From: Stephane Chazelas <stephane@chazelas.org>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: Zsh hackers list <zsh-workers@zsh.org>
Subject: unset, POSIX and the export attribute (Was: [PATCH] Fix crash on unset-through-nameref)
Date: Tue, 5 Mar 2024 19:48:57 +0000 [thread overview]
Message-ID: <20240305194857.6e7ublhkdo276r3k@chazelas.org> (raw)
In-Reply-To: <CAH+w=7bJsoJcDz0aNr9G11On4a_fssw3QJHTrtzQnT75n8A-Hw@mail.gmail.com>
2024-03-05 10:42:18 -0800, Bart Schaefer:
> On Tue, Mar 5, 2024 at 12:19 AM Stephane Chazelas <stephane@chazelas.org> wrote:
> >
> > 2024-03-04 15:18:06 -0800, Bart Schaefer:
> > > On Mon, Mar 4, 2024 at 11:34 AM Stephane Chazelas <stephane@chazelas.org> wrote:
> > > >
> > > > It still retained its export attribute.
> > >
> > > This gets messy because POSIX says that's exactly what's supposed to
> > > happen when unsetting an export, even though in native zsh it normally
> > > doesn't work that way.
> >
> > No, I think you're confusing with:
> >
> > export foo
>
> I'm referring to comments in the C code, e.g.:
>
> * POSIXBUILTINS horror: we need to retain the 'readonly' or 'export'
> * flags of an unset parameter.
> [...]
> if (isset(POSIXBUILTINS)) {
> [...]
> /* This is handled by createparam():
> if (usepm && (pm->node.flags & PM_EXPORTED) && !(off & PM_EXPORTED))
> on |= PM_EXPORTED;
> */
[...]
But AFAICT, that's about the "export var" when var is not
previously set. You can't unset a readonly variable anyway.
zsh retaining the export attribute of a variable upon unset
would make it non-compliant.
POSIX is not ambiguous on that. See
https//pubs.opengroup.org/onlinepubs/9699919799.2018edition/utilities/V3_chap02.html#unset
"unset - unset values and attributes of variables and functions"
"Read-only variables cannot be unset."
--
Stephane
next prev parent reply other threads:[~2024-03-05 22:12 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-04 5:37 [PATCH] Fix crash on unset-through-nameref Bart Schaefer
2024-03-04 6:29 ` Stephane Chazelas
2024-03-04 8:39 ` Bart Schaefer
2024-03-04 19:34 ` Stephane Chazelas
2024-03-04 19:36 ` Stephane Chazelas
2024-03-04 23:50 ` Bart Schaefer
2024-03-05 8:36 ` Stephane Chazelas
2024-03-04 23:18 ` Bart Schaefer
2024-03-05 8:18 ` Stephane Chazelas
2024-03-05 18:42 ` Bart Schaefer
2024-03-05 19:38 ` Stephane Chazelas
2024-03-05 23:16 ` Bart Schaefer
2024-03-06 18:21 ` Stephane Chazelas
2024-03-06 19:17 ` Bart Schaefer
2024-03-06 19:37 ` Bart Schaefer
2024-03-05 19:48 ` Stephane Chazelas [this message]
2024-03-05 19:51 ` Stephane Chazelas
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