1 files changed, 114 insertions, 0 deletions
diff --git a/git-difftool.perl b/git-difftool.perl
new file mode 100755
index 0000000000..d975d072db
--- /dev/null
+++ b/git-difftool.perl
@@ -0,0 +1,114 @@
+#!/usr/bin/env perl
+# Copyright (c) 2009, 2010 David Aguilar
+#
+# This is a wrapper around the GIT_EXTERNAL_DIFF-compatible
+# git-difftool--helper script.
+#
+# This script exports GIT_EXTERNAL_DIFF and GIT_PAGER for use by git.
+# GIT_DIFFTOOL_NO_PROMPT, GIT_DIFFTOOL_PROMPT, and GIT_DIFF_TOOL
+# are exported for use by git-difftool--helper.
+#
+# Any arguments that are unknown to this script are forwarded to 'git diff'.
+
+use strict;
+use warnings;
+use Cwd qw(abs_path);
+use File::Basename qw(dirname);
+
+require Git;
+
+my $DIR = abs_path(dirname($0));
+
+
+sub usage
+{
+	print << 'USAGE';
+usage: git difftool [-t|--tool=<tool>] [-x|--extcmd=<cmd>]
+                    [-y|--no-prompt]   [-g|--gui]
+                    ['git diff' options]
+USAGE
+	exit 1;
+}
+
+sub setup_environment
+{
+	$ENV{PATH} = "$DIR:$ENV{PATH}";
+	$ENV{GIT_PAGER} = '';
+	$ENV{GIT_EXTERNAL_DIFF} = 'git-difftool--helper';
+}
+
+sub exe
+{
+	my $exe = shift;
+	if ($^O eq 'MSWin32' || $^O eq 'msys') {
+		return "$exe.exe";
+	}
+	return $exe;
+}
+
+sub generate_command
+{
+	my @command = (exe('git'), 'diff');
+	my $skip_next = 0;
+	my $idx = -1;
+	for my $arg (@ARGV) {
+		$idx++;
+		if ($skip_next) {
+			$skip_next = 0;
+			next;
+		}
+		if ($arg eq '-t' || $arg eq '--tool') {
+			usage() if $#ARGV <= $idx;
+			$ENV{GIT_DIFF_TOOL} = $ARGV[$idx + 1];
+			$skip_next = 1;
+			next;
+		}
+		if ($arg =~ /^--tool=/) {
+			$ENV{GIT_DIFF_TOOL} = substr($arg, 7);
+			next;
+		}
+		if ($arg eq '-x' || $arg eq '--extcmd') {
+			usage() if $#ARGV <= $idx;
+			$ENV{GIT_DIFFTOOL_EXTCMD} = $ARGV[$idx + 1];
+			$skip_next = 1;
+			next;
+		}
+		if ($arg =~ /^--extcmd=/) {
+			$ENV{GIT_DIFFTOOL_EXTCMD} = substr($arg, 9);
+			next;
+		}
+		if ($arg eq '-g' || $arg eq '--gui') {
+			my $tool = Git::command_oneline('config',
+			                                'diff.guitool');
+			if (length($tool)) {
+				$ENV{GIT_DIFF_TOOL} = $tool;
+			}
+			next;
+		}
+		if ($arg eq '-y' || $arg eq '--no-prompt') {
+			$ENV{GIT_DIFFTOOL_NO_PROMPT} = 'true';
+			delete $ENV{GIT_DIFFTOOL_PROMPT};
+			next;
+		}
+		if ($arg eq '--prompt') {
+			$ENV{GIT_DIFFTOOL_PROMPT} = 'true';
+			delete $ENV{GIT_DIFFTOOL_NO_PROMPT};
+			next;
+		}
+		if ($arg eq '-h' || $arg eq '--help') {
+			usage();
+		}
+		push @command, $arg;
+	}
+	return @command
+}
+
+setup_environment();
+
+# ActiveState Perl for Win32 does not implement POSIX semantics of
+# exec* system call. It just spawns the given executable and finishes
+# the starting program, exiting with code 0.
+# system will at least catch the errors returned by git diff,
+# allowing the caller of git difftool better handling of failures.
+my $rc = system(generate_command());
+exit($rc | ($rc >> 8));