#!/usr/bin/perl
#
# git support for dpkg-source
#
# Copyright © 2007 Joey Hess <joeyh@debian.org>.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
package Dpkg::Source::VCS::git;

use strict;
use warnings;
use Cwd;
use File::Find;
use Dpkg;
use Dpkg::Gettext;

push (@INC, $dpkglibdir);
require 'controllib.pl';

# Remove variables from the environment that might cause git to do
# something unexpected.
delete $ENV{GIT_DIR};
delete $ENV{GIT_INDEX_FILE};
delete $ENV{GIT_OBJECT_DIRECTORY};
delete $ENV{GIT_ALTERNATE_OBJECT_DIRECTORIES};
delete $ENV{GIT_WORK_TREE};

sub import {
	foreach my $dir (split(/:/, $ENV{PATH})) {
		if (-x "$dir/git") {
			return 1;
		}
	}
	main::error(sprintf(_g("This source package can only be unpacked using git, which is not in the PATH.")));
}

sub sanity_check {
	my $srcdir=shift;

	if (! -d "$srcdir/.git") {
		main::error(sprintf(_g("source directory is not the top directory of a git repository (%s/.git not present), but Format git was specified"), $srcdir));
	}
	if (-s "$srcdir/.gitmodules") {
		main::error(sprintf(_g("git repository %s uses submodules. This is not yet supported."), $srcdir));
	}

	# Symlinks from .git to outside could cause unpack failures, or
	# point to files they shouldn't, so check for and don't allow.
	if (-l "$srcdir/.git") {
		main::error(sprintf(_g("%s is a symlink"), "$srcdir/.git"));
	}
	my $abs_srcdir=Cwd::abs_path($srcdir);
	find(sub {
		if (-l $_) {
			if (Cwd::abs_path(readlink($_)) !~ /^\Q$abs_srcdir\E(\/|$)/) {
				main::error(sprintf(_g("%s is a symlink to outside %s"), $File::Find::name, $srcdir));
			}
		}
	}, "$srcdir/.git");

	return 1;
}

# Returns a hash of arrays of git config values.
sub read_git_config {
	my $file=shift;

	my %ret;
	open(GIT_CONFIG, '-|', "git-config", "--file", $file, "--null", "-l") ||
		main::subprocerr("git-config");
	my ($key, $value);
	while (<GIT_CONFIG>) {
		if (! defined $key) {
			$key=$_;
			chomp $key;
			$value="";
		}
		elsif (/(.*)\0(.*)/) {
			$value.=$1;
			push @{$ret{$key}}, $value;
			$key=$2;
			chomp $key;
			$value="";
		}
		else {
			$value.=$1;
		}
	}
	if (defined $key && length $key) {
		push @{$ret{$key}}, $value;
	}
	close(GIT_CONFIG) || main::syserr("git-config exited nonzero");

	return \%ret;
}

# Called before a tarball is created, to prepare the tar directory.
sub prep_tar {
	my $srcdir=shift;
	my $tardir=shift;
	
	sanity_check($srcdir);
	
	my $old_cwd=getcwd();
	chdir($srcdir) ||
		main::syserr(sprintf(_g("unable to chdir to `%s'"), $srcdir));

	# Check for uncommitted files.
	# To support dpkg-source -i, get a list of files
	# equivalent to the ones git-status finds, and remove any
	# ignored files from it.
	my @ignores="--exclude-per-directory=.gitignore";
	my $core_excludesfile=`git-config --get core.excludesfile`;
	chomp $core_excludesfile;
	if (length $core_excludesfile && -e $core_excludesfile) {
		push @ignores, "--exclude-from='$core_excludesfile'";
	}
	if (-e ".git/info/exclude") {
		push @ignores, "--exclude-from=.git/info/exclude";
	}
	open(GIT_LS_FILES, '-|', "git-ls-files", "--modified", "--deleted",
	                                         "--others", @ignores) ||
		main::subprocerr("git-ls-files");
	my @files;
	while (<GIT_LS_FILES>) {
		chomp;
		if (! length $main::diff_ignore_regexp ||
		    ! m/$main::diff_ignore_regexp/o) {
			push @files, $_;
		}
	}
	close(GIT_LS_FILES) || main::syserr("git-ls-files exited nonzero");
	if (@files) {
		main::error(sprintf(_g("uncommitted, not-ignored changes in working directory: %s"),
		            join(" ", @files)));
	}

	# git-clone isn't used to copy the repo because the it might be an
	# unclonable shallow copy.
	chdir($old_cwd) ||
		main::syserr(sprintf(_g("unable to chdir to `%s'"), $old_cwd));
	mkdir($tardir,0755) ||
		main::syserr(sprintf(_g("unable to create `%s'"), $tardir));
	system("cp", "-a", "$srcdir/.git", $tardir);
	$? && main::subprocerr("cp -a $srcdir/.git $tardir");
	chdir($tardir) ||
		main::syserr(sprintf(_g("unable to chdir to `%s'"), $tardir));
	
	# TODO support for creating a shallow clone for those cases where
	# uploading the whole repo history is not desired

	# Clean up the new repo to save space.
	# First, delete the whole reflog, which is not needed in a
	# distributed source package.
	system("rm", "-rf", ".git/logs");
	$? && main::subprocerr("rm -rf .git/logs");
	system("git-gc", "--prune");
	$? && main::subprocerr("git-gc --prune");

	# As an optimisation, remove the index. It will be recreated by git
	# reset during unpack. It's probably small, but you never know, this
	# might save a lot of space.
	unlink(".git/index"); # error intentionally ignored
	
	chdir($old_cwd) ||
		main::syserr(sprintf(_g("unable to chdir to `%s'"), $old_cwd));

	return 1;
}

# Called after a tarball is unpacked, to check out the working copy.
sub post_unpack_tar {
	my $srcdir=shift;
	
	sanity_check($srcdir);

	my $old_cwd=getcwd();
	chdir($srcdir) ||
		main::syserr(sprintf(_g("unable to chdir to `%s'"), $srcdir));

	# Disable git hooks, as unpacking a source package should not
	# involve running code.
	foreach my $hook (glob("./.git/hooks/*")) {
		if (-x $hook) {
			main::warning(sprintf(_g("executable bit set on %s; clearing"), $hook));
			chmod(0666 &~ umask(), $hook) ||
				main::syserr(sprintf(_g("unable to change permission of `%s'"), $hook));
		}
	}
	
	# This is a paranoia measure, since the index is not normally
	# provided by possibly-untrusted third parties, remove it if
	# present (git will recreate it as needed).
	if (-e ".git/index" || -l ".git/index") {
		unlink(".git/index") ||
			main::syserr(sprintf(_g("unable to remove `%s'"), ".git/index"));
	}

	# Comment out potentially probamatic or annoying stuff in
	# .git/config.
	my $safe_fields=qr/^(
		core\.autocrlf			|
		branch\..*			|
		remote\..*			|
		core\.repositoryformatversion	|
		core\.filemode			|
		core\.logallrefupdates		|
		core\.bare
		)$/x;
	my %config=%{read_git_config(".git/config")};
	foreach my $field (keys %config) {
		if ($field =~ /$safe_fields/) {
			delete $config{$field};
		}
		else {
			system("git-config", "--file", ".git/config",
			       "--unset-all", $field);
				$? && main::subprocerr("git-config --file .git/config --unset-all $field");
		}
	}
	if (%config) {
		main::warning(_g("modifying .git/config to comment out some settings"));
		open(GIT_CONFIG, ">>", ".git/config") ||
			main::syserr(sprintf(_g("unstable to append to %s", ".git/config")));
		print GIT_CONFIG "\n# "._g("The following setting(s) were disabled by dpkg-source").":\n";
		foreach my $field (sort keys %config) {
			foreach my $value (@{$config{$field}}) {
				print GIT_CONFIG "# $field=$value\n";
			}
		}
		close GIT_CONFIG;
	}

	# git-checkout is used to repopulate the WC with files
	# and recreate the index.
	system("git-checkout", "-f");
	$? && main::subprocerr("git-clone -f");
	
	chdir($old_cwd) ||
		main::syserr(sprintf(_g("unable to chdir to `%s'"), $old_cwd));

	return 1;
}

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