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 3 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, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "includes.h"
  24
  25 #undef  DBGC_CLASS
  26 #define DBGC_CLASS DBGC_TDB
  27
  28 #define TIMEOUT_LEN 12
  29 #define CACHE_DATA_FMT  "%12u/%s"
  30 #define READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
  31
  32 static TDB_CONTEXT *cache;
  33 static BOOL cache_readonly;
  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         cache_fname = lock_path("gencache.tdb");
  59
  60         DEBUG(5, ("Opening cache file at %s\n", cache_fname));
  61
  62         cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT,
  63                              O_RDWR|O_CREAT, 0644);
  64
  65         if (!cache && (errno == EACCES)) {
  66                 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT, O_RDONLY, 0644);
  67                 if (cache) {
  68                         cache_readonly = True;
  69                         DEBUG(5, ("gencache_init: Opening cache file %s read-only.\n", cache_fname));
  70                 }
  71         }
  72
  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         int ret;
  91         /* tdb_close routine returns -1 on error */
  92         if (!cache) return False;
  93         DEBUG(5, ("Closing cache file\n"));
  94         ret = tdb_close(cache);
  95         cache = NULL;
  96         cache_readonly = False;
  97         return ret != -1;
  98 }
  99
 100
 101 /**
 102  * Set an entry in the cache file. If there's no such
 103  * one, then add it.
 104  *
 105  * @param keystr string that represents a key of this entry
 106  * @param value text representation value being cached
 107  * @param timeout time when the value is expired
 108  *
 109  * @retval true when entry is successfuly stored
 110  * @retval false on failure
 111  **/
 112
 113 BOOL gencache_set(const char *keystr, const char *value, time_t timeout)
 114 {
 115         int ret;
 116         TDB_DATA databuf;
 117         char* valstr = NULL;
 118
 119         /* fail completely if get null pointers passed */
 120         SMB_ASSERT(keystr && value);
 121
 122         if (!gencache_init()) return False;
 123
 124         if (cache_readonly) {
 125                 return False;
 126         }
 127
 128         asprintf(&valstr, CACHE_DATA_FMT, (int)timeout, value);
 129         if (!valstr)
 130                 return False;
 131
 132         databuf = string_term_tdb_data(valstr);
 133         DEBUG(10, ("Adding cache entry with key = %s; value = %s and timeout ="
 134                    " %s (%d seconds %s)\n", keystr, value,ctime(&timeout),
 135                    (int)(timeout - time(NULL)),
 136                    timeout > time(NULL) ? "ahead" : "in the past"));
 137
 138         ret = tdb_store_bystring(cache, keystr, databuf, 0);
 139         SAFE_FREE(valstr);
 140
 141         return ret == 0;
 142 }
 143
 144 /**
 145  * Delete one entry from the cache file.
 146  *
 147  * @param keystr string that represents a key of this entry
 148  *
 149  * @retval true upon successful deletion
 150  * @retval false in case of failure
 151  **/
 152
 153 BOOL gencache_del(const char *keystr)
 154 {
 155         int ret;
 156
 157         /* fail completely if get null pointers passed */
 158         SMB_ASSERT(keystr);
 159
 160         if (!gencache_init()) return False;
 161
 162         if (cache_readonly) {
 163                 return False;
 164         }
 165
 166         DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
 167         ret = tdb_delete_bystring(cache, keystr);
 168
 169         return ret == 0;
 170 }
 171
 172
 173 /**
 174  * Get existing entry from the cache file.
 175  *
 176  * @param keystr string that represents a key of this entry
 177  * @param valstr buffer that is allocated and filled with the entry value
 178  *        buffer's disposing must be done outside
 179  * @param timeout pointer to a time_t that is filled with entry's
 180  *        timeout
 181  *
 182  * @retval true when entry is successfuly fetched
 183  * @retval False for failure
 184  **/
 185
 186 BOOL gencache_get(const char *keystr, char **valstr, time_t *timeout)
 187 {
 188         TDB_DATA databuf;
 189         time_t t;
 190         char *endptr;
 191
 192         /* fail completely if get null pointers passed */
 193         SMB_ASSERT(keystr);
 194
 195         if (!gencache_init()) {
 196                 return False;
 197         }
 198
 199         databuf = tdb_fetch_bystring(cache, keystr);
 200
 201         if (databuf.dptr == NULL) {
 202                 DEBUG(10, ("Cache entry with key = %s couldn't be found\n",
 203                            keystr));
 204                 return False;
 205         }
 206
 207         t = strtol((const char *)databuf.dptr, &endptr, 10);
 208
 209         if ((endptr == NULL) || (*endptr != '/')) {
 210                 DEBUG(2, ("Invalid gencache data format: %s\n", databuf.dptr));
 211                 SAFE_FREE(databuf.dptr);
 212                 return False;
 213         }
 214
 215         DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
 216                    "timeout = %s", t > time(NULL) ? "valid" :
 217                    "expired", keystr, endptr+1, ctime(&t)));
 218
 219         if (t <= time(NULL)) {
 220
 221                 /* We're expired, delete the entry */
 222                 tdb_delete_bystring(cache, keystr);
 223
 224                 SAFE_FREE(databuf.dptr);
 225                 return False;
 226         }
 227
 228         if (valstr) {
 229                 *valstr = SMB_STRDUP(endptr+1);
 230                 if (*valstr == NULL) {
 231                         SAFE_FREE(databuf.dptr);
 232                         DEBUG(0, ("strdup failed\n"));
 233                         return False;
 234                 }
 235         }
 236
 237         SAFE_FREE(databuf.dptr);
 238
 239         if (timeout) {
 240                 *timeout = t;
 241         }
 242
 243         return True;
 244 }
 245
 246
 247 /**
 248  * Iterate through all entries which key matches to specified pattern
 249  *
 250  * @param fn pointer to the function that will be supplied with each single
 251  *        matching cache entry (key, value and timeout) as an arguments
 252  * @param data void pointer to an arbitrary data that is passed directly to the fn
 253  *        function on each call
 254  * @param keystr_pattern pattern the existing entries' keys are matched to
 255  *
 256  **/
 257
 258 void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
 259                       void* data, const char* keystr_pattern)
 260 {
 261         TDB_LIST_NODE *node, *first_node;
 262         TDB_DATA databuf;
 263         char *keystr = NULL, *valstr = NULL, *entry = NULL;
 264         time_t timeout = 0;
 265         int status;
 266         unsigned u;
 267
 268         /* fail completely if get null pointers passed */
 269         SMB_ASSERT(fn && keystr_pattern);
 270
 271         if (!gencache_init()) return;
 272
 273         DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
 274         node = tdb_search_keys(cache, keystr_pattern);
 275         first_node = node;
 276
 277         while (node) {
 278                 char *fmt;
 279
 280                 /* ensure null termination of the key string */
 281                 keystr = SMB_STRNDUP((const char *)node->node_key.dptr, node->node_key.dsize);
 282                 if (!keystr) {
 283                         break;
 284                 }
 285
 286                 /*
 287                  * We don't use gencache_get function, because we need to iterate through
 288                  * all of the entries. Validity verification is up to fn routine.
 289                  */
 290                 databuf = tdb_fetch(cache, node->node_key);
 291                 if (!databuf.dptr || databuf.dsize <= TIMEOUT_LEN) {
 292                         SAFE_FREE(databuf.dptr);
 293                         SAFE_FREE(keystr);
 294                         node = node->next;
 295                         continue;
 296                 }
 297                 entry = SMB_STRNDUP((const char *)databuf.dptr, databuf.dsize);
 298                 if (!entry) {
 299                         SAFE_FREE(databuf.dptr);
 300                         SAFE_FREE(keystr);
 301                         break;
 302                 }
 303
 304                 SAFE_FREE(databuf.dptr);
 305
 306                 valstr = (char *)SMB_MALLOC(databuf.dsize + 1 - TIMEOUT_LEN);
 307                 if (!valstr) {
 308                         SAFE_FREE(entry);
 309                         SAFE_FREE(keystr);
 310                         break;
 311                 }
 312
 313                 asprintf(&fmt, READ_CACHE_DATA_FMT_TEMPLATE, (unsigned int)databuf.dsize - TIMEOUT_LEN);
 314                 if (!fmt) {
 315                         SAFE_FREE(valstr);
 316                         SAFE_FREE(entry);
 317                         SAFE_FREE(keystr);
 318                         break;
 319                 }
 320                 status = sscanf(entry, fmt, &u, valstr);
 321                 SAFE_FREE(fmt);
 322
 323                 if ( status != 2 ) {
 324                         DEBUG(0,("gencache_iterate: invalid return from sscanf %d\n",status));
 325                 }
 326                 timeout = u;
 327
 328                 DEBUG(10, ("Calling function with arguments (key = %s, value = %s, timeout = %s)\n",
 329                            keystr, valstr, ctime(&timeout)));
 330                 fn(keystr, valstr, timeout, data);
 331
 332                 SAFE_FREE(valstr);
 333                 SAFE_FREE(entry);
 334                 SAFE_FREE(keystr);
 335                 node = node->next;
 336         }
 337
 338         tdb_search_list_free(first_node);
 339 }
 340
 341 /********************************************************************
 342  lock a key
 343 ********************************************************************/
 344
 345 int gencache_lock_entry( const char *key )
 346 {
 347         if (!gencache_init())
 348                 return -1;
 349
 350         return tdb_lock_bystring(cache, key);
 351 }
 352
 353 /********************************************************************
 354  unlock a key
 355 ********************************************************************/
 356
 357 void gencache_unlock_entry( const char *key )
 358 {
 359         if (!gencache_init())
 360                 return;
 361
 362         tdb_unlock_bystring(cache, key);
 363         return;
 364 }