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
  26 /****************************************************************************
  27  Stat cache code used in unix_convert.
  28 *****************************************************************************/
  29
  30 /**
  31  * Add an entry into the stat cache.
  32  *
  33  * @param full_orig_name       The original name as specified by the client
  34  * @param orig_translated_path The name on our filesystem.
  35  *
  36  * @note Only the first strlen(orig_translated_path) characters are stored
  37  *       into the cache.  This means that full_orig_name will be internally
  38  *       truncated.
  39  *
  40  */
  41
  42 void stat_cache_add( const char *full_orig_name,
  43                 char *translated_path,
  44                 bool case_sensitive)
  45 {
  46         size_t translated_path_length;
  47         char *original_path;
  48         size_t original_path_length;
  49         char saved_char;
  50         TALLOC_CTX *ctx = talloc_tos();
  51
  52         if (!lp_stat_cache()) {
  53                 return;
  54         }
  55
  56         /*
  57          * Don't cache trivial valid directory entries such as . and ..
  58          */
  59
  60         if ((*full_orig_name == '\0')
  61             || ISDOT(full_orig_name) || ISDOTDOT(full_orig_name)) {
  62                 return;
  63         }
  64
  65         /*
  66          * If we are in case insentive mode, we don't need to
  67          * store names that need no translation - else, it
  68          * would be a waste.
  69          */
  70
  71         if (case_sensitive && (strcmp(full_orig_name, translated_path) == 0)) {
  72                 return;
  73         }
  74
  75         /*
  76          * Remove any trailing '/' characters from the
  77          * translated path.
  78          */
  79
  80         translated_path_length = strlen(translated_path);
  81
  82         if(translated_path[translated_path_length-1] == '/') {
  83                 translated_path_length--;
  84         }
  85
  86         if(case_sensitive) {
  87                 original_path = talloc_strdup(ctx,full_orig_name);
  88         } else {
  89                 original_path = talloc_strdup_upper(ctx,full_orig_name);
  90         }
  91
  92         if (!original_path) {
  93                 return;
  94         }
  95
  96         original_path_length = strlen(original_path);
  97
  98         if(original_path[original_path_length-1] == '/') {
  99                 original_path[original_path_length-1] = '\0';
 100                 original_path_length--;
 101         }
 102
 103         if (original_path_length != translated_path_length) {
 104                 if (original_path_length < translated_path_length) {
 105                         DEBUG(0, ("OOPS - tried to store stat cache entry "
 106                         "for weird length paths [%s] %lu and [%s] %lu)!\n",
 107                                   original_path,
 108                                   (unsigned long)original_path_length,
 109                                   translated_path,
 110                                   (unsigned long)translated_path_length));
 111                         TALLOC_FREE(original_path);
 112                         return;
 113                 }
 114
 115                 /* we only want to index by the first part of original_path,
 116                         up to the length of translated_path */
 117
 118                 original_path[translated_path_length] = '\0';
 119                 original_path_length = translated_path_length;
 120         }
 121
 122         /* Ensure we're null terminated. */
 123         saved_char = translated_path[translated_path_length];
 124         translated_path[translated_path_length] = '\0';
 125
 126         /*
 127          * New entry or replace old entry.
 128          */
 129
 130         memcache_add(
 131                 smbd_memcache(), STAT_CACHE,
 132                 data_blob_const(original_path, original_path_length),
 133                 data_blob_const(translated_path, translated_path_length + 1));
 134
 135         DEBUG(5,("stat_cache_add: Added entry (%lx:size %x) %s -> %s\n",
 136                  (unsigned long)translated_path,
 137                  (unsigned int)translated_path_length,
 138                  original_path,
 139                  translated_path));
 140
 141         translated_path[translated_path_length] = saved_char;
 142         TALLOC_FREE(original_path);
 143 }
 144
 145 /**
 146  * Look through the stat cache for an entry
 147  *
 148  * @param conn    A connection struct to do the stat() with.
 149  * @param name    The path we are attempting to cache, modified by this routine
 150  *                to be correct as far as the cache can tell us. We assume that
 151  *                it is a talloc'ed string from top of stack, we free it if
 152  *                necessary.
 153  * @param dirpath The path as far as the stat cache told us. Also talloced
 154  *                from top of stack.
 155  * @param start   A pointer into name, for where to 'start' in fixing the rest
 156  *                of the name up.
 157  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 158  *
 159  * @return True if we translated (and did a scuccessful stat on) the entire
 160  *                name.
 161  *
 162  */
 163
 164 bool stat_cache_lookup(connection_struct *conn,
 165                         char **pp_name,
 166                         char **pp_dirpath,
 167                         char **pp_start,
 168                         SMB_STRUCT_STAT *pst)
 169 {
 170         char *chk_name;
 171         size_t namelen;
 172         bool sizechanged = False;
 173         unsigned int num_components = 0;
 174         char *translated_path;
 175         size_t translated_path_length;
 176         DATA_BLOB data_val;
 177         char *name;
 178         TALLOC_CTX *ctx = talloc_tos();
 179         struct smb_filename smb_fname;
 180
 181         *pp_dirpath = NULL;
 182         *pp_start = *pp_name;
 183
 184         if (!lp_stat_cache()) {
 185                 return False;
 186         }
 187
 188         name = *pp_name;
 189         namelen = strlen(name);
 190
 191         DO_PROFILE_INC(statcache_lookups);
 192
 193         /*
 194          * Don't lookup trivial valid directory entries.
 195          */
 196         if ((*name == '\0') || ISDOT(name) || ISDOTDOT(name)) {
 197                 return False;
 198         }
 199
 200         if (conn->case_sensitive) {
 201                 chk_name = talloc_strdup(ctx,name);
 202                 if (!chk_name) {
 203                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 204                         return False;
 205                 }
 206
 207         } else {
 208                 chk_name = talloc_strdup_upper(ctx,name);
 209                 if (!chk_name) {
 210                         DEBUG(0, ("stat_cache_lookup: talloc_strdup_upper failed!\n"));
 211                         return False;
 212                 }
 213
 214                 /*
 215                  * In some language encodings the length changes
 216                  * if we uppercase. We need to treat this differently
 217                  * below.
 218                  */
 219                 if (strlen(chk_name) != namelen) {
 220                         sizechanged = True;
 221                 }
 222         }
 223
 224         while (1) {
 225                 char *sp;
 226
 227                 data_val = data_blob_null;
 228
 229                 if (memcache_lookup(
 230                             smbd_memcache(), STAT_CACHE,
 231                             data_blob_const(chk_name, strlen(chk_name)),
 232                             &data_val)) {
 233                         break;
 234                 }
 235
 236                 DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n",
 237                                 chk_name ));
 238                 /*
 239                  * Didn't find it - remove last component for next try.
 240                  */
 241                 if (!(sp = strrchr_m(chk_name, '/'))) {
 242                         /*
 243                          * We reached the end of the name - no match.
 244                          */
 245                         DO_PROFILE_INC(statcache_misses);
 246                         TALLOC_FREE(chk_name);
 247                         return False;
 248                 }
 249
 250                 *sp = '\0';
 251
 252                 /*
 253                  * Count the number of times we have done this, we'll
 254                  * need it when reconstructing the string.
 255                  */
 256
 257                 if (sizechanged) {
 258                         num_components++;
 259                 }
 260
 261                 if ((*chk_name == '\0')
 262                     || ISDOT(chk_name) || ISDOTDOT(chk_name)) {
 263                         DO_PROFILE_INC(statcache_misses);
 264                         TALLOC_FREE(chk_name);
 265                         return False;
 266                 }
 267         }
 268
 269         translated_path = talloc_strdup(ctx,(char *)data_val.data);
 270         if (!translated_path) {
 271                 smb_panic("talloc failed");
 272         }
 273         translated_path_length = data_val.length - 1;
 274
 275         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] "
 276                   "-> [%s]\n", chk_name, translated_path ));
 277         DO_PROFILE_INC(statcache_hits);
 278
 279         ZERO_STRUCT(smb_fname);
 280         smb_fname.base_name = translated_path;
 281
 282         if (SMB_VFS_STAT(conn, &smb_fname) != 0) {
 283                 /* Discard this entry - it doesn't exist in the filesystem. */
 284                 memcache_delete(smbd_memcache(), STAT_CACHE,
 285                                 data_blob_const(chk_name, strlen(chk_name)));
 286                 TALLOC_FREE(chk_name);
 287                 TALLOC_FREE(translated_path);
 288                 return False;
 289         }
 290         *pst = smb_fname.st;
 291
 292         if (!sizechanged) {
 293                 memcpy(*pp_name, translated_path,
 294                        MIN(namelen, translated_path_length));
 295         } else {
 296                 if (num_components == 0) {
 297                         name = talloc_strndup(ctx, translated_path,
 298                                            translated_path_length);
 299                 } else {
 300                         char *sp;
 301
 302                         sp = strnrchr_m(name, '/', num_components);
 303                         if (sp) {
 304                                 name = talloc_asprintf(ctx,"%.*s%s",
 305                                          (int)translated_path_length,
 306                                          translated_path, sp);
 307                         } else {
 308                                 name = talloc_strndup(ctx,
 309                                                 translated_path,
 310                                                 translated_path_length);
 311                         }
 312                 }
 313                 if (name == NULL) {
 314                         /*
 315                          * TODO: Get us out of here with a real error message
 316                          */
 317                         smb_panic("talloc failed");
 318                 }
 319                 TALLOC_FREE(*pp_name);
 320                 *pp_name = name;
 321         }
 322
 323
 324         /* set pointer for 'where to start' on fixing the rest of the name */
 325         *pp_start = &name[translated_path_length];
 326         if (**pp_start == '/') {
 327                 ++*pp_start;
 328         }
 329
 330         *pp_dirpath = translated_path;
 331         TALLOC_FREE(chk_name);
 332         return (namelen == translated_path_length);
 333 }
 334
 335 /***************************************************************************
 336  Tell all smbd's to delete an entry.
 337 **************************************************************************/
 338
 339 void send_stat_cache_delete_message(const char *name)
 340 {
 341 #ifdef DEVELOPER
 342         message_send_all(smbd_messaging_context(),
 343                         MSG_SMB_STAT_CACHE_DELETE,
 344                         name,
 345                         strlen(name)+1,
 346                         NULL);
 347 #endif
 348 }
 349
 350 /***************************************************************************
 351  Delete an entry.
 352 **************************************************************************/
 353
 354 void stat_cache_delete(const char *name)
 355 {
 356         char *lname = talloc_strdup_upper(talloc_tos(), name);
 357
 358         if (!lname) {
 359                 return;
 360         }
 361         DEBUG(10,("stat_cache_delete: deleting name [%s] -> %s\n",
 362                         lname, name ));
 363
 364         memcache_delete(smbd_memcache(), STAT_CACHE,
 365                         data_blob_const(lname, talloc_get_size(lname)-1));
 366         TALLOC_FREE(lname);
 367 }
 368
 369 /***************************************************************
 370  Compute a hash value based on a string key value.
 371  The function returns the bucket index number for the hashed key.
 372  JRA. Use a djb-algorithm hash for speed.
 373 ***************************************************************/
 374
 375 unsigned int fast_string_hash(TDB_DATA *key)
 376 {
 377         unsigned int n = 0;
 378         const char *p;
 379         for (p = (const char *)key->dptr; *p != '\0'; p++) {
 380                 n = ((n << 5) + n) ^ (unsigned int)(*p);
 381         }
 382         return n;
 383 }
 384
 385 /***************************************************************************
 386  Initializes or clears the stat cache.
 387 **************************************************************************/
 388
 389 bool reset_stat_cache( void )
 390 {
 391         if (!lp_stat_cache())
 392                 return True;
 393
 394         memcache_flush(smbd_memcache(), STAT_CACHE);
 395
 396         return True;
 397 }