freebsd-nq/lib/libc/sys/msync.2
Alexander Langer 7167d5b04c Convert caddr_t --> void * for sys/mman.h functions.
mlock, mmap, mprotect, msync, munlock, and munmap are defined by
POSIX as taking void *.  The const modifier has been added to
mlock, munlock, and mprotect as the standard dictates.

minherit comes from OpenBSD and has been updated to conform with
their recent change to void *.

madvise and mincore are not defined by POSIX, but their arguments
have been modified to be consistent with the POSIX-defined functions.
mincore takes a const pointer, but madvise does not due to the
MADV_FREE case.

Discussed with:	bde
1997-12-31 01:22:01 +00:00

99 lines
3.2 KiB
Groff

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.\" @(#)msync.2 8.2 (Berkeley) 6/21/94
.\"
.Dd June 21, 1994
.Dt MSYNC 2
.Os
.Sh NAME
.Nm msync
.Nd synchronize a mapped region
.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 any modified pages back to the filesystem and updates
the file modification time.
If
.Fa len
is 0, all modified pages within the region containing
.Fa addr
will be flushed;
if
.Fa len
is non-zero, only the pages containing
.Fa addr
and
.Fa len
succeeding locations will be examined.
The
.Fa flags
argument may be specified as follows:
.Bd -literal
MS_ASYNC Return immediately (not currently implemented)
MS_SYNC Perform synchronous writes
MS_INVALIDATE Invalidate all cached data
.Ed
.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 negative.
.It Bq Er EINVAL
.Fa flags
was both MS_ASYNC and MS_INVALIDATE. Only one of these flags is allowed.
.It Bq Er EIO
An I/O error occured while writing to the file system.
.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 .