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@lougher.demon.co.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/buffer_head.h>
  27
  28 #include "squashfs_fs.h"
  29 #include "squashfs_fs_sb.h"
  30 #include "squashfs_fs_i.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_unsupported_comp_ops = {
  45         NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
  46 };
  47 #endif
  48
  49 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
  50         NULL, NULL, NULL, 0, "unknown", 0
  51 };
  52
  53 static const struct squashfs_decompressor *decompressor[] = {
  54         &squashfs_zlib_comp_ops,
  55         &squashfs_lzma_unsupported_comp_ops,
  56 #ifdef CONFIG_SQUASHFS_LZO
  57         &squashfs_lzo_comp_ops,
  58 #else
  59         &squashfs_lzo_unsupported_comp_ops,
  60 #endif
  61         &squashfs_unknown_comp_ops
  62 };
  63
  64
  65 const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
  66 {
  67         int i;
  68
  69         for (i = 0; decompressor[i]->id; i++)
  70                 if (id == decompressor[i]->id)
  71                         break;
  72
  73         return decompressor[i];
  74 }