Re: [PATCH 7/9] difftool: teach difftool to handle directory diffs

[Tim Henigan <tim.henigan@gmail.com>]

I have run into a problem with the way that the tmp directories are
populated using 'git update-index' and 'git checkout-index'.  I would
appreciate any feedback that may help me understand what I am doing
wrong.

This is in regard to the following section of code:

On Fri, Mar 16, 2012 at 9:59 PM, Tim Henigan <tim.henigan@gmail.com> wrote:
>
> +sub setup_dir_diff
> +{
> +       # Run the diff; exit immediately if no diff found
> +       my $repo = Git->repository();
> +       my $diffrtn = $repo->command_oneline(['diff', '--raw', '--no-abbrev', '-z', @ARGV]);
> +       exit(0) if (length($diffrtn) == 0);

<snip>

> +       my @rawdiff = split('\0', $diffrtn);
> +
> +       for (my $i=0; $i<@rawdiff; $i+=2) {
> +               my ($lmode, $rmode, $lsha1, $rsha1, $status) = split(' ', substr($rawdiff[$i], 1));
> +               my $path = $rawdiff[$i + 1];
> +
> +               if (($lmode eq $submodule_mode) or ($rmode eq $submodule_mode)) {
> +                       $submodule{$path}{left} = $lsha1;
> +                       $submodule{$path}{right} = $rsha1;
> +                       next;
> +               }
> +
> +               if ($lmode ne $null_mode) {
> +                       $lindex .= "$lmode $lsha1\t$path\0";
> +               }
> +
> +               if ($rmode ne $null_mode) {
> +                       if ($rsha1 ne $null_sha1) {
> +                               $rindex .= "$rmode $rsha1\t$path\0";
> +                       } else {
> +                               push(@working_tree, $path);
> +                       }
> +               }
> +       }
> +
> +       # Populate the left and right directories based on each index file
> +       my ($inpipe, $ctx);
> +       $ENV{GIT_INDEX_FILE} = "$tmpdir/lindex";
> +       ($inpipe, $ctx) = $repo->command_input_pipe(qw/update-index -z --index-info/);
> +       print($inpipe $lindex);
> +       $repo->command_close_pipe($inpipe, $ctx);
> +       $repo->command_oneline(["checkout-index", "-a", "--prefix=$ldir/"]);

When run from the root directory of a Git repository, the 'difftool
--dir-diff' command operates as expected:
  - Temporary index files for each side of the diff are created using
'git update-index'.
  - 'git checkout-index --all --prefix=$tmp' is used to populate the
tmp directory based on the index file.

However, when 'difftool --dir-diff' is run from a subdirectory of the
Git repository, there are problems.
  - The temporary index file generated by 'git update-index' appears
to be correct.
  - 'git checkout-index --all --prefix=$tmp' command does not work
(output tmp dir is empty).

I have tried some combinations of setting $ENV{GIT_DIR} and
$ENV{GIT_WORK_TREE}, but it has not fixed the problem.  Is there
anything obvious that I missed?