/*
   * This file is part of UBIFS.
   *
   * Copyright (C) 2006-2008 Nokia Corporation.
   * Copyright (C) 2006, 2007 University of Szeged, Hungary
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   *
   * 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, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
   *
   * Authors: Adrian Hunter
   *          Artem Bityutskiy (Битюцкий Артём)
   *          Zoltan Sogor
   */
  
  /*
   * This file provides a single place to access to compression and
   * decompression.
   */
  
  #include <linux/crypto.h>
  #include "ubifs.h"
  
  /* Fake description object for the "none" compressor */
  static struct ubifs_compressor none_compr = {
  	.compr_type = UBIFS_COMPR_NONE,

  	.name = "none",

  	.capi_name = "",
  };
  
  #ifdef CONFIG_UBIFS_FS_LZO
  static DEFINE_MUTEX(lzo_mutex);
  
  static struct ubifs_compressor lzo_compr = {
  	.compr_type = UBIFS_COMPR_LZO,
  	.comp_mutex = &lzo_mutex,

  	.name = "lzo",

  	.capi_name = "lzo",
  };
  #else
  static struct ubifs_compressor lzo_compr = {
  	.compr_type = UBIFS_COMPR_LZO,

  	.name = "lzo",

  };
  #endif
  
  #ifdef CONFIG_UBIFS_FS_ZLIB
  static DEFINE_MUTEX(deflate_mutex);
  static DEFINE_MUTEX(inflate_mutex);
  
  static struct ubifs_compressor zlib_compr = {
  	.compr_type = UBIFS_COMPR_ZLIB,
  	.comp_mutex = &deflate_mutex,
  	.decomp_mutex = &inflate_mutex,
  	.name = "zlib",
  	.capi_name = "deflate",
  };
  #else
  static struct ubifs_compressor zlib_compr = {
  	.compr_type = UBIFS_COMPR_ZLIB,
  	.name = "zlib",
  };
  #endif
  
  /* All UBIFS compressors */
  struct ubifs_compressor *ubifs_compressors[UBIFS_COMPR_TYPES_CNT];
  
  /**
   * ubifs_compress - compress data.
   * @in_buf: data to compress
   * @in_len: length of the data to compress
   * @out_buf: output buffer where compressed data should be stored
   * @out_len: output buffer length is returned here
   * @compr_type: type of compression to use on enter, actually used compression
   *              type on exit
   *
   * This function compresses input buffer @in_buf of length @in_len and stores
   * the result in the output buffer @out_buf and the resulting length in
   * @out_len. If the input buffer does not compress, it is just copied to the
   * @out_buf. The same happens if @compr_type is %UBIFS_COMPR_NONE or if
   * compression error occurred.
   *
   * Note, if the input buffer was not compressed, it is copied to the output
   * buffer and %UBIFS_COMPR_NONE is returned in @compr_type.

   */
  void ubifs_compress(const void *in_buf, int in_len, void *out_buf, int *out_len,
  		    int *compr_type)
  {
  	int err;
  	struct ubifs_compressor *compr = ubifs_compressors[*compr_type];
  
  	if (*compr_type == UBIFS_COMPR_NONE)
  		goto no_compr;
  
  	/* If the input data is small, do not even try to compress it */
  	if (in_len < UBIFS_MIN_COMPR_LEN)
  		goto no_compr;
  
  	if (compr->comp_mutex)
  		mutex_lock(compr->comp_mutex);
  	err = crypto_comp_compress(compr->cc, in_buf, in_len, out_buf,

  				   (unsigned int *)out_len);

  	if (compr->comp_mutex)
  		mutex_unlock(compr->comp_mutex);
  	if (unlikely(err)) {
  		ubifs_warn("cannot compress %d bytes, compressor %s, "
  			   "error %d, leave data uncompressed",
  			   in_len, compr->name, err);
  		 goto no_compr;
  	}
  
  	/*

  	 * If the data compressed only slightly, it is better to leave it
  	 * uncompressed to improve read speed.

  	 */

  	if (in_len - *out_len < UBIFS_MIN_COMPRESS_DIFF)

  		goto no_compr;
  
  	return;
  
  no_compr:
  	memcpy(out_buf, in_buf, in_len);
  	*out_len = in_len;
  	*compr_type = UBIFS_COMPR_NONE;
  }
  
  /**
   * ubifs_decompress - decompress data.
   * @in_buf: data to decompress
   * @in_len: length of the data to decompress
   * @out_buf: output buffer where decompressed data should
   * @out_len: output length is returned here
   * @compr_type: type of compression
   *
   * This function decompresses data from buffer @in_buf into buffer @out_buf.
   * The length of the uncompressed data is returned in @out_len. This functions
   * returns %0 on success or a negative error code on failure.
   */
  int ubifs_decompress(const void *in_buf, int in_len, void *out_buf,
  		     int *out_len, int compr_type)
  {
  	int err;
  	struct ubifs_compressor *compr;
  
  	if (unlikely(compr_type < 0 || compr_type >= UBIFS_COMPR_TYPES_CNT)) {
  		ubifs_err("invalid compression type %d", compr_type);
  		return -EINVAL;
  	}
  
  	compr = ubifs_compressors[compr_type];
  
  	if (unlikely(!compr->capi_name)) {
  		ubifs_err("%s compression is not compiled in", compr->name);
  		return -EINVAL;
  	}
  
  	if (compr_type == UBIFS_COMPR_NONE) {
  		memcpy(out_buf, in_buf, in_len);
  		*out_len = in_len;
  		return 0;
  	}
  
  	if (compr->decomp_mutex)
  		mutex_lock(compr->decomp_mutex);
  	err = crypto_comp_decompress(compr->cc, in_buf, in_len, out_buf,

  				     (unsigned int *)out_len);

  	if (compr->decomp_mutex)
  		mutex_unlock(compr->decomp_mutex);
  	if (err)
  		ubifs_err("cannot decompress %d bytes, compressor %s, "
  			  "error %d", in_len, compr->name, err);
  
  	return err;
  }
  
  /**
   * compr_init - initialize a compressor.
   * @compr: compressor description object
   *
   * This function initializes the requested compressor and returns zero in case
   * of success or a negative error code in case of failure.
   */
  static int __init compr_init(struct ubifs_compressor *compr)
  {
  	if (compr->capi_name) {
  		compr->cc = crypto_alloc_comp(compr->capi_name, 0, 0);
  		if (IS_ERR(compr->cc)) {
  			ubifs_err("cannot initialize compressor %s, error %ld",
  				  compr->name, PTR_ERR(compr->cc));
  			return PTR_ERR(compr->cc);
  		}
  	}
  
  	ubifs_compressors[compr->compr_type] = compr;
  	return 0;
  }
  
  /**
   * compr_exit - de-initialize a compressor.
   * @compr: compressor description object
   */
  static void compr_exit(struct ubifs_compressor *compr)
  {
  	if (compr->capi_name)
  		crypto_free_comp(compr->cc);
  	return;
  }
  
  /**
   * ubifs_compressors_init - initialize UBIFS compressors.
   *
   * This function initializes the compressor which were compiled in. Returns
   * zero in case of success and a negative error code in case of failure.
   */
  int __init ubifs_compressors_init(void)
  {
  	int err;
  
  	err = compr_init(&lzo_compr);
  	if (err)
  		return err;
  
  	err = compr_init(&zlib_compr);
  	if (err)
  		goto out_lzo;
  
  	ubifs_compressors[UBIFS_COMPR_NONE] = &none_compr;
  	return 0;
  
  out_lzo:
  	compr_exit(&lzo_compr);
  	return err;
  }
  
  /**
   * ubifs_compressors_exit - de-initialize UBIFS compressors.
   */

  void ubifs_compressors_exit(void)

  {
  	compr_exit(&lzo_compr);
  	compr_exit(&zlib_compr);
  }