source/lib/gencache.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Generic, persistent and shared between processes cache mechanism for use
   5    by various parts of the Samba code
   6
   7    Copyright (C) Rafal Szczesniak    2002
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 #include "includes.h"
  25
  26 #undef  DBGC_CLASS
  27 #define DBGC_CLASS DBGC_TDB
  28
  29 #define TIMEOUT_LEN 12
  30 #define CACHE_DATA_FMT  "%12u/%s"
  31
  32 static TDB_CONTEXT *cache;
  33
  34 /**
  35  * @file gencache.c
  36  * @brief Generic, persistent and shared between processes cache mechanism
  37  *        for use by various parts of the Samba code
  38  *
  39  **/
  40
  41
  42 /**
  43  * Cache initialisation function. Opens cache tdb file or creates
  44  * it if does not exist.
  45  *
  46  * @return true on successful initialisation of the cache or
  47  *         false on failure
  48  **/
  49
  50 BOOL gencache_init(void)
  51 {
  52         char* cache_fname = NULL;
  53
  54         /* skip file open if it's already opened */
  55         if (cache) return True;
  56
  57         asprintf(&cache_fname, "%s/%s", lp_lockdir(), "gencache.tdb");
  58         if (cache_fname)
  59                 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
  60         else {
  61                 DEBUG(0, ("Filename allocation failed.\n"));
  62                 return False;
  63         }
  64
  65         cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT,
  66                              O_RDWR|O_CREAT, 0644);
  67
  68         SAFE_FREE(cache_fname);
  69         if (!cache) {
  70                 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
  71                 return False;
  72         }
  73         return True;
  74 }
  75
  76
  77 /**
  78  * Cache shutdown function. Closes opened cache tdb file.
  79  *
  80  * @return true on successful closing the cache or
  81  *         false on failure during cache shutdown
  82  **/
  83
  84 BOOL gencache_shutdown(void)
  85 {
  86         /* tdb_close routine returns -1 on error */
  87         if (!cache) return False;
  88         DEBUG(5, ("Closing cache file\n"));
  89         return tdb_close(cache) != -1;
  90 }
  91
  92
  93 /**
  94  * Set an entry in the cache file. If there's no such
  95  * one, then add it.
  96  *
  97  * @param keystr string that represents a key of this entry
  98  * @param value text representation value being cached
  99  * @param timeout time when the value is expired
 100  *
 101  * @retval true when entry is successfuly stored
 102  * @retval false on failure
 103  **/
 104
 105 BOOL gencache_set(const char *keystr, const char *value, time_t timeout)
 106 {
 107         int ret;
 108         TDB_DATA keybuf, databuf;
 109         char* valstr = NULL;
 110
 111         /* fail completely if get null pointers passed */
 112         SMB_ASSERT(keystr && value);
 113
 114         if (!gencache_init()) return False;
 115
 116         asprintf(&valstr, CACHE_DATA_FMT, (int)timeout, value);
 117         if (!valstr)
 118                 return False;
 119
 120         keybuf.dptr = strdup(keystr);
 121         keybuf.dsize = strlen(keystr)+1;
 122         databuf.dptr = strdup(valstr);
 123         databuf.dsize = strlen(valstr)+1;
 124         DEBUG(10, ("Adding cache entry with key = %s; value = %s and timeout ="
 125                    " %s (%d seconds %s)\n", keybuf.dptr, value,ctime(&timeout),
 126                    (int)(timeout - time(NULL)),
 127                    timeout > time(NULL) ? "ahead" : "in the past"));
 128
 129         ret = tdb_store(cache, keybuf, databuf, 0);
 130         SAFE_FREE(valstr);
 131         SAFE_FREE(keybuf.dptr);
 132         SAFE_FREE(databuf.dptr);
 133
 134         return ret == 0;
 135 }
 136
 137
 138 /**
 139  * Set existing entry to the cache file.
 140  *
 141  * @param keystr string that represents a key of this entry
 142  * @param valstr text representation value being cached
 143  * @param timeout time when the value is expired
 144  *
 145  * @retval true when entry is successfuly set
 146  * @retval false on failure
 147  **/
 148
 149 BOOL gencache_set_only(const char *keystr, const char *valstr, time_t timeout)
 150 {
 151         int ret = -1;
 152         TDB_DATA keybuf, databuf;
 153         char *old_valstr, *datastr;
 154         time_t old_timeout;
 155
 156         /* fail completely if get null pointers passed */
 157         SMB_ASSERT(keystr && valstr);
 158
 159         if (!gencache_init()) return False;
 160
 161         /*
 162          * Check whether entry exists in the cache
 163          * Don't verify gencache_get exit code, since the entry may be expired
 164          */
 165         gencache_get(keystr, &old_valstr, &old_timeout);
 166
 167         if (!(old_valstr && old_timeout)) return False;
 168
 169         DEBUG(10, ("Setting cache entry with key = %s; old value = %s and old timeout \
 170                    = %s\n", keystr, old_valstr, ctime(&old_timeout)));
 171
 172         asprintf(&datastr, CACHE_DATA_FMT, (int)timeout, valstr);
 173         keybuf.dptr = strdup(keystr);
 174         keybuf.dsize = strlen(keystr)+1;
 175         databuf.dptr = strdup(datastr);
 176         databuf.dsize = strlen(datastr)+1;
 177         DEBUGADD(10, ("New value = %s, new timeout = %s (%d seconds %s)", valstr,
 178                       ctime(&timeout), (int)(timeout - time(NULL)),
 179                       timeout > time(NULL) ? "ahead" : "in the past"));
 180
 181
 182         ret = tdb_store(cache, keybuf, databuf, TDB_REPLACE);
 183
 184         SAFE_FREE(datastr);
 185         SAFE_FREE(old_valstr);
 186         SAFE_FREE(keybuf.dptr);
 187         SAFE_FREE(databuf.dptr);
 188
 189         return ret == 0;
 190 }
 191
 192
 193 /**
 194  * Delete one entry from the cache file.
 195  *
 196  * @param keystr string that represents a key of this entry
 197  *
 198  * @retval true upon successful deletion
 199  * @retval false in case of failure
 200  **/
 201
 202 BOOL gencache_del(const char *keystr)
 203 {
 204         int ret;
 205         TDB_DATA keybuf;
 206
 207         /* fail completely if get null pointers passed */
 208         SMB_ASSERT(keystr);
 209
 210         if (!gencache_init()) return False;
 211
 212         keybuf.dptr = strdup(keystr);
 213         keybuf.dsize = strlen(keystr)+1;
 214         DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
 215         ret = tdb_delete(cache, keybuf);
 216
 217         SAFE_FREE(keybuf.dptr);
 218         return ret == 0;
 219 }
 220
 221
 222 /**
 223  * Get existing entry from the cache file.
 224  *
 225  * @param keystr string that represents a key of this entry
 226  * @param valstr buffer that is allocated and filled with the entry value
 227  *        buffer's disposing must be done outside
 228  * @param timeout pointer to a time_t that is filled with entry's
 229  *        timeout
 230  *
 231  * @retval true when entry is successfuly fetched
 232  * @retval False for failure
 233  **/
 234
 235 BOOL gencache_get(const char *keystr, char **valstr, time_t *timeout)
 236 {
 237         TDB_DATA keybuf, databuf;
 238
 239         /* fail completely if get null pointers passed */
 240         SMB_ASSERT(keystr);
 241
 242         if (!gencache_init())
 243                 return False;
 244
 245         keybuf.dptr = strdup(keystr);
 246         keybuf.dsize = strlen(keystr)+1;
 247         databuf = tdb_fetch(cache, keybuf);
 248         SAFE_FREE(keybuf.dptr);
 249
 250         if (databuf.dptr && databuf.dsize > TIMEOUT_LEN) {
 251                 char* entry_buf = strndup(databuf.dptr, databuf.dsize);
 252                 char *v;
 253                 time_t t;
 254
 255                 v = (char*)malloc(sizeof(char) *
 256                                   (databuf.dsize - TIMEOUT_LEN));
 257
 258                 SAFE_FREE(databuf.dptr);
 259                 sscanf(entry_buf, CACHE_DATA_FMT, (int*)&t, v);
 260                 SAFE_FREE(entry_buf);
 261
 262                 DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
 263                            "timeout = %s\n", t > time(NULL) ? "valid" :
 264                            "expired", keystr, v, ctime(&t)));
 265
 266                 if (valstr)
 267                         *valstr = v;
 268                 else
 269                         SAFE_FREE(v);
 270
 271                 if (timeout)
 272                         *timeout = t;
 273
 274                 return t > time(NULL);
 275
 276         } else {
 277                 SAFE_FREE(databuf.dptr);
 278
 279                 if (valstr)
 280                         *valstr = NULL;
 281
 282                 if (timeout)
 283                         timeout = NULL;
 284
 285                 DEBUG(10, ("Cache entry with key = %s couldn't be found\n",
 286                            keystr));
 287
 288                 return False;
 289         }
 290 }
 291
 292
 293 /**
 294  * Iterate through all entries which key matches to specified pattern
 295  *
 296  * @param fn pointer to the function that will be supplied with each single
 297  *        matching cache entry (key, value and timeout) as an arguments
 298  * @param data void pointer to an arbitrary data that is passed directly to the fn
 299  *        function on each call
 300  * @param keystr_pattern pattern the existing entries' keys are matched to
 301  *
 302  **/
 303
 304 void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
 305                       void* data, const char* keystr_pattern)
 306 {
 307         TDB_LIST_NODE *node, *first_node;
 308         TDB_DATA databuf;
 309         char *keystr = NULL, *valstr = NULL, *entry = NULL;
 310         time_t timeout = 0;
 311
 312         /* fail completely if get null pointers passed */
 313         SMB_ASSERT(fn && keystr_pattern);
 314
 315         if (!gencache_init()) return;
 316
 317         DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
 318         node = tdb_search_keys(cache, keystr_pattern);
 319         first_node = node;
 320
 321         while (node) {
 322                 /* ensure null termination of the key string */
 323                 keystr = strndup(node->node_key.dptr, node->node_key.dsize);
 324
 325                 /*
 326                  * We don't use gencache_get function, because we need to iterate through
 327                  * all of the entries. Validity verification is up to fn routine.
 328                  */
 329                 databuf = tdb_fetch(cache, node->node_key);
 330                 if (!databuf.dptr || databuf.dsize <= TIMEOUT_LEN) {
 331                         SAFE_FREE(databuf.dptr);
 332                         SAFE_FREE(keystr);
 333                         node = node->next;
 334                         continue;
 335                 }
 336                 entry = strndup(databuf.dptr, databuf.dsize);
 337                 SAFE_FREE(databuf.dptr);
 338                 valstr = (char*)malloc(sizeof(char) * (databuf.dsize - TIMEOUT_LEN));
 339                 sscanf(entry, CACHE_DATA_FMT, (int*)(&timeout), valstr);
 340
 341                 DEBUG(10, ("Calling function with arguments (key = %s, value = %s, timeout = %s)\n",
 342                            keystr, valstr, ctime(&timeout)));
 343                 fn(keystr, valstr, timeout, data);
 344
 345                 SAFE_FREE(valstr);
 346                 SAFE_FREE(entry);
 347                 SAFE_FREE(keystr);
 348                 node = node->next;
 349         }
 350
 351         tdb_search_list_free(first_node);
 352 }
 353
 354 /********************************************************************
 355  lock a key
 356 ********************************************************************/
 357
 358 int gencache_lock_entry( const char *key )
 359 {
 360         if (!gencache_init())
 361                 return -1;
 362
 363         return tdb_lock_bystring(cache, key, 0);
 364 }
 365
 366 /********************************************************************
 367  unlock a key
 368 ********************************************************************/
 369
 370 void gencache_unlock_entry( const char *key )
 371 {
 372         if (!gencache_init())
 373                 return;
 374
 375         tdb_unlock_bystring(cache, key);
 376         return;
 377 }
 378
 379