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