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From: Jonathan Nieder <jrnieder@gmail.com>
To: Jeff King <peff@peff.net>
Cc: Eric Rannaud <eric.rannaud@gmail.com>,
	git@vger.kernel.org,
	Johannes Schindelin <johannes.schindelin@gmx.de>,
	Jeremy Serror <jeremy.serror@gmail.com>,
	Brandon Williams <bmwill@google.com>
Subject: Re: git rebase regression: cannot pass a shell expression directly to --exec
Date: Tue, 16 May 2017 09:41:24 -0700	[thread overview]
Message-ID: <20170516164124.GO27400@aiede.svl.corp.google.com> (raw)
In-Reply-To: <20170516033736.23cfkouus3p67vhc@sigill.intra.peff.net>

(+Brandon Williams, who may have more context for execvp-related things)
Hi,

Jeff King wrote:
> On Mon, May 15, 2017 at 11:25:03PM -0400, Jeff King wrote:

>> One hack would be to look for BASH_FUNC_* in the environment and disable
>> the optimization in that case. I think that would make your case Just
>> Work. It doesn't help other oddball cases, like:
>>
>>   - you're trying to run a shell builtin that behaves differently than
>>     its exec-able counterpart
>>
>>   - your shell has some other mechanism for defining commands that we
>>     would not find via exec. I don't know of one offhand. Obviously $ENV
>>     could point to a file which defines some, but for most shells would
>>     not read any startup files for a non-interactive "sh -c" invocation.
>
> So I was thinking something like the patch below, though I guess
> technically you could look for BASH_FUNC_$argv[0]%%, which seems to be
> bash's magic variable name. I hate to get too intimate with those
> details, though.
>
> Another option is to speculatively run "foo" without the shell, and if
> execve fails to find it, then fall back to running the shell. That would
> catch any number of cases where the shell "somehow" finds a command that
> we can't.

Hm.  execvp explicitly does this when it hits ENOEXEC, but not for
ENOENT.  Do you know why that is?

I think we want to behave consistently for shell builtins and for
exported functions --- they are different sides of the same problem,
and behaving differently between the two feels confusing.

Thanks,
Jonathan

  reply	other threads:[~2017-05-16 16:41 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-15 18:08 git rebase regression: cannot pass a shell expression directly to --exec Eric Rannaud
2017-05-16  3:25 ` Jeff King
2017-05-16  3:37   ` Jeff King
2017-05-16 16:41     ` Jonathan Nieder [this message]
2017-05-16 16:47       ` Jeff King
2017-05-16 17:11         ` Eric Rannaud
2017-05-16 17:15         ` Brandon Williams
2017-05-16 17:23           ` Jeff King
2017-05-16 17:30             ` Brandon Williams
2017-05-16 19:14             ` Linus Torvalds
2017-05-16 19:35               ` [TANGENT] run-command: use vfork instead of fork Eric Wong
2017-05-16 20:47                 ` Linus Torvalds
2017-05-16 21:11                   ` Brandon Williams
2017-05-16 20:12               ` git rebase regression: cannot pass a shell expression directly to --exec Johannes Schindelin
2017-05-16 20:27                 ` Linus Torvalds
2017-05-16 17:37         ` Jonathan Nieder
2017-05-16  3:40   ` Junio C Hamano
2017-05-16  3:53     ` Jeff King
2017-05-16  4:08       ` Jeff King
2017-05-16 16:45       ` Eric Rannaud
2017-05-16 10:46     ` Johannes Schindelin
2017-05-16 10:23 ` Johannes Schindelin
2017-05-16 16:18   ` Jeff King
2017-05-16 16:59     ` Eric Rannaud
2017-05-16 17:14       ` Kevin Daudt
2017-05-16 17:29         ` Eric Rannaud
2017-05-16 17:41           ` Jeff King
2017-05-16 17:21       ` Eric Rannaud
2017-05-16 17:37         ` Jeff King

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