bugprone-suspicious-memset-usage¶
This check finds memset()
calls with potential mistakes in their arguments.
Considering the function as void* memset(void* destination, int fill_value,
size_t byte_count)
, the following cases are covered:
Case 1: Fill value is a character ``’0’``
Filling up a memory area with ASCII code 48 characters is not customary,
possibly integer zeroes were intended instead.
The check offers a replacement of '0'
with 0
. Memsetting character
pointers with '0'
is allowed.
Case 2: Fill value is truncated
Memset converts fill_value
to unsigned char
before using it. If
fill_value
is out of unsigned character range, it gets truncated
and memory will not contain the desired pattern.
Case 3: Byte count is zero
Calling memset with a literal zero in its byte_count
argument is likely
to be unintended and swapped with fill_value
. The check offers to swap
these two arguments.
Corresponding cpplint.py check name: runtime/memset
.
Examples:
void foo() {
int i[5] = {1, 2, 3, 4, 5};
int *ip = i;
char c = '1';
char *cp = &c;
int v = 0;
// Case 1
memset(ip, '0', 1); // suspicious
memset(cp, '0', 1); // OK
// Case 2
memset(ip, 0xabcd, 1); // fill value gets truncated
memset(ip, 0x00, 1); // OK
// Case 3
memset(ip, sizeof(int), v); // zero length, potentially swapped
memset(ip, 0, 1); // OK
}