf, databuf;
/* fail completely if get null pointers passed */
SMB_ASSERT(keystr);
if (!gencache_init()) {
return False;
}
keybuf.dptr = SMB_STRDUP(keystr);
keybuf.dsize = strlen(keystr)+1;
databuf = tdb_fetch(cache, keybuf);
SAFE_FREE(keybuf.dptr);
if (databuf.dptr && databuf.dsize > TIMEOUT_LEN) {
char* entry_buf = SMB_STRNDUP(databuf.dptr, databuf.dsize);
char *v;
time_t t;
unsigned u;
int status;
char *fmt;
v = SMB_MALLOC(databuf.dsize + 1 - TIMEOUT_LEN);
if (!v) {
return False;
}
SAFE_FREE(databuf.dptr);
asprintf(&fmt, READ_CACHE_DATA_FMT_TEMPLATE, (unsigned int)databuf.dsize - TIMEOUT_LEN);
if (!fmt) {
SAFE_FREE(v);
return False;
}
status = sscanf(entry_buf, fmt, &u, v);
SAFE_FREE(fmt);
if ( status != 2 ) {
DEBUG(0, ("gencache_get: Invalid return %d from sscanf\n", status ));
}
t = u;
SAFE_FREE(entry_buf);
DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
"timeout = %s", t > time(NULL) ? "valid" :
"expired", keystr, v, ctime(&t)));
if (valstr) {
*valstr = v;
} else {
SAFE_FREE(v);
}
if (timeout) {
*timeout = t;
}
return t > time(NULL);
}
SAFE_FREE(databuf.dptr);
if (valstr) {
*valstr = NULL;
}
if (timeout) {
timeout = NULL;
}
DEBUG(10, ("Cache entry with key = %s couldn't be found\n", keystr));
return False;
}
/**
* Iterate through all entries which key matches to specified pattern
*
* @param fn pointer to the function that will be supplied with each single
* matching cache entry (key, value and timeout) as an arguments
* @param data void pointer to an arbitrary data that is passed directly to the fn
* function on each call
* @param keystr_pattern pattern the existing entries' keys are matched to
*
**/
void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
void* data, const char* keystr_pattern)
{
TDB_LIST_NODE *node, *first_node;
TDB_DATA databuf;
char *keystr = NULL, *valstr = NULL, *entry = NULL;
time_t timeout = 0;
int status;
unsigned u;
/* fail completely if get null pointers passed */
SMB_ASSERT(fn && keystr_pattern);
if (!gencache_init()) return;
DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
node = tdb_search_keys(cache, keystr_pattern);
first_node = node;
while (node) {
char *fmt;
/* ensure null termination of the key string */
keystr = SMB_STRNDUP(node->node_key.dptr, node->node_key.dsize);
if (!keystr) {
return;
}
/*
* We don't use gencache_get function, because we need to iterate through
* all of the entries. Validity verification is up to fn routine.
*/
databuf = tdb_fetch(cache, node->node_key);
if (!databuf.dptr || databuf.dsize <= TIMEOUT_LEN) {
SAFE_FREE(databuf.dptr);
SAFE_FREE(keystr);
node = node->next;
continue;
}
entry = SMB_STRNDUP(databuf.dptr, databuf.dsize);
if (!entry) {
SAFE_FREE(databuf.dptr);
SAFE_FREE(keystr);
return;
}
SAFE_FREE(databuf.dptr);
valstr = SMB_MALLOC(databuf.dsize + 1 - TIMEOUT_LEN);
if (!valstr) {
SAFE_FREE(entry);
SAFE_FREE(keystr);
return;
}
asprintf(&fmt, READ_CACHE_DATA_FMT_TEMPLATE, (unsigned int)databuf.dsize - TIMEOUT_LEN);
if (!fmt) {
SAFE_FREE(valstr);
SAFE_FREE(entry);
SAFE_FREE(keystr);
return;
}
status = sscanf(entry, fmt, &u, valstr);
SAFE_FREE(fmt);
if ( status != 2 ) {
DEBUG(0,("gencache_iterate: invalid return from sscanf %d\n",status));
}
timeout = u;
DEBUG(10, ("Calling function with arguments (key = %s, value = %s, timeout = %s)\n",
keystr, valstr, ctime(&timeout)));
fn(keystr, valstr, timeout, data);
SAFE_FREE(valstr);
SAFE_FREE(entry);
SAFE_FREE(keystr);
node = node->next;
}
tdb_search_list_free(first_node);
}
/********************************************************************
lock a key
********************************************************************/
int gencache_lock_entry( const char *key )
{
if (!gencache_init())
return -1;
return tdb_lock_bystring(cache, key);
}
/********************************************************************
unlock a key
********************************************************************/
void gencache_unlock_entry( const char *key )
{
if (!gencache_init())
return;
tdb_unlock_bystring(cache, key);
return;
}
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