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