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