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