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Re: [PATCH 5/5] run-command: Error out if interpreter not found

From
Jonathan Nieder <jrnieder@gmail.com>
Date
Jan 27, 2012, 09:41 UTC
Message-ID
<20120127094145.GA2611@burratino>
In-Reply-To
<CAH6sp9O7P8bmYA66fY754mn=ogp8OP1i3KQuE_hnrTY46nNAxw@mail.gmail.com>
Frans Klaver wrote:
> Just for my understanding: before a command is executed, a pager
> (less/more or so) is started? We want to avoid starting the pager if
> we won't be able to execute the command?

See [1] for an example of a recent patch touching the relevant code path.

For example: if I run "git --paginate foo", foo is an alias for bar, and the "[pager] bar" configuration is set to point to "otherpager", then without this safety git launches the default pager in preparation for running git-foo, receives ENOENT from execvp("git-foo"), and then the pager has already been launched and it is too late to launch otherpager instead.

> On Fri, Jan 27, 2012 at 9:48 AM, Jonathan Nieder <jrnieder@gmail.com> wrote:
>> I want to like (b), but the downside seems unacceptable.
>
> The downside being: having to figure out what execvp is going to do?
> That would be tantamount to writing your own execvp.
Exactly.
Show 7 quoted lines
>> I honestly
>> don't know if something like (a) would be a good idea if well
>> executed, so I was happy to have the opportunity to try to help
>> massage these patches into a form that would make the answer more
>> obvious.
>
> Given the above information, I'm happy to work on this
I see.

Well, as I said, I don't know. :) And I don't want to give false hopes --- it's perfectly possible and not even unlikely that this is a dead end and any patch in this direction will turn out not to be a good idea and not applied.

That's part of why I was really grateful to Hannes for the reminder to take a step back for a moment and consider whether it's worth it. Maybe there's another way or a more targetted way to take care of the motivational original confusing scenario that leads to execvp errors. (By the way, can you remind me which one that was?)

Jonathan
[1] http://thread.gmane.org/gmane.comp.version-control.git/179635
Previous: Frans KlaverNext: Frans Klaver
Message 29 of 31 in “Add execvp failure diagnostics”
  1. 0/6 Add execvp failure diagnosticsFrans Klaver, Jan 24, 2012
  2. 1/5 t0061: Fix incorrect indentationFrans Klaver, Jan 24, 2012
  3. Junio C HamanoJan 24, 2012
  4. Jonathan NiederJan 24, 2012
  5. Frans KlaverJan 25, 2012
  6. Junio C HamanoJan 25, 2012
  7. Frans KlaverJan 25, 2012
  8. Frans KlaverJan 25, 2012
  9. 2/5 t0061: Add testsFrans Klaver, Jan 24, 2012
  10. Jonathan NiederJan 24, 2012
  11. Frans KlaverJan 25, 2012
  12. 3/5 run-command: Elaborate execvp error checkingFrans Klaver, Jan 24, 2012
  13. Jonathan NiederJan 24, 2012
  14. Frans KlaverJan 25, 2012
  15. Jonathan NiederJan 25, 2012
  16. Frans KlaverJan 25, 2012
  17. Johannes SixtJan 25, 2012
  18. Frans KlaverJan 25, 2012
  19. 4/5 run-command: Warn if PATH entry cannot be searchedFrans Klaver, Jan 24, 2012
  20. 5/5 run-command: Error out if interpreter not foundFrans Klaver, Jan 24, 2012
  21. Jonathan NiederJan 24, 2012
  22. Frans KlaverJan 25, 2012
  23. Johannes SixtJan 25, 2012
  24. Frans KlaverJan 25, 2012
  25. Junio C HamanoJan 26, 2012
  26. Frans KlaverJan 27, 2012
  27. Jonathan NiederJan 27, 2012
  28. Frans KlaverJan 27, 2012
  29. Jonathan NiederJan 27, 2012
  30. Frans KlaverJan 27, 2012
  31. Frans KlaverFeb 4, 2012

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