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
  51         if (!lp_stat_cache())
  52                 return;
  53
  54         ZERO_STRUCT(data_val);
  55
  56         /*
  57          * Don't cache trivial valid directory entries such as . and ..
  58          */
  59
  60         if((*full_orig_name == '\0') || (full_orig_name[0] == '.' &&
  61                                 ((full_orig_name[1] == '\0') ||
  62                                  (full_orig_name[1] == '.' && full_orig_name[1] == '\0'))))
  63                 return;
  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, orig_translated_path) == 0))
  72                 return;
  73
  74         /*
  75          * Remove any trailing '/' characters from the
  76          * translated path.
  77          */
  78
  79         translated_path = SMB_STRDUP(orig_translated_path);
  80         if (!translated_path)
  81                 return;
  82
  83         translated_path_length = strlen(translated_path);
  84
  85         if(translated_path[translated_path_length-1] == '/') {
  86                 translated_path[translated_path_length-1] = '\0';
  87                 translated_path_length--;
  88         }
  89
  90         if(case_sensitive) {
  91                 original_path = SMB_STRDUP(full_orig_name);
  92         } else {
  93                 original_path = strdup_upper(full_orig_name);
  94         }
  95
  96         if (!original_path) {
  97                 SAFE_FREE(translated_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 for weird length paths [%s] %lu and [%s] %lu)!\n",
 111                                   original_path, (unsigned long)original_path_length, translated_path, (unsigned long)translated_path_length));
 112                         SAFE_FREE(original_path);
 113                         SAFE_FREE(translated_path);
 114                         return;
 115                 }
 116
 117                 /* we only want to index by the first part of original_path,
 118                         up to the length of translated_path */
 119
 120                 original_path[translated_path_length] = '\0';
 121                 original_path_length = translated_path_length;
 122         }
 123
 124         /*
 125          * New entry or replace old entry.
 126          */
 127
 128         data_val.dsize = translated_path_length + 1;
 129         data_val.dptr = translated_path;
 130
 131         if (tdb_store_bystring(tdb_stat_cache, original_path, data_val, TDB_REPLACE) != 0) {
 132                 DEBUG(0,("stat_cache_add: Error storing entry %s -> %s\n", original_path, translated_path));
 133         } else {
 134                 DEBUG(5,("stat_cache_add: Added entry (%x:size%x) %s -> %s\n",
 135                         (unsigned int)data_val.dptr, data_val.dsize, original_path, translated_path));
 136         }
 137
 138         SAFE_FREE(original_path);
 139         SAFE_FREE(translated_path);
 140 }
 141
 142 /**
 143  * Look through the stat cache for an entry
 144  *
 145  * @param conn    A connection struct to do the stat() with.
 146  * @param name    The path we are attempting to cache, modified by this routine
 147  *                to be correct as far as the cache can tell us
 148  * @param dirpath The path as far as the stat cache told us.
 149  * @param start   A pointer into name, for where to 'start' in fixing the rest of the name up.
 150  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 151  *
 152  * @return True if we translated (and did a scuccessful stat on) the entire name.
 153  *
 154  */
 155
 156 BOOL stat_cache_lookup(connection_struct *conn, pstring name, pstring dirpath,
 157                        char **start, SMB_STRUCT_STAT *pst)
 158 {
 159         char *chk_name;
 160         size_t namelen;
 161         BOOL sizechanged = False;
 162         unsigned int num_components = 0;
 163
 164         if (!lp_stat_cache())
 165                 return False;
 166
 167         namelen = strlen(name);
 168
 169         *start = name;
 170
 171         DO_PROFILE_INC(statcache_lookups);
 172
 173         /*
 174          * Don't lookup trivial valid directory entries.
 175          */
 176         if((*name == '\0') || (name[0] == '.' &&
 177                                 ((name[1] == '\0') ||
 178                                  (name[1] == '.' && name[1] == '\0'))))
 179                 return False;
 180
 181         if (conn->case_sensitive) {
 182                 chk_name = SMB_STRDUP(name);
 183                 if (!chk_name) {
 184                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 185                         return False;
 186                 }
 187
 188         } else {
 189                 chk_name = strdup_upper(name);
 190                 if (!chk_name) {
 191                         DEBUG(0, ("stat_cache_lookup: strdup_upper failed!\n"));
 192                         return False;
 193                 }
 194
 195                 /*
 196                  * In some language encodings the length changes
 197                  * if we uppercase. We need to treat this differently
 198                  * below.
 199                  */
 200                 if (strlen(chk_name) != namelen)
 201                         sizechanged = True;
 202         }
 203
 204         while (1) {
 205                 TDB_DATA data_val;
 206                 char *sp;
 207
 208                 data_val = tdb_fetch_bystring(tdb_stat_cache, chk_name);
 209                 if(data_val.dptr == NULL || data_val.dsize == 0) {
 210                         DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n", chk_name ));
 211                         /*
 212                          * Didn't find it - remove last component for next try.
 213                          */
 214                         sp = strrchr_m(chk_name, '/');
 215                         if (sp) {
 216                                 *sp = '\0';
 217                                 /*
 218                                  * Count the number of times we have done this,
 219                                  * we'll need it when reconstructing the string.
 220                                  */
 221                                 if (sizechanged)
 222                                         num_components++;
 223
 224                         } else {
 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                         if((*chk_name == '\0') || (strcmp(chk_name, ".") == 0)
 233                                         || (strcmp(chk_name, "..") == 0)) {
 234                                 DO_PROFILE_INC(statcache_misses);
 235                                 SAFE_FREE(chk_name);
 236                                 return False;
 237                         }
 238                 } else {
 239                         BOOL retval;
 240                         char *translated_path = data_val.dptr;
 241                         size_t translated_path_length = data_val.dsize - 1;
 242
 243                         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] -> [%s]\n", chk_name, translated_path ));
 244                         DO_PROFILE_INC(statcache_hits);
 245                         if(SMB_VFS_STAT(conn,translated_path, pst) != 0) {
 246                                 /* Discard this entry - it doesn't exist in the filesystem.  */
 247                                 tdb_delete_bystring(tdb_stat_cache, chk_name);
 248                                 SAFE_FREE(chk_name);
 249                                 SAFE_FREE(data_val.dptr);
 250                                 return False;
 251                         }
 252
 253                         if (!sizechanged) {
 254                                 memcpy(name, translated_path, MIN(sizeof(pstring)-1, translated_path_length));
 255                         } else if (num_components == 0) {
 256                                 pstrcpy(name, translated_path);
 257                         } else {
 258                                 sp = strnrchr_m(name, '/', num_components);
 259                                 if (sp) {
 260                                         pstring last_component;
 261                                         pstrcpy(last_component, sp);
 262                                         pstrcpy(name, translated_path);
 263                                         pstrcat(name, last_component);
 264                                 } else {
 265                                         pstrcpy(name, translated_path);
 266                                 }
 267                         }
 268
 269                         /* set pointer for 'where to start' on fixing the rest of the name */
 270                         *start = &name[translated_path_length];
 271                         if(**start == '/')
 272                                 ++*start;
 273
 274                         pstrcpy(dirpath, translated_path);
 275                         retval = (namelen == translated_path_length) ? True : False;
 276                         SAFE_FREE(chk_name);
 277                         SAFE_FREE(data_val.dptr);
 278                         return retval;
 279                 }
 280         }
 281 }
 282
 283 /***************************************************************
 284  Compute a hash value based on a string key value.
 285  The function returns the bucket index number for the hashed key.
 286  JRA. Use a djb-algorithm hash for speed.
 287 ***************************************************************/
 288
 289 u32 fast_string_hash(TDB_DATA *key)
 290 {
 291         u32 n = 0;
 292         const char *p;
 293         for (p = key->dptr; *p != '\0'; p++) {
 294                 n = ((n << 5) + n) ^ (u32)(*p);
 295         }
 296         return n;
 297 }
 298
 299 /***************************************************************************
 300  Initializes or clears the stat cache.
 301 **************************************************************************/
 302
 303 BOOL reset_stat_cache( void )
 304 {
 305         if (!lp_stat_cache())
 306                 return True;
 307
 308         if (tdb_stat_cache) {
 309                 tdb_close(tdb_stat_cache);
 310         }
 311
 312         /* Create the in-memory tdb using our custom hash function. */
 313         tdb_stat_cache = tdb_open_ex("statcache", 1031, TDB_INTERNAL,
 314                                     (O_RDWR|O_CREAT), 0644, NULL, fast_string_hash);
 315
 316         if (!tdb_stat_cache)
 317                 return False;
 318         return True;
 319 }