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 #include "memcache.h"
  25 #include "smbd/smbd.h"
  26 #include "messages.h"
  27 #include "smbprofile.h"
  28 #include "tdb_compat.h"
  29
  30 /****************************************************************************
  31  Stat cache code used in unix_convert.
  32 *****************************************************************************/
  33
  34 /**
  35  * Add an entry into the stat cache.
  36  *
  37  * @param full_orig_name       The original name as specified by the client
  38  * @param orig_translated_path The name on our filesystem.
  39  *
  40  * @note Only the first strlen(orig_translated_path) characters are stored
  41  *       into the cache.  This means that full_orig_name will be internally
  42  *       truncated.
  43  *
  44  */
  45
  46 void stat_cache_add( const char *full_orig_name,
  47                 char *translated_path,
  48                 bool case_sensitive)
  49 {
  50         size_t translated_path_length;
  51         char *original_path;
  52         size_t original_path_length;
  53         char saved_char;
  54         TALLOC_CTX *ctx = talloc_tos();
  55
  56         if (!lp_stat_cache()) {
  57                 return;
  58         }
  59
  60         /*
  61          * Don't cache trivial valid directory entries such as . and ..
  62          */
  63
  64         if ((*full_orig_name == '\0')
  65             || ISDOT(full_orig_name) || ISDOTDOT(full_orig_name)) {
  66                 return;
  67         }
  68
  69         /*
  70          * If we are in case insentive mode, we don't need to
  71          * store names that need no translation - else, it
  72          * would be a waste.
  73          */
  74
  75         if (case_sensitive && (strcmp(full_orig_name, translated_path) == 0)) {
  76                 return;
  77         }
  78
  79         /*
  80          * Remove any trailing '/' characters from the
  81          * translated path.
  82          */
  83
  84         translated_path_length = strlen(translated_path);
  85
  86         if(translated_path[translated_path_length-1] == '/') {
  87                 translated_path_length--;
  88         }
  89
  90         if(case_sensitive) {
  91                 original_path = talloc_strdup(ctx,full_orig_name);
  92         } else {
  93                 original_path = talloc_strdup_upper(ctx,full_orig_name);
  94         }
  95
  96         if (!original_path) {
  97                 return;
  98         }
  99
 100         original_path_length = strlen(original_path);
 101
 102         if(original_path[original_path_length-1] == '/') {
 103                 original_path[original_path_length-1] = '\0';
 104                 original_path_length--;
 105         }
 106
 107         if (original_path_length != translated_path_length) {
 108                 if (original_path_length < translated_path_length) {
 109                         DEBUG(0, ("OOPS - tried to store stat cache entry "
 110                         "for weird length paths [%s] %lu and [%s] %lu)!\n",
 111                                   original_path,
 112                                   (unsigned long)original_path_length,
 113                                   translated_path,
 114                                   (unsigned long)translated_path_length));
 115                         TALLOC_FREE(original_path);
 116                         return;
 117                 }
 118
 119                 /* we only want to index by the first part of original_path,
 120                         up to the length of translated_path */
 121
 122                 original_path[translated_path_length] = '\0';
 123                 original_path_length = translated_path_length;
 124         }
 125
 126         /* Ensure we're null terminated. */
 127         saved_char = translated_path[translated_path_length];
 128         translated_path[translated_path_length] = '\0';
 129
 130         /*
 131          * New entry or replace old entry.
 132          */
 133
 134         memcache_add(
 135                 smbd_memcache(), STAT_CACHE,
 136                 data_blob_const(original_path, original_path_length),
 137                 data_blob_const(translated_path, translated_path_length + 1));
 138
 139         DEBUG(5,("stat_cache_add: Added entry (%lx:size %x) %s -> %s\n",
 140                  (unsigned long)translated_path,
 141                  (unsigned int)translated_path_length,
 142                  original_path,
 143                  translated_path));
 144
 145         translated_path[translated_path_length] = saved_char;
 146         TALLOC_FREE(original_path);
 147 }
 148
 149 /**
 150  * Look through the stat cache for an entry
 151  *
 152  * @param conn    A connection struct to do the stat() with.
 153  * @param posix_paths Whether to lookup using stat() or lstat()
 154  * @param name    The path we are attempting to cache, modified by this routine
 155  *                to be correct as far as the cache can tell us. We assume that
 156  *                it is a talloc'ed string from top of stack, we free it if
 157  *                necessary.
 158  * @param dirpath The path as far as the stat cache told us. Also talloced
 159  *                from top of stack.
 160  * @param start   A pointer into name, for where to 'start' in fixing the rest
 161  *                of the name up.
 162  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 163  *
 164  * @return True if we translated (and did a scuccessful stat on) the entire
 165  *                name.
 166  *
 167  */
 168
 169 bool stat_cache_lookup(connection_struct *conn,
 170                         bool posix_paths,
 171                         char **pp_name,
 172                         char **pp_dirpath,
 173                         char **pp_start,
 174                         SMB_STRUCT_STAT *pst)
 175 {
 176         char *chk_name;
 177         size_t namelen;
 178         bool sizechanged = False;
 179         unsigned int num_components = 0;
 180         char *translated_path;
 181         size_t translated_path_length;
 182         DATA_BLOB data_val;
 183         char *name;
 184         TALLOC_CTX *ctx = talloc_tos();
 185         struct smb_filename smb_fname;
 186         int ret;
 187
 188         *pp_dirpath = NULL;
 189         *pp_start = *pp_name;
 190
 191         if (!lp_stat_cache()) {
 192                 return False;
 193         }
 194
 195         name = *pp_name;
 196         namelen = strlen(name);
 197
 198         DO_PROFILE_INC(statcache_lookups);
 199
 200         /*
 201          * Don't lookup trivial valid directory entries.
 202          */
 203         if ((*name == '\0') || ISDOT(name) || ISDOTDOT(name)) {
 204                 return False;
 205         }
 206
 207         if (conn->case_sensitive) {
 208                 chk_name = talloc_strdup(ctx,name);
 209                 if (!chk_name) {
 210                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 211                         return False;
 212                 }
 213
 214         } else {
 215                 chk_name = talloc_strdup_upper(ctx,name);
 216                 if (!chk_name) {
 217                         DEBUG(0, ("stat_cache_lookup: talloc_strdup_upper failed!\n"));
 218                         return False;
 219                 }
 220
 221                 /*
 222                  * In some language encodings the length changes
 223                  * if we uppercase. We need to treat this differently
 224                  * below.
 225                  */
 226                 if (strlen(chk_name) != namelen) {
 227                         sizechanged = True;
 228                 }
 229         }
 230
 231         while (1) {
 232                 char *sp;
 233
 234                 data_val = data_blob_null;
 235
 236                 if (memcache_lookup(
 237                             smbd_memcache(), STAT_CACHE,
 238                             data_blob_const(chk_name, strlen(chk_name)),
 239                             &data_val)) {
 240                         break;
 241                 }
 242
 243                 DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n",
 244                                 chk_name ));
 245                 /*
 246                  * Didn't find it - remove last component for next try.
 247                  */
 248                 if (!(sp = strrchr_m(chk_name, '/'))) {
 249                         /*
 250                          * We reached the end of the name - no match.
 251                          */
 252                         DO_PROFILE_INC(statcache_misses);
 253                         TALLOC_FREE(chk_name);
 254                         return False;
 255                 }
 256
 257                 *sp = '\0';
 258
 259                 /*
 260                  * Count the number of times we have done this, we'll
 261                  * need it when reconstructing the string.
 262                  */
 263
 264                 if (sizechanged) {
 265                         num_components++;
 266                 }
 267
 268                 if ((*chk_name == '\0')
 269                     || ISDOT(chk_name) || ISDOTDOT(chk_name)) {
 270                         DO_PROFILE_INC(statcache_misses);
 271                         TALLOC_FREE(chk_name);
 272                         return False;
 273                 }
 274         }
 275
 276         translated_path = talloc_strdup(ctx,(char *)data_val.data);
 277         if (!translated_path) {
 278                 smb_panic("talloc failed");
 279         }
 280         translated_path_length = data_val.length - 1;
 281
 282         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] "
 283                   "-> [%s]\n", chk_name, translated_path ));
 284         DO_PROFILE_INC(statcache_hits);
 285
 286         ZERO_STRUCT(smb_fname);
 287         smb_fname.base_name = translated_path;
 288
 289         if (posix_paths) {
 290                 ret = SMB_VFS_LSTAT(conn, &smb_fname);
 291         } else {
 292                 ret = SMB_VFS_STAT(conn, &smb_fname);
 293         }
 294
 295         if (ret != 0) {
 296                 /* Discard this entry - it doesn't exist in the filesystem. */
 297                 memcache_delete(smbd_memcache(), STAT_CACHE,
 298                                 data_blob_const(chk_name, strlen(chk_name)));
 299                 TALLOC_FREE(chk_name);
 300                 TALLOC_FREE(translated_path);
 301                 return False;
 302         }
 303         *pst = smb_fname.st;
 304
 305         if (!sizechanged) {
 306                 memcpy(*pp_name, translated_path,
 307                        MIN(namelen, translated_path_length));
 308         } else {
 309                 if (num_components == 0) {
 310                         name = talloc_strndup(ctx, translated_path,
 311                                            translated_path_length);
 312                 } else {
 313                         char *sp;
 314
 315                         sp = strnrchr_m(name, '/', num_components);
 316                         if (sp) {
 317                                 name = talloc_asprintf(ctx,"%.*s%s",
 318                                          (int)translated_path_length,
 319                                          translated_path, sp);
 320                         } else {
 321                                 name = talloc_strndup(ctx,
 322                                                 translated_path,
 323                                                 translated_path_length);
 324                         }
 325                 }
 326                 if (name == NULL) {
 327                         /*
 328                          * TODO: Get us out of here with a real error message
 329                          */
 330                         smb_panic("talloc failed");
 331                 }
 332                 TALLOC_FREE(*pp_name);
 333                 *pp_name = name;
 334         }
 335
 336
 337         /* set pointer for 'where to start' on fixing the rest of the name */
 338         *pp_start = &name[translated_path_length];
 339         if (**pp_start == '/') {
 340                 ++*pp_start;
 341         }
 342
 343         *pp_dirpath = translated_path;
 344         TALLOC_FREE(chk_name);
 345         return (namelen == translated_path_length);
 346 }
 347
 348 /***************************************************************************
 349  Tell all smbd's to delete an entry.
 350 **************************************************************************/
 351
 352 void smbd_send_stat_cache_delete_message(struct messaging_context *msg_ctx,
 353                                          const char *name)
 354 {
 355 #ifdef DEVELOPER
 356         message_send_all(msg_ctx,
 357                         MSG_SMB_STAT_CACHE_DELETE,
 358                         name,
 359                         strlen(name)+1,
 360                         NULL);
 361 #endif
 362 }
 363
 364 /***************************************************************************
 365  Delete an entry.
 366 **************************************************************************/
 367
 368 void stat_cache_delete(const char *name)
 369 {
 370         char *lname = talloc_strdup_upper(talloc_tos(), name);
 371
 372         if (!lname) {
 373                 return;
 374         }
 375         DEBUG(10,("stat_cache_delete: deleting name [%s] -> %s\n",
 376                         lname, name ));
 377
 378         memcache_delete(smbd_memcache(), STAT_CACHE,
 379                         data_blob_const(lname, talloc_get_size(lname)-1));
 380         TALLOC_FREE(lname);
 381 }
 382
 383 /***************************************************************
 384  Compute a hash value based on a string key value.
 385  The function returns the bucket index number for the hashed key.
 386  JRA. Use a djb-algorithm hash for speed.
 387 ***************************************************************/
 388
 389 unsigned int fast_string_hash(TDB_DATA *key)
 390 {
 391         unsigned int n = 0;
 392         const char *p;
 393         for (p = (const char *)key->dptr; *p != '\0'; p++) {
 394                 n = ((n << 5) + n) ^ (unsigned int)(*p);
 395         }
 396         return n;
 397 }
 398
 399 /***************************************************************************
 400  Initializes or clears the stat cache.
 401 **************************************************************************/
 402
 403 bool reset_stat_cache( void )
 404 {
 405         if (!lp_stat_cache())
 406                 return True;
 407
 408         memcache_flush(smbd_memcache(), STAT_CACHE);
 409
 410         return True;
 411 }