/*
   * Squashfs - a compressed read only filesystem for Linux
   *
   * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
   * Phillip Lougher <phillip@lougher.demon.co.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.
   *
   * zlib_wrapper.c
   */
  
  
  #include <linux/mutex.h>
  #include <linux/buffer_head.h>

  #include <linux/slab.h>

  #include <linux/zlib.h>
  
  #include "squashfs_fs.h"
  #include "squashfs_fs_sb.h"
  #include "squashfs_fs_i.h"
  #include "squashfs.h"

  #include "decompressor.h"

  static void *zlib_init(struct squashfs_sb_info *dummy)

  {
  	z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
  	if (stream == NULL)
  		goto failed;
  	stream->workspace = kmalloc(zlib_inflate_workspacesize(),
  		GFP_KERNEL);
  	if (stream->workspace == NULL)
  		goto failed;
  
  	return stream;
  
  failed:
  	ERROR("Failed to allocate zlib workspace
  ");
  	kfree(stream);
  	return NULL;
  }

  static void zlib_free(void *strm)

  {
  	z_stream *stream = strm;
  
  	if (stream)
  		kfree(stream->workspace);
  	kfree(stream);
  }

  static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,

  	struct buffer_head **bh, int b, int offset, int length, int srclength,
  	int pages)
  {
  	int zlib_err = 0, zlib_init = 0;
  	int avail, bytes, k = 0, page = 0;

  	z_stream *stream = msblk->stream;

  
  	mutex_lock(&msblk->read_data_mutex);

  	stream->avail_out = 0;
  	stream->avail_in = 0;

  
  	bytes = length;
  	do {

  		if (stream->avail_in == 0 && k < b) {

  			avail = min(bytes, msblk->devblksize - offset);
  			bytes -= avail;
  			wait_on_buffer(bh[k]);
  			if (!buffer_uptodate(bh[k]))
  				goto release_mutex;
  
  			if (avail == 0) {
  				offset = 0;
  				put_bh(bh[k++]);
  				continue;
  			}

  			stream->next_in = bh[k]->b_data + offset;
  			stream->avail_in = avail;

  			offset = 0;
  		}

  		if (stream->avail_out == 0 && page < pages) {
  			stream->next_out = buffer[page++];
  			stream->avail_out = PAGE_CACHE_SIZE;

  		}
  
  		if (!zlib_init) {

  			zlib_err = zlib_inflateInit(stream);

  			if (zlib_err != Z_OK) {
  				ERROR("zlib_inflateInit returned unexpected "
  					"result 0x%x, srclength %d
  ",
  					zlib_err, srclength);
  				goto release_mutex;
  			}
  			zlib_init = 1;
  		}

  		zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);

  		if (stream->avail_in == 0 && k < b)

  			put_bh(bh[k++]);
  	} while (zlib_err == Z_OK);
  
  	if (zlib_err != Z_STREAM_END) {
  		ERROR("zlib_inflate error, data probably corrupt
  ");
  		goto release_mutex;
  	}

  	zlib_err = zlib_inflateEnd(stream);

  	if (zlib_err != Z_OK) {
  		ERROR("zlib_inflate error, data probably corrupt
  ");
  		goto release_mutex;
  	}

  	length = stream->total_out;

  	mutex_unlock(&msblk->read_data_mutex);

  	return length;

  
  release_mutex:
  	mutex_unlock(&msblk->read_data_mutex);
  
  	for (; k < b; k++)
  		put_bh(bh[k]);
  
  	return -EIO;
  }

  
  const struct squashfs_decompressor squashfs_zlib_comp_ops = {
  	.init = zlib_init,
  	.free = zlib_free,
  	.decompress = zlib_uncompress,
  	.id = ZLIB_COMPRESSION,
  	.name = "zlib",
  	.supported = 1
  };