/*
   * Squashfs - a compressed read only filesystem for Linux
   *
   * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
   * Phillip Lougher <phillip@squashfs.org.uk>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version 2,
   * or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
   *
   * decompressor.c
   */
  
  #include <linux/types.h>
  #include <linux/mutex.h>
  #include <linux/slab.h>
  #include <linux/buffer_head.h>
  
  #include "squashfs_fs.h"
  #include "squashfs_fs_sb.h"
  #include "decompressor.h"
  #include "squashfs.h"
  #include "page_actor.h"
  
  /*
   * This file (and decompressor.h) implements a decompressor framework for
   * Squashfs, allowing multiple decompressors to be easily supported
   */
  
  static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
  	NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
  };
  
  #ifndef CONFIG_SQUASHFS_LZO
  static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
  	NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
  };
  #endif
  
  #ifndef CONFIG_SQUASHFS_XZ
  static const struct squashfs_decompressor squashfs_xz_comp_ops = {
  	NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
  };
  #endif
  
  #ifndef CONFIG_SQUASHFS_ZLIB
  static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
  	NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
  };
  #endif
  
  static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
  	NULL, NULL, NULL, NULL, 0, "unknown", 0
  };
  
  static const struct squashfs_decompressor *decompressor[] = {
  	&squashfs_zlib_comp_ops,
  	&squashfs_lzo_comp_ops,
  	&squashfs_xz_comp_ops,
  	&squashfs_lzma_unsupported_comp_ops,
  	&squashfs_unknown_comp_ops
  };
  
  
  const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
  {
  	int i;
  
  	for (i = 0; decompressor[i]->id; i++)
  		if (id == decompressor[i]->id)
  			break;
  
  	return decompressor[i];
  }
  
  
  static void *get_comp_opts(struct super_block *sb, unsigned short flags)
  {
  	struct squashfs_sb_info *msblk = sb->s_fs_info;
  	void *buffer = NULL, *comp_opts;
  	struct squashfs_page_actor *actor = NULL;
  	int length = 0;
  
  	/*
  	 * Read decompressor specific options from file system if present
  	 */
  	if (SQUASHFS_COMP_OPTS(flags)) {
  		buffer = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
  		if (buffer == NULL) {
  			comp_opts = ERR_PTR(-ENOMEM);
  			goto out;
  		}
  
  		actor = squashfs_page_actor_init(&buffer, 1, 0);
  		if (actor == NULL) {
  			comp_opts = ERR_PTR(-ENOMEM);
  			goto out;
  		}
  
  		length = squashfs_read_data(sb,
  			sizeof(struct squashfs_super_block), 0, NULL, actor);
  
  		if (length < 0) {
  			comp_opts = ERR_PTR(length);
  			goto out;
  		}
  	}
  
  	comp_opts = squashfs_comp_opts(msblk, buffer, length);
  
  out:
  	kfree(actor);
  	kfree(buffer);
  	return comp_opts;
  }
  
  
  void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
  {
  	struct squashfs_sb_info *msblk = sb->s_fs_info;
  	void *stream, *comp_opts = get_comp_opts(sb, flags);
  
  	if (IS_ERR(comp_opts))
  		return comp_opts;
  
  	stream = squashfs_decompressor_create(msblk, comp_opts);
  	if (IS_ERR(stream))
  		kfree(comp_opts);
  
  	return stream;
  }