Re: ^D is broken in shell-mode

[David De La Harpe Golden <david@harpegolden.net>]

On 08/06/10 21:22, Stefan Monnier wrote:
>> It now results in a literal ^D being seen by the subproces.
>> I vaguely recall seeing recently that emacs stopped using ICANON mode
>> for ptys; I presume this is the cause?
>
> Yes.
>
>> It's been a long time since I did pty programming, but I seem to recall
>> that at least in some pty states, doing a zero-length write in the pty
>> master will send an end-of-file to the slave tty.  I don't recall the
>> details though...
>

FWIW, The write(3) manpage has this to say (about pipes not ptys):

 > Also,  some  existing  systems (for  example,  Eighth  Edition)
 > permit a write of zero bytes to mean that the reader should get an
 > end-of-file indication; for those systems, a return value of zero
 > from write() indicates a successful write of an end-of-file
 > indication.

That's possibly what Miles is recollecting?

I'm not sure it works for ptys, or that it's actually TRT here...

> I really wish someone could help.

Not necessarily helping:

If you turn off ICANON, it's little wonder EOF char is just
passed through?

This page here:
http://www.lafn.org/~dave/linux/terminalIO.html

makes the claim:

"""
Cooked mode is the default state of your terminal for almost all shells. 
At least when you execute another program with the shell, the terminal 
is put into cooked mode before it makes a call to an exec function.
"""

Stty in shell exec'd processes and shell children do indeed show a 
cooked terminal on my system, so likely emacs when in its capacity as a 
"normal" shell / superior process should be ensuring the pty slave it 
hands to children is ICANON out-of-box?

But n.b. that means the MAX_INPUT/MAX_CANON limits described at that 
link would apply.