bsd/man/man2/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 $
  34 .\"
  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/mman.h>
  45 .Ft int
  46 .Fo msync
  47 .Fa "void *addr"
  48 .Fa "size_t len"
  49 .Fa "int flags"
  50 .Fc
  51 .Sh DESCRIPTION
  52 The
  53 .Fn msync
  54 system call writes modified whole pages back to the filesystem
  55 and updates the file modification time.
  56 Only those pages containing
  57 .Fa addr
  58 and
  59 .Fa len-1
  60 succeeding locations will be examined.
  61 .Pp
  62 The
  63 .Fa flags
  64 argument may be specified as follows:
  65 .Bd -literal
  66 MS_ASYNC        Return immediately
  67 MS_SYNC         Perform synchronous writes
  68 MS_INVALIDATE   Invalidate all cached data
  69 .Ed
  70 .Pp
  71 The
  72 .Fa MS_ASYNC
  73 flag is not permitted to be combined with other flags.
  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 .\" ===========
  83 .It Bq Er EBUSY
  84 Some of the specified addresses are locked
  85 and MS_INVALIDATE is specified.
  86 .\" ===========
  87 .It Bq Er EINVAL
  88 .Fa addr
  89 is not a multiple of the hardware page size.
  90 .\" ===========
  91 .It Bq Er EINVAL
  92 .Fa len
  93 is too large, or less than 1.
  94 .\" ===========
  95 .It Bq Er EINVAL
  96 .Fa flags
  97 is invalid
  98 (e.g., it combines MS_ASYNC with another flag,
  99 which is not permitted).
 100 .\" ===========
 101 .It Bq Er EIO
 102 An I/O error occurs while writing to the file system.
 103 .\" ===========
 104 .It Bq Er ENOMEM
 105 The specified address range is outside of the address range
 106 of the process or includes an unmapped page.
 107 .El
 108 .Sh LEGACY SYNOPSIS
 109 .Fd #include <sys/types.h>
 110 .Fd #include <sys/mman.h>
 111 .Pp
 112 The include file
 113 .In sys/types.h
 114 is necessary.
 115 .Sh SEE ALSO
 116 .Xr madvise 2 ,
 117 .Xr mincore 2 ,
 118 .Xr mprotect 2 ,
 119 .Xr munmap 2 ,
 120 .Xr compat 5
 121 .Sh HISTORY
 122 The
 123 .Fn msync
 124 function first appeared in
 125 .Bx 4.4 .