source/smbd/statcache.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 3.0
   4    stat cache code
   5    Copyright (C) Andrew Tridgell 1992-2000
   6    Copyright (C) Jeremy Allison 1999-200
   7
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 #include "includes.h"
  25
  26 extern BOOL case_sensitive;
  27
  28
  29 /****************************************************************************
  30  Stat cache code used in unix_convert.
  31 *****************************************************************************/
  32
  33 static int global_stat_cache_lookups;
  34 static int global_stat_cache_misses;
  35 static int global_stat_cache_hits;
  36
  37 /****************************************************************************
  38  Stat cache statistics code.
  39 *****************************************************************************/
  40
  41 void print_stat_cache_statistics(void)
  42 {
  43   double eff;
  44
  45   if(global_stat_cache_lookups == 0)
  46     return;
  47
  48   eff = (100.0* (double)global_stat_cache_hits)/(double)global_stat_cache_lookups;
  49
  50   DEBUG(0,("stat cache stats: lookups = %d, hits = %d, misses = %d, \
  51 stat cache was %f%% effective.\n", global_stat_cache_lookups,
  52        global_stat_cache_hits, global_stat_cache_misses, eff ));
  53 }
  54
  55 typedef struct {
  56   int name_len;
  57   char names[2]; /* This is extended via malloc... */
  58 } stat_cache_entry;
  59
  60 #define INIT_STAT_CACHE_SIZE 512
  61 static hash_table stat_cache;
  62
  63 /****************************************************************************
  64  Add an entry into the stat cache.
  65 *****************************************************************************/
  66
  67 void stat_cache_add( char *full_orig_name, char *orig_translated_path)
  68 {
  69   stat_cache_entry *scp;
  70   stat_cache_entry *found_scp;
  71   pstring orig_name;
  72   pstring translated_path;
  73   int namelen;
  74   hash_element *hash_elem;
  75
  76   if (!lp_stat_cache()) return;
  77
  78   namelen = strlen(orig_translated_path);
  79
  80   /*
  81    * Don't cache trivial valid directory entries.
  82    */
  83   if((*full_orig_name == '\0') || (strcmp(full_orig_name, ".") == 0) ||
  84      (strcmp(full_orig_name, "..") == 0))
  85     return;
  86
  87   /*
  88    * If we are in case insentive mode, we need to
  89    * store names that need no translation - else, it
  90    * would be a waste.
  91    */
  92
  93   if(case_sensitive && (strcmp(full_orig_name, orig_translated_path) == 0))
  94     return;
  95
  96   /*
  97    * Remove any trailing '/' characters from the
  98    * translated path.
  99    */
 100
 101   pstrcpy(translated_path, orig_translated_path);
 102   if(translated_path[namelen-1] == '/') {
 103     translated_path[namelen-1] = '\0';
 104     namelen--;
 105   }
 106
 107   /*
 108    * We will only replace namelen characters
 109    * of full_orig_name.
 110    * StrnCpy always null terminates.
 111    */
 112
 113   StrnCpy(orig_name, full_orig_name, namelen);
 114   if(!case_sensitive)
 115     strupper( orig_name );
 116
 117   /*
 118    * Check this name doesn't exist in the cache before we
 119    * add it.
 120    */
 121
 122   if ((hash_elem = hash_lookup(&stat_cache, orig_name))) {
 123     found_scp = (stat_cache_entry *)(hash_elem->value);
 124     if (strcmp((found_scp->names+found_scp->name_len+1), translated_path) == 0) {
 125       return;
 126     } else {
 127       hash_remove(&stat_cache, hash_elem);
 128       if((scp = (stat_cache_entry *)malloc(sizeof(stat_cache_entry)+2*namelen)) == NULL) {
 129         DEBUG(0,("stat_cache_add: Out of memory !\n"));
 130         return;
 131       }
 132       pstrcpy(scp->names, orig_name);
 133       pstrcpy((scp->names+namelen+1), translated_path);
 134       scp->name_len = namelen;
 135       hash_insert(&stat_cache, (char *)scp, orig_name);
 136     }
 137     return;
 138   } else {
 139
 140     /*
 141      * New entry.
 142      */
 143
 144     if((scp = (stat_cache_entry *)malloc(sizeof(stat_cache_entry)+2*namelen)) == NULL) {
 145       DEBUG(0,("stat_cache_add: Out of memory !\n"));
 146       return;
 147     }
 148     pstrcpy(scp->names, orig_name);
 149     pstrcpy(scp->names+namelen+1, translated_path);
 150     scp->name_len = namelen;
 151     hash_insert(&stat_cache, (char *)scp, orig_name);
 152   }
 153
 154   DEBUG(5,("stat_cache_add: Added entry %s -> %s\n", scp->names, (scp->names+scp->name_len+1)));
 155 }
 156
 157 /****************************************************************************
 158  Look through the stat cache for an entry - promote it to the top if found.
 159  Return True if we translated (and did a scuccessful stat on) the entire name.
 160 *****************************************************************************/
 161
 162 BOOL stat_cache_lookup(connection_struct *conn, char *name, char *dirpath,
 163                        char **start, SMB_STRUCT_STAT *pst)
 164 {
 165   stat_cache_entry *scp;
 166   char *trans_name;
 167   pstring chk_name;
 168   int namelen;
 169   hash_element *hash_elem;
 170   char *sp;
 171
 172   if (!lp_stat_cache())
 173     return False;
 174
 175   namelen = strlen(name);
 176
 177   *start = name;
 178   global_stat_cache_lookups++;
 179
 180   /*
 181    * Don't lookup trivial valid directory entries.
 182    */
 183   if((*name == '\0') || (strcmp(name, ".") == 0) || (strcmp(name, "..") == 0)) {
 184     global_stat_cache_misses++;
 185     return False;
 186   }
 187
 188   pstrcpy(chk_name, name);
 189   if(!case_sensitive)
 190     strupper( chk_name );
 191
 192   while (1) {
 193     hash_elem = hash_lookup(&stat_cache, chk_name);
 194     if(hash_elem == NULL) {
 195       /*
 196        * Didn't find it - remove last component for next try.
 197        */
 198       sp = strrchr(chk_name, '/');
 199       if (sp) {
 200         *sp = '\0';
 201       } else {
 202         /*
 203          * We reached the end of the name - no match.
 204          */
 205         global_stat_cache_misses++;
 206         return False;
 207       }
 208       if((*chk_name == '\0') || (strcmp(chk_name, ".") == 0)
 209                           || (strcmp(chk_name, "..") == 0)) {
 210         global_stat_cache_misses++;
 211         return False;
 212       }
 213     } else {
 214       scp = (stat_cache_entry *)(hash_elem->value);
 215       global_stat_cache_hits++;
 216       trans_name = scp->names+scp->name_len+1;
 217       if(conn->vfs_ops.stat(dos_to_unix(trans_name,False), pst) != 0) {
 218         /* Discard this entry - it doesn't exist in the filesystem.  */
 219         hash_remove(&stat_cache, hash_elem);
 220         return False;
 221       }
 222       memcpy(name, trans_name, scp->name_len);
 223       *start = &name[scp->name_len];
 224       if(**start == '/')
 225         ++*start;
 226       StrnCpy( dirpath, trans_name, name - (*start));
 227       return (namelen == scp->name_len);
 228     }
 229   }
 230 }
 231
 232 /*************************************************************************** **
 233  * Initializes or clears the stat cache.
 234  *
 235  *  Input:  none.
 236  *  Output: none.
 237  *
 238  * ************************************************************************** **
 239  */
 240 BOOL reset_stat_cache( void )
 241 {
 242   return hash_table_init( &stat_cache, INIT_STAT_CACHE_SIZE, (compare_function)(strcmp));
 243 } /* reset_stat_cache  */