[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.
.\"
.\"	@(#)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/mman.h>
.Ft int
.Fo msync
.Fa "void *addr"
.Fa "size_t len"
.Fa "int flags"
.Fc
.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.
.Pp
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 EBUSY
Some of the specified addresses are locked
and MS_INVALIDATE is specified.
.\" ===========
.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
is invalid
(e.g., it combines MS_ASYNC with another flag,
which is not permitted).
.\" ===========
.It Bq Er EIO
An I/O error occurs while writing to the file system.
.\" ===========
.It Bq Er ENOMEM
The specified address range is outside of the address range
of the process or includes an unmapped page.
.El
.Sh LEGACY SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/mman.h>
.Pp
The include file
.In sys/types.h
is necessary.
.Sh SEE ALSO
.Xr madvise 2 ,
.Xr mincore 2 ,
.Xr mprotect 2 ,
.Xr munmap 2 ,
.Xr compat 5
.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
9bccf70c A	44	.Fd #include <sys/mman.h>
9bccf70c A	45	.Ft int
2d21ac55 A	46	.Fo msync
	47	.Fa "void *addr"
	48	.Fa "size_t len"
	49	.Fa "int flags"
	50	.Fc
9bccf70c A	51	.Sh DESCRIPTION
	52	The
	53	.Fn msync
55e303ae A	54	system call writes modified whole pages back to the filesystem
	55	and updates the file modification time.
	56	Only those pages containing
9bccf70c A	57	.Fa addr
	58	and
	59	.Fa len-1
	60	succeeding locations will be examined.
2d21ac55	61	.Pp
9bccf70c A	62	The
	63	.Fa flags
	64	argument may be specified as follows:
	65	.Bd -literal
	66	MS_ASYNC Return immediately
	67	MS_SYNC Perform synchronous writes
	68	MS_INVALIDATE Invalidate all cached data
	69	.Ed
55e303ae A	70	.Pp
	71	The
	72	.Fa MS_ASYNC
	73	flag is not permitted to be combined with other flags.
9bccf70c A	74	.Sh RETURN VALUES
	75	If any errors occur, -1 is returned and errno is set to indicate the
	76	error.
	77	Otherwise, a 0 value is returned.
	78	.Sh ERRORS
	79	.Fn msync
	80	will fail if:
	81	.Bl -tag -width Er
2d21ac55 A	82	.\" ===========
	83	.It Bq Er EBUSY
	84	Some of the specified addresses are locked
	85	and MS_INVALIDATE is specified.
	86	.\" ===========
9bccf70c A	87	.It Bq Er EINVAL
	88	.Fa addr
	89	is not a multiple of the hardware page size.
2d21ac55	90	.\" ===========
9bccf70c A	91	.It Bq Er EINVAL
9bccf70c A	92	.Fa len
55e303ae	93	is too large, or less than 1.
2d21ac55	94	.\" ===========
9bccf70c A	95	.It Bq Er EINVAL
9bccf70c A	96	.Fa flags
2d21ac55 A	97	is invalid
	98	(e.g., it combines MS_ASYNC with another flag,
	99	which is not permitted).
	100	.\" ===========
9bccf70c	101	.It Bq Er EIO
2d21ac55 A	102	An I/O error occurs while writing to the file system.
	103	.\" ===========
	104	.It Bq Er ENOMEM
	105	The specified address range is outside of the address range
	106	of the process or includes an unmapped page.
9bccf70c	107	.El
2d21ac55 A	108	.Sh LEGACY SYNOPSIS
	109	.Fd #include <sys/types.h>
	110	.Fd #include <sys/mman.h>
	111	.Pp
	112	The include file
	113	.In sys/types.h
	114	is necessary.
9bccf70c A	115	.Sh SEE ALSO
	116	.Xr madvise 2 ,
	117	.Xr mincore 2 ,
	118	.Xr mprotect 2 ,
2d21ac55 A	119	.Xr munmap 2 ,
2d21ac55 A	120	.Xr compat 5
9bccf70c A	121	.Sh HISTORY
	122	The
	123	.Fn msync
	124	function first appeared in
	125	.Bx 4.4 .