NAME

memset_s — copy a value to all bytes of a memory buffer

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#define __STDC_WANT_LIB_EXT1__ 1

#include <string.h>

errno_t
memset_s(void *s, rsize_t smax, int c, rsize_t n);

DESCRIPTION

The memset_s() function copies the value of c (converted to an unsigned char) into each of the first n bytes of the memory buffer pointed to by s.

Unlike the memset(3C), memset_s() is guaranteed to never be optimized away by the compiler.

The memset_s() function detects the following runtime-constraint violations:

1. s is a NULL pointer.
2. smax or n is greater than RSIZE_MAX.
3. n is greater than smax (buffer overflow).

If runtime-constraint violation is detected, and if s and smax are valid, the memset_s() function copies the value of c (converted to an unsigned char) into each of the first smax bytes of the memory buffer pointed to by s before calling the runtime-constraint handler.

RETURN VALUES

The memset_s() function returns 0 if there was no runtime-constraint violation. Otherwise, a non-zero value is returned.

INTERFACE STABILITY

Standard

MT-LEVEL

Safe

SEE ALSO

memset(3C), set_constraint_handler_s(3C)

STANDARDS

The memset_s() function conforms to ISO/IEC 9899:2011 (“ISO C11”).