linux/fs/squashfs/decompressor.c
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   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
  34/*
  35 * This file (and decompressor.h) implements a decompressor framework for
  36 * Squashfs, allowing multiple decompressors to be easily supported
  37 */
  38
  39static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
  40        NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
  41};
  42
  43#ifndef CONFIG_SQUASHFS_LZO
  44static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
  45        NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
  46};
  47#endif
  48
  49#ifndef CONFIG_SQUASHFS_XZ
  50static const struct squashfs_decompressor squashfs_xz_comp_ops = {
  51        NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
  52};
  53#endif
  54
  55#ifndef CONFIG_SQUASHFS_ZLIB
  56static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
  57        NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
  58};
  59#endif
  60
  61static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
  62        NULL, NULL, NULL, 0, "unknown", 0
  63};
  64
  65static const struct squashfs_decompressor *decompressor[] = {
  66        &squashfs_zlib_comp_ops,
  67        &squashfs_lzo_comp_ops,
  68        &squashfs_xz_comp_ops,
  69        &squashfs_lzma_unsupported_comp_ops,
  70        &squashfs_unknown_comp_ops
  71};
  72
  73
  74const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
  75{
  76        int i;
  77
  78        for (i = 0; decompressor[i]->id; i++)
  79                if (id == decompressor[i]->id)
  80                        break;
  81
  82        return decompressor[i];
  83}
  84
  85
  86void *squashfs_decompressor_init(struct super_block *sb, unsigned short flags)
  87{
  88        struct squashfs_sb_info *msblk = sb->s_fs_info;
  89        void *strm, *buffer = NULL;
  90        int length = 0;
  91
  92        /*
  93         * Read decompressor specific options from file system if present
  94         */
  95        if (SQUASHFS_COMP_OPTS(flags)) {
  96                buffer = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
  97                if (buffer == NULL)
  98                        return ERR_PTR(-ENOMEM);
  99
 100                length = squashfs_read_data(sb, &buffer,
 101                        sizeof(struct squashfs_super_block), 0, NULL,
 102                        PAGE_CACHE_SIZE, 1);
 103
 104                if (length < 0) {
 105                        strm = ERR_PTR(length);
 106                        goto finished;
 107                }
 108        }
 109
 110        strm = msblk->decompressor->init(msblk, buffer, length);
 111
 112finished:
 113        kfree(buffer);
 114
 115        return strm;
 116}
 117
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