Add missing RETURN VALUES/ERRORS sections.

lib/libc/sys/getrusage.2

@@ -141,10 +141,16 @@ and
 account only for real
 I/O; data supplied by the caching mechanism is charged only
 to the first process to read or write the data.
+.Sh RETURN VALUES
+Uponsuccessful completion,
+.Fn getrusage
+returns 0.  Otherwise, a value of -1 is returned and
+.Va errno
+is set to indicate the error.
 .Sh ERRORS
-.Fn Getrusage
-returns -1 on error.
-The possible errors are:
+The
+.Fn getrusage
+function will fail if:
 .Bl -tag -width Er
 .It Bq Er EINVAL
 The

lib/libc/sys/minherit.2

@@ -1,4 +1,4 @@
-.\"	$Id$
+.\"	$Id: minherit.2,v 1.1 1996/02/23 19:56:54 peter Exp $
 .\"
 .\" Copyright (c) 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -53,6 +53,33 @@ changes the specified pages to have the inheritance characteristic
 Not all implementations will guarantee that the inheritance characteristic
 can be set on a page basis;
 the granularity of changes may be as large as an entire region.
+.Sh RETURN VALUES
+Upon successful completion,
+.Fn minherit
+returns 0.  Otherwise, a value of -1 is returned and
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+The
+.Fn minherit
+function will fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The virtual address range specified by the
+.Fa addr
+and
+.Fa len
+arguments is not valid.
+.It Bq Er EACESS
+The flags specified by the
+.Fa inherit
+argument were not valid for the pages specified
+by the
+.Fa addr
+and
+.Fa len
+arguments.
+.El
 .Sh SEE ALSO
 .Xr fork 2 ,
 .Xr madvise 2 , 

lib/libc/sys/open.2

@@ -166,6 +166,13 @@ and calls
 Before returning,
 .Fn open
 enables thread rescheduling.
+.Sh RETURN VALUES
+If successful,
+.Fn open
+returns a non-negative integer, termed a file descriptor.
+It returns -1 on failure, and sets
+.Va errno
+to indicate the error.
 .Sh ERRORS
 The named file is opened unless:
 .Bl -tag -width Er

lib/libc/sys/ptrace.2

@@ -1,4 +1,4 @@
-.\"	$Id: ptrace.2,v 1.4 1996/08/29 21:24:15 wosch Exp $
+.\"	$Id: ptrace.2,v 1.5 1996/09/23 22:22:40 wosch Exp $
 .\"	$NetBSD: ptrace.2,v 1.2 1995/02/27 12:35:37 cgd Exp $
 .\"
 .\" This file is in the public domain.
@@ -201,15 +201,18 @@ it loads the traced process' floating-point registers from the
 pointed to by
 .Fa addr .
 .El
-.Sh ERRORS
+.Sh RETURN VALUES
 Some requests can cause
 .Fn ptrace
 to return
 .Li -1
 as a non-error value; to disambiguate,
 .Va errno
-can be set to 0 before the call and checked afterwards.  The possible
-errors are:
+can be set to 0 before the call and checked afterwards.
+.Sh ERRORS
+The
+.Fn ptrace
+function may fail if:
 .Bl -tag -width 4n
 .It Bq Er ESRCH
 .Bl -bullet -compact

lib/libc/sys/rfork.2

@@ -14,7 +14,7 @@
 .Ft int
 .Fn rfork "int flags"
 .Sh DESCRIPTION
-Forking, vforking or rforking is the only way new processes are created.
+Forking, vforking or rforking are the only ways new processes are created.
 The
 .Fa flags
 argument to
@@ -28,7 +28,7 @@ the open file descriptor table (which, when shared, permits processes
 to open and close files for other processes),
 and open files.
 .Fa Flags
-is the logical OR of some subset of
+is the logical OR of some subset of:
 .Bl -tag -width "RFCNAMEG" -compact -offset indent
 .It RFPROC
 If set a new process is created; otherwise changes affect the
@@ -81,6 +81,16 @@ will sleep, if necessary, until required process resources are available.
 can be implemented as a call to
 .Fn rfork "RFFDG|RFPROC"
 but isn't for backwards compatibility.
+.Sh RETURN VALUES
+Upon successful completion,
+.Fn rfork
+returns a value
+of 0 to the child process and returns the process ID of the child
+process to the parent process.  Otherwise, a value of -1 is returned
+to the parent process, no child process is created, and the global
+variable
+.Va errno
+is set to indicate the error.
 .Sh ERRORS
 .Fn Rfork
 will fail and no child process will be created if:

lib/libc/sys/setsid.2

@@ -50,17 +50,20 @@ process group leader of a new process group and has no controlling
 terminal.
 The calling process is the only process in either the session or the
 process group.
-.Pp
+.Sh RETURN VALUES
 Upon successful completion, the
 .Fn setsid
 function returns the value of the process group ID of the new process
 group, which is the same as the process ID of the calling process.
-.Sh ERRORS
 If an error occurs,
 .Fn setsid
 returns -1 and the global variable
 .Va errno
-is set to indicate the error, as follows:
+is set to indicate the error.
+.Sh ERRORS
+The
+.Fn setsid
+function will fail if:
 .Bl -tag -width Er
 .It Bq Er EPERM
 The calling process is already a process group leader, or the process