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MEMSET_S(3)              BSD Library Functions Manual              MEMSET_S(3)

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 c (converted to an unsigned char) into each of the first n
     bytes of the memory buffer whose starting address is given by s.

     It is a runtime-consrtaints violation if s is a null pointer, or if either of smax or n is larger than
     RSIZE_MAX, or if smax is smaller than n.  If there is a runtime-constraints violation, and if s is not
     a null pointer, and if smax is not larger than RSIZE_MAX, then, before reporting the runtime-con-straints runtime-constraints
     straints violation, memset_s() copies smax bytes to the destination.

     In contrast to the memset(3) function, calls to memset_s() will never be ``optimised away'' by a com-piler. compiler.
     piler.  This property is required by the following sentences in section K.3.7.4.1 of ISO/IEC 9899:2011
     (``ISO C11''):

           Unlike memset(), any call to the memset_s() function shall be evaluated strictly according to the
           rules of the abstract machine as described in (5.1.2.3).  That is, any  call  to  the  memset_s()
           function  shall  assume  that the memory indicated by s and n may be accessible in the future and
           thus must contain the values indicated by c.

RETURN VALUES
     The memset_s() function returns zero for success, or a non-zero error code if there was a runtime-con-straints runtime-constraints
     straints violation.

ERRORS
     memset_s() returns the following error codes.  It does not store the error code in the global errno
     variable:

     [EINVAL]           The s argument was a null pointer.

     [E2BIG]            One or both of smax or n was larger than RSIZE_MAX.

     [EOVERFLOW]        n was larger than smax.

SEE ALSO
     memset(3).

STANDARDS
     The memset_s() function conforms to ISO/IEC 9899:2011 (``ISO C11''), except that the
     set_constraint_handler_s() interface is not supported.

BSD                            February 21, 2012                           BSD