Re: git does not wait on hook exes (^C)

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Feb 21, 2020, 00:01 UTC
Message-ID: <20200221000141.GA6462@camp.crustytoothpaste.net>
In-Reply-To: <CA+dzEB=jJEkuvcX5qDfeXS=mbJu_m=-yUsmHd_KrKAXC3YDe7w@mail.gmail.com>

On 2020-02-20 at 21:14:55, Anthony Sottile wrote:

Show 28 quoted lines

> Here's a small example:
> 
> ```bash
> #!/usr/bin/env bash
> foo() {
>     echo zzz part 2
>     sleep 1
>     echo exiting now
> }
> trap foo SIGINT
> 
> echo zzz part 1
> sleep 10
> ```
> 
> ```console
> $ git --version
> git version 2.25.GIT
> $ git commit --allow-empty -m foo
> zzz part 1
> ^Czzz part 2
> 
> $ exiting now
> ```
> 
> - I pressed ^C during the first sleep
> - control was returned back to my terminal
> - the hook script was still running in the background

I believe the way that SIGINT works on a terminal is that it sends the signal to all processes in the foreground process group. So my guess of what's happening here is that Git and your script both get SIGINT, Git cleans up and exits quickly, leaving your script running.

If so, I'm not sure that Git can do much here. If Git waited for the hook to exit, then a broken or hung hook would cause Git to hang indefinitely, which is not what the user intended when they pressed Ctrl-C. Usually what the user wants is an immediate return to the terminal in such a case, and I think most users would consider it a bug if Git were to wait for its children.

Certainly I'm open to hearing other views on this, though.

-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204