Page MenuHomePhabricator
Files F4823527

libewf_empty_block.c
No OneTemporary
Actions

Size
3 KB
Referenced Files
None
Subscribers
None

libewf_empty_block.c
View Options

/*
* Empty block test functions
*
* Copyright (c) 2006-2011, Joachim Metz <jbmetz@users.sourceforge.net>
*
* Refer to AUTHORS for acknowledgements.
*
* This software is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This software 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 Lesser General Public License
* along with this software. If not, see <http://www.gnu.org/licenses/>.
*/
#include <common.h>
#include <types.h>
#include <liberror.h>
#include "libewf_empty_block.h"
/* The largest primary (or scalar) available
* supported by a single load and store instruction
*/
typedef unsigned long int libewf_aligned_t;
/* Check for empty block
* An emtpy block is a block that contains the same value for every byte
* Returns 1 if block is empty, 0 if not or -1 on error
*/
int libewf_empty_block_test(
const uint8_t *block_buffer,
size_t block_size,
liberror_error_t **error )
{
libewf_aligned_t *aligned_block_iterator = NULL;
libewf_aligned_t *aligned_block_start = NULL;
uint8_t *block_iterator = NULL;
uint8_t *block_start = NULL;
static char *function = "libewf_empty_block_test";
if( block_buffer == NULL )
{
liberror_error_set(
error,
LIBERROR_ERROR_DOMAIN_ARGUMENTS,
LIBERROR_ARGUMENT_ERROR_INVALID_VALUE,
"%s: invalid block buffer.",
function );
return( -1 );
}
if( block_size > (size_t) SSIZE_MAX )
{
liberror_error_set(
error,
LIBERROR_ERROR_DOMAIN_ARGUMENTS,
LIBERROR_ARGUMENT_ERROR_VALUE_EXCEEDS_MAXIMUM,
"%s: invalid block size value exceeds maximum.",
function );
return( -1 );
}
block_start = (uint8_t *) block_buffer;
block_iterator = (uint8_t *) block_buffer + 1;
block_size -= 1;
/* Only optimize for blocks larger than the alignment
*/
if( block_size > ( 2 * sizeof( libewf_aligned_t ) ) )
{
/* Align the block start
*/
while( ( (intptr_t) block_start % sizeof( libewf_aligned_t ) ) != 0 )
{
if( *block_start != *block_iterator )
{
return( 0 );
}
block_start += 1;
block_iterator += 1;
block_size -= 1;
}
/* Align the block iterator
*/
while( ( (intptr_t) block_iterator % sizeof( libewf_aligned_t ) ) != 0 )
{
if( *block_start != *block_iterator )
{
return( 0 );
}
block_iterator += 1;
block_size -= 1;
}
aligned_block_start = (libewf_aligned_t *) block_start;
aligned_block_iterator = (libewf_aligned_t *) block_iterator;
while( block_size > sizeof( libewf_aligned_t ) )
{
if( *aligned_block_start != *aligned_block_iterator )
{
return( 0 );
}
aligned_block_iterator += 1;
block_size -= sizeof( libewf_aligned_t );
}
block_iterator = (uint8_t *) aligned_block_iterator;
}
while( block_size != 0 )
{
if( *block_start != *block_iterator )
{
return( 0 );
}
block_iterator += 1;
block_size -= 1;
}
return( 1 );
}

File Metadata

Mime Type
text/x-c
Expires
Sun, May 11, 5:22 AM (1 d, 5 h)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
1247617
Default Alt Text
libewf_empty_block.c (3 KB)

Event Timeline