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 1999-2004
   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 2 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, write to the Free Software
  20    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 #include "includes.h"
  24
  25 /****************************************************************************
  26  Stat cache code used in unix_convert.
  27 *****************************************************************************/
  28
  29 static TDB_CONTEXT *tdb_stat_cache;
  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, const char *orig_translated_path, BOOL case_sensitive)
  44 {
  45         char *translated_path;
  46         size_t translated_path_length;
  47         TDB_DATA data_val;
  48         char *original_path;
  49         size_t original_path_length;
  50         size_t sc_size = lp_max_stat_cache_size();
  51
  52         if (!lp_stat_cache())
  53                 return;
  54
  55         if (sc_size && (tdb_stat_cache->map_size > sc_size*1024)) {
  56                 reset_stat_cache();
  57         }
  58
  59         ZERO_STRUCT(data_val);
  60
  61         /*
  62          * Don't cache trivial valid directory entries such as . and ..
  63          */
  64
  65         if((*full_orig_name == '\0') || (full_orig_name[0] == '.' &&
  66                                 ((full_orig_name[1] == '\0') ||
  67                                  (full_orig_name[1] == '.' && full_orig_name[2] == '\0'))))
  68                 return;
  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, orig_translated_path) == 0))
  77                 return;
  78
  79         /*
  80          * Remove any trailing '/' characters from the
  81          * translated path.
  82          */
  83
  84         translated_path = SMB_STRDUP(orig_translated_path);
  85         if (!translated_path)
  86                 return;
  87
  88         translated_path_length = strlen(translated_path);
  89
  90         if(translated_path[translated_path_length-1] == '/') {
  91                 translated_path[translated_path_length-1] = '\0';
  92                 translated_path_length--;
  93         }
  94
  95         if(case_sensitive) {
  96                 original_path = SMB_STRDUP(full_orig_name);
  97         } else {
  98                 original_path = strdup_upper(full_orig_name);
  99         }
 100
 101         if (!original_path) {
 102                 SAFE_FREE(translated_path);
 103                 return;
 104         }
 105
 106         original_path_length = strlen(original_path);
 107
 108         if(original_path[original_path_length-1] == '/') {
 109                 original_path[original_path_length-1] = '\0';
 110                 original_path_length--;
 111         }
 112
 113         if (original_path_length != translated_path_length) {
 114                 if (original_path_length < translated_path_length) {
 115                         DEBUG(0, ("OOPS - tried to store stat cache entry for weird length paths [%s] %lu and [%s] %lu)!\n",
 116                                   original_path, (unsigned long)original_path_length, translated_path, (unsigned long)translated_path_length));
 117                         SAFE_FREE(original_path);
 118                         SAFE_FREE(translated_path);
 119                         return;
 120                 }
 121
 122                 /* we only want to index by the first part of original_path,
 123                         up to the length of translated_path */
 124
 125                 original_path[translated_path_length] = '\0';
 126                 original_path_length = translated_path_length;
 127         }
 128
 129         /*
 130          * New entry or replace old entry.
 131          */
 132
 133         data_val.dsize = translated_path_length + 1;
 134         data_val.dptr = translated_path;
 135
 136         if (tdb_store_bystring(tdb_stat_cache, original_path, data_val, TDB_REPLACE) != 0) {
 137                 DEBUG(0,("stat_cache_add: Error storing entry %s -> %s\n", original_path, translated_path));
 138         } else {
 139                 DEBUG(5,("stat_cache_add: Added entry (%lx:size%x) %s -> %s\n",
 140                         (unsigned long)data_val.dptr, (unsigned int)data_val.dsize, original_path, translated_path));
 141         }
 142
 143         SAFE_FREE(original_path);
 144         SAFE_FREE(translated_path);
 145 }
 146
 147 /**
 148  * Look through the stat cache for an entry
 149  *
 150  * @param conn    A connection struct to do the stat() with.
 151  * @param name    The path we are attempting to cache, modified by this routine
 152  *                to be correct as far as the cache can tell us
 153  * @param dirpath The path as far as the stat cache told us.
 154  * @param start   A pointer into name, for where to 'start' in fixing the rest of the name up.
 155  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 156  *
 157  * @return True if we translated (and did a scuccessful stat on) the entire name.
 158  *
 159  */
 160
 161 BOOL stat_cache_lookup(connection_struct *conn, pstring name, pstring dirpath,
 162                        char **start, SMB_STRUCT_STAT *pst)
 163 {
 164         char *chk_name;
 165         size_t namelen;
 166         BOOL sizechanged = False;
 167         unsigned int num_components = 0;
 168
 169         if (!lp_stat_cache())
 170                 return False;
 171
 172         namelen = strlen(name);
 173
 174         *start = name;
 175
 176         DO_PROFILE_INC(statcache_lookups);
 177
 178         /*
 179          * Don't lookup trivial valid directory entries.
 180          */
 181         if((*name == '\0') || (name[0] == '.' &&
 182                                 ((name[1] == '\0') ||
 183                                  (name[1] == '.' && name[1] == '\0'))))
 184                 return False;
 185
 186         if (conn->case_sensitive) {
 187                 chk_name = SMB_STRDUP(name);
 188                 if (!chk_name) {
 189                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 190                         return False;
 191                 }
 192
 193         } else {
 194                 chk_name = strdup_upper(name);
 195                 if (!chk_name) {
 196                         DEBUG(0, ("stat_cache_lookup: strdup_upper failed!\n"));
 197                         return False;
 198                 }
 199
 200                 /*
 201                  * In some language encodings the length changes
 202                  * if we uppercase. We need to treat this differently
 203                  * below.
 204                  */
 205                 if (strlen(chk_name) != namelen)
 206                         sizechanged = True;
 207         }
 208
 209         while (1) {
 210                 TDB_DATA data_val;
 211                 char *sp;
 212
 213                 data_val = tdb_fetch_bystring(tdb_stat_cache, chk_name);
 214                 if(data_val.dptr == NULL || data_val.dsize == 0) {
 215                         DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n", chk_name ));
 216                         /*
 217                          * Didn't find it - remove last component for next try.
 218                          */
 219                         sp = strrchr_m(chk_name, '/');
 220                         if (sp) {
 221                                 *sp = '\0';
 222                                 /*
 223                                  * Count the number of times we have done this,
 224                                  * we'll need it when reconstructing the string.
 225                                  */
 226                                 if (sizechanged)
 227                                         num_components++;
 228
 229                         } else {
 230                                 /*
 231                                  * We reached the end of the name - no match.
 232                                  */
 233                                 DO_PROFILE_INC(statcache_misses);
 234                                 SAFE_FREE(chk_name);
 235                                 return False;
 236                         }
 237                         if((*chk_name == '\0') || (strcmp(chk_name, ".") == 0)
 238                                         || (strcmp(chk_name, "..") == 0)) {
 239                                 DO_PROFILE_INC(statcache_misses);
 240                                 SAFE_FREE(chk_name);
 241                                 return False;
 242                         }
 243                 } else {
 244                         BOOL retval;
 245                         char *translated_path = data_val.dptr;
 246                         size_t translated_path_length = data_val.dsize - 1;
 247
 248                         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] -> [%s]\n", chk_name, translated_path ));
 249                         DO_PROFILE_INC(statcache_hits);
 250                         if(SMB_VFS_STAT(conn,translated_path, pst) != 0) {
 251                                 /* Discard this entry - it doesn't exist in the filesystem.  */
 252                                 tdb_delete_bystring(tdb_stat_cache, chk_name);
 253                                 SAFE_FREE(chk_name);
 254                                 SAFE_FREE(data_val.dptr);
 255                                 return False;
 256                         }
 257
 258                         if (!sizechanged) {
 259                                 memcpy(name, translated_path, MIN(sizeof(pstring)-1, translated_path_length));
 260                         } else if (num_components == 0) {
 261                                 pstrcpy(name, translated_path);
 262                         } else {
 263                                 sp = strnrchr_m(name, '/', num_components);
 264                                 if (sp) {
 265                                         pstring last_component;
 266                                         pstrcpy(last_component, sp);
 267                                         pstrcpy(name, translated_path);
 268                                         pstrcat(name, last_component);
 269                                 } else {
 270                                         pstrcpy(name, translated_path);
 271                                 }
 272                         }
 273
 274                         /* set pointer for 'where to start' on fixing the rest of the name */
 275                         *start = &name[translated_path_length];
 276                         if(**start == '/')
 277                                 ++*start;
 278
 279                         pstrcpy(dirpath, translated_path);
 280                         retval = (namelen == translated_path_length) ? True : False;
 281                         SAFE_FREE(chk_name);
 282                         SAFE_FREE(data_val.dptr);
 283                         return retval;
 284                 }
 285         }
 286 }
 287
 288 /***************************************************************
 289  Compute a hash value based on a string key value.
 290  The function returns the bucket index number for the hashed key.
 291  JRA. Use a djb-algorithm hash for speed.
 292 ***************************************************************/
 293
 294 u32 fast_string_hash(TDB_DATA *key)
 295 {
 296         u32 n = 0;
 297         const char *p;
 298         for (p = key->dptr; *p != '\0'; p++) {
 299                 n = ((n << 5) + n) ^ (u32)(*p);
 300         }
 301         return n;
 302 }
 303
 304 /***************************************************************************
 305  Initializes or clears the stat cache.
 306 **************************************************************************/
 307
 308 BOOL reset_stat_cache( void )
 309 {
 310         if (!lp_stat_cache())
 311                 return True;
 312
 313         if (tdb_stat_cache) {
 314                 tdb_close(tdb_stat_cache);
 315         }
 316
 317         /* Create the in-memory tdb using our custom hash function. */
 318         tdb_stat_cache = tdb_open_ex("statcache", 1031, TDB_INTERNAL,
 319                                     (O_RDWR|O_CREAT), 0644, NULL, fast_string_hash);
 320
 321         if (!tdb_stat_cache)
 322                 return False;
 323         return True;
 324 }