[apple/libc.git] / string / NetBSD / memset_s.3

.\"
.\" Copyright (c) 2012 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Alan Barrett
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.\"	$NetBSD$
.\"
.Dd February 21, 2012
.Dt MEMSET_S 3
.Os
.Sh NAME
.Nm memset_s
.Nd copy a value to all bytes of a memory buffer
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.Fd "#define __STDC_WANT_LIB_EXT1__ 1
.In string.h
.Ft errno_t
.Fn memset_s "void *s" "rsize_t smax" "int c" "rsize_t n"
.Sh DESCRIPTION
The
.Fn memset_s
function copies the value
.Fa c
(converted to an unsigned char)
into each of the first
.Fa n
bytes of the memory buffer whose starting address is given by
.Fa s .
.Pp
It is a runtime-constraints violation if
.Fa s
is a null pointer,
or if either of
.Fa smax
or
.Fa n
is larger than
.Dv RSIZE_MAX ,
or if
.Fa smax
is smaller than
.Fa n .
If there is a runtime-constraints violation, and if
.Fa s
is not a null pointer,
and if
.Fa smax
is not larger than
.Dv RSIZE_MAX ,
then, before reporting the runtime-constraints violation,
.Fn memset_s
copies
.Fa smax
bytes to the destination.
.Pp
In contrast to the
.Xr memset 3
function,
calls to
.Fn memset_s
will never be
.Dq optimised away
by a compiler.
This property is required by the following sentences in
section K.3.7.4.1 of
.St -isoC-2011 :
.Bd -filled -offset indent
Unlike
.Fn memset ,
any call to the
.Fn 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
.Fn memset_s
function shall assume that the memory indicated by
.Fa s
and
.Fa n
may be accessible in the future and thus must contain
the values indicated by
.Fa c .
.Ed
.Sh RETURN VALUES
The
.Fn memset_s
function returns zero for success, or a non-zero error code
if there was a runtime-constraints violation.
.Sh ERRORS
.Fn memset_s
returns the following error codes.
It does not store the error code in the global
.Va errno
variable:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa s
argument was a null pointer.
.It Bq Er E2BIG
One or both of
.Fa smax
or
.Fa n
was larger than
.Dv RSIZE_MAX .
.It Bq Er EOVERFLOW
.Fa n
was larger than
.Fa smax .
.El
.
.Sh SEE ALSO
.Xr memset 3 .
.Sh STANDARDS
The
.Fn memset_s
function conforms to
.St -isoC-2011 ,
except that the
.Fn set_constraint_handler_s
interface is not supported.
Commit	Line	Data
6465356a A	1	.\"
	2	.\" Copyright (c) 2012 The NetBSD Foundation, Inc.
	3	.\" All rights reserved.
	4	.\"
	5	.\" This code is derived from software contributed to The NetBSD Foundation
	6	.\" by Alan Barrett
	7	.\"
	8	.\" Redistribution and use in source and binary forms, with or without
	9	.\" modification, are permitted provided that the following conditions
	10	.\" are met:
	11	.\" 1. Redistributions of source code must retain the above copyright
	12	.\" notice, this list of conditions and the following disclaimer.
	13	.\" 2. Redistributions in binary form must reproduce the above copyright
	14	.\" notice, this list of conditions and the following disclaimer in the
	15	.\" documentation and/or other materials provided with the distribution.
	16	.\"
	17	.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
	18	.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
	19	.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	20	.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
	21	.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	22	.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	23	.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	24	.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	25	.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	26	.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	27	.\" POSSIBILITY OF SUCH DAMAGE.
	28	.\"
	29	.\" $NetBSD$
	30	.\"
	31	.Dd February 21, 2012
	32	.Dt MEMSET_S 3
	33	.Os
	34	.Sh NAME
	35	.Nm memset_s
	36	.Nd copy a value to all bytes of a memory buffer
	37	.Sh LIBRARY
	38	.Lb libc
	39	.Sh SYNOPSIS
	40	.Fd "#define __STDC_WANT_LIB_EXT1__ 1
	41	.In string.h
	42	.Ft errno_t
	43	.Fn memset_s "void *s" "rsize_t smax" "int c" "rsize_t n"
	44	.Sh DESCRIPTION
	45	The
	46	.Fn memset_s
	47	function copies the value
	48	.Fa c
	49	(converted to an unsigned char)
	50	into each of the first
	51	.Fa n
	52	bytes of the memory buffer whose starting address is given by
	53	.Fa s .
	54	.Pp
b061a43b	55	It is a runtime-constraints violation if
6465356a A	56	.Fa s
	57	is a null pointer,
	58	or if either of
	59	.Fa smax
	60	or
	61	.Fa n
	62	is larger than
	63	.Dv RSIZE_MAX ,
	64	or if
	65	.Fa smax
	66	is smaller than
	67	.Fa n .
	68	If there is a runtime-constraints violation, and if
	69	.Fa s
	70	is not a null pointer,
	71	and if
	72	.Fa smax
	73	is not larger than
	74	.Dv RSIZE_MAX ,
	75	then, before reporting the runtime-constraints violation,
	76	.Fn memset_s
	77	copies
	78	.Fa smax
	79	bytes to the destination.
	80	.Pp
	81	In contrast to the
	82	.Xr memset 3
	83	function,
	84	calls to
	85	.Fn memset_s
	86	will never be
	87	.Dq optimised away
	88	by a compiler.
	89	This property is required by the following sentences in
	90	section K.3.7.4.1 of
	91	.St -isoC-2011 :
	92	.Bd -filled -offset indent
	93	Unlike
	94	.Fn memset ,
	95	any call to the
	96	.Fn memset_s
	97	function shall be evaluated strictly according to the rules of
	98	the abstract machine as described in (5.1.2.3).
	99	That is, any call to the
	100	.Fn memset_s
	101	function shall assume that the memory indicated by
	102	.Fa s
	103	and
	104	.Fa n
	105	may be accessible in the future and thus must contain
	106	the values indicated by
	107	.Fa c .
	108	.Ed
	109	.Sh RETURN VALUES
	110	The
	111	.Fn memset_s
	112	function returns zero for success, or a non-zero error code
	113	if there was a runtime-constraints violation.
	114	.Sh ERRORS
	115	.Fn memset_s
	116	returns the following error codes.
	117	It does not store the error code in the global
	118	.Va errno
	119	variable:
120	.Bl -tag -width Er
121	.It Bq Er EINVAL
122	The
123	.Fa s
124	argument was a null pointer.
125	.It Bq Er E2BIG
126	One or both of
127	.Fa smax
128	or
129	.Fa n
130	was larger than
131	.Dv RSIZE_MAX .
132	.It Bq Er EOVERFLOW
133	.Fa n
134	was larger than
135	.Fa smax .
136	.El
137	.
138	.Sh SEE ALSO
139	.Xr memset 3 .
140	.Sh STANDARDS
141	The
142	.Fn memset_s
143	function conforms to
144	.St -isoC-2011 ,
145	except that the
146	.Fn set_constraint_handler_s
147	interface is not supported.