[apple/xnu.git] / bsd / man / man2 / msync.2

.\" Copyright (c) 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" 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.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
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.\"	@(#)msync.2	8.2 (Berkeley) 6/21/94
.\" $FreeBSD: src/lib/libc/sys/msync.2,v 1.17 2000/04/21 09:41:53 phantom Exp $
.\"
.Dd June 21, 1994
.Dt MSYNC 2
.Os
.Sh NAME
.Nm msync
.Nd synchronize a mapped region
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/mman.h>
.Ft int
.Fn msync "void *addr" "size_t len" "int flags"
.Sh DESCRIPTION
The
.Fn msync
system call writes modified whole pages back to the filesystem
and updates the file modification time.
Only those pages containing 
.Fa addr
and
.Fa len-1
succeeding locations will be examined.
The
.Fa flags
argument may be specified as follows:
.Bd -literal
MS_ASYNC	Return immediately
MS_SYNC		Perform synchronous writes
MS_INVALIDATE	Invalidate all cached data
.Ed
.Pp
The
.Fa MS_ASYNC
flag is not permitted to be combined with other flags.
.Sh RETURN VALUES
If any errors occur, -1 is returned and errno is set to indicate the
error.
Otherwise, a 0 value is returned.
.Sh ERRORS
.Fn msync
will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
.Fa addr
is not a multiple of the hardware page size.
.It Bq Er EINVAL
.Fa len
is too large, or less than 1.
.It Bq Er EINVAL
.Fa flags
combined MS_ASYNC with another flag, which is not permitted.
.It Bq Er EIO
An I/O error occurred while writing to the file system.
.El
.Sh SEE ALSO
.Xr madvise 2 ,
.Xr mincore 2 ,
.Xr mprotect 2 ,
.Xr munmap 2
.Sh HISTORY
The
.Fn msync
function first appeared in
.Bx 4.4 .
Commit	Line	Data
9bccf70c A	1	.\" Copyright (c) 1991, 1993
	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" @(#)msync.2 8.2 (Berkeley) 6/21/94
	33	.\" $FreeBSD: src/lib/libc/sys/msync.2,v 1.17 2000/04/21 09:41:53 phantom Exp $
	34	.\"
	35	.Dd June 21, 1994
	36	.Dt MSYNC 2
	37	.Os
	38	.Sh NAME
	39	.Nm msync
	40	.Nd synchronize a mapped region
	41	.Sh LIBRARY
	42	.Lb libc
	43	.Sh SYNOPSIS
	44	.Fd #include <sys/types.h>
	45	.Fd #include <sys/mman.h>
	46	.Ft int
	47	.Fn msync "void *addr" "size_t len" "int flags"
	48	.Sh DESCRIPTION
	49	The
	50	.Fn msync
55e303ae A	51	system call writes modified whole pages back to the filesystem
	52	and updates the file modification time.
	53	Only those pages containing
9bccf70c A	54	.Fa addr
	55	and
	56	.Fa len-1
	57	succeeding locations will be examined.
	58	The
	59	.Fa flags
	60	argument may be specified as follows:
	61	.Bd -literal
	62	MS_ASYNC Return immediately
	63	MS_SYNC Perform synchronous writes
	64	MS_INVALIDATE Invalidate all cached data
	65	.Ed
55e303ae A	66	.Pp
	67	The
	68	.Fa MS_ASYNC
	69	flag is not permitted to be combined with other flags.
9bccf70c A	70	.Sh RETURN VALUES
	71	If any errors occur, -1 is returned and errno is set to indicate the
	72	error.
	73	Otherwise, a 0 value is returned.
	74	.Sh ERRORS
	75	.Fn msync
	76	will fail if:
	77	.Bl -tag -width Er
	78	.It Bq Er EINVAL
	79	.Fa addr
	80	is not a multiple of the hardware page size.
	81	.It Bq Er EINVAL
	82	.Fa len
55e303ae	83	is too large, or less than 1.
9bccf70c A	84	.It Bq Er EINVAL
9bccf70c A	85	.Fa flags
55e303ae	86	combined MS_ASYNC with another flag, which is not permitted.
9bccf70c A	87	.It Bq Er EIO
	88	An I/O error occurred while writing to the file system.
	89	.El
	90	.Sh SEE ALSO
	91	.Xr madvise 2 ,
	92	.Xr mincore 2 ,
	93	.Xr mprotect 2 ,
	94	.Xr munmap 2
	95	.Sh HISTORY
	96	The
	97	.Fn msync
	98	function first appeared in
	99	.Bx 4.4 .