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 39 static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = { 40 NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0 41 }; 42 43 #ifndef CONFIG_SQUASHFS_LZO 44 static 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 50 static 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 56 static const struct squashfs_decompressor squashfs_zlib_comp_ops = { 57 NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0 58 }; 59 #endif 60 61 static const struct squashfs_decompressor squashfs_unknown_comp_ops = { 62 NULL, NULL, NULL, 0, "unknown", 0 63 }; 64 65 static 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 74 const 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 86 void *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); 111 112 finished: 113 kfree(buffer); 114 115 return strm; 116 } 117