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
   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   int name_len;
  34   char names[2]; /* This is extended via malloc... */
  35 } stat_cache_entry;
  36
  37 #define INIT_STAT_CACHE_SIZE 512
  38 static hash_table stat_cache;
  39
  40 /****************************************************************************
  41  Add an entry into the stat cache.
  42 *****************************************************************************/
  43
  44 void stat_cache_add( char *full_orig_name, char *orig_translated_path)
  45 {
  46   stat_cache_entry *scp;
  47   stat_cache_entry *found_scp;
  48   pstring orig_name;
  49   pstring translated_path;
  50   int namelen;
  51   hash_element *hash_elem;
  52
  53   if (!lp_stat_cache()) return;
  54
  55   namelen = strlen(orig_translated_path);
  56
  57   /*
  58    * Don't cache trivial valid directory entries.
  59    */
  60   if((*full_orig_name == '\0') || (strcmp(full_orig_name, ".") == 0) ||
  61      (strcmp(full_orig_name, "..") == 0))
  62     return;
  63
  64   /*
  65    * If we are in case insentive mode, we need to
  66    * store names that need no translation - else, it
  67    * would be a waste.
  68    */
  69
  70   if(case_sensitive && (strcmp(full_orig_name, orig_translated_path) == 0))
  71     return;
  72
  73   /*
  74    * Remove any trailing '/' characters from the
  75    * translated path.
  76    */
  77
  78   pstrcpy(translated_path, orig_translated_path);
  79   if(translated_path[namelen-1] == '/') {
  80     translated_path[namelen-1] = '\0';
  81     namelen--;
  82   }
  83
  84   /*
  85    * We will only replace namelen characters
  86    * of full_orig_name.
  87    * StrnCpy always null terminates.
  88    */
  89
  90   StrnCpy(orig_name, full_orig_name, namelen);
  91   if(!case_sensitive)
  92     strupper( orig_name );
  93
  94   /*
  95    * Check this name doesn't exist in the cache before we
  96    * add it.
  97    */
  98
  99   if ((hash_elem = hash_lookup(&stat_cache, orig_name))) {
 100     found_scp = (stat_cache_entry *)(hash_elem->value);
 101     if (strcmp((found_scp->names+found_scp->name_len+1), translated_path) == 0) {
 102       return;
 103     } else {
 104       hash_remove(&stat_cache, hash_elem);
 105       if((scp = (stat_cache_entry *)malloc(sizeof(stat_cache_entry)+2*namelen)) == NULL) {
 106         DEBUG(0,("stat_cache_add: Out of memory !\n"));
 107         return;
 108       }
 109       pstrcpy(scp->names, orig_name);
 110       pstrcpy((scp->names+namelen+1), translated_path);
 111       scp->name_len = namelen;
 112       hash_insert(&stat_cache, (char *)scp, orig_name);
 113     }
 114     return;
 115   } else {
 116
 117     /*
 118      * New entry.
 119      */
 120
 121     if((scp = (stat_cache_entry *)malloc(sizeof(stat_cache_entry)+2*namelen)) == NULL) {
 122       DEBUG(0,("stat_cache_add: Out of memory !\n"));
 123       return;
 124     }
 125     safe_strcpy(scp->names, orig_name, namelen);
 126     safe_strcpy(scp->names+namelen+1, translated_path, namelen);
 127     scp->name_len = namelen;
 128     hash_insert(&stat_cache, (char *)scp, orig_name);
 129   }
 130
 131   DEBUG(5,("stat_cache_add: Added entry %s -> %s\n", scp->names, (scp->names+scp->name_len+1)));
 132 }
 133
 134 /****************************************************************************
 135  Look through the stat cache for an entry - promote it to the top if found.
 136  Return True if we translated (and did a scuccessful stat on) the entire name.
 137 *****************************************************************************/
 138
 139 BOOL stat_cache_lookup(connection_struct *conn, char *name, char *dirpath,
 140                        char **start, SMB_STRUCT_STAT *pst)
 141 {
 142   stat_cache_entry *scp;
 143   char *trans_name;
 144   pstring chk_name;
 145   int namelen;
 146   hash_element *hash_elem;
 147   char *sp;
 148
 149   if (!lp_stat_cache())
 150     return False;
 151
 152   namelen = strlen(name);
 153
 154   *start = name;
 155
 156   DO_PROFILE_INC(statcache_lookups);
 157
 158   /*
 159    * Don't lookup trivial valid directory entries.
 160    */
 161   if((*name == '\0') || (strcmp(name, ".") == 0) || (strcmp(name, "..") == 0)) {
 162     DO_PROFILE_INC(statcache_misses);
 163     return False;
 164   }
 165
 166   pstrcpy(chk_name, name);
 167   if(!case_sensitive)
 168     strupper( chk_name );
 169
 170   while (1) {
 171     hash_elem = hash_lookup(&stat_cache, chk_name);
 172     if(hash_elem == NULL) {
 173       /*
 174        * Didn't find it - remove last component for next try.
 175        */
 176       sp = strrchr_m(chk_name, '/');
 177       if (sp) {
 178         *sp = '\0';
 179       } else {
 180         /*
 181          * We reached the end of the name - no match.
 182          */
 183         DO_PROFILE_INC(statcache_misses);
 184         return False;
 185       }
 186       if((*chk_name == '\0') || (strcmp(chk_name, ".") == 0)
 187                           || (strcmp(chk_name, "..") == 0)) {
 188         DO_PROFILE_INC(statcache_misses);
 189         return False;
 190       }
 191     } else {
 192       scp = (stat_cache_entry *)(hash_elem->value);
 193       DO_PROFILE_INC(statcache_hits);
 194       trans_name = scp->names+scp->name_len+1;
 195       if(vfs_stat(conn,trans_name, pst) != 0) {
 196         /* Discard this entry - it doesn't exist in the filesystem.  */
 197         hash_remove(&stat_cache, hash_elem);
 198         return False;
 199       }
 200       memcpy(name, trans_name, scp->name_len);
 201       *start = &name[scp->name_len];
 202       if(**start == '/')
 203         ++*start;
 204       StrnCpy( dirpath, trans_name, name - (*start));
 205       return (namelen == scp->name_len);
 206     }
 207   }
 208 }
 209
 210 /*************************************************************************** **
 211  * Initializes or clears the stat cache.
 212  *
 213  *  Input:  none.
 214  *  Output: none.
 215  *
 216  * ************************************************************************** **
 217  */
 218 BOOL reset_stat_cache( void )
 219 {
 220         static BOOL initialised;
 221         if (!lp_stat_cache()) return True;
 222
 223         if (initialised) {
 224                 hash_clear(&stat_cache);
 225         }
 226
 227         initialised = hash_table_init( &stat_cache, INIT_STAT_CACHE_SIZE,
 228                                        (compare_function)(strcmp));
 229         return initialised;
 230 } /* reset_stat_cache  */