Commit Graph

335 Commits

Author SHA1 Message Date
Ed Schouten
328d9d2c96 Make TIOCSTI work again.
It looks like I didn't implement this when I imported MPSAFE TTY.
Applications like mail(1) still use this. I think it's conceptually bad.

Tested by:	Pete French <petefrench ticketswitch com>
MFC after:	2 weeks
2010-01-04 20:59:52 +00:00
Robert Noland
cfd7bacef2 Update d_mmap() to accept vm_ooffset_t and vm_memattr_t.
This replaces d_mmap() with the d_mmap2() implementation and also
changes the type of offset to vm_ooffset_t.

Purge d_mmap2().

All driver modules will need to be rebuilt since D_VERSION is also
bumped.

Reviewed by:	jhb@
MFC after:	Not in this lifetime...
2009-12-29 21:51:28 +00:00
Ed Schouten
6eaf04022b Don't allocate an input buffer for a TTY when the receiver is turned off.
When the termios CREAD flag is not set, it makes little sense to
allocate an input buffer. Just set the size to 0 in this case to reduce
memory footprint.

Disallow CREAD to be disabled for pseudo-devices to prevent
foot-shooting.
2009-12-01 19:14:57 +00:00
Konstantin Belousov
a3de221dbe Among signal generation syscalls, only sigqueue(2) is allowed by POSIX
to fail due to lack of resources to queue siginfo. Add KSI_SIGQ flag
that allows sigqueue_add() to fail while trying to allocate memory for
new siginfo. When the flag is not set, behaviour is the same as for
KSI_TRAP: if memory cannot be allocated, set bit in sq_kill. KSI_TRAP is
kept to preserve KBI.

Add SI_KERNEL si_code, to be used in siginfo.si_code when signal is
generated by kernel. Deliver siginfo when signal is generated by kill(2)
family of syscalls (SI_USER with properly filled si_uid and si_pid), or
by kernel (SI_KERNEL, mostly job control or SIGIO). Since KSI_SIGQ flag
is not set for the ksi, low memory condition cause old behaviour.

Keep psignal(9) KBI intact, but modify it to generate SI_KERNEL
si_code. Pgsignal(9) and gsignal(9) now take ksi explicitely. Add
pksignal(9) that behaves like psignal but takes ksi, and ddb kill
command implemented as pksignal(..., ksi = NULL) to not do allocation
while in debugger.

While there, remove some register specifiers and use ANSI C prototypes.

Reviewed by:	davidxu
MFC after:	1 month
2009-11-17 11:39:15 +00:00
Ed Schouten
6015f6f35a Properly set the low watermarks when reducing the baud rate.
Now that buffers are deallocated lazily, we should not use
tty*q_getsize() to obtain the buffer size to calculate the low
watermarks. Doing this may cause the watermark to be placed outside the
typical buffer size.

This caused some regressions after my previous commit to the TTY code,
which allows pseudo-devices to resize the buffers as well.

Reported by:	yongari, dougb
MFC after:	1 week
2009-10-19 07:17:37 +00:00
Ed Schouten
5ed8d12443 Allow the buffer size to be configured for pseudo-like TTY devices.
Devices that don't implement param() (which means they don't support
hardware parameters such as flow control, baud rate) hardcode the baud
rate to TTYDEF_SPEED. This means the buffer size cannot be configured,
which is a little inconvenient when using canonical mode with big lines
of input, etc.

Make it adjustable, but do clamp it between B50 and B115200 to prevent
awkward buffer sizes. Remove the baud rate assignment from
/etc/gettytab. Trust the kernel to fill in a proper value.

Reported by:	Mikolaj Golub <to my trociny gmail com>
MFC after:	1 month
2009-10-18 19:48:53 +00:00
Ed Schouten
99087885be Make lock devices work properly.
It turned out I did add the code to use the init state devices to set
the termios structure when opening the device, but it seems I totally
forgot to add the bits required to force the actual locking of flags
through the lock state devices.

Reported by:	ru
MFC after:	1 week (to be discussed)
2009-10-18 19:45:44 +00:00
Robert Watson
e76d823b81 Use C99 initialization for struct filterops.
Obtained from:	Mac OS X
Sponsored by:	Apple Inc.
MFC after:	3 weeks
2009-09-12 20:03:45 +00:00
Ed Schouten
6b53d5c0e7 Fix regressions in return events of poll() on TTYs.
As pointed out, POLLHUP should be generated, even if it hasn't been
specified on input. It is also not allowed to return both POLLOUT and
POLLHUP at the same time.

Reported by:	jilles
Approved by:	re (kib)
2009-07-08 10:21:52 +00:00
Ed Schouten
f9bb1cf010 Add FIONWRITE support to TTYs.
TTYs already supported TIOCOUTQ, but FIONWRITE seems to be a more
generic name for this.

Approved by:	re (kib)
2009-06-28 12:02:15 +00:00
Ed Schouten
9801591468 Improve my last commit: use a separate condvar to serialize.
The advantage of using a separate condvar is that we can just use
cv_signal(9) instead of cv_broadcast(9). It makes no sense to wake up
multiple threads. It also makes the TTY code easier to understand.
t_dcdwait sounds totally unrelated.
2009-06-23 21:43:02 +00:00
Ed Schouten
2d41cf3a24 Use dcdwait to block threads to serialize writes.
I suspect the usage of bgwait causes a lot of spurious wakeups when
threads are blocked in the background, because they will be woken up
each time a write() call is performed.

Also wakeup dcdwait when the TTY is abandoned.
2009-06-23 21:33:26 +00:00
Ed Schouten
f8f6146082 Improve nested jail awareness of devfs by handling credentials.
Now that we start to use credentials on character devices more often
(because of MPSAFE TTY), move the prison-checks that are in place in the
TTY code into devfs.

Instead of strictly comparing the prisons, use the more common
prison_check() function to compare credentials. This means that
pseudo-terminals are only visible in devfs by processes within the same
jail and parent jails.

Even though regular users in parent jails can now interact with
pseudo-terminals from child jails, this seems to be the right approach.
These processes are also capable of interacting with the jailed
processes anyway, through signals for example.

Reviewed by:	kib, rwatson (older version)
2009-06-20 14:50:32 +00:00
Ed Schouten
eaaaf1906b Perform some more cleanups to in-kernel session handling.
The code that was in place in exit1() was mainly based on code from the
old TTY layer. The main reason behind this, was because at one moment I
ran a system that had two TTY layers in place at the same time. It is
now sufficient to do the following:

- Remove references from the session structure to the TTY vnode and the
  session leader.

- If we have a controlling TTY and the session used by the TTY is equal
  to our session, send the SIGHUP.

- If we have a vnode to the controlling TTY which has not been revoked,
  revoke it.

While there, change sys/kern/tty.c to use s_ttyp in the comparison
instead of s_ttyvp. It should not make any difference, because s_ttyvp
can only become null when the session leader already left, but it's
nicer to compare against the proper value.
2009-06-15 20:45:51 +00:00
Ed Schouten
9c373a81a3 Make tcsetsid(3) work on revoked TTYs.
Right now the only way to make tcsetsid(3)/TIOCSCTTY work, is by
ensuring the session leader is dead. This means that an application that
catches SIGHUPs and performs a sleep prevents us from assigning a new
session leader.

Change the code to make it work on revoked TTYs as well. This allows us
to change init(8) to make the shutdown script run in a more clean
environment.
2009-06-15 19:17:52 +00:00
Ed Schouten
13ace80b16 Revert my previous change, because it reintroduces an old regression.
Because our rc scripts also open the /etc/ttyv* nodes, it revokes the
console, preventing startup messages from being displayed.

I really have to think about this. Maybe we should just give the console
its own TTY and let it build on top of other TTYs. I'm still not sure
what to do with input handling there.
2009-06-12 21:21:17 +00:00
Ed Schouten
4650ad4cc0 Prevent yet another staircase effect bug in the console device.
Even though I thought I fixed the staircase issue (and I was no longer
able to reproduce it), I got some reports of the issue still being
there. It turns out the staircase effect still occurred when
/dev/console was kept open while killing the getty on the same TTY
(ttyv0).

For some reason I can't figure out how the old TTY code dealt with that,
so I assume the issue has always been there. I only exposed it more by
merging consolectl with ttyv0, which means that the issue was present,
even on systems without a serial console.

I'm now marking the console device as being closed when closing the
regular TTY device node. This means that when the getty shuts down,
init(8) will open /dev/console, which means the termios attributes will
always be reset in this case.
2009-06-12 20:29:55 +00:00
Konstantin Belousov
d8b0556c6d Adapt vfs kqfilter to the shared vnode lock used by zfs write vop. Use
vnode interlock to protect the knote fields [1]. The locking assumes
that shared vnode lock is held, thus we get exclusive access to knote
either by exclusive vnode lock protection, or by shared vnode lock +
vnode interlock.

Do not use kl_locked() method to assert either lock ownership or the
fact that curthread does not own the lock. For shared locks, ownership
is not recorded, e.g. VOP_ISLOCKED can return LK_SHARED for the shared
lock not owned by curthread, causing false positives in kqueue subsystem
assertions about knlist lock.

Remove kl_locked method from knlist lock vector, and add two separate
assertion methods kl_assert_locked and kl_assert_unlocked, that are
supposed to use proper asserts. Change knlist_init accordingly.

Add convenience function knlist_init_mtx to reduce number of arguments
for typical knlist initialization.

Submitted by:	jhb [1]
Noted by:	jhb [2]
Reviewed by:	jhb
Tested by:	rnoland
2009-06-10 20:59:32 +00:00
Konstantin Belousov
ce3fa4d5cf Do not dereference vp->v_rdev without holding any of dev_mtx or vnode
lock. Use code similar to devfs_fp_check(), but inlined to feet other
checks performed by ttyhook_register().

Reviewed by:	ed
2009-06-08 13:34:45 +00:00
Ed Schouten
c5e30cc02b Last minute TTY API change: remove mutex argument from tty_alloc().
I don't want people to override the mutex when allocating a TTY. It has
to be there, to keep drivers like syscons happy. So I'm creating a
tty_alloc_mutex() which can be used in those cases. tty_alloc_mutex()
should eventually be removed.

The advantage of this approach, is that we can just remove a function,
without breaking the regular API in the future.
2009-05-29 06:41:23 +00:00
Ed Schouten
8b0d29d858 Get rid of M_TEMP. 2009-05-26 18:33:36 +00:00
Ed Schouten
47e6a3971f Block when initially opening a TTY multiple times.
In the original MPSAFE TTY code, I changed the behaviour by returning
EBUSY. I thought this made more sense, because it's basically a race to
see who gets the TTY first.

It turns out this is not a good change, because it also causes EBUSY to
be returned when another process is closing the TTY. This can happen
during startup, when /etc/rc (or one of its children) is still busy
draining its data and /sbin/init is attempting to open the TTY to spawn
a getty.

Reported by:	bz
Tested by:	bz
2009-05-24 12:32:03 +00:00
Jeff Roberson
bf422e5f27 - Implement a lockless file descriptor lookup algorithm in
fget_unlocked().
 - Save old file descriptor tables created on expansion until
   the entire descriptor table is freed so that pointers may be
   followed without regard for expanders.
 - Mark the file zone as NOFREE so we may attempt to reference
   potentially freed files.
 - Convert several fget_locked() users to fget_unlocked().  This
   requires us to manage reference counts explicitly but reduces
   locking overhead in the common case.
2009-05-14 03:24:22 +00:00
Ed Schouten
3382ac3233 Remove unneeded check for SESS_LEADER().
We perform the same check ~10 lines above.
2009-05-04 11:11:10 +00:00
Ed Schouten
e3b0b98073 Fix tty_wait_background() to comply with standards.
It turns out my handling of SIGTTOU and SIGTTIN didn't entirely comply
to the standards. It is true that in the SIGTTOU case we should not
return EIO when the signal is ignored/blocked, but in the SIGTTIN case
we must.

See also:	POSIX issue 7 section 11.1.4
2009-04-08 15:56:50 +00:00
Ed Schouten
c4d4bcdaf6 Improve my previous changes to the TTY code: also remove memcpy().
It's better to just use internal language constructs, because it is
likely the compiler has a better opinion on whether to perform inlining,
which is very likely to happen to struct winsize.

Submitted by:	Christoph Mallon <christoph mallon gmx de>
2009-03-01 09:50:13 +00:00
Ed Schouten
4b2d6aaf4b Replace bcopy() calls inside the TTY layer with memcpy()/strlcpy().
In all these cases the buffers never overlap. Program names are also
likely to be shorter, so use a regular strlcpy() to copy p_comm.
2009-02-28 14:20:26 +00:00
Ed Schouten
c0086bf202 Serialize write() calls on TTYs.
Just like the old TTY layer, the current MPSAFE TTY layer does not make
any attempt to serialize calls of write(). Data is copied into the
kernel in 256 (TTY_STACKBUF) byte chunks. If a write() call occurs at
the same time, the data may interleave. This is especially likely when
the TTY starts blocking, because the output queue reaches the high
watermark.

I've implemented this by adding a new flag, TTY_BUSY_OUT, which is used
to mark a TTY as having a thread stuck in write(). Because I don't want
non-blocking processes to be possibly blocked by a sleeping thread, I'm
still allowing it to bypass the protection. According to this message,
the Linux kernel returns EAGAIN in such cases, but I think that's a
little too restrictive:

	http://kerneltrap.org/index.php?q=mailarchive/linux-kernel/2007/5/2/85418/thread

PR:		kern/118287
2009-02-11 16:28:49 +00:00
Ed Schouten
c3328b2ab8 Don't leave the console TTY constantly open.
When we leave the console TTY constantly open, we never reset the
termios attributes. This causes output processing, echoing, etc. not to
be reset to the proper values when going into single user mode after the
system has booted. It also causes nl-to-crnl-conversion not to take
place during shutdown, which causes a `staircase effect'.

This patch adds a new TTY flag, TF_OPENED_CONS, which is set when the
TTY is opened through /dev/console. Because the flags are only used by
the kernel and the pstat(8) utility, I've decided to renumber the TTY
flags. This shouldn't be an issue, because the TTY layer is not yet part
of a stable release.

Reported by:	Mark Atkinson <atkin901 yahoo com>
Tested by:	sepotvin
2009-02-05 14:21:09 +00:00
Ed Schouten
41ba7e9b13 Slightly improve the design of the TTY buffer.
The TTY buffers used the standard <sys/queue.h> lists. Unfortunately
they have a big shortcoming. If you want to have a double linked list,
but no tail pointer, it's still not possible to obtain the previous
element in the list. Inside the buffers we don't need them. This is why
I switched to custom linked list macros. The macros will also keep track
of the amount of items in the list. Because it doesn't use a sentinel,
we can just initialize the queues with zero.

In its simplest form (the output queue), we will only keep two
references to blocks in the queue, namely the head of the list and the
last block in use. All free blocks are stored behind the last block in
use.

I noticed there was a very subtle bug in the previous code: in a very
uncommon corner case, it would uma_zfree() a block in the queue before
calling memcpy() to extract the data from the block.
2009-02-03 19:58:28 +00:00
Ed Schouten
8e700fb80c Use the proper flag to let kern.ttys be executed without Giant.
Pointed out by:	jhb
2009-01-26 16:43:18 +00:00
Ed Schouten
bfcbfff0c7 Mark kern.ttys as MPSAFE.
sysctl now allows Giantless calls, so make kern.ttys use this. If it
needs Giant, it locks the proper TTY anyway.
2009-01-24 18:20:15 +00:00
Ed Schouten
bcca92c0e5 Fix a corner case in my previous commit.
Even though there are not many setups that have absolutely no console
device, make sure a close() on a TTY doesn't dereference a null pointer.
2009-01-02 23:39:29 +00:00
Ed Schouten
916501c81c Don't let /dev/console be revoked if the TTY below is being closed.
During startup some of the syscons TTY's are used to set attributes like
the screensaver and mouse options. These actions cause /dev/console to
be rendered unusable.

Fix the issue by leaving the TTY opened when it is used as the console
device.

Reported by:	imp
2009-01-02 23:32:43 +00:00
Ed Schouten
9d34a1338c Let wchan names more closely match pre-MPSAFE TTY behaviour.
Right now the wchan strings "ttyinp" and "ttybgw" only differ one
character from the strings we used prior to MPSAFE TTY. Just rename them
back to their pre-MPSAFE TTY counterparts.

Also rename "ttylck" to "ttymtx", which should make it more clear that a
process is blocked on the TTY mutex, not some other form of locking.
2008-12-20 09:36:40 +00:00
Ivan Voras
bb501b18e8 Further beautify the lock strings to be more pleasing to the eye and
self documenting within 6 characters.

Reviewed by:	ed (older version)
Approved by:	gnn (older version)
2008-12-19 14:49:14 +00:00
Ivan Voras
0e469db660 Remove spaces in wait object names to make top (1) output prettier and
unbreak scripts that examine ps (1) output.

Reviewed by:	ed
Approved by:	gnn (mentor)
2008-12-18 15:25:33 +00:00
Alexander Motin
a9385ad10f Change ttyhook_register() second argument from thread to process pointer.
Thread was not really needed there, while previous ng_tty implementation
that used thread pointer had locking issues (using sx while holding mutex).
2008-12-13 21:17:46 +00:00
Ed Schouten
5bbae50149 Reduce the default baud rate of PTY's to 9600.
On RELENG_6 (and probably RELENG_7) we see our syscons windows and
pseudo-terminals have the following buffer sizes:

| LINE RAW CAN OUT IHIWT ILOWT OHWT LWT     COL STATE  SESS      PGID DISC
| ttyv0  0   0   0  7680  6720 2052 256       7 OCcl       1146  1146 term
| ttyp0  0   0   0  7680  6720 1296 256       0 OCc       82033 82033 term

These buffer sizes make no sense, because we often have much more output
than input, but I guess having higher input buffer sizes improves
guarantees of the system.

On MPSAFE TTY I just sent both the input and output buffer sizes to 7
KB, which is pretty big on a standard FreeBSD install with 8 syscons
windows and some PTY's. Reduce the baud rate to 9600 baud, which means
we now have the following buffer sizes:

|  LINE   INQ  CAN  LIN  LOW  OUTQ  USE  LOW   COL  SESS  PGID STATE
| ttyv0  1920    0    0  192  1984    0  199     7  2401  2401 Oil
| pts/0  1920    0    0  192  1984    0  199  5631  1305  2526 Oi

This is a lot smaller, but for pseudo-devices this should be good
enough. You need to do a lot of punching to fill up a 7.5 KB input
buffer. If it turns out things don't work out this way, we'll just
switch to 19200 baud.
2008-11-08 20:40:39 +00:00
Ed Schouten
37a9f58275 Clamp the values of t_column to 5 digits in pstat -t' and show all ttys'.
We often run into these very high column numbers when we run curses
applications, because they don't print any newlines. This messes up the
table output of `pstat -t'. If these numbers get really high, they
aren't of any use to the reader anyway. Convert them to `99999' when
they run out of bounds.
2008-11-01 13:40:46 +00:00
Ed Schouten
c9dba40cc8 Reimplement the /dev/console device node.
One of the pieces of code that I had left alone during the development
of the MPSAFE TTY layer, was tty_cons.c. This file actually has two
different functions:

- It contains low-level console input/output routines (cnputc(), etc).

- It creates /dev/console and wraps all its cdevsw calls to the
  appropriate TTY.

This commit reimplements the second set of functions by moving it
directly into the TTY layer. /dev/console is now a character device node
that's basically a regular TTY, but does a lookup of `si_drv1' each time
you open it. d_write has also been changed to call log_console().
d_close() is not present, because we must make sure we don't revoke the
TTY after writing a log message to it.

Even though I'm not convinced this is in line with the future directions
of our console code, it is a good move for now. It removes recursive
locking from the top half of the TTY layer. The previous implementation
called into the TTY layer with Giant held.

I'm renaming tty_cons.c to kern_cons.c now. The code hardly contains any
TTY related bits, so we'd better give it a less misleading name.

Tested by:	Andrzej Tobola <ato iem pw edu pl>,
		Carlos A.M. dos Santos <unixmania gmail com>,
		Eygene Ryabinkin <rea-fbsd codelabs ru>
2008-11-01 08:35:28 +00:00
Andrew Thompson
93113aac8c Fix spelling mistake in the last rev. 2008-10-21 14:44:25 +00:00
Andrew Thompson
8429751f67 If we have getc_inject hooked then the outq buffer is inaccessible to the
driver so skip the drain rather than waiting indefinitely.

Reviewed by:	ed
2008-10-21 14:18:45 +00:00
Ed Schouten
f6dd5c15fd Import some improvements to the TTY code from the MPSAFE TTY branch.
- Change the ddb(4) commands to be more useful (by thompsa@):
  - `show ttys' is now called `show all ttys'. This command will now
    also display the address where the TTY data structure resides.
  - Add `show tty <addr>', which dumps the TTY in a readable form.

- Place an upper bound on the TTY buffer sizes. Some drivers do not want
  to care about baud rates. Protect these drivers by preventing the TTY
  buffers from getting enormous. Right now we'll just clamp it to 64K,
  which is pretty high, taking into account that these buffers are only
  used by the built-in discipline.

- Only call ttydev_leave() when needed. Back in April/May the TTY
  reference counting mechanism was a little different, which required us
  to call ttydev_leave() each time we finished a cdev operation.
  Nowadays we only need to call ttydev_leave() when we really mark it as
  being closed.

- Improve return codes of read() and write() on TTY device nodes.

- Make sure we really wake up all blocked threads when the driver calls
  tty_rel_gone(). There were some possible code paths where we didn't
  properly wake up any readers/writers.

- Add extra assertions to prevent sleeping on a TTY that has been
  abandoned by the driver.

- Use ttydev_cdevsw as a more reliable method to figure out whether a
  device node is a real TTY device node.

Obtained from:	//depot/projects/mpsafetty/...
Reviewed by:	thompsa
2008-10-15 16:58:35 +00:00
Ed Schouten
dacf7de1a6 Don't forget to initialize `int error' in ttydev_open().
I've had some reports in the past that opening an already opened TTY
through, for example, /dev/tty can fail with random error codes. Looking
at ttydev_open(), I can see there is a way `error' is returned without
initialising it. Even though I haven't had any confirmation this fixes
the bug, I'll fix it anyway.

Reported by:	Andrzej Tobola <ato iem pw edu pl>
2008-09-26 18:17:04 +00:00
Ed Schouten
4c7428e1ff Fix a crash when calling tty_rel_free() while draining during closure.
Yesterday I got two reports of potential crashes, related to TTY
deallocation during device closure. When a thread is in TF_OPENCLOSE,
draining its output upon closure, we should not allow calls to
tty_rel_free() to happen at the same time. This could cause the TTY to
be torn down twice.

PR:		kern/127561
Reported by:	KOIE Hidetaka <koie suri co jp>
Discussed with:	thompsa
2008-09-24 11:16:09 +00:00
Ed Schouten
a1215e37a4 Introduce a hooks layer for the MPSAFE TTY layer.
One of the features that prevented us from fixing some of the TTY
consumers to work once again, was an interface that allowed consumers to
do the following:

- `Sniff' incoming data, which is used by the snp(4) driver.

- Take direct control of the input and output paths of a TTY, which is
  used by ng_tty(4), ppp(4), sl(4), etc.

There's no practical advantage in committing a hooks layer without
having any consumers. In P4 there is a preliminary port of snp(4) and
thompsa@ is busy porting ng_tty(4) to this interface. I already want to
have it in the tree, because this may stimulate others to work on the
remaining modules.

Discussed with:	thompsa
Obtained from:	//depot/projects/mpsafetty/...
2008-09-22 19:25:14 +00:00
Ed Schouten
42ff2756c7 Fix minor TTY API inconsistency.
Unlike tty_rel_gone() and tty_rel_sess(), the tty_rel_pgrp() routine
does not unlock the TTY. I once had the idea to make the code call
tty_rel_pgrp() and tty_rel_sess(), picking up the TTY lock once. This
turned out a little harder than I expected, so this is how it works now.

It's a lot easier if we just let tty_rel_pgrp() unlock the TTY, because
the other routines do this anyway.
2008-09-16 14:57:23 +00:00
Ed Schouten
3c8574bc8a Make TIOCCONS use priv_check() instead of checking /dev/console permissions.
As discussed with Robert on IRC, checking the permissions on
/dev/console to see if we can call TIOCCONS could be unreliable. When we
run a chroot() without a devfs instance mounted inside, it won't
actually check the permissions on the device node inside the devfs
instance.

Using the already existing PRIV_TTY_CONSOLE for this seems like a better
idea.

Approved by:	rwatson
2008-09-06 14:43:32 +00:00
Ed Schouten
64308260f6 Implement pts(4) packet mode.
As reported by several users on the mailing lists, applications like
screen(1) fail to properly handle ^S and ^Q characters. This was because
MPSAFE TTY didn't implement packet mode (TIOCPKT) yet. Add basic packet
mode support to make these applications work again.

Obtained from:	//depot/projects/mpsafetty/...
2008-09-04 16:39:02 +00:00