Re: Corner case bug caused by shell dependent behavior

From: Jeff King <peff@peff.net>
Date: Mar 14, 2014, 02:28 UTC
Message-ID: <20140314022845.GA19757@sigill.intra.peff.net>
In-Reply-To: <20140314000213.GA3739@ibr.ch>

On Fri, Mar 14, 2014 at 01:02:13AM +0100, Uwe Storbeck wrote:

Show 13 quoted lines

> When your system shell (/bin/sh) is a dash control sequences in
> strings get interpreted by the echo command. A commit message
> which ends with the string '\n' may result in a garbage line in
> the todo list of an interactive rebase which causes the rebase
> to fail.
> 
> To reproduce the behavior (with dash as /bin/sh):
> 
>   mkdir test && cd test && git init
>   echo 1 >foo && git add foo
>   git commit -m"this commit message ends with '\n'"
>   echo 2 >foo && git commit -a --fixup HEAD
>   git rebase -i --autosquash --root

Hmph. We ran into this before and fixed all of the sites (e.g., d1c3b10 and 938791c). This one appears to have been added a few months later (by 68d5d03).

> Maybe there are more places where it would be more robust to use
> printf instead of echo.

FWIW, I just looked through the other uses of "echo" in git-rebase*.sh, and I think this is the only problematic case.

> -			echo "$sha1 $action $prefix $rest"
> +			printf "%s %s %s %s\n" "$sha1" "$action" "$prefix" "$rest"

Looks obviously correct. The echo just below here does not need the same treatment, as "$rest" is the problematic bit ("$prefix" is always "fixup" or "squash").

-Peff