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macro: introduce u64_multiply_safe() to avoid overflow

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Just a paranoia.
This commit is contained in:
Yu Watanabe
2023-10-19 18:31:44 +09:00
parent b39907c712
commit ffee7b97e3
3 changed files with 34 additions and 2 deletions
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src/test/test-macro.c
+25
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@@ -1012,4 +1012,29 @@ TEST(round_up) {
TEST_ROUND_UP_BY_TYPE(uint64_t, UINT64_MAX);
}
TEST(u64_multiply_safe) {
assert_se(u64_multiply_safe(0, 0) == 0);
assert_se(u64_multiply_safe(10, 0) == 0);
assert_se(u64_multiply_safe(0, 10) == 0);
assert_se(u64_multiply_safe(10, 10) == 100);
assert_se(u64_multiply_safe(UINT64_MAX, 0) == 0);
assert_se(u64_multiply_safe(UINT64_MAX, 1) == UINT64_MAX);
assert_se(u64_multiply_safe(UINT64_MAX, 2) == 0);
assert_se(u64_multiply_safe(0, UINT64_MAX) == 0);
assert_se(u64_multiply_safe(1, UINT64_MAX) == UINT64_MAX);
assert_se(u64_multiply_safe(2, UINT64_MAX) == 0);
assert_se(u64_multiply_safe(UINT64_MAX / 2, 0) == 0);
assert_se(u64_multiply_safe(UINT64_MAX / 2, 1) == UINT64_MAX / 2);
assert_se(u64_multiply_safe(UINT64_MAX / 2, 2) == UINT64_MAX - 1);
assert_se(u64_multiply_safe(UINT64_MAX / 2, 3) == 0);
assert_se(u64_multiply_safe(0, UINT64_MAX / 2) == 0);
assert_se(u64_multiply_safe(1, UINT64_MAX / 2) == UINT64_MAX / 2);
assert_se(u64_multiply_safe(2, UINT64_MAX / 2) == UINT64_MAX - 1);
assert_se(u64_multiply_safe(3, UINT64_MAX / 2) == 0);
assert_se(u64_multiply_safe(UINT64_MAX, UINT64_MAX) == 0);
}
DEFINE_TEST_MAIN(LOG_INFO);