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/*
* Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it 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; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdlib.h>
#include <errno.h>
#include <ipxe/fault.h>
/** @file
*
* Fault injection
*
*/
/**
* Inject fault with a specified probability
*
* @v rate Reciprocal of fault probability (must be non-zero)
* @ret rc Return status code
*/
int inject_fault_nonzero ( unsigned int rate ) {
/* Do nothing unless we want to inject a fault now */
if ( ( random() % rate ) != 0 )
return 0;
/* Generate error number here so that faults can be injected
* into files that don't themselves have error file
* identifiers (via errfile.h).
*/
return -EFAULT;
}
/**
* Corrupt data with a specified probability
*
* @v rate Reciprocal of fault probability (must be non-zero)
* @v data Data
* @v len Length of data
* @ret rc Return status code
*/
void inject_corruption_nonzero ( unsigned int rate, const void *data,
size_t len ) {
uint8_t *writable;
size_t offset;
/* Do nothing if we have no data to corrupt */
if ( ! len )
return;
/* Do nothing unless we want to inject a fault now */
if ( ! inject_fault_nonzero ( rate ) )
return;
/* Get a writable pointer to the nominally read-only data */
writable = ( ( uint8_t * ) data );
/* Pick a random victim byte and zap it */
offset = ( random() % len );
writable[offset] ^= random();
}
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