source4/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 #include "lib/tdb/include/tdbutil.h"
  26 #include "system/time.h"
  27 #include "system/filesys.h"
  28 #include "db_wrap.h"
  29
  30 #undef  DBGC_CLASS
  31 #define DBGC_CLASS DBGC_TDB
  32
  33 #define TIMEOUT_LEN 12
  34 #define CACHE_DATA_FMT  "%12u/%s"
  35
  36 static struct tdb_wrap *cache;
  37
  38 /**
  39  * @file gencache.c
  40  * @brief Generic, persistent and shared between processes cache mechanism
  41  *        for use by various parts of the Samba code
  42  *
  43  **/
  44
  45
  46 /**
  47  * Cache initialisation function. Opens cache tdb file or creates
  48  * it if does not exist.
  49  *
  50  * @return true on successful initialisation of the cache or
  51  *         false on failure
  52  **/
  53
  54 BOOL gencache_init(void)
  55 {
  56         char* cache_fname = NULL;
  57
  58         /* skip file open if it's already opened */
  59         if (cache) return True;
  60
  61         asprintf(&cache_fname, "%s/%s", lp_lockdir(), "gencache.tdb");
  62         if (cache_fname)
  63                 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
  64         else {
  65                 DEBUG(0, ("Filename allocation failed.\n"));
  66                 return False;
  67         }
  68
  69         cache = tdb_wrap_open(NULL, cache_fname, 0, TDB_DEFAULT,
  70                               O_RDWR|O_CREAT, 0644);
  71
  72         SAFE_FREE(cache_fname);
  73         if (!cache) {
  74                 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
  75                 return False;
  76         }
  77         return True;
  78 }
  79
  80
  81 /**
  82  * Cache shutdown function. Closes opened cache tdb file.
  83  *
  84  * @return true on successful closing the cache or
  85  *         false on failure during cache shutdown
  86  **/
  87
  88 BOOL gencache_shutdown(void)
  89 {
  90         if (!cache) return False;
  91         DEBUG(5, ("Closing cache file\n"));
  92         talloc_free(cache);
  93         return True;
  94 }
  95
  96
  97 /**
  98  * Set an entry in the cache file. If there's no such
  99  * one, then add it.
 100  *
 101  * @param keystr string that represents a key of this entry
 102  * @param value text representation value being cached
 103  * @param timeout time when the value is expired
 104  *
 105  * @retval true when entry is successfuly stored
 106  * @retval false on failure
 107  **/
 108
 109 BOOL gencache_set(const char *keystr, const char *value, time_t timeout)
 110 {
 111         int ret;
 112         TDB_DATA keybuf, databuf;
 113         char* valstr = NULL;
 114
 115         /* fail completely if get null pointers passed */
 116         SMB_ASSERT(keystr && value);
 117
 118         if (!gencache_init()) return False;
 119
 120         asprintf(&valstr, CACHE_DATA_FMT, (int)timeout, value);
 121         if (!valstr)
 122                 return False;
 123
 124         keybuf.dptr = strdup(keystr);
 125         keybuf.dsize = strlen(keystr)+1;
 126         databuf.dptr = strdup(valstr);
 127         databuf.dsize = strlen(valstr)+1;
 128         DEBUG(10, ("Adding cache entry with key = %s; value = %s and timeout \
 129                    = %s (%d seconds %s)\n", keybuf.dptr, value, ctime(&timeout),
 130                    (int)(timeout - time(NULL)), timeout > time(NULL) ? "ahead" : "in the past"));
 131
 132         ret = tdb_store(cache->tdb, keybuf, databuf, 0);
 133         SAFE_FREE(valstr);
 134         SAFE_FREE(keybuf.dptr);
 135         SAFE_FREE(databuf.dptr);
 136
 137         return ret == 0;
 138 }
 139
 140
 141 /**
 142  * Set existing entry to the cache file.
 143  *
 144  * @param keystr string that represents a key of this entry
 145  * @param valstr text representation value being cached
 146  * @param timeout time when the value is expired
 147  *
 148  * @retval true when entry is successfuly set
 149  * @retval false on failure
 150  **/
 151
 152 BOOL gencache_set_only(const char *keystr, const char *valstr, time_t timeout)
 153 {
 154         int ret = -1;
 155         TDB_DATA keybuf, databuf;
 156         char *old_valstr, *datastr;
 157         time_t old_timeout;
 158
 159         /* fail completely if get null pointers passed */
 160         SMB_ASSERT(keystr && valstr);
 161
 162         if (!gencache_init()) return False;
 163
 164         /*
 165          * Check whether entry exists in the cache
 166          * Don't verify gencache_get exit code, since the entry may be expired
 167          */
 168         gencache_get(keystr, &old_valstr, &old_timeout);
 169
 170         if (!(old_valstr && old_timeout)) return False;
 171
 172         DEBUG(10, ("Setting cache entry with key = %s; old value = %s and old timeout \
 173                    = %s\n", keystr, old_valstr, ctime(&old_timeout)));
 174
 175         asprintf(&datastr, CACHE_DATA_FMT, (int)timeout, valstr);
 176         keybuf.dptr = strdup(keystr);
 177         keybuf.dsize = strlen(keystr)+1;
 178         databuf.dptr = strdup(datastr);
 179         databuf.dsize = strlen(datastr)+1;
 180         DEBUGADD(10, ("New value = %s, new timeout = %s (%d seconds %s)", valstr,
 181                       ctime(&timeout), (int)(timeout - time(NULL)),
 182                       timeout > time(NULL) ? "ahead" : "in the past"));
 183
 184
 185         ret = tdb_store(cache->tdb, keybuf, databuf, TDB_REPLACE);
 186
 187         SAFE_FREE(datastr);
 188         SAFE_FREE(old_valstr);
 189         SAFE_FREE(keybuf.dptr);
 190         SAFE_FREE(databuf.dptr);
 191
 192         return ret == 0;
 193 }
 194
 195
 196 /**
 197  * Delete one entry from the cache file.
 198  *
 199  * @param keystr string that represents a key of this entry
 200  *
 201  * @retval true upon successful deletion
 202  * @retval false in case of failure
 203  **/
 204
 205 BOOL gencache_del(const char *keystr)
 206 {
 207         int ret;
 208         TDB_DATA keybuf;
 209
 210         /* fail completely if get null pointers passed */
 211         SMB_ASSERT(keystr);
 212
 213         if (!gencache_init()) return False;
 214
 215         keybuf.dptr = strdup(keystr);
 216         keybuf.dsize = strlen(keystr)+1;
 217         DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
 218         ret = tdb_delete(cache->tdb, keybuf);
 219
 220         SAFE_FREE(keybuf.dptr);
 221         return ret == 0;
 222 }
 223
 224
 225 /**
 226  * Get existing entry from the cache file.
 227  *
 228  * @param keystr string that represents a key of this entry
 229  * @param valstr buffer that is allocated and filled with the entry value
 230  *        buffer's disposing must be done outside
 231  * @param timeout pointer to a time_t that is filled with entry's
 232  *        timeout
 233  *
 234  * @retval true when entry is successfuly fetched
 235  * @retval False for failure
 236  **/
 237
 238 BOOL gencache_get(const char *keystr, char **valstr, time_t *timeout)
 239 {
 240         TDB_DATA keybuf, databuf;
 241
 242         /* fail completely if get null pointers passed */
 243         SMB_ASSERT(keystr);
 244
 245         if (!gencache_init())
 246                 return False;
 247
 248         keybuf.dptr = strdup(keystr);
 249         keybuf.dsize = strlen(keystr)+1;
 250         databuf = tdb_fetch(cache->tdb, keybuf);
 251         SAFE_FREE(keybuf.dptr);
 252
 253         if (databuf.dptr && databuf.dsize > TIMEOUT_LEN) {
 254                 char* entry_buf = strndup(databuf.dptr, databuf.dsize);
 255                 char *v;
 256                 time_t t;
 257                 unsigned i;
 258
 259                 v = malloc_array_p(char, databuf.dsize - TIMEOUT_LEN);
 260
 261                 SAFE_FREE(databuf.dptr);
 262                 sscanf(entry_buf, CACHE_DATA_FMT, (int*)&i, v);
 263                 SAFE_FREE(entry_buf);
 264                 t = i;
 265
 266                 DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
 267                            "timeout = %s\n", t > time(NULL) ? "valid" :
 268                            "expired", keystr, v, ctime(&t)));
 269
 270                 if (valstr)
 271                         *valstr = v;
 272                 else
 273                         SAFE_FREE(v);
 274
 275                 if (timeout)
 276                         *timeout = t;
 277
 278                 return t > time(NULL);
 279
 280         } else {
 281                 SAFE_FREE(databuf.dptr);
 282
 283                 if (valstr)
 284                         *valstr = NULL;
 285
 286                 if (timeout)
 287                         timeout = NULL;
 288
 289                 DEBUG(10, ("Cache entry with key = %s couldn't be found\n",
 290                            keystr));
 291
 292                 return False;
 293         }
 294 }
 295
 296
 297 /**
 298  * Iterate through all entries which key matches to specified pattern
 299  *
 300  * @param fn pointer to the function that will be supplied with each single
 301  *        matching cache entry (key, value and timeout) as an arguments
 302  * @param data void pointer to an arbitrary data that is passed directly to the fn
 303  *        function on each call
 304  * @param keystr_pattern pattern the existing entries' keys are matched to
 305  *
 306  **/
 307
 308 void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
 309                       void* data, const char* keystr_pattern)
 310 {
 311         TDB_LIST_NODE *node, *first_node;
 312         TDB_DATA databuf;
 313         char *keystr = NULL, *valstr = NULL, *entry = NULL;
 314         time_t timeout = 0;
 315         unsigned i;
 316
 317         /* fail completely if get null pointers passed */
 318         SMB_ASSERT(fn && keystr_pattern);
 319
 320         if (!gencache_init()) return;
 321
 322         DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
 323         node = tdb_search_keys(cache->tdb, keystr_pattern);
 324         first_node = node;
 325
 326         while (node) {
 327                 /* ensure null termination of the key string */
 328                 keystr = strndup(node->node_key.dptr, node->node_key.dsize);
 329
 330                 /*
 331                  * We don't use gencache_get function, because we need to iterate through
 332                  * all of the entries. Validity verification is up to fn routine.
 333                  */
 334                 databuf = tdb_fetch(cache->tdb, node->node_key);
 335                 if (!databuf.dptr || databuf.dsize <= TIMEOUT_LEN) {
 336                         SAFE_FREE(databuf.dptr);
 337                         SAFE_FREE(keystr);
 338                         node = node->next;
 339                         continue;
 340                 }
 341                 entry = strndup(databuf.dptr, databuf.dsize);
 342                 SAFE_FREE(databuf.dptr);
 343                 valstr = malloc_array_p(char, databuf.dsize - TIMEOUT_LEN);
 344                 sscanf(entry, CACHE_DATA_FMT, (int*)(&i), valstr);
 345                 timeout = i;
 346
 347                 DEBUG(10, ("Calling function with arguments (key = %s, value = %s, timeout = %s)\n",
 348                            keystr, valstr, ctime(&timeout)));
 349                 fn(keystr, valstr, timeout, data);
 350
 351                 SAFE_FREE(valstr);
 352                 SAFE_FREE(entry);
 353                 SAFE_FREE(keystr);
 354                 node = node->next;
 355         }
 356
 357         tdb_search_list_free(first_node);
 358 }
 359
 360 /********************************************************************
 361  lock a key
 362 ********************************************************************/
 363
 364 int gencache_lock_entry( const char *key )
 365 {
 366         return tdb_lock_bystring(cache->tdb, key);
 367 }
 368
 369 /********************************************************************
 370  unlock a key
 371 ********************************************************************/
 372
 373 void gencache_unlock_entry( const char *key )
 374 {
 375         tdb_unlock_bystring(cache->tdb, key);
 376 }
 377
 378