1.\" $NetBSD: msync.2,v 1.8 1995/10/12 15:41:09 jtc Exp $ 2.\" 3.\" Copyright (c) 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)msync.2 8.1 (Berkeley) 6/9/93 35.\" 36.Dd June 9, 1993 37.Dt MSYNC 2 38.Os 39.Sh NAME 40.Nm msync 41.Nd synchronize a mapped region 42.Sh SYNOPSIS 43.Fd #include <sys/types.h> 44.Fd #include <sys/mman.h> 45.Ft int 46.Fn msync "caddr_t addr" "size_t len" 47.Sh DESCRIPTION 48The 49.Fn msync 50system call 51writes any modified pages back to the filesystem and updates 52the file modification time. 53If 54.Fa len 55is 0, all modified pages within the region containing 56.Fa addr 57will be flushed; 58if 59.Fa len 60is non-zero, only the pages containing 61.Fa addr 62and 63.Fa len 64succeeding locations will be examined. 65Any required synchronization of memory caches 66will also take place at this time. 67Filesystem operations on a file that is mapped for shared modifications 68are unpredictable except after an 69.Fn msync . 70.Sh ERRORS 71The following errors may be reported: 72.Bl -tag -width Er 73.It Bq Er EINVAL 74The 75.Fa addr 76parameter was not page aligned. 77.It Bq Er EINVAL 78The 79.Fa addr 80parameter did not specify an address part of a mapped region. 81.It Bq Er EINVAL 82The 83.Fa len 84parameter was negative. 85.It Bq Er EIO 86An I/O error occured while writing to the file system. 87.Sh SEE ALSO 88.Xr madvise 2 , 89.Xr munmap 2 , 90.Xr mprotect 2 , 91.Xr mincore 2 92.Sh HISTORY 93The 94.Fn msync 95function first appeared in 4.4BSD. 96