/*
   * LZO decompressor for the Linux kernel. Code borrowed from the lzo
   * implementation by Markus Franz Xaver Johannes Oberhumer.
   *
   * Linux kernel adaptation:
   * Copyright (C) 2009
   * Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
   *
   * Original code:
   * Copyright (C) 1996-2005 Markus Franz Xaver Johannes Oberhumer
   * All Rights Reserved.
   *
   * lzop and the LZO library are free software; you can redistribute them
   * and/or modify them under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of
   * the License, 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; see the file COPYING.
   * If not, write to the Free Software Foundation, Inc.,
   * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   *
   * Markus F.X.J. Oberhumer
   * <markus@oberhumer.com>
   * http://www.oberhumer.com/opensource/lzop/
   */
  
  #ifdef STATIC
  #include "lzo/lzo1x_decompress.c"
  #else
  #include <linux/slab.h>
  #include <linux/decompress/unlzo.h>
  #endif
  
  #include <linux/types.h>
  #include <linux/lzo.h>
  #include <linux/decompress/mm.h>
  
  #include <linux/compiler.h>
  #include <asm/unaligned.h>
  
  static const unsigned char lzop_magic[] = {
  	0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a };
  
  #define LZO_BLOCK_SIZE        (256*1024l)
  #define HEADER_HAS_FILTER      0x00000800L
  
  STATIC inline int INIT parse_header(u8 *input, u8 *skip)
  {
  	int l;
  	u8 *parse = input;
  	u8 level = 0;
  	u16 version;
  
  	/* read magic: 9 first bits */
  	for (l = 0; l < 9; l++) {
  		if (*parse++ != lzop_magic[l])
  			return 0;
  	}
  	/* get version (2bytes), skip library version (2),
  	 * 'need to be extracted' version (2) and
  	 * method (1) */
  	version = get_unaligned_be16(parse);
  	parse += 7;
  	if (version >= 0x0940)
  		level = *parse++;
  	if (get_unaligned_be32(parse) & HEADER_HAS_FILTER)
  		parse += 8; /* flags + filter info */
  	else
  		parse += 4; /* flags */
  
  	/* skip mode and mtime_low */
  	parse += 8;
  	if (version >= 0x0940)
  		parse += 4;	/* skip mtime_high */
  
  	l = *parse++;
  	/* don't care about the file name, and skip checksum */
  	parse += l + 4;
  
  	*skip = parse - input;
  	return 1;
  }
  
  STATIC inline int INIT unlzo(u8 *input, int in_len,
  				int (*fill) (void *, unsigned int),
  				int (*flush) (void *, unsigned int),
  				u8 *output, int *posp,
  				void (*error_fn) (char *x))
  {
  	u8 skip = 0, r = 0;
  	u32 src_len, dst_len;
  	size_t tmp;
  	u8 *in_buf, *in_buf_save, *out_buf;

  	int ret = -1;

  
  	set_error_fn(error_fn);
  
  	if (output) {
  		out_buf = output;
  	} else if (!flush) {
  		error("NULL output pointer and no flush function provided");
  		goto exit;
  	} else {
  		out_buf = malloc(LZO_BLOCK_SIZE);
  		if (!out_buf) {
  			error("Could not allocate output buffer");
  			goto exit;
  		}
  	}
  
  	if (input && fill) {
  		error("Both input pointer and fill function provided, don't know what to do");
  		goto exit_1;
  	} else if (input) {
  		in_buf = input;
  	} else if (!fill || !posp) {
  		error("NULL input pointer and missing position pointer or fill function");
  		goto exit_1;
  	} else {
  		in_buf = malloc(lzo1x_worst_compress(LZO_BLOCK_SIZE));
  		if (!in_buf) {
  			error("Could not allocate input buffer");
  			goto exit_1;
  		}
  	}
  	in_buf_save = in_buf;
  
  	if (posp)
  		*posp = 0;
  
  	if (fill)
  		fill(in_buf, lzo1x_worst_compress(LZO_BLOCK_SIZE));
  
  	if (!parse_header(input, &skip)) {
  		error("invalid header");
  		goto exit_2;
  	}
  	in_buf += skip;
  
  	if (posp)
  		*posp = skip;
  
  	for (;;) {
  		/* read uncompressed block size */
  		dst_len = get_unaligned_be32(in_buf);
  		in_buf += 4;
  
  		/* exit if last block */
  		if (dst_len == 0) {
  			if (posp)
  				*posp += 4;
  			break;
  		}
  
  		if (dst_len > LZO_BLOCK_SIZE) {
  			error("dest len longer than block size");
  			goto exit_2;
  		}
  
  		/* read compressed block size, and skip block checksum info */
  		src_len = get_unaligned_be32(in_buf);
  		in_buf += 8;
  
  		if (src_len <= 0 || src_len > dst_len) {
  			error("file corrupted");
  			goto exit_2;
  		}
  
  		/* decompress */
  		tmp = dst_len;

  
  		/* When the input data is not compressed at all,
  		 * lzo1x_decompress_safe will fail, so call memcpy()
  		 * instead */
  		if (unlikely(dst_len == src_len))
  			memcpy(out_buf, in_buf, src_len);
  		else {
  			r = lzo1x_decompress_safe((u8 *) in_buf, src_len,

  						out_buf, &tmp);

  			if (r != LZO_E_OK || dst_len != tmp) {
  				error("Compressed data violation");
  				goto exit_2;
  			}

  		}

  		if (flush)
  			flush(out_buf, dst_len);
  		if (output)
  			out_buf += dst_len;
  		if (posp)
  			*posp += src_len + 12;
  		if (fill) {
  			in_buf = in_buf_save;
  			fill(in_buf, lzo1x_worst_compress(LZO_BLOCK_SIZE));
  		} else
  			in_buf += src_len;
  	}

  	ret = 0;

  exit_2:
  	if (!input)
  		free(in_buf);
  exit_1:
  	if (!output)
  		free(out_buf);
  exit:

  	return ret;

  }
  
  #define decompress unlzo