/*
   * Squashfs - a compressed read only filesystem for Linux
   *
   * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010

   * 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.
   *
   * xz_wrapper.c
   */
  
  
  #include <linux/mutex.h>
  #include <linux/buffer_head.h>
  #include <linux/slab.h>
  #include <linux/xz.h>

  #include <linux/bitops.h>

  
  #include "squashfs_fs.h"
  #include "squashfs_fs_sb.h"

  #include "squashfs.h"
  #include "decompressor.h"
  
  struct squashfs_xz {
  	struct xz_dec *state;
  	struct xz_buf buf;
  };

  struct comp_opts {
  	__le32 dictionary_size;
  	__le32 flags;
  };

  static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff,
  	int len)

  {

  	struct comp_opts *comp_opts = buff;
  	struct squashfs_xz *stream;
  	int dict_size = msblk->block_size;
  	int err, n;
  
  	if (comp_opts) {
  		/* check compressor options are the expected length */
  		if (len < sizeof(*comp_opts)) {
  			err = -EIO;
  			goto failed;
  		}
  
  		dict_size = le32_to_cpu(comp_opts->dictionary_size);
  
  		/* the dictionary size should be 2^n or 2^n+2^(n+1) */
  		n = ffs(dict_size) - 1;
  		if (dict_size != (1 << n) && dict_size != (1 << n) +
  						(1 << (n + 1))) {
  			err = -EIO;
  			goto failed;
  		}
  	}
  
  	dict_size = max_t(int, dict_size, SQUASHFS_METADATA_SIZE);

  	stream = kmalloc(sizeof(*stream), GFP_KERNEL);
  	if (stream == NULL) {
  		err = -ENOMEM;

  		goto failed;

  	}

  	stream->state = xz_dec_init(XZ_PREALLOC, dict_size);
  	if (stream->state == NULL) {
  		kfree(stream);
  		err = -ENOMEM;

  		goto failed;

  	}

  
  	return stream;
  
  failed:

  	ERROR("Failed to initialise xz decompressor
  ");
  	return ERR_PTR(err);

  }
  
  
  static void squashfs_xz_free(void *strm)
  {
  	struct squashfs_xz *stream = strm;
  
  	if (stream) {
  		xz_dec_end(stream->state);
  		kfree(stream);
  	}
  }
  
  
  static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
  	struct buffer_head **bh, int b, int offset, int length, int srclength,
  	int pages)
  {
  	enum xz_ret xz_err;
  	int avail, total = 0, k = 0, page = 0;
  	struct squashfs_xz *stream = msblk->stream;
  
  	mutex_lock(&msblk->read_data_mutex);
  
  	xz_dec_reset(stream->state);
  	stream->buf.in_pos = 0;
  	stream->buf.in_size = 0;
  	stream->buf.out_pos = 0;
  	stream->buf.out_size = PAGE_CACHE_SIZE;
  	stream->buf.out = buffer[page++];
  
  	do {
  		if (stream->buf.in_pos == stream->buf.in_size && k < b) {
  			avail = min(length, msblk->devblksize - offset);
  			length -= avail;
  			wait_on_buffer(bh[k]);
  			if (!buffer_uptodate(bh[k]))
  				goto release_mutex;

  			stream->buf.in = bh[k]->b_data + offset;
  			stream->buf.in_size = avail;
  			stream->buf.in_pos = 0;
  			offset = 0;
  		}
  
  		if (stream->buf.out_pos == stream->buf.out_size
  							&& page < pages) {
  			stream->buf.out = buffer[page++];
  			stream->buf.out_pos = 0;
  			total += PAGE_CACHE_SIZE;
  		}
  
  		xz_err = xz_dec_run(stream->state, &stream->buf);
  
  		if (stream->buf.in_pos == stream->buf.in_size && k < b)
  			put_bh(bh[k++]);
  	} while (xz_err == XZ_OK);
  
  	if (xz_err != XZ_STREAM_END) {
  		ERROR("xz_dec_run error, data probably corrupt
  ");
  		goto release_mutex;
  	}
  
  	if (k < b) {
  		ERROR("xz_uncompress error, input remaining
  ");
  		goto release_mutex;
  	}
  
  	total += stream->buf.out_pos;
  	mutex_unlock(&msblk->read_data_mutex);
  	return total;
  
  release_mutex:
  	mutex_unlock(&msblk->read_data_mutex);
  
  	for (; k < b; k++)
  		put_bh(bh[k]);
  
  	return -EIO;
  }
  
  const struct squashfs_decompressor squashfs_xz_comp_ops = {
  	.init = squashfs_xz_init,
  	.free = squashfs_xz_free,
  	.decompress = squashfs_xz_uncompress,
  	.id = XZ_COMPRESSION,
  	.name = "xz",
  	.supported = 1
  };