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 #ifndef CONFIG_SQUASHFS_ZSTD 69 static const struct squashfs_decompressor squashfs_zstd_comp_ops = { 70 NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0 71 }; 72 #endif 73 74 static const struct squashfs_decompressor squashfs_unknown_comp_ops = { 75 NULL, NULL, NULL, NULL, 0, "unknown", 0 76 }; 77 78 static 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 89 const 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 } 99 100 101 static 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); 134 135 out: 136 kfree(actor); 137 kfree(buffer); 138 return comp_opts; 139 } 140 141 142 void *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