STDCKDINT(3) FreeBSD Library Functions Manual STDCKDINT(3)
NAME
stdckdint - checked integer arithmetic
SYNOPSIS
#include <stdckdint.h>
bool
ckd_add(type1 *result, type2 a, type3 b);
bool
ckd_sub(type1 *result, type2 a, type3 b);
bool
ckd_mul(type1 *result, type2 a, type3 b);
DESCRIPTION
The function-like macros ckd_add, ckd_sub, and ckd_mul perform checked
integer addition, subtraction, and multiplication, respectively. If the
result of adding, subtracting, or multiplying a and b as if their
respective types had infinite range fits in type1, it is stored in the
location pointed to by result and the macro evaluates to false.
Otherwise, the macro evaluates to true and the contents of the location
pointed to by result is the result of the operation wrapped to the range
of type1.
RETURN VALUES
The ckd_add, ckd_sub, and ckd_mul macros evaluate to true if the
requested operation overflowed the result type and false otherwise.
EXAMPLES
#include <assert.h>
#include <limits.h>
#include <stdckdint.h>
int main(void)
{
int result;
assert(!ckd_add(&result, INT_MAX, 0));
assert(result == INT_MAX);
assert(ckd_add(&result, INT_MAX, 1));
assert(result == INT_MIN);
assert(!ckd_sub(&result, INT_MIN, 0));
assert(result == INT_MIN);
assert(ckd_sub(&result, INT_MIN, 1));
assert(result == INT_MAX);
assert(!ckd_mul(&result, INT_MAX / 2, 2));
assert(result == INT_MAX - 1);
assert(ckd_mul(&result, INT_MAX / 2 + 1, 2));
assert(result == INT_MIN);
return 0;
}
HISTORY
The ckd_add, ckd_sub, and ckd_mul macros were first introduced in
FreeBSD 14.0.
AUTHORS
The ckd_add, ckd_sub, and ckd_mul macros and this manual page were
written by Dag-Erling Smorgrav <
[email protected]>.
FreeBSD 14.1-RELEASE-p8 September 5, 2023 FreeBSD 14.1-RELEASE-p8