openssh 2.9p1: data loss when stdout sent to a pipe

[Markus Friedl]

On Fri, Jun 15, 2001 at 02:19:44PM -0400, Philip Spencer wrote:
> --- openssh-2.9p1/clientloop.c.losesdata	Fri Apr 20 08:50:51 2001
> +++ openssh-2.9p1/clientloop.c	Fri Jun 15 14:13:32 2001
> @@ -787,12 +787,15 @@
> 
>  	if (!compat20) {
>  		/* enable nonblocking unless tty */
> +                /* REMOVED for now since it prevents ssh command output from
> +                   being reliably sent to a pipe. - PHS 2001/06/15
>  		if (!isatty(fileno(stdin)))
>  			set_nonblock(fileno(stdin));
>  		if (!isatty(fileno(stdout)))
>  			set_nonblock(fileno(stdout));
>  		if (!isatty(fileno(stderr)))
>  			set_nonblock(fileno(stderr));
> +                */
>  		max_fd = MAX(max_fd, fileno(stdin));
>  		max_fd = MAX(max_fd, fileno(stdout));
>  		max_fd = MAX(max_fd, fileno(stderr));
> 
> Now, presumably those lines were added to the source code to address some
> other problem (perhaps one of the hanging problems I see mentioned on the
> list?) So simply removing them as per my patch above, while it works fine
> on our site, probably isn't the optimal solution.

we now do this (in -current):

        /* restore blocking io */
        if (!isatty(fileno(stdin)))
                unset_nonblock(fileno(stdin));
        if (!isatty(fileno(stdout)))
                unset_nonblock(fileno(stdout));
        if (!isatty(fileno(stderr)))
                unset_nonblock(fileno(stderr));

before flushing stdout/stderr.

-m