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 #define READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
  32
  33 static TDB_CONTEXT *cache;
  34
  35 /**
  36  * @file gencache.c
  37  * @brief Generic, persistent and shared between processes cache mechanism
  38  *        for use by various parts of the Samba code
  39  *
  40  **/
  41
  42
  43 /**
  44  * Cache initialisation function. Opens cache tdb file or creates
  45  * it if does not exist.
  46  *
  47  * @return true on successful initialisation of the cache or
  48  *         false on failure
  49  **/
  50
  51 BOOL gencache_init(void)
  52 {
  53         char* cache_fname = NULL;
  54
  55         /* skip file open if it's already opened */
  56         if (cache) return True;
  57
  58         asprintf(&cache_fname, "%s/%s", lp_lockdir(), "gencache.tdb");
  59         if (cache_fname)
  60                 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
  61         else {
  62                 DEBUG(0, ("Filename allocation failed.\n"));
  63                 return False;
  64         }
  65
  66         cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT,
  67                              O_RDWR|O_CREAT, 0644);
  68
  69         SAFE_FREE(cache_fname);
  70         if (!cache) {
  71                 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
  72                 return False;
  73         }
  74         return True;
  75 }
  76
  77
  78 /**
  79  * Cache shutdown function. Closes opened cache tdb file.
  80  *
  81  * @return true on successful closing the cache or
  82  *         false on failure during cache shutdown
  83  **/
  84
  85 BOOL gencache_shutdown(void)
  86 {
  87         int ret;
  88         /* tdb_close routine returns -1 on error */
  89         if (!cache) return False;
  90         DEBUG(5, ("Closing cache file\n"));
  91         ret = tdb_close(cache);
  92         cache = NULL;
  93         return ret != -1;
  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 = SMB_STRDUP(keystr);
 125         keybuf.dsize = strlen(keystr)+1;
 126         databuf.dptr = SMB_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)),
 131                    timeout > time(NULL) ? "ahead" : "in the past"));
 132
 133         ret = tdb_store(cache, keybuf, databuf, 0);
 134         SAFE_FREE(valstr);
 135         SAFE_FREE(keybuf.dptr);
 136         SAFE_FREE(databuf.dptr);
 137
 138         return ret == 0;
 139 }
 140
 141
 142 /**
 143  * Set existing entry to the cache file.
 144  *
 145  * @param keystr string that represents a key of this entry
 146  * @param valstr text representation value being cached
 147  * @param timeout time when the value is expired
 148  *
 149  * @retval true when entry is successfuly set
 150  * @retval false on failure
 151  **/
 152
 153 BOOL gencache_set_only(const char *keystr, const char *valstr, time_t timeout)
 154 {
 155         int ret = -1;
 156         TDB_DATA keybuf, databuf;
 157         char *old_valstr, *datastr;
 158         time_t old_timeout;
 159
 160         /* fail completely if get null pointers passed */
 161         SMB_ASSERT(keystr && valstr);
 162
 163         if (!gencache_init()) return False;
 164
 165         /*
 166          * Check whether entry exists in the cache
 167          * Don't verify gencache_get exit code, since the entry may be expired
 168          */
 169         gencache_get(keystr, &old_valstr, &old_timeout);
 170
 171         if (!(old_valstr && old_timeout)) return False;
 172
 173         DEBUG(10, ("Setting cache entry with key = %s; old value = %s and old timeout \
 174                    = %s\n", keystr, old_valstr, ctime(&old_timeout)));
 175
 176         asprintf(&datastr, CACHE_DATA_FMT, (int)timeout, valstr);
 177         keybuf.dptr = SMB_STRDUP(keystr);
 178         keybuf.dsize = strlen(keystr)+1;
 179         databuf.dptr = SMB_STRDUP(datastr);
 180         databuf.dsize = strlen(datastr)+1;
 181         DEBUGADD(10, ("New value = %s, new timeout = %s (%d seconds %s)", valstr,
 182                       ctime(&timeout), (int)(timeout - time(NULL)),
 183                       timeout > time(NULL) ? "ahead" : "in the past"));
 184
 185
 186         ret = tdb_store(cache, keybuf, databuf, TDB_REPLACE);
 187
 188         SAFE_FREE(datastr);
 189         SAFE_FREE(old_valstr);
 190         SAFE_FREE(keybuf.dptr);
 191         SAFE_FREE(databuf.dptr);
 192
 193         return ret == 0;
 194 }
 195
 196
 197 /**
 198  * Delete one entry from the cache file.
 199  *
 200  * @param keystr string that represents a key of this entry
 201  *
 202  * @retval true upon successful deletion
 203  * @retval false in case of failure
 204  **/
 205
 206 BOOL gencache_del(const char *keystr)
 207 {
 208         int ret;
 209         TDB_DATA keybuf;
 210
 211         /* fail completely if get null pointers passed */
 212         SMB_ASSERT(keystr);
 213
 214         if (!gencache_init()) return False;
 215
 216         keybuf.dptr = SMB_STRDUP(keystr);
 217         keybuf.dsize = strlen(keystr)+1;
 218         DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
 219         ret = tdb_delete(cache, keybuf);
 220
 221         SAFE_FREE(keybuf.dptr);
 222         return ret == 0;
 223 }
 224
 225
 226 /**
 227  * Get existing entry from the cache file.
 228  *
 229  * @param keystr string that represents a key of this entry
 230  * @param valstr buffer that is allocated and filled with the entry value
 231  *        buffer's disposing must be done outside
 232  * @param timeout pointer to a time_t that is filled with entry's
 233  *        timeout
 234  *
 235  * @retval true when entry is successfuly fetched
 236  * @retval False for failure
 237  **/
 238
 239 BOOL gencache_get(const char *keystr, char **valstr, time_t *timeout)
 240 {
 241         TDB_DATA keybuf, databuf;
 242
 243         /* fail completely if get null pointers passed */
 244         SMB_ASSERT(keystr);
 245
 246         if (!gencache_init()) {
 247                 return False;
 248         }
 249
 250         keybuf.dptr = SMB_STRDUP(keystr);
 251         keybuf.dsize = strlen(keystr)+1;
 252         databuf = tdb_fetch(cache, keybuf);
 253         SAFE_FREE(keybuf.dptr);
 254
 255         if (databuf.dptr && databuf.dsize > TIMEOUT_LEN) {
 256                 char* entry_buf = SMB_STRNDUP(databuf.dptr, databuf.dsize);
 257                 char *v;
 258                 time_t t;
 259                 unsigned u;
 260                 int status;
 261                 char *fmt;
 262
 263                 v = SMB_MALLOC(databuf.dsize + 1 - TIMEOUT_LEN);
 264                 if (!v) {
 265                         return False;
 266                 }
 267
 268                 SAFE_FREE(databuf.dptr);
 269
 270                 asprintf(&fmt, READ_CACHE_DATA_FMT_TEMPLATE, (unsigned int)databuf.dsize - TIMEOUT_LEN);
 271                 if (!fmt) {
 272                         SAFE_FREE(v);
 273                         return False;
 274                 }
 275
 276                 status = sscanf(entry_buf, fmt, &u, v);
 277                 SAFE_FREE(fmt);
 278
 279                 if ( status != 2 ) {
 280                         DEBUG(0, ("gencache_get: Invalid return %d from sscanf\n", status ));
 281                 }
 282                 t = u;
 283                 SAFE_FREE(entry_buf);
 284
 285                 DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
 286                            "timeout = %s", t > time(NULL) ? "valid" :
 287                            "expired", keystr, v, ctime(&t)));
 288
 289                 if (valstr) {
 290                         *valstr = v;
 291                 } else {
 292                         SAFE_FREE(v);
 293                 }
 294
 295                 if (timeout) {
 296                         *timeout = t;
 297                 }
 298
 299                 return t > time(NULL);
 300
 301         }
 302
 303         SAFE_FREE(databuf.dptr);
 304
 305         if (valstr) {
 306                 *valstr = NULL;
 307         }
 308         if (timeout) {
 309                 timeout = NULL;
 310         }
 311
 312         DEBUG(10, ("Cache entry with key = %s couldn't be found\n", keystr));
 313         return False;
 314 }
 315
 316 /**
 317  * Iterate through all entries which key matches to specified pattern
 318  *
 319  * @param fn pointer to the function that will be supplied with each single
 320  *        matching cache entry (key, value and timeout) as an arguments
 321  * @param data void pointer to an arbitrary data that is passed directly to the fn
 322  *        function on each call
 323  * @param keystr_pattern pattern the existing entries' keys are matched to
 324  *
 325  **/
 326
 327 void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
 328                       void* data, const char* keystr_pattern)
 329 {
 330         TDB_LIST_NODE *node, *first_node;
 331         TDB_DATA databuf;
 332         char *keystr = NULL, *valstr = NULL, *entry = NULL;
 333         time_t timeout = 0;
 334         int status;
 335         unsigned u;
 336
 337         /* fail completely if get null pointers passed */
 338         SMB_ASSERT(fn && keystr_pattern);
 339
 340         if (!gencache_init()) return;
 341
 342         DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
 343         node = tdb_search_keys(cache, keystr_pattern);
 344         first_node = node;
 345
 346         while (node) {
 347                 char *fmt;
 348
 349                 /* ensure null termination of the key string */
 350                 keystr = SMB_STRNDUP(node->node_key.dptr, node->node_key.dsize);
 351                 if (!keystr) {
 352                         break;
 353                 }
 354
 355                 /*
 356                  * We don't use gencache_get function, because we need to iterate through
 357                  * all of the entries. Validity verification is up to fn routine.
 358                  */
 359                 databuf = tdb_fetch(cache, node->node_key);
 360                 if (!databuf.dptr || databuf.dsize <= TIMEOUT_LEN) {
 361                         SAFE_FREE(databuf.dptr);
 362                         SAFE_FREE(keystr);
 363                         node = node->next;
 364                         continue;
 365                 }
 366                 entry = SMB_STRNDUP(databuf.dptr, databuf.dsize);
 367                 if (!entry) {
 368                         SAFE_FREE(databuf.dptr);
 369                         SAFE_FREE(keystr);
 370                         break;
 371                 }
 372
 373                 SAFE_FREE(databuf.dptr);
 374
 375                 valstr = SMB_MALLOC(databuf.dsize + 1 - TIMEOUT_LEN);
 376                 if (!valstr) {
 377                         SAFE_FREE(entry);
 378                         SAFE_FREE(keystr);
 379                         break;
 380                 }
 381
 382                 asprintf(&fmt, READ_CACHE_DATA_FMT_TEMPLATE, (unsigned int)databuf.dsize - TIMEOUT_LEN);
 383                 if (!fmt) {
 384                         SAFE_FREE(valstr);
 385                         SAFE_FREE(entry);
 386                         SAFE_FREE(keystr);
 387                         break;
 388                 }
 389                 status = sscanf(entry, fmt, &u, valstr);
 390                 SAFE_FREE(fmt);
 391
 392                 if ( status != 2 ) {
 393                         DEBUG(0,("gencache_iterate: invalid return from sscanf %d\n",status));
 394                 }
 395                 timeout = u;
 396
 397                 DEBUG(10, ("Calling function with arguments (key = %s, value = %s, timeout = %s)\n",
 398                            keystr, valstr, ctime(&timeout)));
 399                 fn(keystr, valstr, timeout, data);
 400
 401                 SAFE_FREE(valstr);
 402                 SAFE_FREE(entry);
 403                 SAFE_FREE(keystr);
 404                 node = node->next;
 405         }
 406
 407         tdb_search_list_free(first_node);
 408 }
 409
 410 /********************************************************************
 411  lock a key
 412 ********************************************************************/
 413
 414 int gencache_lock_entry( const char *key )
 415 {
 416         if (!gencache_init())
 417                 return -1;
 418
 419         return tdb_lock_bystring(cache, key);
 420 }
 421
 422 /********************************************************************
 423  unlock a key
 424 ********************************************************************/
 425
 426 void gencache_unlock_entry( const char *key )
 427 {
 428         if (!gencache_init())
 429                 return;
 430
 431         tdb_unlock_bystring(cache, key);
 432         return;
 433 }
 434
 435