msync — synchronize a file with a memory map
#include <sys/mman.h>
int msync( |
void *addr, |
| size_t length, | |
int flags); |
msync() flushes changes made
to the in-core copy of a file that was mapped into memory
using mmap(2) back to disk.
Without use of this call there is no guarantee that changes
are written back before munmap(2) is called. To be
more precise, the part of the file that corresponds to the
memory area starting at addr and having length
length is
updated.
The flags argument
may have the bits MS_ASYNC,
MS_SYNC, and MS_INVALIDATE set, but not both
MS_ASYNC and MS_SYNC. MS_ASYNC specifies that an update be
scheduled, but the call returns immediately. MS_SYNC asks for an update and waits for it
to complete. MS_INVALIDATE asks
to invalidate other mappings of the same file (so that they
can be updated with the fresh values just written).
On success, zero is returned. On error, −1 is
returned, and errno is set
appropriately.
MS_INVALIDATE was
specified in flags, and a memory lock
exists for the specified address range.
addr is not
a multiple of PAGESIZE; or any bit other than
MS_ASYNC | MS_INVALIDATE | MS_SYNC is set in flags; or both
MS_SYNC and MS_ASYNC are set in flags.
The indicated memory (or part of it) was not mapped.
POSIX.1-2001.
This call was introduced in Linux 1.3.21, and then used EFAULT instead of ENOMEM. In Linux 2.4.19 this was changed to the POSIX value ENOMEM.
On POSIX systems on which msync() is available, both _POSIX_MAPPED_FILES and _POSIX_SYNCHRONIZED_IO are defined in
<unistd.h>
to a value greater than 0. (See also sysconf(3).)
This page is part of release 3.24 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at
http://www.kernel.org/doc/man-pages/.
|
Copyright (C) 1996 Andries Brouwer (aebcwi.nl) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. |