tty: add EXTPROC support for LINEMODE

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, and the data will be the contents of a struct termios. This allows the process on the server side of the pty to know when the state of the terminal has changed, and what the new state is.

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 For historical reference, a good copy of the relevant files can be found here: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

---
Howard Chu (2):
Add EXTPROC tty support for Telnet LINEMODE
Add arch-specific EXTPROC definitions

 arch/alpha/include/asm/ioctls.h     |    2 ++
 arch/alpha/include/asm/termbits.h   |    1 +
 arch/arm/include/asm/ioctls.h       |    2 ++
 arch/arm/include/asm/termbits.h     |    1 +
 arch/avr32/include/asm/ioctls.h     |    2 ++
 arch/avr32/include/asm/termbits.h   |    1 +
 arch/cris/include/asm/ioctls.h      |    2 ++
 arch/cris/include/asm/termbits.h    |    1 +
 arch/frv/include/asm/ioctls.h       |    2 ++
 arch/frv/include/asm/termbits.h     |    1 +
 arch/h8300/include/asm/ioctls.h     |    2 ++
 arch/h8300/include/asm/termbits.h   |    1 +
 arch/ia64/include/asm/ioctls.h      |    2 ++
 arch/ia64/include/asm/termbits.h    |    1 +
 arch/m32r/include/asm/ioctls.h      |    2 ++
 arch/m32r/include/asm/termbits.h    |    1 +
 arch/m68k/include/asm/ioctls.h      |    2 ++
 arch/m68k/include/asm/termbits.h    |    1 +
 arch/mips/include/asm/ioctls.h      |    3 ++-
 arch/mips/include/asm/termbits.h    |    1 +
 arch/mn10300/include/asm/ioctls.h   |    2 ++
 arch/mn10300/include/asm/termbits.h |    1 +
 arch/parisc/include/asm/ioctls.h    |    2 ++
 arch/parisc/include/asm/termbits.h  |    1 +
 arch/powerpc/include/asm/ioctls.h   |    2 ++
 arch/powerpc/include/asm/termbits.h |    1 +
 arch/s390/include/asm/ioctls.h      |    2 ++
 arch/sh/include/asm/ioctls.h        |    2 ++
 arch/sparc/include/asm/ioctls.h     |    2 ++
 arch/sparc/include/asm/termbits.h   |    1 +
 arch/xtensa/include/asm/ioctls.h    |    2 ++
 arch/xtensa/include/asm/termbits.h  |    1 +
 drivers/char/n_tty.c                |   25 ++++++++++++++++++++++---
 drivers/char/pty.c                  |   13 +++++++++++++
 drivers/char/tty_ioctl.c            |   18 ++++++++++++------
 fs/compat_ioctl.c                   |    1 +
 include/asm-generic/ioctls.h        |    2 ++
 include/asm-generic/termbits.h      |    1 +
 include/linux/tty.h                 |    1 +
 39 files changed, 101 insertions(+), 10 deletions(-)

  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/