From 2bd0276e7608bf2d16d523c4bdc5ecf399d97e31 Mon Sep 17 00:00:00 2001
From: Thadeu Lima de Souza Cascardo <cascardo@cascardo.eti.br>
Date: Thu, 23 Apr 2015 21:42:53 -0300
Subject: [PATCH] Print essential and build-essential packages

Parse Packages file and print all packages needed for essential and
build-essential.
---
 debsort.pl | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 debsort.pl

diff --git a/debsort.pl b/debsort.pl
new file mode 100644
index 0000000..1066656
--- /dev/null
+++ b/debsort.pl
@@ -0,0 +1,84 @@
+#!/usr/bin/env perl
+#
+#   Copyright 2014 Thadeu Lima de Souza Cascardo <cascardo@cascardo.info>
+#
+#   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 3 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, see <http://www.gnu.org/licenses/>.
+#
+
+use strict;
+use warnings;
+
+open(PACKAGES, "<Packages");
+open(SOURCES, "<Sources");
+
+my @packages = ();
+my %depends = ();
+my %priority = ();
+my %essential = ();
+
+sub add_depends {
+	my ($package, $depends) = @_;
+	my $deps = [];
+	my @vdeps = split(",", $depends);
+	for my $i (@vdeps) {
+		$i =~ qr,([0-9a-z-+.]+),;
+		push @$deps, $1;
+	}
+	$depends{$package} = $deps;
+}
+
+my $package;
+while (<PACKAGES>) {
+	if (/^Package: ([0-9a-z-+.]+)/) {
+		$package = $1;
+		push @packages, $package;
+	}
+	if (/^Depends: (.*)/) {
+		add_depends($package, $1);
+	}
+	if (/^Priority: (.*)/) {
+		$priority{$package} = $1;
+	}
+	if (/^Essential: yes/) {
+		$essential{$package} = "yes";
+	}
+}
+
+close(PACKAGES);
+close(SOURCES);
+
+my @pp = ();
+
+my @visit = ();
+
+for my $i (keys %essential) {
+	push @visit, $i;
+}
+push @visit, "build-essential";
+
+while (@visit) {
+	my $n = pop @visit;
+	next if grep /^$n$/, @pp;
+	push @pp, $n;
+	my $l = $depends{$n};
+	for my $d (@$l) {
+		if (!grep /^$d$/, @pp && !grep /^$d$/, @visit) {
+			push @visit, $d;
+		}
+	}
+}
+
+for my $i (@pp) {
+	print "$i\n";
+}
-- 
2.20.1