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 5¤    #!/usr/bin/perl
use lib (split(/:/, $ENV{GITPERLLIB} || "/usr/share/perl5"));
# Copyright (c) 2009, 2010 David Aguilar
# Copyright (c) 2012 Tim Henigan
#
# 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.
# The GIT_DIFF* variables are exported for use by git-difftool--helper.
#
# Any arguments that are unknown to this script are forwarded to 'git diff'.

use 5.008;
use strict;
use warnings;
use Error qw(:try);
use File::Basename qw(dirname);
use File::Copy;
use File::Find;
use File::stat;
use File::Path qw(mkpath rmtree);
use File::Temp qw(tempdir);
use Getopt::Long qw(:config pass_through);
use Git;

sub usage
{
	my $exitcode = shift;
	print << 'USAGE';
usage: git difftool [-t|--tool=<tool>] [--tool-help]
                    [-x|--extcmd=<cmd>]
                    [-g|--gui] [--no-gui]
                    [--prompt] [-y|--no-prompt]
                    [-d|--dir-diff]
                    ['git diff' options]
USAGE
	exit($exitcode);
}

sub find_worktree
{
	my ($repo) = @_;

	# Git->repository->wc_path() does not honor changes to the working
	# tree location made by $ENV{GIT_WORK_TREE} or the 'core.worktree'
	# config variable.
	my $worktree;
	my $env_worktree = $ENV{GIT_WORK_TREE};
	my $core_worktree = Git::config('core.worktree');

	if (defined($env_worktree) and (length($env_worktree) > 0)) {
		$worktree = $env_worktree;
	} elsif (defined($core_worktree) and (length($core_worktree) > 0)) {
		$worktree = $core_worktree;
	} else {
		$worktree = $repo->wc_path();
	}

	return $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', $cmd);
	exit($rc | ($rc >> 8));
}

sub exit_cleanup
{
	my ($tmpdir, $status) = @_;
	my $errno = $!;
	rmtree($tmpdir);
	if ($status and $errno) {
		my ($package, $file, $line) = caller();
		warn "$file line $line: $errno\n";
	}
	exit($status | ($status >> 8));
}

sub use_wt_file
{
	my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
	my $null_sha1 = '0' x 40;

	if ($sha1 ne $null_sha1 and not $symlinks) {
		return 0;
	}

	if (! -e "$workdir/$file") {
		# If the file doesn't exist in the working tree, we cannot
		# use it.
		return (0, $null_sha1);
	}

	my $wt_sha1 = $repo->command_oneline('hash-object', "$workdir/$file");
	my $use = ($sha1 eq $null_sha1) || ($sha1 eq $wt_sha1);
	return ($use, $wt_sha1);
}

sub changed_files
{
	my ($repo_path, $index, $worktree) = @_;
	$ENV{GIT_INDEX_FILE} = $index;
	$ENV{GIT_WORK_TREE} = $worktree;
	my $must_unset_git_dir = 0;
	if (not defined($ENV{GIT_DIR})) {
		$must_unset_git_dir = 1;
		$ENV{GIT_DIR} = $repo_path;
	}

	my @refreshargs = qw/update-index --really-refresh -q --unmerged/;
	my @gitargs = qw/diff-files --name-only -z/;
	try {
		Git::command_oneline(@refreshargs);
	} catch Git::Error::Command with {};

	my $line = Git::command_oneline(@gitargs);
	my @files;
	if (defined $line) {
		@files = split('\0', $line);
	} else {
		@files = ();
	}

	delete($ENV{GIT_INDEX_FILE});
	delete($ENV{GIT_WORK_TREE});
	delete($ENV{GIT_DIR}) if ($must_unset_git_dir);

	return map { $_ => 1 } @files;
}

sub setup_dir_diff
{
	my ($repo, $workdir, $symlinks) = @_;

	# Run the diff; exit immediately if no diff found
	# 'Repository' and 'WorkingCopy' must be explicitly set to insure that
	# if $GIT_DIR and $GIT_WORK_TREE are set in ENV, they are actually used
	# by Git->repository->command*.
	my $repo_path = $repo->repo_path();
	my %repo_args = (Repository => $repo_path, WorkingCopy => $workdir);
	my $diffrepo = Git->repository(%repo_args);

	my @gitargs = ('diff', '--raw', '--no-abbrev', '-z', @ARGV);
	my $diffrtn = $diffrepo->command_oneline(@gitargs);
	exit(0) unless defined($diffrtn);

	# Build index info for left and right sides of the diff
	my $submodule_mode = '160000';
	my $symlink_mode = '120