Re: [PATCH 2/2] difftool: don't assume that default sh is sane

[John Keeping <john@keeping.me.uk>]

On Sat, Jul 19, 2014 at 05:35:17PM +0100, Charles Bailey wrote:
> From: Charles Bailey <cbailey32@bloomberg.net>
> 
> git-difftool used to create a command list script containing $( ... )
> and explicitly call "sh -c" with this list.
> 
> Instead, allow mergetool --tool-help to take a mode parameter and call
> mergetool directly to invoke the show_tool_help function. This mode
> parameter is intented for use solely by difftool.
> 
> Signed-off-by: Charles Bailey <cbailey32@bloomberg.net>
> ---
> Another issue for Solaris. Originally I had a fix for this that
> substituted "@SHELL_PATH@" even inside perl scripts but I felt that
> having an interface for show_tool_help was a little neater all round but
> I welcome alternative views.
> 
>  git-difftool.perl |  6 +-----
>  git-mergetool.sh  | 12 +++++++++++-
>  2 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/git-difftool.perl b/git-difftool.perl
> index 18ca61e..598fcc2 100755
> --- a/git-difftool.perl
> +++ b/git-difftool.perl
> @@ -47,13 +47,9 @@ sub find_worktree
>  
>  sub print_tool_help
>  {
> -	my $cmd = 'TOOL_MODE=diff';
> -	$cmd .= ' && . "$(git --exec-path)/git-mergetool--lib"';
> -	$cmd .= ' && show_tool_help';
> -
>  	# See the comment at the bottom of file_diff() for the reason behind
>  	# using system() followed by exit() instead of exec().
> -	my $rc = system('sh', '-c', $cmd);
> +	my $rc = system(qw(git mergetool --tool-help=diff));
>  	exit($rc | ($rc >> 8));
>  }
>  
> diff --git a/git-mergetool.sh b/git-mergetool.sh
> index e969dd0..d32b663 100755
> --- a/git-mergetool.sh
> +++ b/git-mergetool.sh
> @@ -320,7 +320,17 @@ guessed_merge_tool=false
>  while test $# != 0
>  do
>  	case "$1" in
> -	--tool-help)
> +	--tool-help*)
> +		case "$#,$1" in
> +		1,*=*)

What's the reason for forcing `--tool-help` to be the last option?
Wouldn't it be simpler to just change the top-level case statement to:

	--tool-help=*)
		TOOL_MODE=${1#--tool-help=}
		show_tool_help
		;;
	--tool-help)
		show_tool_help
		;;

> +			TOOL_MODE=$(expr "z$1" : 'z-[^=]*=\(.*\)')
> +			;;
> +		1,--tool-help)
> +			;;
> +		*)
> +			usage
> +			;;
> +		esac
>  		show_tool_help
>  		;;
>  	-t|--tool*)
> -- 
> 2.0.2.611.g8c85416