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_LZO 45 static const struct squashfs_decompressor squashfs_lzo_comp_ops = { 46 NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0 47 }; 48 #endif 49 50 #ifndef CONFIG_SQUASHFS_XZ 51 static const struct squashfs_decompressor squashfs_xz_comp_ops = { 52 NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0 53 }; 54 #endif 55 56 #ifndef CONFIG_SQUASHFS_ZLIB 57 static const struct squashfs_decompressor squashfs_zlib_comp_ops = { 58 NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0 59 }; 60 #endif 61 62 static const struct squashfs_decompressor squashfs_unknown_comp_ops = { 63 NULL, NULL, NULL, NULL, 0, "unknown", 0 64 }; 65 66 static const struct squashfs_decompressor *decompressor[] = { 67 &squashfs_zlib_comp_ops, 68 &squashfs_lzo_comp_ops, 69 &squashfs_xz_comp_ops, 70 &squashfs_lzma_unsupported_comp_ops, 71 &squashfs_unknown_comp_ops 72 }; 73 74 75 const struct squashfs_decompressor *squashfs_lookup_decompressor(int id) 76 { 77 int i; 78 79 for (i = 0; decompressor[i]->id; i++) 80 if (id == decompressor[i]->id) 81 break; 82 83 return decompressor[i]; 84 } 85 86 87 static void *get_comp_opts(struct super_block *sb, unsigned short flags) 88 { 89 struct squashfs_sb_info *msblk = sb->s_fs_info; 90 void *buffer = NULL, *comp_opts; 91 struct squashfs_page_actor *actor = NULL; 92 int length = 0; 93 94 /* 95 * Read decompressor specific options from file system if present 96 */ 97 if (SQUASHFS_COMP_OPTS(flags)) { 98 buffer = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL); 99 if (buffer == NULL) { 100 comp_opts = ERR_PTR(-ENOMEM); 101 goto out; 102 } 103 104 actor = squashfs_page_actor_init(&buffer, 1, 0); 105 if (actor == NULL) { 106 comp_opts = ERR_PTR(-ENOMEM); 107 goto out; 108 } 109 110 length = squashfs_read_data(sb, 111 sizeof(struct squashfs_super_block), 0, NULL, actor); 112 113 if (length < 0) { 114 comp_opts = ERR_PTR(length); 115 goto out; 116 } 117 } 118 119 comp_opts = squashfs_comp_opts(msblk, buffer, length); 120 121 out: 122 kfree(actor); 123 kfree(buffer); 124 return comp_opts; 125 } 126 127 128 void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags) 129 { 130 struct squashfs_sb_info *msblk = sb->s_fs_info; 131 void *stream, *comp_opts = get_comp_opts(sb, flags); 132 133 if (IS_ERR(comp_opts)) 134 return comp_opts; 135 136 stream = squashfs_decompressor_create(msblk, comp_opts); 137 if (IS_ERR(stream)) 138 kfree(comp_opts); 139 140 return stream; 141 } 142