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
  68#ifndef CONFIG_SQUASHFS_ZSTD
  69static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
  70        NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
  71};
  72#endif
  73
  74static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
  75        NULL, NULL, NULL, NULL, 0, "unknown", 0
  76};
  77
  78static const struct squashfs_decompressor *decompressor[] = {
  79        &squashfs_zlib_comp_ops,
  80        &squashfs_lz4_comp_ops,
  81        &squashfs_lzo_comp_ops,
  82        &squashfs_xz_comp_ops,
  83        &squashfs_lzma_unsupported_comp_ops,
  84        &squashfs_zstd_comp_ops,
  85        &squashfs_unknown_comp_ops
  86};
  87
  88
  89const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
  90{
  91        int i;
  92
  93        for (i = 0; decompressor[i]->id; i++)
  94                if (id == decompressor[i]->id)
  95                        break;
  96
  97        return decompressor[i];
  98}
  99
 100
 101static void *get_comp_opts(struct super_block *sb, unsigned short flags)
 102{
 103        struct squashfs_sb_info *msblk = sb->s_fs_info;
 104        void *buffer = NULL, *comp_opts;
 105        struct squashfs_page_actor *actor = NULL;
 106        int length = 0;
 107
 108        /*
 109         * Read decompressor specific options from file system if present
 110         */
 111        if (SQUASHFS_COMP_OPTS(flags)) {
 112                buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
 113                if (buffer == NULL) {
 114                        comp_opts = ERR_PTR(-ENOMEM);
 115                        goto out;
 116                }
 117
 118                actor = squashfs_page_actor_init(&buffer, 1, 0);
 119                if (actor == NULL) {
 120                        comp_opts = ERR_PTR(-ENOMEM);
 121                        goto out;
 122                }
 123
 124                length = squashfs_read_data(sb,
 125                        sizeof(struct squashfs_super_block), 0, NULL, actor);
 126
 127                if (length < 0) {
 128                        comp_opts = ERR_PTR(length);
 129                        goto out;
 130                }
 131        }
 132
 133        comp_opts = squashfs_comp_opts(msblk, buffer, length);
 134
 135out:
 136        kfree(actor);
 137        kfree(buffer);
 138        return comp_opts;
 139}
 140
 141
 142void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
 143{
 144        struct squashfs_sb_info *msblk = sb->s_fs_info;
 145        void *stream, *comp_opts = get_comp_opts(sb, flags);
 146
 147        if (IS_ERR(comp_opts))
 148                return comp_opts;
 149
 150        stream = squashfs_decompressor_create(msblk, comp_opts);
 151        if (IS_ERR(stream))
 152                kfree(comp_opts);
 153
 154        return stream;
 155}
 156