Weird interaction between zpty and trap

Weird interaction between zpty and trap

[Felipe Contreras]

Hi,

Playing around with zpty I noticed some error messages coming
seemingly out of nowhere until I realized there was a trap.

Should the command executed by zpty keep the EXIT trap?

    zmodload zsh/zpty

    exec 3>&2
    die() { echo >&3 "die"; }
    trap 'die' EXIT
    zpty c ':'
    trap - EXIT

-- 
Felipe Contreras

Re: Weird interaction between zpty and trap

[Bart Schaefer]

On Tue, Mar 21, 2023 at 9:50 PM Felipe Contreras
<felipe.contreras@gmail.com> wrote:
>
> Should the command executed by zpty keep the EXIT trap?

Tough call.  It's technically a subshell, so by that distinction it
should follow the rules for subshells.

Aside, I never really thought about it before, but why wasn't zpty
implemented using the clone module?  Just to avoid a dependency?

Re: Weird interaction between zpty and trap

[Felipe Contreras]

On Wed, Mar 22, 2023 at 4:06 PM Bart Schaefer <schaefer@brasslantern.com> wrote:
>
> On Tue, Mar 21, 2023 at 9:50 PM Felipe Contreras
> <felipe.contreras@gmail.com> wrote:
> >
> > Should the command executed by zpty keep the EXIT trap?
>
> Tough call.  It's technically a subshell, so by that distinction it
> should follow the rules for subshells.

The documentation of trap says:

    ZERR and DEBUG traps are kept within subshells, while other traps are reset.

That sounds like EXIT should be reset.

-- 
Felipe Contreras

Re: Weird interaction between zpty and trap

[Felipe Contreras]

On Wed, Mar 22, 2023 at 5:07 PM Felipe Contreras
<felipe.contreras@gmail.com> wrote:
>
> On Wed, Mar 22, 2023 at 4:06 PM Bart Schaefer <schaefer@brasslantern.com> wrote:
> >
> > On Tue, Mar 21, 2023 at 9:50 PM Felipe Contreras
> > <felipe.contreras@gmail.com> wrote:
> > >
> > > Should the command executed by zpty keep the EXIT trap?
> >
> > Tough call.  It's technically a subshell, so by that distinction it
> > should follow the rules for subshells.
>
> The documentation of trap says:
>
>     ZERR and DEBUG traps are kept within subshells, while other traps are reset.
>
> That sounds like EXIT should be reset.

OK. I'm just going to assume it's a bug in zsh I'll have to workaround
by removing the EXIT trap manually every time inside the zpty
subshell.

-- 
Felipe Contreras