fs/squashfs/decompressor.c

   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 }