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 1999-2000
   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 extern BOOL case_sensitive;
  26
  27
  28 /****************************************************************************
  29  Stat cache code used in unix_convert.
  30 *****************************************************************************/
  31
  32 typedef struct {
  33         char *original_path;
  34         char *translated_path;
  35         size_t translated_path_length;
  36         char names[2]; /* This is extended via malloc... */
  37 } stat_cache_entry;
  38
  39 #define INIT_STAT_CACHE_SIZE 512
  40 static hash_table stat_cache;
  41
  42 /**
  43  * Add an entry into the stat cache.
  44  *
  45  * @param full_orig_name       The original name as specified by the client
  46  * @param orig_translated_path The name on our filesystem.
  47  *
  48  * @note Only the first strlen(orig_translated_path) characters are stored
  49  *       into the cache.  This means that full_orig_name will be internally
  50  *       truncated.
  51  *
  52  */
  53
  54 void stat_cache_add( const char *full_orig_name, const char *orig_translated_path)
  55 {
  56   stat_cache_entry *scp;
  57   stat_cache_entry *found_scp;
  58   char *translated_path;
  59   size_t translated_path_length;
  60
  61   char *original_path;
  62   size_t original_path_length;
  63
  64   hash_element *hash_elem;
  65
  66   if (!lp_stat_cache()) return;
  67
  68   /*
  69    * Don't cache trivial valid directory entries.
  70    */
  71   if((*full_orig_name == '\0') || (strcmp(full_orig_name, ".") == 0) ||
  72      (strcmp(full_orig_name, "..") == 0))
  73     return;
  74
  75   /*
  76    * If we are in case insentive mode, we don't need to
  77    * store names that need no translation - else, it
  78    * would be a waste.
  79    */
  80
  81   if(case_sensitive && (strcmp(full_orig_name, orig_translated_path) == 0))
  82     return;
  83
  84   /*
  85    * Remove any trailing '/' characters from the
  86    * translated path.
  87    */
  88
  89   translated_path = strdup(orig_translated_path);
  90   if (!translated_path)
  91           return;
  92
  93   translated_path_length = strlen(translated_path);
  94
  95   if(translated_path[translated_path_length-1] == '/') {
  96     translated_path[translated_path_length-1] = '\0';
  97     translated_path_length--;
  98   }
  99
 100   original_path = strdup(full_orig_name);
 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(!case_sensitive)
 114           strupper(original_path);
 115
 116   if (original_path_length != translated_path_length) {
 117           if (original_path_length < translated_path_length) {
 118                   DEBUG(0, ("OOPS - tried to store stat cache entry for werid length paths [%s] %u and [%s] %u)!\n", original_path, original_path_length, translated_path, translated_path_length));
 119                   SAFE_FREE(original_path);
 120                   SAFE_FREE(translated_path);
 121                   return;
 122           }
 123
 124           /* we only want to store the first part of original_path,
 125              up to the length of translated_path */
 126
 127           original_path[translated_path_length] = '\0';
 128           original_path_length = translated_path_length;
 129   }
 130
 131   /*
 132    * Check this name doesn't exist in the cache before we
 133    * add it.
 134    */
 135
 136   if ((hash_elem = hash_lookup(&stat_cache, original_path))) {
 137           found_scp = (stat_cache_entry *)(hash_elem->value);
 138           if (strcmp((found_scp->translated_path), orig_translated_path) == 0) {
 139                   /* already in hash table */
 140                   SAFE_FREE(original_path);
 141                   SAFE_FREE(translated_path);
 142                   return;
 143           }
 144           /* hash collision - remove before we re-add */
 145           hash_remove(&stat_cache, hash_elem);
 146   }
 147
 148   /*
 149    * New entry.
 150    */
 151
 152   if((scp = (stat_cache_entry *)malloc(sizeof(stat_cache_entry)
 153                                        +original_path_length
 154                                        +translated_path_length)) == NULL) {
 155           DEBUG(0,("stat_cache_add: Out of memory !\n"));
 156           SAFE_FREE(original_path);
 157           SAFE_FREE(translated_path);
 158           return;
 159   }
 160
 161   scp->original_path = scp->names;
 162   scp->translated_path = scp->names + original_path_length + 1;
 163   safe_strcpy(scp->original_path, original_path, original_path_length);
 164   safe_strcpy(scp->translated_path, translated_path, translated_path_length);
 165   scp->translated_path_length = translated_path_length;
 166
 167   hash_insert(&stat_cache, (char *)scp, original_path);
 168
 169   SAFE_FREE(original_path);
 170   SAFE_FREE(translated_path);
 171
 172   DEBUG(5,("stat_cache_add: Added entry %s -> %s\n", scp->original_path, scp->translated_path));
 173 }
 174
 175 /**
 176  * Look through the stat cache for an entry
 177  *
 178  * The hash-table's internals will promote it to the top if found.
 179  *
 180  * @param conn    A connection struct to do the stat() with.
 181  * @param name    The path we are attempting to cache, modified by this routine
 182  *                to be correct as far as the cache can tell us
 183  * @param dirpath The path as far as the stat cache told us.
 184  * @param start   A pointer into name, for where to 'start' in fixing the rest of the name up.
 185  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 186  *
 187  * @return True if we translated (and did a scuccessful stat on) the entire name.
 188  *
 189  */
 190
 191 BOOL stat_cache_lookup(connection_struct *conn, pstring name, pstring dirpath,
 192                        char **start, SMB_STRUCT_STAT *pst)
 193 {
 194   stat_cache_entry *scp;
 195   pstring chk_name;
 196   size_t namelen;
 197   hash_element *hash_elem;
 198   char *sp;
 199
 200   if (!lp_stat_cache())
 201     return False;
 202
 203   namelen = strlen(name);
 204
 205   *start = name;
 206
 207   DO_PROFILE_INC(statcache_lookups);
 208
 209   /*
 210    * Don't lookup trivial valid directory entries.
 211    */
 212   if((*name == '\0') || (strcmp(name, ".") == 0) || (strcmp(name, "..") == 0)) {
 213     DO_PROFILE_INC(statcache_misses);
 214     return False;
 215   }
 216
 217   pstrcpy(chk_name, name);
 218   if(!case_sensitive)
 219     strupper( chk_name );
 220
 221   while (1) {
 222     hash_elem = hash_lookup(&stat_cache, chk_name);
 223     if(hash_elem == NULL) {
 224       /*
 225        * Didn't find it - remove last component for next try.
 226        */
 227       sp = strrchr_m(chk_name, '/');
 228       if (sp) {
 229         *sp = '\0';
 230       } else {
 231         /*
 232          * We reached the end of the name - no match.
 233          */
 234         DO_PROFILE_INC(statcache_misses);
 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         return False;
 241       }
 242     } else {
 243       scp = (stat_cache_entry *)(hash_elem->value);
 244       DO_PROFILE_INC(statcache_hits);
 245       if(SMB_VFS_STAT(conn,scp->translated_path, pst) != 0) {
 246         /* Discard this entry - it doesn't exist in the filesystem.  */
 247         hash_remove(&stat_cache, hash_elem);
 248         return False;
 249       }
 250       memcpy(name, scp->translated_path, MIN(sizeof(pstring)-1, scp->translated_path_length));
 251
 252       /* set pointer for 'where to start' on fixing the rest of the name */
 253       *start = &name[scp->translated_path_length];
 254       if(**start == '/')
 255         ++*start;
 256
 257       pstrcpy(dirpath, scp->translated_path);
 258       return (namelen == scp->translated_path_length);
 259     }
 260   }
 261 }
 262
 263 /*************************************************************************** **
 264  * Initializes or clears the stat cache.
 265  *
 266  *  Input:  none.
 267  *  Output: none.
 268  *
 269  * ************************************************************************** **
 270  */
 271 BOOL reset_stat_cache( void )
 272 {
 273         static BOOL initialised;
 274         if (!lp_stat_cache()) return True;
 275
 276         if (initialised) {
 277                 hash_clear(&stat_cache);
 278         }
 279
 280         initialised = hash_table_init( &stat_cache, INIT_STAT_CACHE_SIZE,
 281                                        (compare_function)(strcmp));
 282         return initialised;
 283 } /* reset_stat_cache  */