sys/msync.2

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  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 $
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  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
  44 .Fd #include <sys/types.h>
  45 .Fd #include <sys/mman.h>
  46 .Ft int
  47 .Fn msync "void *addr" "size_t len" "int flags"
  48 .Sh DESCRIPTION
  49 The
  50 .Fn msync
  51 system call
  52 writes any modified pages back to the filesystem and updates
  53 the file modification time.
  54 If
  55 .Fa len
  56 is 0, all modified pages within the region containing
  57 .Fa addr
  58 will be flushed;
  59 if
  60 .Fa len
  61 is non-zero, only those pages containing
  62 .Fa addr
  63 and
  64 .Fa len-1
  65 succeeding locations will be examined.
  66 The
  67 .Fa flags
  68 argument may be specified as follows:
  69 .Bd -literal
  70 MS_ASYNC        Return immediately
  71 MS_SYNC         Perform synchronous writes
  72 MS_INVALIDATE   Invalidate all cached data
  73 .Ed
  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
  82 .It Bq Er EINVAL
  83 .Fa addr
  84 is not a multiple of the hardware page size.
  85 .It Bq Er EINVAL
  86 .Fa len
  87 is too large or negative.
  88 .It Bq Er EINVAL
  89 .Fa flags
  90 was both MS_ASYNC and MS_INVALIDATE.
  91 Only one of these flags is allowed.
  92 .It Bq Er EIO
  93 An I/O error occurred while writing to the file system.
  94 .Sh SEE ALSO
  95 .Xr madvise 2 ,
  96 .Xr mincore 2 ,
  97 .Xr mprotect 2 ,
  98 .Xr munmap 2
  99 .Sh HISTORY
 100 The
 101 .Fn msync
 102 function first appeared in
 103 .Bx 4.4 .