source3/smbd/statcache.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    stat cache code
   4    Copyright (C) Andrew Tridgell 1992-2000
   5    Copyright (C) Jeremy Allison 1999-2007
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2003
   7    Copyright (C) Volker Lendecke 2007
   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 /****************************************************************************
  26  Stat cache code used in unix_convert.
  27 *****************************************************************************/
  28
  29 static TDB_CONTEXT *tdb_stat_cache;
  30
  31 /**
  32  * Add an entry into the stat cache.
  33  *
  34  * @param full_orig_name       The original name as specified by the client
  35  * @param orig_translated_path The name on our filesystem.
  36  *
  37  * @note Only the first strlen(orig_translated_path) characters are stored
  38  *       into the cache.  This means that full_orig_name will be internally
  39  *       truncated.
  40  *
  41  */
  42
  43 void stat_cache_add( const char *full_orig_name,
  44                 char *translated_path,
  45                 bool case_sensitive)
  46 {
  47         size_t translated_path_length;
  48         TDB_DATA data_val;
  49         char *original_path;
  50         size_t original_path_length;
  51         size_t sc_size = lp_max_stat_cache_size();
  52         char saved_char;
  53         TALLOC_CTX *ctx = talloc_tos();
  54
  55         if (!lp_stat_cache()) {
  56                 return;
  57         }
  58
  59         if (sc_size && (tdb_map_size(tdb_stat_cache) > sc_size*1024)) {
  60                 reset_stat_cache();
  61         }
  62
  63         ZERO_STRUCT(data_val);
  64
  65         /*
  66          * Don't cache trivial valid directory entries such as . and ..
  67          */
  68
  69         if ((*full_orig_name == '\0')
  70             || ISDOT(full_orig_name) || ISDOTDOT(full_orig_name)) {
  71                 return;
  72         }
  73
  74         /*
  75          * If we are in case insentive mode, we don't need to
  76          * store names that need no translation - else, it
  77          * would be a waste.
  78          */
  79
  80         if (case_sensitive && (strcmp(full_orig_name, translated_path) == 0)) {
  81                 return;
  82         }
  83
  84         /*
  85          * Remove any trailing '/' characters from the
  86          * translated path.
  87          */
  88
  89         translated_path_length = strlen(translated_path);
  90
  91         if(translated_path[translated_path_length-1] == '/') {
  92                 translated_path_length--;
  93         }
  94
  95         if(case_sensitive) {
  96                 original_path = talloc_strdup(ctx,full_orig_name);
  97         } else {
  98                 original_path = talloc_strdup_upper(ctx,full_orig_name);
  99         }
 100
 101         if (!original_path) {
 102                 return;
 103         }
 104
 105         original_path_length = strlen(original_path);
 106
 107         if(original_path[original_path_length-1] == '/') {
 108                 original_path[original_path_length-1] = '\0';
 109                 original_path_length--;
 110         }
 111
 112         if (original_path_length != translated_path_length) {
 113                 if (original_path_length < translated_path_length) {
 114                         DEBUG(0, ("OOPS - tried to store stat cache entry "
 115                         "for weird length paths [%s] %lu and [%s] %lu)!\n",
 116                                   original_path,
 117                                   (unsigned long)original_path_length,
 118                                   translated_path,
 119                                   (unsigned long)translated_path_length));
 120                         TALLOC_FREE(original_path);
 121                         return;
 122                 }
 123
 124                 /* we only want to index by the first part of original_path,
 125                         up to the length of translated_path */
 126
 127                 original_path[translated_path_length] = '\0';
 128                 original_path_length = translated_path_length;
 129         }
 130
 131         /* Ensure we're null terminated. */
 132         saved_char = translated_path[translated_path_length];
 133         translated_path[translated_path_length] = '\0';
 134
 135         data_val.dsize = translated_path_length + 1;
 136         data_val.dptr = (uint8 *)translated_path;
 137
 138         /*
 139          * New entry or replace old entry.
 140          */
 141
 142         if (tdb_store_bystring(tdb_stat_cache, original_path, data_val,
 143                                 TDB_REPLACE) != 0) {
 144                 DEBUG(0,("stat_cache_add: Error storing entry %s -> %s\n",
 145                                         original_path, translated_path));
 146         } else {
 147                 DEBUG(5,("stat_cache_add: Added entry (%lx:size%x) %s -> %s\n",
 148                         (unsigned long)data_val.dptr,
 149                         (unsigned int)data_val.dsize,
 150                         original_path,
 151                         translated_path));
 152         }
 153
 154         translated_path[translated_path_length] = saved_char;
 155         TALLOC_FREE(original_path);
 156 }
 157
 158 /**
 159  * Look through the stat cache for an entry
 160  *
 161  * @param conn    A connection struct to do the stat() with.
 162  * @param name    The path we are attempting to cache, modified by this routine
 163  *                to be correct as far as the cache can tell us. We assume that
 164  *                it is a talloc'ed string from top of stack, we free it if
 165  *                necessary.
 166  * @param dirpath The path as far as the stat cache told us. Also talloced
 167  *                from top of stack.
 168  * @param start   A pointer into name, for where to 'start' in fixing the rest
 169  *                of the name up.
 170  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 171  *
 172  * @return True if we translated (and did a scuccessful stat on) the entire
 173  *                name.
 174  *
 175  */
 176
 177 bool stat_cache_lookup(connection_struct *conn,
 178                         char **pp_name,
 179                         char **pp_dirpath,
 180                         char **pp_start,
 181                         SMB_STRUCT_STAT *pst)
 182 {
 183         char *chk_name;
 184         size_t namelen;
 185         bool sizechanged = False;
 186         unsigned int num_components = 0;
 187         char *translated_path;
 188         size_t translated_path_length;
 189         TDB_DATA data_val;
 190         char *name;
 191         TALLOC_CTX *ctx = talloc_tos();
 192
 193         *pp_dirpath = NULL;
 194         *pp_start = *pp_name;
 195
 196         if (!lp_stat_cache()) {
 197                 return False;
 198         }
 199
 200         name = *pp_name;
 201         namelen = strlen(name);
 202
 203         DO_PROFILE_INC(statcache_lookups);
 204
 205         /*
 206          * Don't lookup trivial valid directory entries.
 207          */
 208         if ((*name == '\0') || ISDOT(name) || ISDOTDOT(name)) {
 209                 return False;
 210         }
 211
 212         if (conn->case_sensitive) {
 213                 chk_name = talloc_strdup(ctx,name);
 214                 if (!chk_name) {
 215                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 216                         return False;
 217                 }
 218
 219         } else {
 220                 chk_name = talloc_strdup_upper(ctx,name);
 221                 if (!chk_name) {
 222                         DEBUG(0, ("stat_cache_lookup: strdup_upper failed!\n"));
 223                         return False;
 224                 }
 225
 226                 /*
 227                  * In some language encodings the length changes
 228                  * if we uppercase. We need to treat this differently
 229                  * below.
 230                  */
 231                 if (strlen(chk_name) != namelen) {
 232                         sizechanged = True;
 233                 }
 234         }
 235
 236         while (1) {
 237                 char *sp;
 238
 239                 data_val = tdb_fetch_bystring(tdb_stat_cache, chk_name);
 240
 241                 if (data_val.dptr != NULL && data_val.dsize != 0) {
 242                         break;
 243                 }
 244
 245                 DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n",
 246                                 chk_name ));
 247                 /*
 248                  * Didn't find it - remove last component for next try.
 249                  */
 250                 if (!(sp = strrchr_m(chk_name, '/'))) {
 251                         /*
 252                          * We reached the end of the name - no match.
 253                          */
 254                         DO_PROFILE_INC(statcache_misses);
 255                         TALLOC_FREE(chk_name);
 256                         return False;
 257                 }
 258
 259                 *sp = '\0';
 260
 261                 /*
 262                  * Count the number of times we have done this, we'll
 263                  * need it when reconstructing the string.
 264                  */
 265
 266                 if (sizechanged) {
 267                         num_components++;
 268                 }
 269
 270                 if ((*chk_name == '\0')
 271                     || ISDOT(chk_name) || ISDOTDOT(chk_name)) {
 272                         DO_PROFILE_INC(statcache_misses);
 273                         TALLOC_FREE(chk_name);
 274                         return False;
 275                 }
 276         }
 277
 278         translated_path = talloc_strdup(ctx,(char *)data_val.dptr);
 279         if (!translated_path) {
 280                 smb_panic("talloc failed");
 281         }
 282         translated_path_length = data_val.dsize - 1;
 283         SAFE_FREE(data_val.dptr);
 284
 285         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] "
 286                   "-> [%s]\n", chk_name, translated_path ));
 287         DO_PROFILE_INC(statcache_hits);
 288
 289         if (SMB_VFS_STAT(conn, translated_path, pst) != 0) {
 290                 /* Discard this entry - it doesn't exist in the filesystem. */
 291                 tdb_delete_bystring(tdb_stat_cache, chk_name);
 292                 TALLOC_FREE(chk_name);
 293                 TALLOC_FREE(translated_path);
 294                 return False;
 295         }
 296
 297         if (!sizechanged) {
 298                 memcpy(*pp_name, translated_path,
 299                        MIN(namelen, translated_path_length));
 300         } else {
 301                 if (num_components == 0) {
 302                         name = talloc_strndup(ctx, translated_path,
 303                                            translated_path_length);
 304                 } else {
 305                         char *sp;
 306
 307                         sp = strnrchr_m(name, '/', num_components);
 308                         if (sp) {
 309                                 name = talloc_asprintf(ctx,"%.*s%s",
 310                                          (int)translated_path_length,
 311                                          translated_path, sp);
 312                         } else {
 313                                 name = talloc_strndup(ctx,
 314                                                 translated_path,
 315                                                 translated_path_length);
 316                         }
 317                 }
 318                 if (name == NULL) {
 319                         /*
 320                          * TODO: Get us out of here with a real error message
 321                          */
 322                         smb_panic("talloc failed");
 323                 }
 324                 TALLOC_FREE(*pp_name);
 325                 *pp_name = name;
 326         }
 327
 328
 329         /* set pointer for 'where to start' on fixing the rest of the name */
 330         *pp_start = &name[translated_path_length];
 331         if (**pp_start == '/') {
 332                 ++*pp_start;
 333         }
 334
 335         *pp_dirpath = translated_path;
 336         TALLOC_FREE(chk_name);
 337         return (namelen == translated_path_length);
 338 }
 339
 340 /***************************************************************************
 341  Tell all smbd's to delete an entry.
 342 **************************************************************************/
 343
 344 void send_stat_cache_delete_message(const char *name)
 345 {
 346 #ifdef DEVELOPER
 347         message_send_all(smbd_messaging_context(),
 348                         MSG_SMB_STAT_CACHE_DELETE,
 349                         name,
 350                         strlen(name)+1,
 351                         NULL);
 352 #endif
 353 }
 354
 355 /***************************************************************************
 356  Delete an entry.
 357 **************************************************************************/
 358
 359 void stat_cache_delete(const char *name)
 360 {
 361         char *lname = talloc_strdup_upper(talloc_tos(), name);
 362
 363         if (!lname) {
 364                 return;
 365         }
 366         DEBUG(10,("stat_cache_delete: deleting name [%s] -> %s\n",
 367                         lname, name ));
 368
 369         tdb_delete_bystring(tdb_stat_cache, lname);
 370         TALLOC_FREE(lname);
 371 }
 372
 373 /***************************************************************
 374  Compute a hash value based on a string key value.
 375  The function returns the bucket index number for the hashed key.
 376  JRA. Use a djb-algorithm hash for speed.
 377 ***************************************************************/
 378
 379 unsigned int fast_string_hash(TDB_DATA *key)
 380 {
 381         unsigned int n = 0;
 382         const char *p;
 383         for (p = (const char *)key->dptr; *p != '\0'; p++) {
 384                 n = ((n << 5) + n) ^ (unsigned int)(*p);
 385         }
 386         return n;
 387 }
 388
 389 /***************************************************************************
 390  Initializes or clears the stat cache.
 391 **************************************************************************/
 392
 393 bool reset_stat_cache( void )
 394 {
 395         if (!lp_stat_cache())
 396                 return True;
 397
 398         if (tdb_stat_cache) {
 399                 tdb_close(tdb_stat_cache);
 400         }
 401
 402         /* Create the in-memory tdb using our custom hash function. */
 403         tdb_stat_cache = tdb_open_ex("statcache", 1031, TDB_INTERNAL,
 404                                 (O_RDWR|O_CREAT), 0644, NULL, fast_string_hash);
 405
 406         if (!tdb_stat_cache)
 407                 return False;
 408         return True;
 409 }