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.Dd May 6, 2018
.Dt cryb_memcpy_s 3
.Os
.Sh NAME
.Nm cryb_memcpy_s
.Nd safely copy one buffer to another
.Sh LIBRARY
.Lb libcryb-core
.Sh SYNOPSIS
.In cryb/memcpy_s.h
.Ft errno_t
.Fn cryb_memcpy_s "void * restrict d" "rsize_t dsz" "const void * restrict s" "rsize_t n"
.Sh DESCRIPTION
The
.Nm cryb_memcpy_s
function copies the first
.Va n
bytes of the buffer pointed to by
.Va s
into the buffer pointed to by
.Va d ,
of size
.Va dsz .
If
.Va s
is
.Dv NULL ,
.Va n
is greater than
.Va dsz
or
.Dv RSIZE_MAX
or the source and destination overlap, the buffer pointed to by
.Va d
is filled with zeroes and an error is returned.
.Sh RETURN VALUES
The
.Fn cryb_memcpy_s
function returns zero if successful and a non-zero error code if an
error occurred.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Va d
argument was
.Dv NULL
or the source and destination ranges were found to overlap.
.It Bq Er ERANGE
Either or both of the
.Va dsz
and
.Va n
arguments were greater than
.Dv SIZE_MAX .
.It Bq Er EOVERFLOW
The
.Va n
argument was greater than the
.Va dsz
argument.
.El
.Sh IMPLEMENTATION NOTES
If the
.Dv HAVE_MEMCPY_S
preprocessor macro is defined to 0 or undefined, the
.In cryb/memcpy_s.h
header provides a
.Fn memcpy_s
macro as an alias to
.Fn cryb_memcpy_s .
.Pp
Software that includes
.In cryb/memcpy_s.h
should ensure that the
.Dv HAVE_ERRNO_T ,
.Dv HAVE_RSIZE_T ,
.Dv HAVE_RSIZE_MAX
and
.Dv HAVE_MEMCPY_S
macros correctly reflect the availability of these features at compile
time.
For projects that use the GNU autotools, this can be achieved by
including the following code in
.Pa configure.ac :
.Bd -literal -offset indent
AC_CHECK_TYPES([errno_t], [], [], [[#include <errno.h>]])
AC_CHECK_TYPES([rsize_t], [], [], [[#include <stdint.h>]])
AC_CHECK_DECL([RSIZE_MAX], [], [], [[#include <stdint.h>]])
AC_CHECK_FUNCS([memcpy_s])
.Ed
.Sh SEE ALSO
.Xr cryb_memset_s 3 ,
.Xr memcpy 3
.Sh STANDARDS
The
.Fn cryb_memcpy_s
function is equivalent to the
.Fn memcpy_s
function described in ISO/IEC 9899:2011
.Pq Dq C11
section K.3.7.1.1.
.Sh AUTHORS
The
.Fn cryb_memcpy_s
function and this manual page were written for the University of Oslo
by
.An Dag-Erling Sm\(/orgrav Aq Mt d.e.smorgrav@usit.uio.no .