explicit_memset(3) - NetBSD Manual Pages

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EXPLICIT_MEMSET(3)      NetBSD Library Functions Manual     EXPLICIT_MEMSET(3)


NAME
explicit_memset -- guarantee writing a byte to a byte string
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <string.h> void * explicit_memset(void *b, int c, size_t len);
DESCRIPTION
The explicit_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
consttime_memequal(3), memset(3)
HISTORY
The explicit_memset() function appeared in NetBSD 7.0. NetBSD 9.99 August 28, 2013 NetBSD 9.99
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