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ewf_crc.c
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ewf_crc.c
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/*
* EWF CRC handling
*
* Copyright (c) 2006-2007, Joachim Metz <forensics@hoffmannbv.nl>,
* Hoffmann Investigations. All rights reserved.
*
* Refer to AUTHORS for acknowledgements.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of the creator, related organisations, nor the names of
* its contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
* - All advertising materials mentioning features or use of this software
* must acknowledge the contribution by people stated in the acknowledgements.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER, COMPANY AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "libewf_includes.h"
#if defined( HAVE_ZLIB_H ) && defined( HAVE_LIBZ )
#include <zlib.h>
#endif
#include "libewf_common.h"
#include "libewf_endian.h"
#include "libewf_notify.h"
#include "ewf_crc.h"
/* Reads the CRC from a file descriptor
* Returns the amount of bytes read if successful, or -1 on error
*/
ssize_t ewf_crc_read( EWF_CRC *crc, int file_descriptor )
{
uint8_t buffer[ 4 ];
ssize_t count = 0;
size_t size = EWF_CRC_SIZE;
if( crc == NULL )
{
LIBEWF_WARNING_PRINT( "ewf_crc_read: invalid CRC.\n" );
return( -1 );
}
count = libewf_common_read( file_descriptor, buffer, size );
if( count < (ssize_t) size )
{
LIBEWF_WARNING_PRINT( "ewf_crc_read: unable to read CRC.\n" );
return( -1 );
}
if( libewf_endian_convert_32bit( crc, buffer ) != 1 )
{
LIBEWF_WARNING_PRINT( "ewf_crc_read: unable to convert CRC value.\n" );
return( -1 );
}
return( count );
}
/* Writes the CRC to a file descriptor
* Returns the amount of bytes written, or -1 on error
*/
ssize_t ewf_crc_write( EWF_CRC *crc, int file_descriptor )
{
uint8_t buffer[ 4 ];
ssize_t count = 0;
size_t size = EWF_CRC_SIZE;
if( crc == NULL )
{
LIBEWF_WARNING_PRINT( "ewf_crc_write: invalid CRC.\n" );
return( -1 );
}
if( libewf_endian_revert_32bit( *crc, buffer ) != 1 )
{
LIBEWF_WARNING_PRINT( "ewf_crc_write: unable to revert CRC value.\n" );
return( -1 );
}
count = libewf_common_write( file_descriptor, buffer, size );
if( count < (ssize_t) size )
{
LIBEWF_WARNING_PRINT( "ewf_crc_write: error writing CRC.\n" );
return( -1 );
}
return( count );
}
/* Calculates the EWF CRC
* When calling this function to start a new CRC "previous_key" should be 1
* Returns 1 if calculation is successful, or -1 on error
*
* The original algorithm was taken from the ASR data web site
*/
int8_t ewf_crc_calculate( EWF_CRC *crc, uint8_t *buffer, size_t size, uint32_t previous_key )
{
if( crc == NULL )
{
LIBEWF_WARNING_PRINT( "ewf_crc_calculate: invalid CRC.\n" );
return( -1 );
}
if( buffer == NULL )
{
LIBEWF_WARNING_PRINT( "ewf_crc_calculate: invalid buffer.\n" );
return( -1 );
}
if( size > (size_t) SSIZE_MAX )
{
LIBEWF_WARNING_PRINT( "ewf_crc_calculate: invalid size value exceeds maximum.\n" );
return( -1 );
}
*crc = (EWF_CRC) adler32( (uLong) previous_key, (const Bytef *) buffer, (uInt) size );
return( 1 );
}

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