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 40 static 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 45 static 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 51 static 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 57 static 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 63 static const struct squashfs_decompressor squashfs_zlib_comp_ops = { 64 NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0 65 }; 66 #endif 67 68 static const struct squashfs_decompressor squashfs_unknown_comp_ops = { 69 NULL, NULL, NULL, NULL, 0, "unknown", 0 70 }; 71 72 static 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 82 const 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 94 static 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); 127 128 out: 129 kfree(actor); 130 kfree(buffer); 131 return comp_opts; 132 } 133 134 135 void *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