Re: [PATCH] rollback index if git-commit is interrupted by a signal

> If git-commit is interrupted by a signal, the index.lock file may be 
> left in the repository.  This patch teaches git to break them, and adds 
> a test.
> 
> This will usually happen if you ^Z the editor, and then either close the 
> terminal or kill git.  However, the patch is more defensive and sets up 
> the signal handlers so that the entire creation of the index is 
> protected.
> 
> Signed-off-by: Paolo Bonzini <bonzini@gnu.org>
> ---
>  builtin-commit.c  |   25 ++++++++++++++-----------
>  t/t7502-commit.sh |   14 ++++++++++++++
>  2 files changed, 28 insertions(+), 11 deletions(-)
> 
> 	rollback_index_files handles cleanly the case when the lock
> 	had not been established; git-status tests check for this.
> 
> 	The test is a bit tricky.  To find git's PID, I use a separate shell
> 	so that I can "exec" git: git will then inherit the same PID as the
> 	shell, which I get with $$.  Using a subshell does not work because bash
> 	optimizes subshells and does not fork a copy of itself -- this however
> 	means that it will not be able to really honor the "exec" command,
> 	and git will get a different PID!
> 	
> diff --git a/builtin-commit.c b/builtin-commit.c
> index b294c1f..ef8b1f0 100644
> --- a/builtin-commit.c
> +++ b/builtin-commit.c
> @@ -111,17 +111,8 @@ static struct option builtin_commit_options[] = {
>  
>  static void rollback_index_files(void)
>  {
> -	switch (commit_style) {
> -	case COMMIT_AS_IS:
> -		break; /* nothing to do */
> -	case COMMIT_NORMAL:
> -		rollback_lock_file(&index_lock);
> -		break;
> -	case COMMIT_PARTIAL:
> -		rollback_lock_file(&index_lock);
> -		rollback_lock_file(&false_lock);
> -		break;
> -	}
> +	rollback_lock_file(&index_lock);
> +	rollback_lock_file(&false_lock);
>  }