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 "memcache.h"
  25 #include "smbd/smbd.h"
  26 #include "messages.h"
  27 #include "smbprofile.h"
  28 #include "tdb_compat.h"
  29
  30 /****************************************************************************
  31  Stat cache code used in unix_convert.
  32 *****************************************************************************/
  33
  34 /**
  35  * Add an entry into the stat cache.
  36  *
  37  * @param full_orig_name       The original name as specified by the client
  38  * @param orig_translated_path The name on our filesystem.
  39  *
  40  * @note Only the first strlen(orig_translated_path) characters are stored
  41  *       into the cache.  This means that full_orig_name will be internally
  42  *       truncated.
  43  *
  44  */
  45
  46 void stat_cache_add( const char *full_orig_name,
  47                 char *translated_path,
  48                 bool case_sensitive)
  49 {
  50         size_t translated_path_length;
  51         char *original_path;
  52         size_t original_path_length;
  53         char saved_char;
  54         TALLOC_CTX *ctx = talloc_tos();
  55
  56         if (!lp_stat_cache()) {
  57                 return;
  58         }
  59
  60         /*
  61          * Don't cache trivial valid directory entries such as . and ..
  62          */
  63
  64         if ((*full_orig_name == '\0')
  65             || ISDOT(full_orig_name) || ISDOTDOT(full_orig_name)) {
  66                 return;
  67         }
  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, translated_path) == 0)) {
  76                 return;
  77         }
  78
  79         /*
  80          * Remove any trailing '/' characters from the
  81          * translated path.
  82          */
  83
  84         translated_path_length = strlen(translated_path);
  85
  86         if(translated_path[translated_path_length-1] == '/') {
  87                 translated_path_length--;
  88         }
  89
  90         if(case_sensitive) {
  91                 original_path = talloc_strdup(ctx,full_orig_name);
  92         } else {
  93                 original_path = talloc_strdup_upper(ctx,full_orig_name);
  94         }
  95
  96         if (!original_path) {
  97                 return;
  98         }
  99
 100         original_path_length = strlen(original_path);
 101
 102         if(original_path[original_path_length-1] == '/') {
 103                 original_path[original_path_length-1] = '\0';
 104                 original_path_length--;
 105         }
 106
 107         if (original_path_length != translated_path_length) {
 108                 if (original_path_length < translated_path_length) {
 109                         DEBUG(0, ("OOPS - tried to store stat cache entry "
 110                         "for weird length paths [%s] %lu and [%s] %lu)!\n",
 111                                   original_path,
 112                                   (unsigned long)original_path_length,
 113                                   translated_path,
 114                                   (unsigned long)translated_path_length));
 115                         TALLOC_FREE(original_path);
 116                         return;
 117                 }
 118
 119                 /* we only want to index by the first part of original_path,
 120                         up to the length of translated_path */
 121
 122                 original_path[translated_path_length] = '\0';
 123                 original_path_length = translated_path_length;
 124         }
 125
 126         /* Ensure we're null terminated. */
 127         saved_char = translated_path[translated_path_length];
 128         translated_path[translated_path_length] = '\0';
 129
 130         /*
 131          * New entry or replace old entry.
 132          */
 133
 134         memcache_add(
 135                 smbd_memcache(), STAT_CACHE,
 136                 data_blob_const(original_path, original_path_length),
 137                 data_blob_const(translated_path, translated_path_length + 1));
 138
 139         DEBUG(5,("stat_cache_add: Added entry (%lx:size %x) %s -> %s\n",
 140                  (unsigned long)translated_path,
 141                  (unsigned int)translated_path_length,
 142                  original_path,
 143                  translated_path));
 144
 145         translated_path[translated_path_length] = saved_char;
 146         TALLOC_FREE(original_path);
 147 }
 148
 149 /**
 150  * Look through the stat cache for an entry
 151  *
 152  * @param conn    A connection struct to do the stat() with.
 153  * @param name    The path we are attempting to cache, modified by this routine
 154  *                to be correct as far as the cache can tell us. We assume that
 155  *                it is a talloc'ed string from top of stack, we free it if
 156  *                necessary.
 157  * @param dirpath The path as far as the stat cache told us. Also talloced
 158  *                from top of stack.
 159  * @param start   A pointer into name, for where to 'start' in fixing the rest
 160  *                of the name up.
 161  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 162  *
 163  * @return True if we translated (and did a scuccessful stat on) the entire
 164  *                name.
 165  *
 166  */
 167
 168 bool stat_cache_lookup(connection_struct *conn,
 169                         char **pp_name,
 170                         char **pp_dirpath,
 171                         char **pp_start,
 172                         SMB_STRUCT_STAT *pst)
 173 {
 174         char *chk_name;
 175         size_t namelen;
 176         bool sizechanged = False;
 177         unsigned int num_components = 0;
 178         char *translated_path;
 179         size_t translated_path_length;
 180         DATA_BLOB data_val;
 181         char *name;
 182         TALLOC_CTX *ctx = talloc_tos();
 183         struct smb_filename smb_fname;
 184
 185         *pp_dirpath = NULL;
 186         *pp_start = *pp_name;
 187
 188         if (!lp_stat_cache()) {
 189                 return False;
 190         }
 191
 192         name = *pp_name;
 193         namelen = strlen(name);
 194
 195         DO_PROFILE_INC(statcache_lookups);
 196
 197         /*
 198          * Don't lookup trivial valid directory entries.
 199          */
 200         if ((*name == '\0') || ISDOT(name) || ISDOTDOT(name)) {
 201                 return False;
 202         }
 203
 204         if (conn->case_sensitive) {
 205                 chk_name = talloc_strdup(ctx,name);
 206                 if (!chk_name) {
 207                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 208                         return False;
 209                 }
 210
 211         } else {
 212                 chk_name = talloc_strdup_upper(ctx,name);
 213                 if (!chk_name) {
 214                         DEBUG(0, ("stat_cache_lookup: talloc_strdup_upper failed!\n"));
 215                         return False;
 216                 }
 217
 218                 /*
 219                  * In some language encodings the length changes
 220                  * if we uppercase. We need to treat this differently
 221                  * below.
 222                  */
 223                 if (strlen(chk_name) != namelen) {
 224                         sizechanged = True;
 225                 }
 226         }
 227
 228         while (1) {
 229                 char *sp;
 230
 231                 data_val = data_blob_null;
 232
 233                 if (memcache_lookup(
 234                             smbd_memcache(), STAT_CACHE,
 235                             data_blob_const(chk_name, strlen(chk_name)),
 236                             &data_val)) {
 237                         break;
 238                 }
 239
 240                 DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n",
 241                                 chk_name ));
 242                 /*
 243                  * Didn't find it - remove last component for next try.
 244                  */
 245                 if (!(sp = strrchr_m(chk_name, '/'))) {
 246                         /*
 247                          * We reached the end of the name - no match.
 248                          */
 249                         DO_PROFILE_INC(statcache_misses);
 250                         TALLOC_FREE(chk_name);
 251                         return False;
 252                 }
 253
 254                 *sp = '\0';
 255
 256                 /*
 257                  * Count the number of times we have done this, we'll
 258                  * need it when reconstructing the string.
 259                  */
 260
 261                 if (sizechanged) {
 262                         num_components++;
 263                 }
 264
 265                 if ((*chk_name == '\0')
 266                     || ISDOT(chk_name) || ISDOTDOT(chk_name)) {
 267                         DO_PROFILE_INC(statcache_misses);
 268                         TALLOC_FREE(chk_name);
 269                         return False;
 270                 }
 271         }
 272
 273         translated_path = talloc_strdup(ctx,(char *)data_val.data);
 274         if (!translated_path) {
 275                 smb_panic("talloc failed");
 276         }
 277         translated_path_length = data_val.length - 1;
 278
 279         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] "
 280                   "-> [%s]\n", chk_name, translated_path ));
 281         DO_PROFILE_INC(statcache_hits);
 282
 283         ZERO_STRUCT(smb_fname);
 284         smb_fname.base_name = translated_path;
 285
 286         if (SMB_VFS_STAT(conn, &smb_fname) != 0) {
 287                 /* Discard this entry - it doesn't exist in the filesystem. */
 288                 memcache_delete(smbd_memcache(), STAT_CACHE,
 289                                 data_blob_const(chk_name, strlen(chk_name)));
 290                 TALLOC_FREE(chk_name);
 291                 TALLOC_FREE(translated_path);
 292                 return False;
 293         }
 294         *pst = smb_fname.st;
 295
 296         if (!sizechanged) {
 297                 memcpy(*pp_name, translated_path,
 298                        MIN(namelen, translated_path_length));
 299         } else {
 300                 if (num_components == 0) {
 301                         name = talloc_strndup(ctx, translated_path,
 302                                            translated_path_length);
 303                 } else {
 304                         char *sp;
 305
 306                         sp = strnrchr_m(name, '/', num_components);
 307                         if (sp) {
 308                                 name = talloc_asprintf(ctx,"%.*s%s",
 309                                          (int)translated_path_length,
 310                                          translated_path, sp);
 311                         } else {
 312                                 name = talloc_strndup(ctx,
 313                                                 translated_path,
 314                                                 translated_path_length);
 315                         }
 316                 }
 317                 if (name == NULL) {
 318                         /*
 319                          * TODO: Get us out of here with a real error message
 320                          */
 321                         smb_panic("talloc failed");
 322                 }
 323                 TALLOC_FREE(*pp_name);
 324                 *pp_name = name;
 325         }
 326
 327
 328         /* set pointer for 'where to start' on fixing the rest of the name */
 329         *pp_start = &name[translated_path_length];
 330         if (**pp_start == '/') {
 331                 ++*pp_start;
 332         }
 333
 334         *pp_dirpath = translated_path;
 335         TALLOC_FREE(chk_name);
 336         return (namelen == translated_path_length);
 337 }
 338
 339 /***************************************************************************
 340  Tell all smbd's to delete an entry.
 341 **************************************************************************/
 342
 343 void send_stat_cache_delete_message(struct messaging_context *msg_ctx,
 344                                     const char *name)
 345 {
 346 #ifdef DEVELOPER
 347         message_send_all(msg_ctx,
 348                         MSG_SMB_STAT_CACHE_DELETE,
 349                         name,
 350                         strlen(name)+1,
 351                         NULL);
 352 #endif
 353 }
 354
 355 /***************************************************************************
 356  Delete an entry.
 357 **************************************************************************/
 358
 359 void stat_cache_delete(const char *name)
 360 {
 361         char *lname = talloc_strdup_upper(talloc_tos(), name);
 362
 363         if (!lname) {
 364                 return;
 365         }
 366         DEBUG(10,("stat_cache_delete: deleting name [%s] -> %s\n",
 367                         lname, name ));
 368
 369         memcache_delete(smbd_memcache(), STAT_CACHE,
 370                         data_blob_const(lname, talloc_get_size(lname)-1));
 371         TALLOC_FREE(lname);
 372 }
 373
 374 /***************************************************************
 375  Compute a hash value based on a string key value.
 376  The function returns the bucket index number for the hashed key.
 377  JRA. Use a djb-algorithm hash for speed.
 378 ***************************************************************/
 379
 380 unsigned int fast_string_hash(struct TDB_DATA *key)
 381 {
 382         unsigned int n = 0;
 383         const char *p;
 384         for (p = (const char *)key->dptr; *p != '\0'; p++) {
 385                 n = ((n << 5) + n) ^ (unsigned int)(*p);
 386         }
 387         return n;
 388 }
 389
 390 /***************************************************************************
 391  Initializes or clears the stat cache.
 392 **************************************************************************/
 393
 394 bool reset_stat_cache( void )
 395 {
 396         if (!lp_stat_cache())
 397                 return True;
 398
 399         memcache_flush(smbd_memcache(), STAT_CACHE);
 400
 401         return True;
 402 }