Re: Possible ZSH bug with IO direction

["Peter A. Castro" <doctor@fruitbat.org>]

On Mon, 25 Apr 2016, Bart Schaefer wrote:

> Date: Mon, 25 Apr 2016 10:47:49 -0700
> From: Bart Schaefer <schaefer@brasslantern.com>
> To: Peter A. Castro <doctor@fruitbat.org>
> Cc: Zsh hackers list <zsh-workers@zsh.org>
> Subject: Re: Possible ZSH bug with IO direction
> 
> On Mon, Apr 25, 2016 at 10:31 AM, Peter A. Castro <doctor@fruitbat.org> wrote:
>>
>> I believe the best solution is to teach Zsh code to handle CR+LF properly,
>
> Which means we're back to the "dozens of source modules" you mentioned.
> There's no central place for this; because of vagaries of other I/O systems
> (e.g. STREAMS modules), there's not even a consistent use of stdio vs.
> low-level read/write (though at least they're usually not mixed on the same
> descriptors).

Yes...I had noticed that in my first few attempts at "fixing" the code.
I quickly became overwhelmed at the scope of things.

> I haven't looked closely at this (and have no idea whether it's possible with
> the pre-main hook in place) but perhaps put the descriptors back into
> binary mode somewhere in exec.c between whatever passes for zfork()
> on cygwin and the actual execve() of any external process?  We mostly
> know when a zsh builtin vs. an external command is being run.

I did consider this, but there's something about using the pre-main hooks 
that prevents resetting the attributes.  I'll ask Corinna about it, but I 
suspect there isn't a way of doing it once the pre-main has been invoked.

In anycase, this also leads to your next comment:

> Either way the external commands are on their own -- the question is
> whether they're better off getting binary when they expect text or the
> other way around (as currently).

That is its own can of worms.  The later is what mostly-works for 95% of 
the use-cases.  There is no good solution here, I'm afraid.

So, to sum things up:
   pre-main hook is bad.
   CR+LF is evil.
   Teaching the code to grok CR+LF is hard.
   Users don't like change and expect things to "just work".

Am I missing anything?  :-/

-- 
--=> Peter A. Castro
Email: doctor at fruitbat dot org / Peter dot Castro at oracle dot com
 	"Cats are just autistic Dogs" -- Dr. Tony Attwood