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 "../lib/util/memcache.h"
  25 #include "smbd/smbd.h"
  26 #include "messages.h"
  27 #include "serverid.h"
  28 #include "smbprofile.h"
  29 #include <tdb.h>
  30
  31 /****************************************************************************
  32  Stat cache code used in unix_convert.
  33 *****************************************************************************/
  34
  35 /**
  36  * Add an entry into the stat cache.
  37  *
  38  * @param full_orig_name       The original name as specified by the client
  39  * @param orig_translated_path The name on our filesystem.
  40  *
  41  * @note Only the first strlen(orig_translated_path) characters are stored
  42  *       into the cache.  This means that full_orig_name will be internally
  43  *       truncated.
  44  *
  45  */
  46
  47 void stat_cache_add( const char *full_orig_name,
  48                 char *translated_path,
  49                 bool case_sensitive)
  50 {
  51         size_t translated_path_length;
  52         char *original_path;
  53         size_t original_path_length;
  54         char saved_char;
  55         TALLOC_CTX *ctx = talloc_tos();
  56
  57         if (!lp_stat_cache()) {
  58                 return;
  59         }
  60
  61         /*
  62          * Don't cache trivial valid directory entries such as . and ..
  63          */
  64
  65         if ((*full_orig_name == '\0')
  66             || ISDOT(full_orig_name) || ISDOTDOT(full_orig_name)) {
  67                 return;
  68         }
  69
  70         /*
  71          * If we are in case insentive mode, we don't need to
  72          * store names that need no translation - else, it
  73          * would be a waste.
  74          */
  75
  76         if (!case_sensitive && (strcmp(full_orig_name, translated_path) == 0)) {
  77                 return;
  78         }
  79
  80         /*
  81          * Remove any trailing '/' characters from the
  82          * translated path.
  83          */
  84
  85         translated_path_length = strlen(translated_path);
  86
  87         if(translated_path[translated_path_length-1] == '/') {
  88                 translated_path_length--;
  89         }
  90
  91         if(case_sensitive) {
  92                 original_path = talloc_strdup(ctx,full_orig_name);
  93         } else {
  94                 original_path = talloc_strdup_upper(ctx,full_orig_name);
  95         }
  96
  97         if (!original_path) {
  98                 return;
  99         }
 100
 101         original_path_length = strlen(original_path);
 102
 103         if(original_path[original_path_length-1] == '/') {
 104                 original_path[original_path_length-1] = '\0';
 105                 original_path_length--;
 106         }
 107
 108         if (original_path_length != translated_path_length) {
 109                 if (original_path_length < translated_path_length) {
 110                         DEBUG(0, ("OOPS - tried to store stat cache entry "
 111                         "for weird length paths [%s] %lu and [%s] %lu)!\n",
 112                                   original_path,
 113                                   (unsigned long)original_path_length,
 114                                   translated_path,
 115                                   (unsigned long)translated_path_length));
 116                         TALLOC_FREE(original_path);
 117                         return;
 118                 }
 119
 120                 /* we only want to index by the first part of original_path,
 121                         up to the length of translated_path */
 122
 123                 original_path[translated_path_length] = '\0';
 124                 original_path_length = translated_path_length;
 125         }
 126
 127         /* Ensure we're null terminated. */
 128         saved_char = translated_path[translated_path_length];
 129         translated_path[translated_path_length] = '\0';
 130
 131         /*
 132          * New entry or replace old entry.
 133          */
 134
 135         memcache_add(
 136                 smbd_memcache(), STAT_CACHE,
 137                 data_blob_const(original_path, original_path_length),
 138                 data_blob_const(translated_path, translated_path_length + 1));
 139
 140         DEBUG(5,("stat_cache_add: Added entry (%lx:size %x) %s -> %s\n",
 141                  (unsigned long)translated_path,
 142                  (unsigned int)translated_path_length,
 143                  original_path,
 144                  translated_path));
 145
 146         translated_path[translated_path_length] = saved_char;
 147         TALLOC_FREE(original_path);
 148 }
 149
 150 /**
 151  * Look through the stat cache for an entry
 152  *
 153  * @param conn    A connection struct to do the stat() with.
 154  * @param posix_paths Whether to lookup using stat() or lstat()
 155  * @param name    The path we are attempting to cache, modified by this routine
 156  *                to be correct as far as the cache can tell us. We assume that
 157  *                it is a talloc'ed string from top of stack, we free it if
 158  *                necessary.
 159  * @param dirpath The path as far as the stat cache told us. Also talloced
 160  *                from top of stack.
 161  * @param start   A pointer into name, for where to 'start' in fixing the rest
 162  *                of the name up.
 163  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 164  *
 165  * @return True if we translated (and did a scuccessful stat on) the entire
 166  *                name.
 167  *
 168  */
 169
 170 bool stat_cache_lookup(connection_struct *conn,
 171                         bool posix_paths,
 172                         char **pp_name,
 173                         char **pp_dirpath,
 174                         char **pp_start,
 175                         SMB_STRUCT_STAT *pst)
 176 {
 177         char *chk_name;
 178         size_t namelen;
 179         bool sizechanged = False;
 180         unsigned int num_components = 0;
 181         char *translated_path;
 182         size_t translated_path_length;
 183         DATA_BLOB data_val;
 184         char *name;
 185         TALLOC_CTX *ctx = talloc_tos();
 186         struct smb_filename smb_fname;
 187         int ret;
 188
 189         *pp_dirpath = NULL;
 190         *pp_start = *pp_name;
 191
 192         if (!lp_stat_cache()) {
 193                 return False;
 194         }
 195
 196         name = *pp_name;
 197         namelen = strlen(name);
 198
 199         DO_PROFILE_INC(statcache_lookups);
 200
 201         /*
 202          * Don't lookup trivial valid directory entries.
 203          */
 204         if ((*name == '\0') || ISDOT(name) || ISDOTDOT(name)) {
 205                 return False;
 206         }
 207
 208         if (conn->case_sensitive) {
 209                 chk_name = talloc_strdup(ctx,name);
 210                 if (!chk_name) {
 211                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 212                         return False;
 213                 }
 214
 215         } else {
 216                 chk_name = talloc_strdup_upper(ctx,name);
 217                 if (!chk_name) {
 218                         DEBUG(0, ("stat_cache_lookup: talloc_strdup_upper failed!\n"));
 219                         return False;
 220                 }
 221
 222                 /*
 223                  * In some language encodings the length changes
 224                  * if we uppercase. We need to treat this differently
 225                  * below.
 226                  */
 227                 if (strlen(chk_name) != namelen) {
 228                         sizechanged = True;
 229                 }
 230         }
 231
 232         while (1) {
 233                 char *sp;
 234
 235                 data_val = data_blob_null;
 236
 237                 if (memcache_lookup(
 238                             smbd_memcache(), STAT_CACHE,
 239                             data_blob_const(chk_name, strlen(chk_name)),
 240                             &data_val)) {
 241                         break;
 242                 }
 243
 244                 DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n",
 245                                 chk_name ));
 246                 /*
 247                  * Didn't find it - remove last component for next try.
 248                  */
 249                 if (!(sp = strrchr_m(chk_name, '/'))) {
 250                         /*
 251                          * We reached the end of the name - no match.
 252                          */
 253                         DO_PROFILE_INC(statcache_misses);
 254                         TALLOC_FREE(chk_name);
 255                         return False;
 256                 }
 257
 258                 *sp = '\0';
 259
 260                 /*
 261                  * Count the number of times we have done this, we'll
 262                  * need it when reconstructing the string.
 263                  */
 264                 num_components++;
 265
 266                 if ((*chk_name == '\0')
 267                     || ISDOT(chk_name) || ISDOTDOT(chk_name)) {
 268                         DO_PROFILE_INC(statcache_misses);
 269                         TALLOC_FREE(chk_name);
 270                         return False;
 271                 }
 272         }
 273
 274         translated_path = talloc_strdup(ctx,(char *)data_val.data);
 275         if (!translated_path) {
 276                 smb_panic("talloc failed");
 277         }
 278         translated_path_length = data_val.length - 1;
 279
 280         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] "
 281                   "-> [%s]\n", chk_name, translated_path ));
 282         DO_PROFILE_INC(statcache_hits);
 283
 284         ZERO_STRUCT(smb_fname);
 285         smb_fname.base_name = translated_path;
 286
 287         if (posix_paths) {
 288                 ret = SMB_VFS_LSTAT(conn, &smb_fname);
 289         } else {
 290                 ret = SMB_VFS_STAT(conn, &smb_fname);
 291         }
 292
 293         if (ret != 0) {
 294                 /* Discard this entry - it doesn't exist in the filesystem. */
 295                 memcache_delete(smbd_memcache(), STAT_CACHE,
 296                                 data_blob_const(chk_name, strlen(chk_name)));
 297                 TALLOC_FREE(chk_name);
 298                 TALLOC_FREE(translated_path);
 299                 return False;
 300         }
 301         /*
 302          * Only copy the stat struct back if we actually hit the full path
 303          */
 304         if (num_components == 0) {
 305                 *pst = smb_fname.st;
 306         }
 307
 308         if (!sizechanged) {
 309                 memcpy(*pp_name, translated_path,
 310                        MIN(namelen, translated_path_length));
 311         } else {
 312                 if (num_components == 0) {
 313                         name = talloc_strndup(ctx, translated_path,
 314                                            translated_path_length);
 315                 } else {
 316                         char *sp;
 317
 318                         sp = strnrchr_m(name, '/', num_components);
 319                         if (sp) {
 320                                 name = talloc_asprintf(ctx,"%.*s%s",
 321                                          (int)translated_path_length,
 322                                          translated_path, sp);
 323                         } else {
 324                                 name = talloc_strndup(ctx,
 325                                                 translated_path,
 326                                                 translated_path_length);
 327                         }
 328                 }
 329                 if (name == NULL) {
 330                         /*
 331                          * TODO: Get us out of here with a real error message
 332                          */
 333                         smb_panic("talloc failed");
 334                 }
 335                 TALLOC_FREE(*pp_name);
 336                 *pp_name = name;
 337         }
 338
 339
 340         /* set pointer for 'where to start' on fixing the rest of the name */
 341         *pp_start = &name[translated_path_length];
 342         if (**pp_start == '/') {
 343                 ++*pp_start;
 344         }
 345
 346         *pp_dirpath = translated_path;
 347         TALLOC_FREE(chk_name);
 348         return (namelen == translated_path_length);
 349 }
 350
 351 /***************************************************************************
 352  Tell all smbd's to delete an entry.
 353 **************************************************************************/
 354
 355 void smbd_send_stat_cache_delete_message(struct messaging_context *msg_ctx,
 356                                          const char *name)
 357 {
 358 #ifdef DEVELOPER
 359         messaging_send_all(msg_ctx,
 360                            MSG_SMB_STAT_CACHE_DELETE,
 361                            name,
 362                            strlen(name)+1);
 363 #endif
 364 }
 365
 366 /***************************************************************************
 367  Delete an entry.
 368 **************************************************************************/
 369
 370 void stat_cache_delete(const char *name)
 371 {
 372         char *lname = talloc_strdup_upper(talloc_tos(), name);
 373
 374         if (!lname) {
 375                 return;
 376         }
 377         DEBUG(10,("stat_cache_delete: deleting name [%s] -> %s\n",
 378                         lname, name ));
 379
 380         memcache_delete(smbd_memcache(), STAT_CACHE,
 381                         data_blob_const(lname, talloc_get_size(lname)-1));
 382         TALLOC_FREE(lname);
 383 }
 384
 385 /***************************************************************
 386  Compute a hash value based on a string key value.
 387  The function returns the bucket index number for the hashed key.
 388  JRA. Use a djb-algorithm hash for speed.
 389 ***************************************************************/
 390
 391 unsigned int fast_string_hash(TDB_DATA *key)
 392 {
 393         unsigned int n = 0;
 394         const char *p;
 395         for (p = (const char *)key->dptr; *p != '\0'; p++) {
 396                 n = ((n << 5) + n) ^ (unsigned int)(*p);
 397         }
 398         return n;
 399 }
 400
 401 /***************************************************************************
 402  Initializes or clears the stat cache.
 403 **************************************************************************/
 404
 405 bool reset_stat_cache( void )
 406 {
 407         if (!lp_stat_cache())
 408                 return True;
 409
 410         memcache_flush(smbd_memcache(), STAT_CACHE);
 411
 412         return True;
 413 }