mirror of
https://github.com/wiiu-env/libntfs.git
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607 lines
15 KiB
C
607 lines
15 KiB
C
/**
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* cache.c : deal with LRU caches
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*
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* Copyright (c) 2008-2010 Jean-Pierre Andre
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*
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* This program/include file is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as published
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* by the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program/include file is distributed in the hope that it will be
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* useful, but WITHOUT ANY WARRANTY; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (in the main directory of the NTFS-3G
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* distribution in the file COPYING); if not, write to the Free Software
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* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#ifdef HAVE_STDLIB_H
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#include <stdlib.h>
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#endif
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#ifdef HAVE_STRING_H
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#include <string.h>
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#endif
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#include "types.h"
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#include "security.h"
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#include "cache.h"
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#include "misc.h"
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#include "logging.h"
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/*
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* General functions to deal with LRU caches
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*
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* The cached data have to be organized in a structure in which
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* the first fields must follow a mandatory pattern and further
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* fields may contain any fixed size data. They are stored in an
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* LRU list.
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*
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* A compare function must be provided for finding a wanted entry
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* in the cache. Another function may be provided for invalidating
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* an entry to facilitate multiple invalidation.
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*
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* These functions never return error codes. When there is a
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* shortage of memory, data is simply not cached.
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* When there is a hashing bug, hashing is dropped, and sequential
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* searches are used.
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*/
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/*
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* Enter a new hash index, after a new record has been inserted
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*
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* Do not call when a record has been modified (with no key change)
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*/
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static void inserthashindex(struct CACHE_HEADER *cache,
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struct CACHED_GENERIC *current)
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{
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int h;
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struct HASH_ENTRY *link;
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struct HASH_ENTRY *first;
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if (cache->dohash) {
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h = cache->dohash(current);
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if ((h >= 0) && (h < cache->max_hash)) {
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/* get a free link and insert at top of hash list */
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link = cache->free_hash;
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if (link) {
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cache->free_hash = link->next;
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first = cache->first_hash[h];
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if (first)
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link->next = first;
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else
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link->next = NULL;
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link->entry = current;
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cache->first_hash[h] = link;
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} else {
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ntfs_log_error("No more hash entries,"
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" cache %s hashing dropped\n",
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cache->name);
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cache->dohash = (cache_hash)NULL;
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}
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} else {
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ntfs_log_error("Illegal hash value,"
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" cache %s hashing dropped\n",
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cache->name);
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cache->dohash = (cache_hash)NULL;
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}
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}
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}
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/*
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* Drop a hash index when a record is about to be deleted
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*/
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static void drophashindex(struct CACHE_HEADER *cache,
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const struct CACHED_GENERIC *current, int hash)
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{
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struct HASH_ENTRY *link;
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struct HASH_ENTRY *previous;
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if (cache->dohash) {
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if ((hash >= 0) && (hash < cache->max_hash)) {
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/* find the link and unlink */
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link = cache->first_hash[hash];
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previous = (struct HASH_ENTRY*)NULL;
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while (link && (link->entry != current)) {
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previous = link;
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link = link->next;
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}
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if (link) {
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if (previous)
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previous->next = link->next;
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else
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cache->first_hash[hash] = link->next;
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link->next = cache->free_hash;
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cache->free_hash = link;
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} else {
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ntfs_log_error("Bad hash list,"
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" cache %s hashing dropped\n",
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cache->name);
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cache->dohash = (cache_hash)NULL;
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}
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} else {
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ntfs_log_error("Illegal hash value,"
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" cache %s hashing dropped\n",
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cache->name);
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cache->dohash = (cache_hash)NULL;
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}
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}
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}
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/*
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* Fetch an entry from cache
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*
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* returns the cache entry, or NULL if not available
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* The returned entry may be modified, but not freed
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*/
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struct CACHED_GENERIC *ntfs_fetch_cache(struct CACHE_HEADER *cache,
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const struct CACHED_GENERIC *wanted, cache_compare compare)
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{
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struct CACHED_GENERIC *current;
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struct CACHED_GENERIC *previous;
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struct HASH_ENTRY *link;
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int h;
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current = (struct CACHED_GENERIC*)NULL;
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if (cache) {
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if (cache->dohash) {
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/*
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* When possible, use the hash table to
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* locate the entry if present
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*/
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h = cache->dohash(wanted);
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link = cache->first_hash[h];
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while (link && compare(link->entry, wanted))
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link = link->next;
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if (link)
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current = link->entry;
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}
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if (!cache->dohash) {
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/*
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* Search sequentially in LRU list if no hash table
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* or if hashing has just failed
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*/
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current = cache->most_recent_entry;
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while (current
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&& compare(current, wanted)) {
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current = current->next;
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}
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}
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if (current) {
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previous = current->previous;
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cache->hits++;
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if (previous) {
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/*
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* found and not at head of list, unlink from current
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* position and relink as head of list
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*/
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previous->next = current->next;
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if (current->next)
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current->next->previous
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= current->previous;
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else
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cache->oldest_entry
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= current->previous;
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current->next = cache->most_recent_entry;
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current->previous
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= (struct CACHED_GENERIC*)NULL;
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cache->most_recent_entry->previous = current;
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cache->most_recent_entry = current;
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}
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}
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cache->reads++;
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}
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return (current);
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}
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/*
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* Enter an inode number into cache
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* returns the cache entry or NULL if not possible
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*/
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struct CACHED_GENERIC *ntfs_enter_cache(struct CACHE_HEADER *cache,
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const struct CACHED_GENERIC *item,
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cache_compare compare)
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{
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struct CACHED_GENERIC *current;
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struct CACHED_GENERIC *before;
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struct HASH_ENTRY *link;
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int h;
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current = (struct CACHED_GENERIC*)NULL;
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if (cache) {
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if (cache->dohash) {
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/*
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* When possible, use the hash table to
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* find out whether the entry if present
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*/
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h = cache->dohash(item);
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link = cache->first_hash[h];
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while (link && compare(link->entry, item))
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link = link->next;
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if (link) {
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current = link->entry;
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}
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}
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if (!cache->dohash) {
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/*
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* Search sequentially in LRU list to locate the end,
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* and find out whether the entry is already in list
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* As we normally go to the end, no statistics is
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* kept.
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*/
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current = cache->most_recent_entry;
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while (current
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&& compare(current, item)) {
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current = current->next;
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}
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}
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if (!current) {
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/*
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* Not in list, get a free entry or reuse the
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* last entry, and relink as head of list
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* Note : we assume at least three entries, so
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* before, previous and first are different when
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* an entry is reused.
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*/
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if (cache->free_entry) {
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current = cache->free_entry;
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cache->free_entry = cache->free_entry->next;
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if (item->varsize) {
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current->variable = ntfs_malloc(
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item->varsize);
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} else
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current->variable = (void*)NULL;
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current->varsize = item->varsize;
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if (!cache->oldest_entry)
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cache->oldest_entry = current;
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} else {
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/* reusing the oldest entry */
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current = cache->oldest_entry;
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before = current->previous;
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before->next = (struct CACHED_GENERIC*)NULL;
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if (cache->dohash)
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drophashindex(cache,current,
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cache->dohash(current));
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if (cache->dofree)
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cache->dofree(current);
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cache->oldest_entry = current->previous;
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if (item->varsize) {
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if (current->varsize)
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current->variable = realloc(
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current->variable,
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item->varsize);
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else
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current->variable = ntfs_malloc(
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item->varsize);
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} else {
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if (current->varsize)
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free(current->variable);
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current->variable = (void*)NULL;
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}
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current->varsize = item->varsize;
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}
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current->next = cache->most_recent_entry;
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current->previous = (struct CACHED_GENERIC*)NULL;
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if (cache->most_recent_entry)
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cache->most_recent_entry->previous = current;
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cache->most_recent_entry = current;
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memcpy(current->payload, item->payload, cache->fixed_size);
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if (item->varsize) {
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if (current->variable) {
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memcpy(current->variable,
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item->variable, item->varsize);
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} else {
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/*
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* no more memory for variable part
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* recycle entry in free list
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* not an error, just uncacheable
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*/
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cache->most_recent_entry = current->next;
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current->next = cache->free_entry;
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cache->free_entry = current;
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current = (struct CACHED_GENERIC*)NULL;
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}
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} else {
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current->variable = (void*)NULL;
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current->varsize = 0;
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}
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if (cache->dohash && current)
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inserthashindex(cache,current);
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}
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cache->writes++;
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}
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return (current);
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}
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/*
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* Invalidate a cache entry
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* The entry is moved to the free entry list
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* A specific function may be called for entry deletion
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*/
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static void do_invalidate(struct CACHE_HEADER *cache,
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struct CACHED_GENERIC *current, int flags)
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{
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struct CACHED_GENERIC *previous;
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previous = current->previous;
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if ((flags & CACHE_FREE) && cache->dofree)
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cache->dofree(current);
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/*
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* Relink into free list
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*/
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if (current->next)
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current->next->previous = current->previous;
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else
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cache->oldest_entry = current->previous;
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if (previous)
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previous->next = current->next;
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else
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cache->most_recent_entry = current->next;
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current->next = cache->free_entry;
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cache->free_entry = current;
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if (current->variable)
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free(current->variable);
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current->varsize = 0;
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}
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/*
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* Invalidate entries in cache
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*
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* Several entries may have to be invalidated (at least for inodes
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* associated to directories which have been renamed), a different
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* compare function may be provided to select entries to invalidate
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*
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* Returns the number of deleted entries, this can be used by
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* the caller to signal a cache corruption if the entry was
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* supposed to be found.
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*/
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int ntfs_invalidate_cache(struct CACHE_HEADER *cache,
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const struct CACHED_GENERIC *item, cache_compare compare,
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int flags)
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{
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struct CACHED_GENERIC *current;
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struct CACHED_GENERIC *next;
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struct HASH_ENTRY *link;
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int count;
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int h;
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current = (struct CACHED_GENERIC*)NULL;
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count = 0;
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if (cache) {
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if (!(flags & CACHE_NOHASH) && cache->dohash) {
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/*
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* When possible, use the hash table to
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* find out whether the entry if present
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*/
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h = cache->dohash(item);
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link = cache->first_hash[h];
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while (link) {
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if (compare(link->entry, item))
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link = link->next;
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else {
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current = link->entry;
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link = link->next;
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if (current) {
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drophashindex(cache,current,h);
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do_invalidate(cache,
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current,flags);
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count++;
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}
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}
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}
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}
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if ((flags & CACHE_NOHASH) || !cache->dohash) {
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/*
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* Search sequentially in LRU list
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*/
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current = cache->most_recent_entry;
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while (current) {
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if (!compare(current, item)) {
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next = current->next;
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if (cache->dohash)
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drophashindex(cache,current,
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cache->dohash(current));
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do_invalidate(cache,current,flags);
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current = next;
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count++;
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} else {
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current = current->next;
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}
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}
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}
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}
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return (count);
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}
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int ntfs_remove_cache(struct CACHE_HEADER *cache,
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struct CACHED_GENERIC *item, int flags)
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{
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int count;
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count = 0;
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if (cache) {
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if (cache->dohash)
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drophashindex(cache,item,cache->dohash(item));
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do_invalidate(cache,item,flags);
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count++;
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}
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return (count);
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}
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/*
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* Free memory allocated to a cache
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*/
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static void ntfs_free_cache(struct CACHE_HEADER *cache)
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{
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struct CACHED_GENERIC *entry;
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if (cache) {
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for (entry=cache->most_recent_entry; entry; entry=entry->next) {
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if (cache->dofree)
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cache->dofree(entry);
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if (entry->variable)
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free(entry->variable);
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}
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free(cache);
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}
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}
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/*
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* Create a cache
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*
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* Returns the cache header, or NULL if the cache could not be created
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*/
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static struct CACHE_HEADER *ntfs_create_cache(const char *name,
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cache_free dofree, cache_hash dohash,
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int full_item_size,
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int item_count, int max_hash)
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{
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struct CACHE_HEADER *cache;
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struct CACHED_GENERIC *pc;
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struct CACHED_GENERIC *qc;
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struct HASH_ENTRY *ph;
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struct HASH_ENTRY *qh;
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struct HASH_ENTRY **px;
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size_t size;
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int i;
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size = sizeof(struct CACHE_HEADER) + item_count*full_item_size;
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if (max_hash)
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size += item_count*sizeof(struct HASH_ENTRY)
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+ max_hash*sizeof(struct HASH_ENTRY*);
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cache = (struct CACHE_HEADER*)ntfs_malloc(size);
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if (cache) {
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/* header */
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cache->name = name;
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cache->dofree = dofree;
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if (dohash && max_hash) {
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cache->dohash = dohash;
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cache->max_hash = max_hash;
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} else {
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cache->dohash = (cache_hash)NULL;
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cache->max_hash = 0;
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}
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cache->fixed_size = full_item_size - sizeof(struct CACHED_GENERIC);
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cache->reads = 0;
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cache->writes = 0;
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cache->hits = 0;
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/* chain the data entries, and mark an invalid entry */
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cache->most_recent_entry = (struct CACHED_GENERIC*)NULL;
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cache->oldest_entry = (struct CACHED_GENERIC*)NULL;
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cache->free_entry = &cache->entry[0];
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pc = &cache->entry[0];
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for (i=0; i<(item_count - 1); i++) {
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qc = (struct CACHED_GENERIC*)((char*)pc
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+ full_item_size);
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pc->next = qc;
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pc->variable = (void*)NULL;
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pc->varsize = 0;
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pc = qc;
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}
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/* special for the last entry */
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pc->next = (struct CACHED_GENERIC*)NULL;
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pc->variable = (void*)NULL;
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pc->varsize = 0;
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if (max_hash) {
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/* chain the hash entries */
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ph = (struct HASH_ENTRY*)(((char*)pc) + full_item_size);
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cache->free_hash = ph;
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for (i=0; i<(item_count - 1); i++) {
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qh = &ph[1];
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ph->next = qh;
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ph = qh;
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}
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/* special for the last entry */
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if (item_count) {
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ph->next = (struct HASH_ENTRY*)NULL;
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}
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/* create and initialize the hash indexes */
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px = (struct HASH_ENTRY**)&ph[1];
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cache->first_hash = px;
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for (i=0; i<max_hash; i++)
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px[i] = (struct HASH_ENTRY*)NULL;
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} else {
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cache->free_hash = (struct HASH_ENTRY*)NULL;
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cache->first_hash = (struct HASH_ENTRY**)NULL;
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}
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}
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return (cache);
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}
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/*
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* Create all LRU caches
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*
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* No error return, if creation is not possible, cacheing will
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* just be not available
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*/
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void ntfs_create_lru_caches(ntfs_volume *vol)
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{
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#if CACHE_INODE_SIZE
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/* inode cache */
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vol->xinode_cache = ntfs_create_cache("inode",(cache_free)NULL,
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ntfs_dir_inode_hash, sizeof(struct CACHED_INODE),
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CACHE_INODE_SIZE, 2*CACHE_INODE_SIZE);
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#endif
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#if CACHE_NIDATA_SIZE
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/* idata cache */
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vol->nidata_cache = ntfs_create_cache("nidata",
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ntfs_inode_nidata_free, ntfs_inode_nidata_hash,
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sizeof(struct CACHED_NIDATA),
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CACHE_NIDATA_SIZE, 2*CACHE_NIDATA_SIZE);
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#endif
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#if CACHE_LOOKUP_SIZE
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/* lookup cache */
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vol->lookup_cache = ntfs_create_cache("lookup",
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(cache_free)NULL, ntfs_dir_lookup_hash,
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sizeof(struct CACHED_LOOKUP),
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CACHE_LOOKUP_SIZE, 2*CACHE_LOOKUP_SIZE);
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#endif
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vol->securid_cache = ntfs_create_cache("securid",(cache_free)NULL,
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(cache_hash)NULL,sizeof(struct CACHED_SECURID), CACHE_SECURID_SIZE, 0);
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#if CACHE_LEGACY_SIZE
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vol->legacy_cache = ntfs_create_cache("legacy",(cache_free)NULL,
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(cache_hash)NULL, sizeof(struct CACHED_PERMISSIONS_LEGACY), CACHE_LEGACY_SIZE, 0);
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#endif
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}
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/*
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* Free all LRU caches
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*/
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void ntfs_free_lru_caches(ntfs_volume *vol)
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{
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#if CACHE_INODE_SIZE
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ntfs_free_cache(vol->xinode_cache);
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#endif
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#if CACHE_NIDATA_SIZE
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ntfs_free_cache(vol->nidata_cache);
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#endif
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#if CACHE_LOOKUP_SIZE
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ntfs_free_cache(vol->lookup_cache);
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#endif
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ntfs_free_cache(vol->securid_cache);
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#if CACHE_LEGACY_SIZE
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ntfs_free_cache(vol->legacy_cache);
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#endif
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}
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