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 1999-2000
   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  Stat cache code used in unix_convert.
  29 *****************************************************************************/
  30
  31 typedef struct {
  32         char *original_path;
  33         char *translated_path;
  34         size_t translated_path_length;
  35         char names[2]; /* This is extended via malloc... */
  36 } stat_cache_entry;
  37
  38 #define INIT_STAT_CACHE_SIZE 512
  39 static hash_table stat_cache;
  40
  41 /**
  42  * Add an entry into the stat cache.
  43  *
  44  * @param full_orig_name       The original name as specified by the client
  45  * @param orig_translated_path The name on our filesystem.
  46  *
  47  * @note Only the first strlen(orig_translated_path) characters are stored
  48  *       into the cache.  This means that full_orig_name will be internally
  49  *       truncated.
  50  *
  51  */
  52
  53 void stat_cache_add( const char *full_orig_name, const char *orig_translated_path)
  54 {
  55         stat_cache_entry *scp;
  56         stat_cache_entry *found_scp;
  57         char *translated_path;
  58         size_t translated_path_length;
  59
  60         char *original_path;
  61         size_t original_path_length;
  62
  63         hash_element *hash_elem;
  64
  65         if (!lp_stat_cache())
  66                 return;
  67
  68         /*
  69          * Don't cache trivial valid directory entries such as . and ..
  70          */
  71
  72         if((*full_orig_name == '\0') || (full_orig_name[0] == '.' &&
  73                                 ((full_orig_name[1] == '\0') ||
  74                                  (full_orig_name[1] == '.' && full_orig_name[1] == '\0'))))
  75                 return;
  76
  77         /*
  78          * If we are in case insentive mode, we don't need to
  79          * store names that need no translation - else, it
  80          * would be a waste.
  81          */
  82
  83         if(case_sensitive && (strcmp(full_orig_name, orig_translated_path) == 0))
  84                 return;
  85
  86         /*
  87          * Remove any trailing '/' characters from the
  88          * translated path.
  89          */
  90
  91         translated_path = strdup(orig_translated_path);
  92         if (!translated_path)
  93                 return;
  94
  95         translated_path_length = strlen(translated_path);
  96
  97         if(translated_path[translated_path_length-1] == '/') {
  98                 translated_path[translated_path_length-1] = '\0';
  99                 translated_path_length--;
 100         }
 101
 102         if(case_sensitive) {
 103                 original_path = strdup(full_orig_name);
 104         } else {
 105                 original_path = strdup_upper(full_orig_name);
 106         }
 107
 108         if (!original_path) {
 109                 SAFE_FREE(translated_path);
 110                 return;
 111         }
 112
 113         original_path_length = strlen(original_path);
 114
 115         if(original_path[original_path_length-1] == '/') {
 116                 original_path[original_path_length-1] = '\0';
 117                 original_path_length--;
 118         }
 119
 120         if (original_path_length != translated_path_length) {
 121                 if (original_path_length < translated_path_length) {
 122                         DEBUG(0, ("OOPS - tried to store stat cache entry for weird length paths [%s] %u and [%s] %u)!\n",
 123                                                 original_path, original_path_length, translated_path, translated_path_length));
 124                         SAFE_FREE(original_path);
 125                         SAFE_FREE(translated_path);
 126                         return;
 127                 }
 128
 129                 /* we only want to store the first part of original_path,
 130                         up to the length of translated_path */
 131
 132                 original_path[translated_path_length] = '\0';
 133                 original_path_length = translated_path_length;
 134         }
 135
 136         /*
 137          * Check this name doesn't exist in the cache before we
 138          * add it.
 139          */
 140
 141         if ((hash_elem = hash_lookup(&stat_cache, original_path))) {
 142                 found_scp = (stat_cache_entry *)(hash_elem->value);
 143                 if (strcmp((found_scp->translated_path), orig_translated_path) == 0) {
 144                         /* already in hash table */
 145                         SAFE_FREE(original_path);
 146                         SAFE_FREE(translated_path);
 147                         return;
 148                 }
 149                 /* hash collision - remove before we re-add */
 150                 hash_remove(&stat_cache, hash_elem);
 151         }
 152
 153         /*
 154          * New entry.
 155          */
 156
 157         if((scp = (stat_cache_entry *)malloc(sizeof(stat_cache_entry)
 158                                                 +original_path_length
 159                                                 +translated_path_length)) == NULL) {
 160                 DEBUG(0,("stat_cache_add: Out of memory !\n"));
 161                 SAFE_FREE(original_path);
 162                 SAFE_FREE(translated_path);
 163                 return;
 164         }
 165
 166         scp->original_path = scp->names;
 167         /* pointer into the structure... */
 168         scp->translated_path = scp->names + original_path_length + 1;
 169         safe_strcpy(scp->original_path, original_path, original_path_length);
 170         safe_strcpy(scp->translated_path, translated_path, translated_path_length);
 171         scp->translated_path_length = translated_path_length;
 172
 173         hash_insert(&stat_cache, (char *)scp, original_path);
 174
 175         SAFE_FREE(original_path);
 176         SAFE_FREE(translated_path);
 177
 178         DEBUG(5,("stat_cache_add: Added entry %s -> %s\n", scp->original_path, scp->translated_path));
 179 }
 180
 181 /**
 182  * Look through the stat cache for an entry
 183  *
 184  * The hash-table's internals will promote it to the top if found.
 185  *
 186  * @param conn    A connection struct to do the stat() with.
 187  * @param name    The path we are attempting to cache, modified by this routine
 188  *                to be correct as far as the cache can tell us
 189  * @param dirpath The path as far as the stat cache told us.
 190  * @param start   A pointer into name, for where to 'start' in fixing the rest of the name up.
 191  * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 192  *
 193  * @return True if we translated (and did a scuccessful stat on) the entire name.
 194  *
 195  */
 196
 197 BOOL stat_cache_lookup(connection_struct *conn, pstring name, pstring dirpath,
 198                        char **start, SMB_STRUCT_STAT *pst)
 199 {
 200         stat_cache_entry *scp;
 201         char *chk_name;
 202         size_t namelen;
 203         hash_element *hash_elem;
 204         char *sp;
 205         BOOL sizechanged = False;
 206         unsigned int num_components = 0;
 207
 208         if (!lp_stat_cache())
 209                 return False;
 210
 211         namelen = strlen(name);
 212
 213         *start = name;
 214
 215         DO_PROFILE_INC(statcache_lookups);
 216
 217         /*
 218          * Don't lookup trivial valid directory entries.
 219          */
 220         if((*name == '\0') || (name[0] == '.' &&
 221                                 ((name[1] == '\0') ||
 222                                  (name[1] == '.' && name[1] == '\0'))))
 223                 return False;
 224
 225         if (case_sensitive) {
 226                 chk_name = strdup(name);
 227                 if (!chk_name) {
 228                         DEBUG(0, ("stat_cache_lookup: strdup failed!\n"));
 229                         return False;
 230                 }
 231
 232         } else {
 233                 chk_name = strdup_upper(name);
 234                 if (!chk_name) {
 235                         DEBUG(0, ("stat_cache_lookup: strdup_upper failed!\n"));
 236                         return False;
 237                 }
 238
 239                 /*
 240                  * In some language encodings the length changes
 241                  * if we uppercase. We need to treat this differently
 242                  * below.
 243                  */
 244                 if (strlen(chk_name) != namelen)
 245                         sizechanged = True;
 246         }
 247
 248         while (1) {
 249                 hash_elem = hash_lookup(&stat_cache, chk_name);
 250                 if(hash_elem == NULL) {
 251                         DEBUG(10,("stat_cache_lookup: lookup failed for name [%s]\n", chk_name ));
 252                         /*
 253                          * Didn't find it - remove last component for next try.
 254                          */
 255                         sp = strrchr_m(chk_name, '/');
 256                         if (sp) {
 257                                 *sp = '\0';
 258                                 /*
 259                                  * Count the number of times we have done this,
 260                                  * we'll need it when reconstructing the string.
 261                                  */
 262                                 if (sizechanged)
 263                                         num_components++;
 264
 265                         } else {
 266                                 /*
 267                                  * We reached the end of the name - no match.
 268                                  */
 269                                 DO_PROFILE_INC(statcache_misses);
 270                                 SAFE_FREE(chk_name);
 271                                 return False;
 272                         }
 273                         if((*chk_name == '\0') || (strcmp(chk_name, ".") == 0)
 274                                         || (strcmp(chk_name, "..") == 0)) {
 275                                 DO_PROFILE_INC(statcache_misses);
 276                                 SAFE_FREE(chk_name);
 277                                 return False;
 278                         }
 279                 } else {
 280                         scp = (stat_cache_entry *)(hash_elem->value);
 281                         DEBUG(10,("stat_cache_lookup: lookup succeeded for name [%s] -> [%s]\n", chk_name, scp->translated_path ));
 282                         DO_PROFILE_INC(statcache_hits);
 283                         if(SMB_VFS_STAT(conn,scp->translated_path, pst) != 0) {
 284                                 /* Discard this entry - it doesn't exist in the filesystem.  */
 285                                 hash_remove(&stat_cache, hash_elem);
 286                                 SAFE_FREE(chk_name);
 287                                 return False;
 288                         }
 289
 290                         if (!sizechanged) {
 291                                 memcpy(name, scp->translated_path, MIN(sizeof(pstring)-1, scp->translated_path_length));
 292                         } else if (num_components == 0) {
 293                                 pstrcpy(name, scp->translated_path);
 294                         } else {
 295                                 sp = strnrchr_m(name, '/', num_components);
 296                                 if (sp) {
 297                                         pstring last_component;
 298                                         pstrcpy(last_component, sp);
 299                                         pstrcpy(name, scp->translated_path);
 300                                         pstrcat(name, last_component);
 301                                 } else {
 302                                         pstrcpy(name, scp->translated_path);
 303                                 }
 304                         }
 305
 306                         /* set pointer for 'where to start' on fixing the rest of the name */
 307                         *start = &name[scp->translated_path_length];
 308                         if(**start == '/')
 309                                 ++*start;
 310
 311                         pstrcpy(dirpath, scp->translated_path);
 312                         SAFE_FREE(chk_name);
 313                         return (namelen == scp->translated_path_length);
 314                 }
 315         }
 316 }
 317
 318 /*************************************************************************** **
 319  * Initializes or clears the stat cache.
 320  *
 321  *  Input:  none.
 322  *  Output: none.
 323  *
 324  * ************************************************************************** **
 325  */
 326 BOOL reset_stat_cache( void )
 327 {
 328         static BOOL initialised;
 329         if (!lp_stat_cache())
 330                 return True;
 331
 332         if (initialised) {
 333                 hash_clear(&stat_cache);
 334         }
 335
 336         initialised = hash_table_init( &stat_cache, INIT_STAT_CACHE_SIZE,
 337                                        (compare_function)(strcmp));
 338         return initialised;
 339 }