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 1999-2004
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2003
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23
  24 /****************************************************************************
  25  Stat cache code used in unix_convert.
  26 *****************************************************************************/
  27
  28 static TDB_CONTEXT *tdb_stat_cache;
  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, const char *orig_translated_path, BOOL case_sensitive)
  43 {
  44         char *translated_path;
  45         size_t translated_path_length;
  46         TDB_DATA data_val;
  47         char *original_path;
  48         size_t original_path_length;
  49         size_t sc_size = lp_max_stat_cache_size();
  50
  51         if (!lp_stat_cache())
  52                 return;
  53
  54         if (sc_size && (tdb_map_size(tdb_stat_cache) > sc_size*1024)) {
  55                 reset_stat_cache();
  56         }
  57
  58         ZERO_STRUCT(data_val);
  59
  60         /*
  61          * Don't cache trivial valid directory entries such as . and ..
  62          */
  63
  64         if((*full_orig_name == '\0') || (full_orig_name[0] == '.' &&
  65                                 ((full_orig_name[1] == '\0') ||
  66                                  (full_orig_name[1] == '.' && full_orig_name[2] == '\0'))))
  67                 return;
  68
  69         /*
  70          * If we are in case insentive mode, we don't need to
  71          * store names that need no translation - else, it
  72          * would be a waste.
  73          */
  74
  75         if(case_sensitive && (strcmp(full_orig_name, orig_translated_path) == 0))
  76                 return;
  77
  78         /*
  79          * Remove any trailing '/' characters from the
  80          * translated path.
  81          */
  82
  83         translated_path = SMB_STRDUP(orig_translated_path);
  84         if (!translated_path)
  85                 return;
  86
  87         translated_path_length = strlen(translated_path);
  88
  89         if(translated_path[translated_path_length-1] == '/') {
  90                 translated_path[translated_path_length-1] = '\0';
  91                 translated_path_length--;
  92         }
  93
  94         if(case_sensitive) {
  95                 original_path = SMB_STRDUP(full_orig_name);
  96         } else {
  97                 original_path = strdup_upper(full_orig_name);
  98         }
  99
 100         if (!original_path) {
 101                 SAFE_FREE(translated_path);
 102                 return;
 103         }
 104
 105         original_path_length = strlen(original_path);
 106
 107         if(original_path[original_path_length-1] == '/') {
 108                 original_path[original_path_length-1] = '\0';
 109                 original_path_length--;
 110         }
 111
 112         if (original_path_length != translated_path_length) {
 113                 if (original_path_length < translated_path_length) {
 114                         DEBUG(0, ("OOPS - tried to store stat cache entry for weird length paths [%s] %lu and [%s] %lu)!\n",
 115                                   original_path, (unsigned long)original_path_length, translated_path, (unsigned long)translated_path_length));
 116                         SAFE_FREE(original_path);
 117                         SAFE_FREE(translated_path);
 118                         return;
 119                 }
 120
 121                 /* we only want to index by the first part of original_path,
 122                         up to the length of translated_path */
 123
 124                 original_path[translated_path_length] = '\0';
 125                 original_path_length = translated_path_length;
 126         }
 127
 128         /*
 129          * New entry or replace old entry.
 130          */
 131
 132         data_val.dsize = translated_path_length + 1;
 133         data_val.dptr = (uint8 *)translated_path;
 134
 135         if (tdb_store_bystring(tdb_stat_cache, original_path, data_val, TDB_REPLACE) != 0) {
 136                 DEBUG(0,("stat_cache_add: Error storing entry %s -> %s\n", original_path, translated_path));
 137         } else {
 138                 DEBUG(5,("stat_cache_add: Added entry (%lx:size%x) %s -> %s\n",
 139                         (unsigned long)data_val.dptr, (unsigned int)data_val.dsize, original_path, translated_path));
 140         }
 141
 142         SAFE_FREE(original_path);
 143         SAFE_FREE(translated_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
 152  * @param dirpath The path as far as the stat cache told us.
 153  * @param start   A pointer into name, for where to 'start' in fixing the rest of the name up.
 154  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 155  *
 156  * @return True if we translated (and did a scuccessful stat on) the entire name.
 157  *
 158  */
 159
 160 BOOL stat_cache_lookup(connection_struct *conn, pstring name, pstring dirpath,
 161                        char **start, SMB_STRUCT_STAT *pst)
 162 {
 163         char *chk_name;
 164         size_t namelen;
 165         BOOL sizechanged = False;
 166         unsigned int num_components = 0;
 167         char *translated_path;
 168         size_t translated_path_length;
 169         TDB_DATA data_val;
 170
 171         if (!lp_stat_cache())
 172                 return False;
 173
 174         namelen = strlen(name);
 175
 176         *start = name;
 177
 178         DO_PROFILE_INC(statcache_lookups);
 179
 180         /*
 181          * Don't lookup trivial valid directory entries.
 182          */
 183         if((*name == '\0') || (name[0] == '.' &&
 184                                 ((name[1] == '\0') ||
 185                                  (name[1] == '.' && name[1] == '\0'))))
 186                 return False;
 187
 188         if (conn->case_sensitive) {
 189                 chk_name = SMB_STRDUP(name);
 190                 if (!chk_name) {
 191                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 192                         return False;
 193                 }
 194
 195         } else {
 196                 chk_name = strdup_upper(name);
 197                 if (!chk_name) {
 198                         DEBUG(0, ("stat_cache_lookup: strdup_upper failed!\n"));
 199                         return False;
 200                 }
 201
 202                 /*
 203                  * In some language encodings the length changes
 204                  * if we uppercase. We need to treat this differently
 205                  * below.
 206                  */
 207                 if (strlen(chk_name) != namelen)
 208                         sizechanged = True;
 209         }
 210
 211         while (1) {
 212                 char *sp;
 213
 214                 data_val = tdb_fetch_bystring(tdb_stat_cache, chk_name);
 215
 216                 if (data_val.dptr != NULL && data_val.dsize != 0) {
 217                         break;
 218                 }
 219
 220                 DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n", chk_name ));
 221                 /*
 222                  * Didn't find it - remove last component for next try.
 223                  */
 224                 if (!(sp = strrchr_m(chk_name, '/'))) {
 225                         /*
 226                          * We reached the end of the name - no match.
 227                          */
 228                         DO_PROFILE_INC(statcache_misses);
 229                         SAFE_FREE(chk_name);
 230                         return False;
 231                 }
 232
 233                 *sp = '\0';
 234
 235                 /*
 236                  * Count the number of times we have done this, we'll
 237                  * need it when reconstructing the string.
 238                  */
 239                 if (sizechanged)
 240                         num_components++;
 241
 242                 if ((*chk_name == '\0')
 243                     || ISDOT(chk_name) || ISDOTDOT(chk_name)) {
 244                         DO_PROFILE_INC(statcache_misses);
 245                         SAFE_FREE(chk_name);
 246                         return False;
 247                 }
 248         }
 249
 250         translated_path = (char *)data_val.dptr;
 251         translated_path_length = data_val.dsize - 1;
 252
 253         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] "
 254                   "-> [%s]\n", chk_name, translated_path ));
 255         DO_PROFILE_INC(statcache_hits);
 256
 257         if (SMB_VFS_STAT(conn, translated_path, pst) != 0) {
 258                 /* Discard this entry - it doesn't exist in the filesystem. */
 259                 tdb_delete_bystring(tdb_stat_cache, chk_name);
 260                 SAFE_FREE(chk_name);
 261                 SAFE_FREE(data_val.dptr);
 262                 return False;
 263         }
 264
 265         if (!sizechanged) {
 266                 memcpy(name, translated_path,
 267                        MIN(sizeof(pstring)-1, translated_path_length));
 268         } else if (num_components == 0) {
 269                 pstrcpy(name, translated_path);
 270         } else {
 271                 char *sp;
 272
 273                 sp = strnrchr_m(name, '/', num_components);
 274                 if (sp) {
 275                         pstring last_component;
 276                         pstrcpy(last_component, sp);
 277                         pstrcpy(name, translated_path);
 278                         pstrcat(name, last_component);
 279                 } else {
 280                         pstrcpy(name, translated_path);
 281                 }
 282         }
 283
 284         /* set pointer for 'where to start' on fixing the rest of the name */
 285         *start = &name[translated_path_length];
 286         if (**start == '/')
 287                 ++*start;
 288
 289         pstrcpy(dirpath, translated_path);
 290         SAFE_FREE(chk_name);
 291         SAFE_FREE(data_val.dptr);
 292         return (namelen == translated_path_length);
 293 }
 294
 295 /***************************************************************************
 296  Tell all smbd's to delete an entry.
 297 **************************************************************************/
 298
 299 void send_stat_cache_delete_message(const char *name)
 300 {
 301 #ifdef DEVELOPER
 302         message_send_all(smbd_messaging_context(),
 303                         MSG_SMB_STAT_CACHE_DELETE,
 304                         name,
 305                         strlen(name)+1,
 306                         NULL);
 307 #endif
 308 }
 309
 310 /***************************************************************************
 311  Delete an entry.
 312 **************************************************************************/
 313
 314 void stat_cache_delete(const char *name)
 315 {
 316         char *lname = strdup_upper(name);
 317
 318         if (!lname) {
 319                 return;
 320         }
 321         DEBUG(10,("stat_cache_delete: deleting name [%s] -> %s\n",
 322                         lname, name ));
 323
 324         tdb_delete_bystring(tdb_stat_cache, lname);
 325         SAFE_FREE(lname);
 326 }
 327
 328 /***************************************************************
 329  Compute a hash value based on a string key value.
 330  The function returns the bucket index number for the hashed key.
 331  JRA. Use a djb-algorithm hash for speed.
 332 ***************************************************************/
 333
 334 unsigned int fast_string_hash(TDB_DATA *key)
 335 {
 336         unsigned int n = 0;
 337         const char *p;
 338         for (p = (const char *)key->dptr; *p != '\0'; p++) {
 339                 n = ((n << 5) + n) ^ (unsigned int)(*p);
 340         }
 341         return n;
 342 }
 343
 344 /***************************************************************************
 345  Initializes or clears the stat cache.
 346 **************************************************************************/
 347
 348 BOOL reset_stat_cache( void )
 349 {
 350         if (!lp_stat_cache())
 351                 return True;
 352
 353         if (tdb_stat_cache) {
 354                 tdb_close(tdb_stat_cache);
 355         }
 356
 357         /* Create the in-memory tdb using our custom hash function. */
 358         tdb_stat_cache = tdb_open_ex("statcache", 1031, TDB_INTERNAL,
 359                                     (O_RDWR|O_CREAT), 0644, NULL, fast_string_hash);
 360
 361         if (!tdb_stat_cache)
 362                 return False;
 363         return True;
 364 }