document generic ioctls. ok art@

1 files changed, 49 insertions, 1 deletions

diff --git a/lib/libc/sys/ioctl.2 b/lib/libc/sys/ioctl.2
index 4a0d402f990..7397f552c06 100644
--- a/lib/libc/sys/ioctl.2
+++ b/lib/libc/sys/ioctl.2
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ioctl.2,v 1.12 2002/05/01 08:03:29 mpech Exp $
+.\"	$OpenBSD: ioctl.2,v 1.13 2002/08/08 03:59:57 wcobb Exp $
 .\"	$NetBSD: ioctl.2,v 1.5 1995/02/27 12:33:47 cgd Exp $
 .\"
 .\" Copyright (c) 1980, 1991, 1993
@@ -83,6 +83,54 @@ Macros and defines used in specifying an ioctl
 .Fa request
 are located in the file
 .Ao Pa sys/ioctl.h Ac .
+.Sh GENERIC IOCTLS
+Some ioctls are applicable to any file descriptor.
+These include:
+.Bl -tag -width "xxxxxx"
+.It Dv FIOCLEX
+Set close-on-exec flag.
+The file will be closed when
+.Xr exec 3
+is invoked.
+.It Dv FIONCLEX
+Clear close-on-exec flag.
+The file will remain open across
+.Xr exec 3 .
+.El
+.Pp
+Some generic ioctls are not implemented for all types of file
+descriptors.
+These include:
+.Bl -tag -width "xxxxxx"
+.It Dv FIONREAD "int"
+Get the number of bytes that are immediately available for reading.
+.It Dv FIONBIO "int"
+Set non-blocking I/O mode if the argument is non-zero.
+In non-blocking mode,
+.Xr read 2
+or
+.Xr write 2
+calls return \-1 and set
+.Va errno
+to
+.Er EAGAIN
+immediately when no data is available.
+.It Dv FIONASYNC "int"
+Set asynchronous I/O mode if the argument is non-zero.
+In asynchronous mode, the process or process group specified by
+.Dv FIOSETOWN
+will start receiving
+.Dv SIGIO
+signals when data is available.
+The
+.Dv SIGIO
+signal will be delivered when data is available on the file
+descriptor.
+.It Dv FIOSETOWN, FIOGETOWN "int"
+Set/get the process or the process group (if negative) that should receive
+.Dv SIGIO
+signals when data is available.
+.El
 .Sh RETURN VALUES
 If an error has occurred, a value of \-1 is returned and
 .Va errno