samba-mirror/source3/smbd/statcache.c

/* 
   Unix SMB/CIFS implementation.
   stat cache code
   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Jeremy Allison 1999-2000
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2003
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

extern BOOL case_sensitive;


/****************************************************************************
 Stat cache code used in unix_convert.
*****************************************************************************/

typedef struct {
	char *original_path;
	char *translated_path;
	size_t translated_path_length;
	char names[2]; /* This is extended via malloc... */
} stat_cache_entry;

#define INIT_STAT_CACHE_SIZE 512
static hash_table stat_cache;

/**
 * Add an entry into the stat cache.
 *
 * @param full_orig_name       The original name as specified by the client
 * @param orig_translated_path The name on our filesystem.
 * 
 * @note Only the first strlen(orig_translated_path) characters are stored 
 *       into the cache.  This means that full_orig_name will be internally
 *       truncated.
 *
 */

void stat_cache_add( const char *full_orig_name, const char *orig_translated_path)
{
  stat_cache_entry *scp;
  stat_cache_entry *found_scp;
  char *translated_path;
  size_t translated_path_length;

  char *original_path;
  size_t original_path_length;

  hash_element *hash_elem;

  if (!lp_stat_cache()) return;

  /*
   * Don't cache trivial valid directory entries.
   */
  if((*full_orig_name == '\0') || (strcmp(full_orig_name, ".") == 0) ||
     (strcmp(full_orig_name, "..") == 0))
    return;

  /*
   * If we are in case insentive mode, we don't need to
   * store names that need no translation - else, it
   * would be a waste.
   */

  if(case_sensitive && (strcmp(full_orig_name, orig_translated_path) == 0))
    return;

  /*
   * Remove any trailing '/' characters from the
   * translated path.
   */

  translated_path = strdup(orig_translated_path);
  if (!translated_path)
	  return;

  translated_path_length = strlen(translated_path);

  if(translated_path[translated_path_length-1] == '/') {
    translated_path[translated_path_length-1] = '\0';
    translated_path_length--;
  }

  original_path = strdup(full_orig_name);
  if (!original_path) {
	  SAFE_FREE(translated_path);
	  return;
  }

  original_path_length = strlen(original_path);

  if(original_path[original_path_length-1] == '/') {
    original_path[original_path_length-1] = '\0';
    original_path_length--;
  }

  if(!case_sensitive)
	  strupper(original_path);

  if (original_path_length != translated_path_length) {
	  if (original_path_length < translated_path_length) {
		  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));
		  SAFE_FREE(original_path);
		  SAFE_FREE(translated_path);
		  return;
	  }

	  /* we only want to store the first part of original_path,
	     up to the length of translated_path */

	  original_path[translated_path_length] = '\0';
	  original_path_length = translated_path_length;
  }

  /*
   * Check this name doesn't exist in the cache before we 
   * add it.
   */

  if ((hash_elem = hash_lookup(&stat_cache, original_path))) {
	  found_scp = (stat_cache_entry *)(hash_elem->value);
	  if (strcmp((found_scp->translated_path), orig_translated_path) == 0) {
		  /* already in hash table */
		  SAFE_FREE(original_path);
		  SAFE_FREE(translated_path);
		  return;
	  }
	  /* hash collision - remove before we re-add */
	  hash_remove(&stat_cache, hash_elem);
  }  
  
  /*
   * New entry.
   */
  
  if((scp = (stat_cache_entry *)malloc(sizeof(stat_cache_entry)
				       +original_path_length
				       +translated_path_length)) == NULL) {
	  DEBUG(0,("stat_cache_add: Out of memory !\n"));
	  SAFE_FREE(original_path);
	  SAFE_FREE(translated_path);
	  return;
  }

  scp->original_path = scp->names;
  scp->translated_path = scp->names + original_path_length + 1;
  safe_strcpy(scp->original_path, original_path, original_path_length);
  safe_strcpy(scp->translated_path, translated_path, translated_path_length);
  scp->translated_path_length = translated_path_length;

  hash_insert(&stat_cache, (char *)scp, original_path);

  SAFE_FREE(original_path);
  SAFE_FREE(translated_path);

  DEBUG(5,("stat_cache_add: Added entry %s -> %s\n", scp->original_path, scp->translated_path));
}

/**
 * Look through the stat cache for an entry
 *
 * The hash-table's internals will promote it to the top if found.
 *
 * @param conn    A connection struct to do the stat() with.
 * @param name    The path we are attempting to cache, modified by this routine
 *                to be correct as far as the cache can tell us
 * @param dirpath The path as far as the stat cache told us.
 * @param start   A pointer into name, for where to 'start' in fixing the rest of the name up.
 * @param psd     A stat buffer, NOT from the cache, but just a side-effect.
 *
 * @return True if we translated (and did a scuccessful stat on) the entire name.
 *
 */

BOOL stat_cache_lookup(connection_struct *conn, pstring name, pstring dirpath, 
		       char **start, SMB_STRUCT_STAT *pst)
{
  stat_cache_entry *scp;
  pstring chk_name;
  size_t namelen;
  hash_element *hash_elem;
  char *sp;

  if (!lp_stat_cache())
    return False;
 
  namelen = strlen(name);

  *start = name;

  DO_PROFILE_INC(statcache_lookups);

  /*
   * Don't lookup trivial valid directory entries.
   */
  if((*name == '\0') || (strcmp(name, ".") == 0) || (strcmp(name, "..") == 0)) {
    DO_PROFILE_INC(statcache_misses);
    return False;
  }

  pstrcpy(chk_name, name);
  if(!case_sensitive)
    strupper( chk_name );

  while (1) {
    hash_elem = hash_lookup(&stat_cache, chk_name);
    if(hash_elem == NULL) {
      /*
       * Didn't find it - remove last component for next try.
       */
      sp = strrchr_m(chk_name, '/');
      if (sp) {
        *sp = '\0';
      } else {
        /*
         * We reached the end of the name - no match.
         */
	DO_PROFILE_INC(statcache_misses);
        return False;
      }
      if((*chk_name == '\0') || (strcmp(chk_name, ".") == 0)
                          || (strcmp(chk_name, "..") == 0)) {
	DO_PROFILE_INC(statcache_misses);
        return False;
      }
    } else {
      scp = (stat_cache_entry *)(hash_elem->value);
      DO_PROFILE_INC(statcache_hits);
      if(SMB_VFS_STAT(conn,scp->translated_path, pst) != 0) {
        /* Discard this entry - it doesn't exist in the filesystem.  */
        hash_remove(&stat_cache, hash_elem);
        return False;
      }
      memcpy(name, scp->translated_path, MIN(sizeof(pstring)-1, scp->translated_path_length));

      /* set pointer for 'where to start' on fixing the rest of the name */
      *start = &name[scp->translated_path_length];
      if(**start == '/')
        ++*start;

      pstrcpy(dirpath, scp->translated_path);
      return (namelen == scp->translated_path_length);
    }
  }
}

/*************************************************************************** **
 * Initializes or clears the stat cache.
 *
 *  Input:  none.
 *  Output: none.
 *
 * ************************************************************************** **
 */
BOOL reset_stat_cache( void )
{
	static BOOL initialised;
	if (!lp_stat_cache()) return True;

	if (initialised) {
		hash_clear(&stat_cache);
	}

	initialised = hash_table_init( &stat_cache, INIT_STAT_CACHE_SIZE, 
				       (compare_function)(strcmp));
	return initialised;
} /* reset_stat_cache  */