+sub resolve_git_dir {
+ my ($cd) = @_;
+ my @cmd = qw(git rev-parse --git-dir);
+ my $cmd = join(' ', @cmd);
+ my $pid = open my $fh, '-|';
+ defined $pid or die "forking $cmd failed: $!\n";
+ if ($pid == 0) {
+ if (defined $cd) {
+ chdir $cd or die "chdir $cd failed: $!\n";
+ }
+ exec @cmd;
+ die "Failed to exec $cmd: $!\n";
+ } else {
+ my $dir = eval {
+ local $/;
+ <$fh>;
+ };
+ close $fh or die "error in $cmd: $!\n";
+ chomp $dir;
+ return $cd if ($dir eq '.' && defined $cd);
+ $dir;