NAME
explicit_memset —
guarantee writing a byte to a byte
string
LIBRARY
library “libc”
SYNOPSIS
#include
<string.h>
void *
explicit_memset(void
*b, int c,
size_t len);
DESCRIPTION
Theexplicit_memset()
function writes len bytes of value
c (converted to an unsigned char) to the string
b. It is guaranteed not to be optimized away by the
compiler even if b is no longer used and is about to be
freed or go out of scope.
RETURN VALUES
The explicit_memset() function returns the
original value of b.
EXAMPLES
Create a buffer on the stack for a secret key, use it, and then zero it in memory before throwing it away.
void
f(void)
{
uint8_t key[32];
crypto_random(key, sizeof(key));
do_crypto_stuff(key, sizeof(key));
...
explicit_memset(key, 0, sizeof(key));
}
SEE ALSO
HISTORY
The explicit_memset() function appeared in
NetBSD 7.0.