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 $
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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 writes modified whole pages back to the filesystem
  52 and updates the file modification time.
  53 Only those pages containing
  54 .Fa addr
  55 and
  56 .Fa len-1
  57 succeeding locations will be examined.
  58 The
  59 .Fa flags
  60 argument may be specified as follows:
  61 .Bd -literal
  62 MS_ASYNC        Return immediately
  63 MS_SYNC         Perform synchronous writes
  64 MS_INVALIDATE   Invalidate all cached data
  65 .Ed
  66 .Pp
  67 The
  68 .Fa MS_ASYNC
  69 flag is not permitted to be combined with other flags.
  70 .Sh RETURN VALUES
  71 If any errors occur, -1 is returned and errno is set to indicate the
  72 error.
  73 Otherwise, a 0 value is returned.
  74 .Sh ERRORS
  75 .Fn msync
  76 will fail if:
  77 .Bl -tag -width Er
  78 .It Bq Er EINVAL
  79 .Fa addr
  80 is not a multiple of the hardware page size.
  81 .It Bq Er EINVAL
  82 .Fa len
  83 is too large, or less than 1.
  84 .It Bq Er EINVAL
  85 .Fa flags
  86 combined MS_ASYNC with another flag, which is not permitted.
  87 .It Bq Er EIO
  88 An I/O error occurred while writing to the file system.
  89 .El
  90 .Sh SEE ALSO
  91 .Xr madvise 2 ,
  92 .Xr mincore 2 ,
  93 .Xr mprotect 2 ,
  94 .Xr munmap 2
  95 .Sh HISTORY
  96 The
  97 .Fn msync
  98 function first appeared in
  99 .Bx 4.4 .