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/* nbdkit
* Copyright Red Hat
*
* 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 Red Hat nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY RED HAT 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 RED HAT 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 <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#undef NDEBUG /* Keep test strong even for nbdkit built without assertions */
#include <assert.h>
#include "checked-overflow.h"
#define TEST_ADD(a, b, result, expected_overflow, expected_result) \
do { \
bool actual_overflow; \
\
actual_overflow = ADD_OVERFLOW_FALLBACK ((a), (b), (result)); \
assert (actual_overflow == (expected_overflow)); \
assert (*(result) == (expected_result)); \
actual_overflow = ADD_OVERFLOW_FALLBACK ((b), (a), (result)); \
assert (actual_overflow == (expected_overflow)); \
assert (*(result) == (expected_result)); \
} while (0)
#define TEST_MUL(a, b, result, expected_overflow, expected_result) \
do { \
bool actual_overflow; \
\
actual_overflow = MUL_OVERFLOW_FALLBACK ((a), (b), (result)); \
assert (actual_overflow == (expected_overflow)); \
assert (*(result) == (expected_result)); \
actual_overflow = MUL_OVERFLOW_FALLBACK ((b), (a), (result)); \
assert (actual_overflow == (expected_overflow)); \
assert (*(result) == (expected_result)); \
} while (0)
/* Define these const-qualified objects because the UINTN_MAX object-like
* macros in <stdint.h> have "post integer promotion" types. Therefore,
* UINT16_MAX and UINT8_MAX most commonly have type "int". And that trips the
* signedness check in ADD_OVERFLOW_FALLBACK().
*/
static const uintmax_t umax_max = UINTMAX_MAX;
static const uint64_t u64_max = UINT64_MAX;
static const uint32_t u32_max = UINT32_MAX;
static const uint16_t u16_max = UINT16_MAX;
static const uint8_t u8_max = UINT8_MAX;
static const size_t size_max = SIZE_MAX;
int
main (void)
{
union {
uintmax_t umax;
uint64_t u64;
uint32_t u32;
uint16_t u16;
uint8_t u8;
size_t sz;
} result;
bool overflow;
/* "max + 0" and "0 + max" evaluate to "max", without overflow. */
TEST_ADD (umax_max, 0u, &result.umax, false, umax_max);
TEST_ADD (u64_max, 0u, &result.u64, false, u64_max);
TEST_ADD (u32_max, 0u, &result.u32, false, u32_max);
TEST_ADD (u16_max, 0u, &result.u16, false, u16_max);
TEST_ADD (u8_max, 0u, &result.u8, false, u8_max);
TEST_ADD (size_max, 0u, &result.sz, false, size_max);
/* "max + 1" and "1 + max" overflow to zero. */
TEST_ADD (umax_max, 1u, &result.umax, true, 0);
TEST_ADD (u64_max, 1u, &result.u64, true, 0);
TEST_ADD (u32_max, 1u, &result.u32, true, 0);
TEST_ADD (u16_max, 1u, &result.u16, true, 0);
TEST_ADD (u8_max, 1u, &result.u8, true, 0);
TEST_ADD (size_max, 1u, &result.sz, true, 0);
/* Adding umax_max (i.e., all-bits-one) amounts (with overflow) to
* subtracting one.
*/
TEST_ADD (umax_max, umax_max, &result.umax, true, umax_max - 1);
TEST_ADD (u64_max, umax_max, &result.u64, true, u64_max - 1);
TEST_ADD (u32_max, umax_max, &result.u32, true, u32_max - 1);
TEST_ADD (u16_max, umax_max, &result.u16, true, u16_max - 1);
TEST_ADD (u8_max, umax_max, &result.u8, true, u8_max - 1);
TEST_ADD (size_max, umax_max, &result.sz, true, size_max - 1);
/* "max * 0" and "0 * max" evaluate to 0, without overflow. */
TEST_MUL (umax_max, 0u, &result.umax, false, 0);
TEST_MUL (u64_max, 0u, &result.u64, false, 0);
TEST_MUL (u32_max, 0u, &result.u32, false, 0);
TEST_MUL (u16_max, 0u, &result.u16, false, 0);
TEST_MUL (u8_max, 0u, &result.u8, false, 0);
TEST_MUL (size_max, 0u, &result.sz, false, 0);
/* "max * 1" and "1 * max" evaluate to "max", without overflow. */
TEST_MUL (umax_max, 1u, &result.umax, false, umax_max);
TEST_MUL (u64_max, 1u, &result.u64, false, u64_max);
TEST_MUL (u32_max, 1u, &result.u32, false, u32_max);
TEST_MUL (u16_max, 1u, &result.u16, false, u16_max);
TEST_MUL (u8_max, 1u, &result.u8, false, u8_max);
TEST_MUL (size_max, 1u, &result.sz, false, size_max);
/* "max * 2" and "2 * max" evaluate (with overflow) to "max - 1". */
TEST_MUL (umax_max, 2u, &result.umax, true, umax_max - 1);
TEST_MUL (u64_max, 2u, &result.u64, true, u64_max - 1);
TEST_MUL (u32_max, 2u, &result.u32, true, u32_max - 1);
TEST_MUL (u16_max, 2u, &result.u16, true, u16_max - 1);
TEST_MUL (u8_max, 2u, &result.u8, true, u8_max - 1);
TEST_MUL (size_max, 2u, &result.sz, true, size_max - 1);
/* factor 255 -> 3 5 17
* factor 65535 -> 3 5 17 257
* factor 4294967295 -> 3 5 17 257 65537
* factor 18446744073709551615 -> 3 5 17 257 641 65537 6700417
*
* Note: every time we double the width, we multiply the previous maximum
* 0xF...F with 0x10...01:
*
* 0xF (= 3 * 5) * 0x11 (= 17) = 0xFF
* 0xFF * 0x101 (= 257) = 0xFFFF
* 0xFFFF * 0x10001 (= 65537) = 0xFFFFFFFF
* 0xFFFFFFFF * 0x100000001 (= 641 * 6700417) = 0xFFFFFFFFFFFFFFFF
*
* Perform the above multiplications, advacing with prime factors.
*/
overflow = MUL_OVERFLOW_FALLBACK (3u, 5u, &result.u8);
assert (!overflow);
assert (result.u8 == 0xF);
overflow = MUL_OVERFLOW_FALLBACK (result.u8, 17u, &result.u8);
assert (!overflow);
assert (result.u8 == UINT8_MAX);
overflow = MUL_OVERFLOW_FALLBACK (result.u8, 257u, &result.u16);
assert (!overflow);
assert (result.u16 == UINT16_MAX);
overflow = MUL_OVERFLOW_FALLBACK (result.u16, 65537ul, &result.u32);
assert (!overflow);
assert (result.u32 == UINT32_MAX);
overflow = MUL_OVERFLOW_FALLBACK (result.u32, 641u, &result.u64);
assert (!overflow);
overflow = MUL_OVERFLOW_FALLBACK (result.u64, 6700417ul, &result.u64);
assert (!overflow);
assert (result.u64 == UINT64_MAX);
return 0;
}
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