GNU bug report logs - #73405
wrap-program should use the basename of $0 as arg0

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: bug-guix <bug-guix <at> gnu.org>
Subject: wrap-program should use the basename of $0 as arg0
Date: Sat, 21 Sep 2024 14:51:43 +0900

Hi,

I believe wrap-program should be using

--8<---------------cut here---------------start------------->8---
exec -a ${0##*/} ...
--8<---------------cut here---------------end--------------->8---

instead of

--8<---------------cut here---------------start------------->8---
exec -a "$0" ...
--8<---------------cut here---------------end--------------->8---

as the later will use the full file name of the command
(/gnu/store/.../bin/something) instead of just the command name, which
is more conventional.

I made this discovery while investigating a segfault that occured in a
wrapped 'cling'; adjusting the wrapper script to read as:

--8<---------------cut here---------------start------------->8---
#!/gnu/store/3jhfhxdf6v5ms10x5zmnl166dh3yhbr1-bash-minimal-5.1.16/bin/bash
exec -a ${0##*/} "/gnu/store/0ccm05058yjd5qi8hcdr70ymhf9q6cc2-cling-1.1/bin/.cling-real" "$@"
--8<---------------cut here---------------end--------------->8---

where the value of -a becomes 'cling' instead of its full file name
resolved the issue. The original wrapper reads like:

--8<---------------cut here---------------start------------->8---
#!/gnu/store/3jhfhxdf6v5ms10x5zmnl166dh3yhbr1-bash-minimal-5.1.16/bin/bash
exec -a "$0" "/gnu/store/l8875yavr1nls7n3i3yx8ah0s1lasn43-cling-1.1/bin/.cling-real" "$@"
--8<---------------cut here---------------end--------------->8---

It's probably rare that this "problem" would manifest itself so
critically, but still, I think it'd be good to adjust our wrap-program
procedure.  I'll send a patch.

-- 
Thanks,
Maxim

Message #10 received at 73405-done <at> debbugs.gnu.org (full text, mbox):

From: Ludovic Courtès <ludo <at> gnu.org>
To: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
Cc: 73416-done <at> debbugs.gnu.org, Andreas Enge <andreas <at> enge.fr>,
 73405-done <at> debbugs.gnu.org
Subject: Re: bug#73416: [PATCH core-updates] build: Set $0 to basename of
 command in `wrap-program'.
Date: Sat, 22 Mar 2025 23:35:28 +0100

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

> * guix/build/utils.scm (wrap-program): Set the value of the -a option of
> `exec' in the wrapper to ${0##*/} instead of $0, to use its base name instead
> of the complete file name.
>
> Fixes: https://issues.guix.gnu.org/73405
> Change-Id: Iec5984d4d934c8df88a90ff653947f7d07413ae4

Applied to ‘core-packages-team’, thanks!

Ludo’.

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