[fault] Add inject_corruption() to randomly corrupt data
Provide an inject_corruption() function that can be used to randomly corrupt data bytes with configurable probabilities. Signed-off-by: Michael Brown <mcb30@ipxe.org>
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@ -51,3 +51,32 @@ int inject_fault_nonzero ( unsigned int rate ) {
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*/
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return -EFAULT;
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}
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/**
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* Corrupt data with a specified probability
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*
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* @v rate Reciprocal of fault probability (must be non-zero)
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* @v data Data
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* @v len Length of data
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* @ret rc Return status code
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*/
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void inject_corruption_nonzero ( unsigned int rate, const void *data,
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size_t len ) {
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uint8_t *writable;
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size_t offset;
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/* Do nothing if we have no data to corrupt */
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if ( ! len )
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return;
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/* Do nothing unless we want to inject a fault now */
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if ( ! inject_fault_nonzero ( rate ) )
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return;
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/* Get a writable pointer to the nominally read-only data */
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writable = ( ( uint8_t * ) data );
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/* Pick a random victim byte and zap it */
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offset = ( random() % len );
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writable[offset] ^= random();
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}
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@ -9,9 +9,12 @@
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <stdint.h>
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#include <config/fault.h>
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extern int inject_fault_nonzero ( unsigned int rate );
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extern void inject_corruption_nonzero ( unsigned int rate, const void *data,
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size_t len );
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/**
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* Inject fault with a specified probability
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@ -29,4 +32,22 @@ inject_fault ( unsigned int rate ) {
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return inject_fault_nonzero ( rate );
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}
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/**
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* Corrupt data with a specified probability
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*
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* @v rate Reciprocal of fault probability (zero for no faults)
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* @v data Data
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* @v len Length of data
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* @ret rc Return status code
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*/
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static inline __attribute__ (( always_inline )) void
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inject_corruption ( unsigned int rate, const void *data, size_t len ) {
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/* Force dead code elimination in non-fault-injecting builds */
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if ( rate == 0 )
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return;
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return inject_corruption_nonzero ( rate, data, len );
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}
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#endif /* _IPXE_FAULT_H */
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