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Check that integer types don't use padding bits in selftest

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This commit modifies programs/test/selftest to include a check that
none of the standard integer types (unsigned) [short, int, long, long]
uses padding bits, which we currently don't support.

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Hanno Becker 2018-10-16 13:22:44 +01:00 committed by Dave Rodgman
parent a91b68564c
commit 4ab3850605
1 changed files with 60 additions and 0 deletions
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60
programs/test/selftest.c
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@ -50,6 +50,7 @@
#include "mbedtls/timing.h"
#include "mbedtls/nist_kw.h"
#include <limits.h>
#include <string.h>
#if defined(MBEDTLS_PLATFORM_C)
@ -360,6 +361,65 @@ int main( int argc, char *argv[] )
mbedtls_exit( MBEDTLS_EXIT_FAILURE );
}
/*
* The C standard allows padding bits in the representation
* of standard integer types, but our code does currently not
* support them.
*
* Here we check that the underlying C implementation doesn't
* use padding bits, and fail cleanly if it does.
*
* The check works by casting the maximum value representable
* by a given integer type into the unpadded integer type of the
* same bit-width and checking that it agrees with the maximum value
* of that unpadded type. For example, for a 4-byte int,
* MAX_INT should be 0x7fffffff in int32_t. This assumes that
* CHAR_BIT == 8, which is checked in check_config.h.
*/
#define CHECK_PADDING_SIGNED(TYPE, NAME) \
do \
{ \
if( ( sizeof( TYPE ) == 2 && \
(int16_t) NAME ## _MAX != 0x7FFF ) || \
( sizeof( TYPE ) == 4 && \
(int32_t) NAME ## _MAX != 0x7FFFFFFF ) || \
( sizeof( TYPE ) == 8 && \
(int64_t) NAME ## _MAX != 0x7FFFFFFFFFFFFFFF ) ) \
{ \
mbedtls_printf( "Type '" #TYPE "' has padding bits\n" ); \
mbedtls_exit( MBEDTLS_EXIT_FAILURE ); \
} \
} while( 0 )
#define CHECK_PADDING_UNSIGNED(TYPE, NAME) \
do \
{ \
if( ( sizeof( TYPE ) == 2 && \
(uint16_t) NAME ## _MAX != 0xFFFF ) || \
( sizeof( TYPE ) == 4 && \
(uint32_t) NAME ## _MAX != 0xFFFFFFFF ) || \
( sizeof( TYPE ) == 8 && \
(uint64_t) NAME ## _MAX != 0xFFFFFFFFFFFFFFFF ) ) \
{ \
mbedtls_printf( "Type '" #TYPE "' has padding bits\n" ); \
mbedtls_exit( MBEDTLS_EXIT_FAILURE ); \
} \
} while( 0 )
CHECK_PADDING_SIGNED( short, SHRT );
CHECK_PADDING_SIGNED( int, INT );
CHECK_PADDING_SIGNED( long, LONG );
CHECK_PADDING_SIGNED( long long, LLONG );
CHECK_PADDING_UNSIGNED( unsigned short, USHRT );
CHECK_PADDING_UNSIGNED( unsigned, UINT );
CHECK_PADDING_UNSIGNED( unsigned long, ULONG );
CHECK_PADDING_UNSIGNED( unsigned long long, ULLONG );
#undef CHECK_PADDING_SIGNED
#undef CHECK_PADDING_UNSIGNED
/*
* Make sure we have a snprintf that correctly zero-terminates
*/