- detail protections.

- add RETURN VALUES section.
from OpenBSD.

lib/libc/sys/mprotect.2

@@ -1,4 +1,4 @@
-.\"	$NetBSD: mprotect.2,v 1.12 2002/02/08 01:28:19 ross Exp $
+.\"	$NetBSD: mprotect.2,v 1.13 2002/08/11 14:36:33 yamt Exp $
 .\"
 .\" Copyright (c) 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -53,6 +53,29 @@ changes the specified pages to have protection
 .Fa prot .
 Not all implementations will guarantee protection on a page basis;
 the granularity of protection changes may be as large as an entire region.
+.Pp
+The protections (region accessibility) are specified in the
+.Fa prot
+argument by
+.Tn OR Ns 'ing
+the following values:
+.Pp
+.Bl -tag -width MAP_FIXEDX
+.It Dv PROT_EXEC
+Pages may be executed.
+.It Dv PROT_READ
+Pages may be read.
+.It Dv PROT_WRITE
+Pages may be written.
+.It Dv PROT_NONE
+No permissions.
+.El
+.Sh RETURN VALUES
+Upon successful completion,
+a value of 0 is returned.
+Otherwise, a value of \-1 is returned and
+.Va errno
+is set to indicate the error.
 .Sh SEE ALSO
 .Xr madvise 2 ,
 .Xr mincore 2 ,