ssh localhost yes | true

[Kyle McKay]

Yup, you're right.  Apple has disabled the USE_PIPES define in their  
source code.

Here's the original file:

http://www.opensource.apple.com/darwinsource/10.5.6/OpenSSH-95.1.5/openssh/session.c.orig

And the file they're using:

http://www.opensource.apple.com/darwinsource/10.5.6/OpenSSH-95.1.5/openssh/session.c

Here's the diff:

--- session.c.orig
+++ session.c
@@ -424,7 +424,9 @@
  	}
  }

+#ifndef __APPLE__
  #define USE_PIPES
+#endif
  /*
   * This is called to fork and execute a command when we have no  
tty.  This
   * will call do_child from the child, and server_loop from the  
parent after
@@ -2082,8 +2084,10 @@
  		n_bytes = packet_remaining();
  	tty_parse_modes(s->ttyfd, &n_bytes);

+#ifndef __APPLE_PRIVPTY__
  	if (!use_privsep)
  		pty_setowner(s->pw, s->tty);
+#endif

  	/* Set window size from the packet. */
  	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s- 
 >ypixel);
@@ -2321,9 +2325,11 @@
  	if (s->pid != 0)
  		record_logout(s->pid, s->tty, s->pw->pw_name);

+#ifndef __APPLE_PRIVPTY__
  	/* Release the pseudo-tty. */
  	if (getuid() == 0)
  		pty_release(s->tty);
+#endif

  	/*
  	 * Close the server side of the socket pairs.  We must do this after

Thanks for your help.

Kyle

On Apr 20, 2009, at 23:53, Damien Miller wrote:
> On Mon, 20 Apr 2009, Kyle McKay wrote:
>
>> Thanks for your response.
>>
>> On Apr 20, 2009, at 23:10, Damien Miller wrote:
>>>
>>> This doesn't look like bug#85 based on what you sent below. It looks
>>> more like a whatever that you were running failing to notice its  
>>> stdout
>>> closing.
>>
>> Actually after looking at this some more, I think Apple's sshd is  
>> just
>> missing the Bug 85 patch and I think the debug messages back this up.
>
> No, Apple's sshd clearly does have the bug #85 patch:
>
>> debug2: channel 0: rcvd eow
>
> Would not be printed otherwise. Perhaps they have forcibly disabled
> USE_PIPES in session.c? It is required for the patch to correctly
> function.
>
>> And in this case sshd included the Bug 85 fix and so was using  
>> pipes to
>> communicate with the child and the child therefore got a SIGPIPE on  
>> the input
>> open -> closed transition and exited.
>
> No, in both cases the signalling between sshd and the child process is
> identical from the logs. There may be differences depending on whether
> Apple has modified their sshd to avoid using pipes (thwarting the
> half-close fix in the process), but you will need to post a full debug
> log from the server to tell.
>
> -d