#!/usr/bin/perl
# $Id: grub,v 1.3 2003/12/04 12:33:15 at Exp $
#--------------------------------------------------------------------
# Copyright (C) 2000, 2001, 2002 by MandrakeSoft.
# Chmouel Boudjnah <chmouel@mandrakesoft.com>.
#
# Redistribution of this file is permitted under the terms of the GNU 
# Public License (GPL)
#--------------------------------------------------------------------
# Copyright (C) 2003 by ALT Linux Team,
# Alexey Tourbin <at@altlinux.org>.
#--------------------------------------------------------------------
# description: Add/remove entry for grub bootloader.

use strict;
use bootloader_utils qw(mnt2dev getroot);

use Getopt::Long qw(GetOptions);
GetOptions "r|remove" => \my $remove, "m|memtest" => \my $memtest
	and (my $version = shift) and (@ARGV == 0)
	or die "usage: $0 [-r|--remove] [-m|--memtest] version\n";

sub dev2grub {
	my $dev = shift;
	my ($disk, $part) = $dev =~ /([^\d\s]+)(\d+)/
		or return;
# Sample device.map entry:
# (hd0) /dev/hda
# Sample convertion:
# /dev/hda5 => (hd0,4)
	$part--;
	my $map = $ENV{GRUB_DEVICE_MAP} || "/boot/grub/device.map";
	open my $fh, $map
		or return;
	my $grub_part;
	while (<$fh>) {
		if (/\((\w+d\d+)\)\s+\Q$disk\E$/) {
			$grub_part = "($1,$part)";
			last;
		}
	}
	return $grub_part;
}

my $boot = mnt2dev("/boot") ? "" : "/boot";
my $grub_part = dev2grub(getroot());
die "Can't convert grub_partition\n" unless $grub_part;

sub add_memtest {
	local $_ = shift;
	/\/memtest-\Q$version\E\b/
		or $_ .= <<EOF;

title memtest86-$version
kernel $grub_part$boot/memtest-$version.bin
EOF
	return $_;
}

sub remove_memtest {
	local $_ = shift;
	my @sections = split /^(?=title\s)/m;
	@sections =  grep { !/\/memtest-\Q$version\E\b/ } @sections;
	return join "" => @sections;
}

sub add_kernel {
	local $_ = shift;
	/\/vmlinuz-\Q$version\E\b/
		or $_ .= <<EOF;

title $version
kernel $grub_part$boot/vmlinuz-$version
initrd $grub_part$boot/initrd-$version.img
EOF
	return $_;
}

sub remove_kernel {
	local $_ = shift;
	my @sections = split /^(?=title\s)/m;
	@sections =  grep { !/\/vmlinuz-\Q$version\E\b/ } @sections;
	return join "" => @sections;
}

{
# open menu.lst for update
	my $menu_lst = $ENV{GRUB_MENU_LST} || "/boot/grub/menu.lst";
	open my $fh, "+<", $menu_lst
		or die "Cannot open $menu_lst\n";
	local $/ = undef;
	my $content = <$fh>;
	
# modify the content
	if ($memtest && $remove) {
		$content = remove_memtest($content);
	} elsif ($memtest) {
		$content = add_memtest($content);
	} elsif ($remove) {
		$content = remove_kernel($content);
	} else {
		$content = add_kernel($content);
	}
# debug
	print $content;
	exit 0;

# do the update
	seek $fh, 0, 0;
	print $fh $content;
	truncate $fh, tell $fh;
# autoclosed
}