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.\" 34.Dd June 21, 1994 35.Dt MSYNC 2 36.Os 37.Sh NAME 38.Nm msync 39.Nd synchronize a mapped region 40.Sh SYNOPSIS 41.Fd #include <sys/types.h> 42.Fd #include <sys/mman.h> 43.Ft int 44.Fn msync "void *addr" "size_t len" "int flags" 45.Sh DESCRIPTION 46The 47.Fn msync 48system call 49writes any modified pages back to the filesystem and updates 50the file modification time. 51If 52.Fa len 53is 0, all modified pages within the region containing 54.Fa addr 55will be flushed; 56if 57.Fa len 58is non-zero, only the pages containing 59.Fa addr 60and 61.Fa len 62succeeding locations will be examined. 63The 64.Fa flags 65argument may be specified as follows: 66.Bd -literal 67MS_ASYNC Return immediately (not currently implemented) 68MS_SYNC Perform synchronous writes 69MS_INVALIDATE Invalidate all cached data 70.Ed 71.Sh RETURN VALUES 72If any errors occur, -1 is returned and errno is set to indicate the 73error. Otherwise, a 0 value is returned. 74.Sh ERRORS 75.Fn msync 76will fail if: 77.Bl -tag -width Er 78.It Bq Er EINVAL 79.Fa addr 80is not a multiple of the hardware page size. 81.It Bq Er EINVAL 82.Fa len 83is too large or negative. 84.It Bq Er EINVAL 85.Fa flags 86was both MS_ASYNC and MS_INVALIDATE. Only one of these flags is allowed. 87.It Bq Er EIO 88An I/O error occured while writing to the file system. 89.Sh SEE ALSO 90.Xr madvise 2 , 91.Xr mincore 2 , 92.Xr mprotect 2 , 93.Xr munmap 2 94.Sh HISTORY 95The 96.Fn msync 97function first appeared in 98.Bx 4.4 . 99