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