source/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
 179         *pp_dirpath = NULL;
 180         *pp_start = *pp_name;
 181
 182         if (!lp_stat_cache()) {
 183                 return False;
 184         }
 185
 186         name = *pp_name;
 187         namelen = strlen(name);
 188
 189         DO_PROFILE_INC(statcache_lookups);
 190
 191         /*
 192          * Don't lookup trivial valid directory entries.
 193          */
 194         if ((*name == '\0') || ISDOT(name) || ISDOTDOT(name)) {
 195                 return False;
 196         }
 197
 198         if (conn->case_sensitive) {
 199                 chk_name = talloc_strdup(ctx,name);
 200                 if (!chk_name) {
 201                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 202                         return False;
 203                 }
 204
 205         } else {
 206                 chk_name = talloc_strdup_upper(ctx,name);
 207                 if (!chk_name) {
 208                         DEBUG(0, ("stat_cache_lookup: strdup_upper failed!\n"));
 209                         return False;
 210                 }
 211
 212                 /*
 213                  * In some language encodings the length changes
 214                  * if we uppercase. We need to treat this differently
 215                  * below.
 216                  */
 217                 if (strlen(chk_name) != namelen) {
 218                         sizechanged = True;
 219                 }
 220         }
 221
 222         while (1) {
 223                 char *sp;
 224
 225                 data_val = data_blob_null;
 226
 227                 if (memcache_lookup(
 228                             smbd_memcache(), STAT_CACHE,
 229                             data_blob_const(chk_name, strlen(chk_name)),
 230                             &data_val)) {
 231                         break;
 232                 }
 233
 234                 DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n",
 235                                 chk_name ));
 236                 /*
 237                  * Didn't find it - remove last component for next try.
 238                  */
 239                 if (!(sp = strrchr_m(chk_name, '/'))) {
 240                         /*
 241                          * We reached the end of the name - no match.
 242                          */
 243                         DO_PROFILE_INC(statcache_misses);
 244                         TALLOC_FREE(chk_name);
 245                         return False;
 246                 }
 247
 248                 *sp = '\0';
 249
 250                 /*
 251                  * Count the number of times we have done this, we'll
 252                  * need it when reconstructing the string.
 253                  */
 254
 255                 if (sizechanged) {
 256                         num_components++;
 257                 }
 258
 259                 if ((*chk_name == '\0')
 260                     || ISDOT(chk_name) || ISDOTDOT(chk_name)) {
 261                         DO_PROFILE_INC(statcache_misses);
 262                         TALLOC_FREE(chk_name);
 263                         return False;
 264                 }
 265         }
 266
 267         translated_path = talloc_strdup(ctx,(char *)data_val.data);
 268         if (!translated_path) {
 269                 smb_panic("talloc failed");
 270         }
 271         translated_path_length = data_val.length - 1;
 272
 273         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] "
 274                   "-> [%s]\n", chk_name, translated_path ));
 275         DO_PROFILE_INC(statcache_hits);
 276
 277         if (SMB_VFS_STAT(conn, translated_path, pst) != 0) {
 278                 /* Discard this entry - it doesn't exist in the filesystem. */
 279                 memcache_delete(smbd_memcache(), STAT_CACHE,
 280                                 data_blob_const(chk_name, strlen(chk_name)));
 281                 TALLOC_FREE(chk_name);
 282                 TALLOC_FREE(translated_path);
 283                 return False;
 284         }
 285
 286         if (!sizechanged) {
 287                 memcpy(*pp_name, translated_path,
 288                        MIN(namelen, translated_path_length));
 289         } else {
 290                 if (num_components == 0) {
 291                         name = talloc_strndup(ctx, translated_path,
 292                                            translated_path_length);
 293                 } else {
 294                         char *sp;
 295
 296                         sp = strnrchr_m(name, '/', num_components);
 297                         if (sp) {
 298                                 name = talloc_asprintf(ctx,"%.*s%s",
 299                                          (int)translated_path_length,
 300                                          translated_path, sp);
 301                         } else {
 302                                 name = talloc_strndup(ctx,
 303                                                 translated_path,
 304                                                 translated_path_length);
 305                         }
 306                 }
 307                 if (name == NULL) {
 308                         /*
 309                          * TODO: Get us out of here with a real error message
 310                          */
 311                         smb_panic("talloc failed");
 312                 }
 313                 TALLOC_FREE(*pp_name);
 314                 *pp_name = name;
 315         }
 316
 317
 318         /* set pointer for 'where to start' on fixing the rest of the name */
 319         *pp_start = &name[translated_path_length];
 320         if (**pp_start == '/') {
 321                 ++*pp_start;
 322         }
 323
 324         *pp_dirpath = translated_path;
 325         TALLOC_FREE(chk_name);
 326         return (namelen == translated_path_length);
 327 }
 328
 329 /***************************************************************************
 330  Tell all smbd's to delete an entry.
 331 **************************************************************************/
 332
 333 void send_stat_cache_delete_message(const char *name)
 334 {
 335 #ifdef DEVELOPER
 336         message_send_all(smbd_messaging_context(),
 337                         MSG_SMB_STAT_CACHE_DELETE,
 338                         name,
 339                         strlen(name)+1,
 340                         NULL);
 341 #endif
 342 }
 343
 344 /***************************************************************************
 345  Delete an entry.
 346 **************************************************************************/
 347
 348 void stat_cache_delete(const char *name)
 349 {
 350         char *lname = talloc_strdup_upper(talloc_tos(), name);
 351
 352         if (!lname) {
 353                 return;
 354         }
 355         DEBUG(10,("stat_cache_delete: deleting name [%s] -> %s\n",
 356                         lname, name ));
 357
 358         memcache_delete(smbd_memcache(), STAT_CACHE,
 359                         data_blob_const(lname, talloc_get_size(lname)-1));
 360         TALLOC_FREE(lname);
 361 }
 362
 363 /***************************************************************
 364  Compute a hash value based on a string key value.
 365  The function returns the bucket index number for the hashed key.
 366  JRA. Use a djb-algorithm hash for speed.
 367 ***************************************************************/
 368
 369 unsigned int fast_string_hash(TDB_DATA *key)
 370 {
 371         unsigned int n = 0;
 372         const char *p;
 373         for (p = (const char *)key->dptr; *p != '\0'; p++) {
 374                 n = ((n << 5) + n) ^ (unsigned int)(*p);
 375         }
 376         return n;
 377 }
 378
 379 /***************************************************************************
 380  Initializes or clears the stat cache.
 381 **************************************************************************/
 382
 383 bool reset_stat_cache( void )
 384 {
 385         if (!lp_stat_cache())
 386                 return True;
 387
 388         memcache_flush(smbd_memcache(), STAT_CACHE);
 389
 390         return True;
 391 }