LXR linux/fs/squashfs/decompressor.c

   1/*
   2 * Squashfs - a compressed read only filesystem for Linux
   3 *
   4 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
   5 * Phillip Lougher <phillip@squashfs.org.uk>
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License
   9 * as published by the Free Software Foundation; either version 2,
  10 * or (at your option) any later version.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program; if not, write to the Free Software
  19 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  20 *
  21 * decompressor.c
  22 */
  23
  24#include <linux/types.h>
  25#include <linux/mutex.h>
  26#include <linux/slab.h>
  27#include <linux/buffer_head.h>
  28
  29#include "squashfs_fs.h"
  30#include "squashfs_fs_sb.h"
  31#include "decompressor.h"
  32#include "squashfs.h"
  33#include "page_actor.h"
  34
  35/*
  36 * This file (and decompressor.h) implements a decompressor framework for
  37 * Squashfs, allowing multiple decompressors to be easily supported
  38 */
  39
  40static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
  41        NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
  42};
  43
  44#ifndef CONFIG_SQUASHFS_LZ4
  45static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
  46        NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
  47};
  48#endif
  49
  50#ifndef CONFIG_SQUASHFS_LZO
  51static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
  52        NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
  53};
  54#endif
  55
  56#ifndef CONFIG_SQUASHFS_XZ
  57static const struct squashfs_decompressor squashfs_xz_comp_ops = {
  58        NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
  59};
  60#endif
  61
  62#ifndef CONFIG_SQUASHFS_ZLIB
  63static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
  64        NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
  65};
  66#endif
  67
  68static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
  69        NULL, NULL, NULL, NULL, 0, "unknown", 0
  70};
  71
  72static const struct squashfs_decompressor *decompressor[] = {
  73        &squashfs_zlib_comp_ops,
  74        &squashfs_lz4_comp_ops,
  75        &squashfs_lzo_comp_ops,
  76        &squashfs_xz_comp_ops,
  77        &squashfs_lzma_unsupported_comp_ops,
  78        &squashfs_unknown_comp_ops
  79};
  80
  81
  82const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
  83{
  84        int i;
  85
  86        for (i = 0; decompressor[i]->id; i++)
  87                if (id == decompressor[i]->id)
  88                        break;
  89
  90        return decompressor[i];
  91}
  92
  93
  94static void *get_comp_opts(struct super_block *sb, unsigned short flags)
  95{
  96        struct squashfs_sb_info *msblk = sb->s_fs_info;
  97        void *buffer = NULL, *comp_opts;
  98        struct squashfs_page_actor *actor = NULL;
  99        int length = 0;
 100
 101        /*
 102         * Read decompressor specific options from file system if present
 103         */
 104        if (SQUASHFS_COMP_OPTS(flags)) {
 105                buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
 106                if (buffer == NULL) {
 107                        comp_opts = ERR_PTR(-ENOMEM);
 108                        goto out;
 109                }
 110
 111                actor = squashfs_page_actor_init(&buffer, 1, 0);
 112                if (actor == NULL) {
 113                        comp_opts = ERR_PTR(-ENOMEM);
 114                        goto out;
 115                }
 116
 117                length = squashfs_read_data(sb,
 118                        sizeof(struct squashfs_super_block), 0, NULL, actor);
 119
 120                if (length < 0) {
 121                        comp_opts = ERR_PTR(length);
 122                        goto out;
 123                }
 124        }
 125
 126        comp_opts = squashfs_comp_opts(msblk, buffer, length);
 127
 128out:
 129        kfree(actor);
 130        kfree(buffer);
 131        return comp_opts;
 132}
 133
 134
 135void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
 136{
 137        struct squashfs_sb_info *msblk = sb->s_fs_info;
 138        void *stream, *comp_opts = get_comp_opts(sb, flags);
 139
 140        if (IS_ERR(comp_opts))
 141                return comp_opts;
 142
 143        stream = squashfs_decompressor_create(msblk, comp_opts);
 144        if (IS_ERR(stream))
 145                kfree(comp_opts);
 146
 147        return stream;
 148}
 149