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@lougher.demon.co.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 55static const struct squashfs_decompressor squashfs_unknown_comp_ops = { 56 NULL, NULL, NULL, 0, "unknown", 0 57}; 58 59static const struct squashfs_decompressor *decompressor[] = { 60 &squashfs_zlib_comp_ops, 61 &squashfs_lzo_comp_ops, 62 &squashfs_xz_comp_ops, 63 &squashfs_lzma_unsupported_comp_ops, 64 &squashfs_unknown_comp_ops 65}; 66 67 68const struct squashfs_decompressor *squashfs_lookup_decompressor(int id) 69{ 70 int i; 71 72 for (i = 0; decompressor[i]->id; i++) 73 if (id == decompressor[i]->id) 74 break; 75 76 return decompressor[i]; 77} 78 79 80void *squashfs_decompressor_init(struct super_block *sb, unsigned short flags) 81{ 82 struct squashfs_sb_info *msblk = sb->s_fs_info; 83 void *strm, *buffer = NULL; 84 int length = 0; 85 86 /* 87 * Read decompressor specific options from file system if present 88 */ 89 if (SQUASHFS_COMP_OPTS(flags)) { 90 buffer = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL); 91 if (buffer == NULL) 92 return ERR_PTR(-ENOMEM); 93 94 length = squashfs_read_data(sb, &buffer, 95 sizeof(struct squashfs_super_block), 0, NULL, 96 PAGE_CACHE_SIZE, 1); 97 98 if (length < 0) { 99 strm = ERR_PTR(length); 100 goto finished; 101 } 102 } 103 104 strm = msblk->decompressor->init(msblk, buffer, length); 105 106finished: 107 kfree(buffer); 108 109 return strm; 110} 111