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 == NULL) {
  60                 DEBUG(0, ("Filename allocation failed.\n"));
  61                 return False;
  62         }
  63
  64         DEBUG(5, ("Opening cache file at %s\n", cache_fname));
  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 = CONST_DISCARD(char *, keystr);
 125         keybuf.dsize = strlen(keystr)+1;
 126         databuf.dptr = 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
 136         return ret == 0;
 137 }
 138
 139 /**
 140  * Delete one entry from the cache file.
 141  *
 142  * @param keystr string that represents a key of this entry
 143  *
 144  * @retval true upon successful deletion
 145  * @retval false in case of failure
 146  **/
 147
 148 BOOL gencache_del(const char *keystr)
 149 {
 150         int ret;
 151         TDB_DATA keybuf;
 152
 153         /* fail completely if get null pointers passed */
 154         SMB_ASSERT(keystr);
 155
 156         if (!gencache_init()) return False;
 157
 158         keybuf.dptr = CONST_DISCARD(char *, keystr);
 159         keybuf.dsize = strlen(keystr)+1;
 160         DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
 161         ret = tdb_delete(cache, keybuf);
 162
 163         return ret == 0;
 164 }
 165
 166
 167 /**
 168  * Get existing entry from the cache file.
 169  *
 170  * @param keystr string that represents a key of this entry
 171  * @param valstr buffer that is allocated and filled with the entry value
 172  *        buffer's disposing must be done outside
 173  * @param timeout pointer to a time_t that is filled with entry's
 174  *        timeout
 175  *
 176  * @retval true when entry is successfuly fetched
 177  * @retval False for failure
 178  **/
 179
 180 BOOL gencache_get(const char *keystr, char **valstr, time_t *timeout)
 181 {
 182         TDB_DATA keybuf, databuf;
 183         time_t t;
 184         char *endptr;
 185
 186         /* fail completely if get null pointers passed */
 187         SMB_ASSERT(keystr);
 188
 189         if (!gencache_init()) {
 190                 return False;
 191         }
 192
 193         keybuf.dptr = CONST_DISCARD(char *, keystr);
 194         keybuf.dsize = strlen(keystr)+1;
 195         databuf = tdb_fetch(cache, keybuf);
 196
 197         if (databuf.dptr == NULL) {
 198                 DEBUG(10, ("Cache entry with key = %s couldn't be found\n",
 199                            keystr));
 200                 return False;
 201         }
 202
 203         t = strtol(databuf.dptr, &endptr, 10);
 204
 205         if ((endptr == NULL) || (*endptr != '/')) {
 206                 DEBUG(2, ("Invalid gencache data format: %s\n", databuf.dptr));
 207                 SAFE_FREE(databuf.dptr);
 208                 return False;
 209         }
 210
 211         DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
 212                    "timeout = %s", t > time(NULL) ? "valid" :
 213                    "expired", keystr, endptr+1, ctime(&t)));
 214
 215         if (valstr) {
 216                 *valstr = SMB_STRDUP(endptr+1);
 217                 if (*valstr == NULL) {
 218                         SAFE_FREE(databuf.dptr);
 219                         DEBUG(0, ("strdup failed\n"));
 220                         return False;
 221                 }
 222         }
 223
 224         SAFE_FREE(databuf.dptr);
 225
 226         if (timeout) {
 227                 *timeout = t;
 228         }
 229
 230         return t > time(NULL);
 231 }
 232
 233
 234 /**
 235  * Iterate through all entries which key matches to specified pattern
 236  *
 237  * @param fn pointer to the function that will be supplied with each single
 238  *        matching cache entry (key, value and timeout) as an arguments
 239  * @param data void pointer to an arbitrary data that is passed directly to the fn
 240  *        function on each call
 241  * @param keystr_pattern pattern the existing entries' keys are matched to
 242  *
 243  **/
 244
 245 void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
 246                       void* data, const char* keystr_pattern)
 247 {
 248         TDB_LIST_NODE *node, *first_node;
 249         TDB_DATA databuf;
 250         char *keystr = NULL, *valstr = NULL, *entry = NULL;
 251         time_t timeout = 0;
 252         int status;
 253         unsigned u;
 254
 255         /* fail completely if get null pointers passed */
 256         SMB_ASSERT(fn && keystr_pattern);
 257
 258         if (!gencache_init()) return;
 259
 260         DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
 261         node = tdb_search_keys(cache, keystr_pattern);
 262         first_node = node;
 263
 264         while (node) {
 265                 char *fmt;
 266
 267                 /* ensure null termination of the key string */
 268                 keystr = SMB_STRNDUP(node->node_key.dptr, node->node_key.dsize);
 269                 if (!keystr) {
 270                         break;
 271                 }
 272
 273                 /*
 274                  * We don't use gencache_get function, because we need to iterate through
 275                  * all of the entries. Validity verification is up to fn routine.
 276                  */
 277                 databuf = tdb_fetch(cache, node->node_key);
 278                 if (!databuf.dptr || databuf.dsize <= TIMEOUT_LEN) {
 279                         SAFE_FREE(databuf.dptr);
 280                         SAFE_FREE(keystr);
 281                         node = node->next;
 282                         continue;
 283                 }
 284                 entry = SMB_STRNDUP(databuf.dptr, databuf.dsize);
 285                 if (!entry) {
 286                         SAFE_FREE(databuf.dptr);
 287                         SAFE_FREE(keystr);
 288                         break;
 289                 }
 290
 291                 SAFE_FREE(databuf.dptr);
 292
 293                 valstr = (char *)SMB_MALLOC(databuf.dsize + 1 - TIMEOUT_LEN);
 294                 if (!valstr) {
 295                         SAFE_FREE(entry);
 296                         SAFE_FREE(keystr);
 297                         break;
 298                 }
 299
 300                 asprintf(&fmt, READ_CACHE_DATA_FMT_TEMPLATE, (unsigned int)databuf.dsize - TIMEOUT_LEN);
 301                 if (!fmt) {
 302                         SAFE_FREE(valstr);
 303                         SAFE_FREE(entry);
 304                         SAFE_FREE(keystr);
 305                         break;
 306                 }
 307                 status = sscanf(entry, fmt, &u, valstr);
 308                 SAFE_FREE(fmt);
 309
 310                 if ( status != 2 ) {
 311                         DEBUG(0,("gencache_iterate: invalid return from sscanf %d\n",status));
 312                 }
 313                 timeout = u;
 314
 315                 DEBUG(10, ("Calling function with arguments (key = %s, value = %s, timeout = %s)\n",
 316                            keystr, valstr, ctime(&timeout)));
 317                 fn(keystr, valstr, timeout, data);
 318
 319                 SAFE_FREE(valstr);
 320                 SAFE_FREE(entry);
 321                 SAFE_FREE(keystr);
 322                 node = node->next;
 323         }
 324
 325         tdb_search_list_free(first_node);
 326 }
 327
 328 /********************************************************************
 329  lock a key
 330 ********************************************************************/
 331
 332 int gencache_lock_entry( const char *key )
 333 {
 334         if (!gencache_init())
 335                 return -1;
 336
 337         return tdb_lock_bystring(cache, key);
 338 }
 339
 340 /********************************************************************
 341  unlock a key
 342 ********************************************************************/
 343
 344 void gencache_unlock_entry( const char *key )
 345 {
 346         if (!gencache_init())
 347                 return;
 348
 349         tdb_unlock_bystring(cache, key);
 350         return;
 351 }