ClabureDB: Classified Bug-Reports Database

  /*
   * 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 = "no compression",
         .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,
                                   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;
        }

        /*
         * Presently, we just require that compression results in less data,
         * rather than any defined minimum compression ratio or amount.
         */
        if (ALIGN(*out_len, 8) >= ALIGN(in_len, 8))
                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,
                                     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 __exit ubifs_compressors_exit(void)
{
        compr_exit(&lzo_compr);
        compr_exit(&zlib_compr);
}