GNU bug report logs - #73416
[PATCH core-updates] build: Set $0 to basename of command in `wrap-program'.

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Message #29 received at 73416 <at> debbugs.gnu.org (full text, mbox):

From: Tomas Volf <~@wolfsden.cz>
To: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
Cc: 73416 <at> debbugs.gnu.org, Andreas Enge <andreas <at> enge.fr>,
 Liam Hupfer <liam <at> hpfr.net>, Ludovic Courtès <ludo <at> gnu.org>
Subject: Re: [bug#73416] [PATCH core-updates] build: Set $0 to basename of
 command in `wrap-program'.
Date: Wed, 06 Aug 2025 21:58:48 +0200

Maxim Cournoyer <maxim.cournoyer <at> gmail.com> writes:

> Hi,
>
> Tomas Volf <~@wolfsden.cz> writes:
>
>> Liam Hupfer <liam <at> hpfr.net> writes:
>>
>>> On second thought, though, I think we should consider reverting the
>>> change to ‘wrap-program’. [bug#73405: wrap-program should use the
>>> basename of $0 as arg0] does not describe why ‘cling’ was segfaulting,
>>> but I suspect it’s due to similar bad assumptions about argv[0] as the
>>> Emacs issue.
>>>
>>> I think wrappers should be as transparent as possible—however the user
>>> invokes a command should be preserved in argv[0], whether using a
>>> basename with PATH resolution or a relative or absolute filename. We
>>> shouldn’t coerce argv[0] to a basename when the wrapper wasn’t called
>>> that way. 99% of the time argv[0] is irrelevant, but the common case I’m
>>> considering is programs that log how they were called—it’s disorienting
>>> for the wrapper to affect that.
>>>
>>> Maybe we can expose an argument to wrap-program to use the basename
>>> approach, but IMO we should be handling the root cause in cases where
>>> problems occur and pushing upstreams to handle arbitrary argv[0] values
>>> robustly.
>>>
>>> WDYT? Thanks!
>>
>> This member of the peanut gallery supports the revert.  Exactly as you
>> say, the wrappers should be as transparent as possible.  So this
>> mangling feels wrong.
>
> After giving it some more thoughts, I agree. I think I had originally
> worked under the assumption that $0 would always expand to the absolute
> file name of the wrapper because of the wapper itself, but that's not
> the case; $0 exactly matches the way the user or launcher called the
> application, so it makes sense to preserve that information.
>
> It'll have to be done on the next core-packages branch though, as it's a
> world rebuild change.

There seems to be a `world-rebuild' branch now, which sounds like a good
fit?

Tomas

-- 
There are only two hard things in Computer Science:
cache invalidation, naming things and off-by-one errors.

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