tty: Add EXTPROC support for LINEMODE

This patch is against the 2.6.34 source.

Paraphrased from the 1989 BSD patch by David Borman @ cray.com:

     These are the changes needed for the kernel to support
     LINEMODE in the server.

     There is a new bit in the termios local flag word, EXTPROC.
     When this bit is set, several aspects of the terminal driver
     are disabled.  Input line editing, character echo, and mapping
     of signals are all disabled.  This allows the telnetd to turn
     off these functions when in linemode, but still keep track of
     what state the user wants the terminal to be in.

     New ioctl:
         TIOCSIG         Generate a signal to processes in the
                         current process group of the pty.

     There is a new mode for packet driver, the TIOCPKT_IOCTL bit.
     When packet mode is turned on in the pty, and the EXTPROC bit
     is set, then whenever the state of the pty is changed, the
     next read on the master side of the pty will have the TIOCPKT_IOCTL
     bit set.  This allows the process on the server side of the pty
     to know when the state of the terminal has changed; it can then
     issue the appropriate ioctl to retrieve the new state.

Since the original BSD patches accompanied the source code for telnet
I've left that reference here, but obviously the feature is useful for
any remote terminal protocol, including ssh.

The corresponding feature has existed in the BSD tty driver since 1989.
For historical reference, a good copy of the relevant files can be found
here:

http://anonsvn.mit.edu/viewvc/krb5/trunk/src/appl/telnet/?pathrev=17741

Signed-off-by: Howard Chu <hyc@symas.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 3 insertions, 1 deletions

diff --git a/arch/mips/include/asm/ioctls.h b/arch/mips/include/asm/ioctls.h
index 2fb9e1693bf7..d87cb0465693 100644
--- a/arch/mips/include/asm/ioctls.h
+++ b/arch/mips/include/asm/ioctls.h
@@ -41,7 +41,7 @@
 #define	 TIOCPKT_START		0x08	/* start output */
 #define	 TIOCPKT_NOSTOP		0x10	/* no more ^S, ^Q */
 #define	 TIOCPKT_DOSTOP		0x20	/* now do ^S ^Q */
-/* #define  TIOCPKT_IOCTL		0x40	state change of pty driver */
+#define  TIOCPKT_IOCTL		0x40	/* state change of pty driver */
 #define TIOCSWINSZ	_IOW('t', 103, struct winsize)	/* set window size */
 #define TIOCGWINSZ	_IOR('t', 104, struct winsize)	/* get window size */
 #define TIOCNOTTY	0x5471		/* void tty association */
@@ -83,6 +83,7 @@
 #define TCSETSF2	_IOW('T', 0x2D, struct termios2)
 #define TIOCGPTN	_IOR('T', 0x30, unsigned int) /* Get Pty Number (of pty-mux device) */
 #define TIOCSPTLCK	_IOW('T', 0x31, int)  /* Lock/unlock Pty */
+#define TIOCSIG		_IOW('T', 0x36, int)  /* Generate signal on Pty slave */
 
 /* I hope the range from 0x5480 on is free ... */
 #define TIOCSCTTY	0x5480		/* become controlling tty */
diff --git a/arch/mips/include/asm/termbits.h b/arch/mips/include/asm/termbits.h
index c83c68444e86..76630b396fac 100644
--- a/arch/mips/include/asm/termbits.h
+++ b/arch/mips/include/asm/termbits.h
@@ -203,6 +203,7 @@ struct ktermios {
 #define PENDIN	0040000		/* Retype pending input (state).  */
 #define TOSTOP	0100000		/* Send SIGTTOU for background output.  */
 #define ITOSTOP	TOSTOP
+#define EXTPROC	0200000		/* External processing on pty */
 
 /* ioctl (fd, TIOCSERGETLSR, &result) where result may be as below */
 #define TIOCSER_TEMT    0x01	/* Transmitter physically empty */