#!/usr/bin/python2.6
# -*- coding: utf-8 -*-
#
# Univention Grub menu.lst generator
#
# Copyright 2012 Univention GmbH
#
# http://www.univention.de/
#
# All rights reserved.
#
# The source code of this program is made available
# under the terms of the GNU Affero General Public License version 3
# (GNU AGPL V3) as published by the Free Software Foundation.
#
# Binary versions of this program provided by Univention to you as
# well as other copyrighted, protected or trademarked materials like
# Logos, graphics, fonts, specific documentations and configurations,
# cryptographic keys etc. are subject to a license agreement between
# you and Univention and not subject to the GNU AGPL V3.
#
# In the case you use this program under the terms of the GNU AGPL V3,
# the program is provided 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public
# License with the Debian GNU/Linux or Univention distribution in file
# /usr/share/common-licenses/AGPL-3; if not, see
# <http://www.gnu.org/licenses/>.

import os
import sys
import re
import optparse
from shutil import copyfile
import univention.config_registry as ucr

configRegistry = ucr.ConfigRegistry()
configRegistry.load()

parser = optparse.OptionParser()
parser.add_option("-f", "--force", action="store_true",
		dest="force", default=False, help="Force writing menu.lst")
parser.add_option("-n", "--dry-run", action="store_true",
		dest="dry", default=False, help="Print to stdout instead of menu.lst")
parser.add_option("-c", "--commandline", "--append", action="store",
		dest="args", default='nosplash', help="Additional kernel command line arguments")
parser.add_option("-r", "--root", action="store",
		dest="root", default=None, help="Overwrite grub root device")
options, args = parser.parse_args()

if configRegistry.is_false('grub/generate-menu-lst', False):
	print >>sys.stderr, "Disables via grub/generate-menu-lst"
	if options.force:
		print >>sys.stderr, "Forced!"
	else:
		sys.exit(0)

os.chdir("/boot")
if os.path.exists("grub/menu.lst"):
	f = open("grub/menu.lst", "r")
	for line in f:
		if "auto-generated through univention-grub-generate-menu-lst" in line:
			break
	else:
		print >>sys.stderr, "menu.lst already exists. This typically happens if you have updated from UCS 2.4"
		print >>sys.stderr, "and haven't converted from chain loading"
		if options.force:
			print >>sys.stderr, "Forced!"
		else:
			sys.exit(0)

try:
	grub2 = open("grub/grub.cfg", "r")
except OSError, e:
	print >>sys.stderr, "Failed to open grub.cfg: %s" % (e,)
	sys.exit(1)

print >>sys.stderr, "Generating legacy menu.lst from grub.cfg"

if os.path.exists("grub/menu.lst"):
	if options.dry:
		print >>sys.stderr, "Skip moving!"
	else:
		copyfile("grub/menu.lst", "grub/menu.lst.bak")

if options.dry:
	out = sys.stdout
else:
	out = open("grub/menu.lst", "w")
print >>out, "# This Grub configuration is auto-generated through univention-grub-generate-menu-lst."
print >>out, "# It is used when booting UCS 3.0 as a Xen DomU with an older version of PyGrub."
print >>out, ""
print >>out, "default 0"
print >>out, "timeout %s" % configRegistry.get("grub/timeout", "5")
print >>out, ""

name = kernel = initrd = None
root = options.root
kernels = []

RE_MENUENTRY = re.compile(r"^menuentry '([^']*)' .*")
RE_ROOT = re.compile(r"^\s+set\s+root='\((hd[0-9]+|/dev/\w+d[a-z]),msdos([0-9]+)\)'")
RE_LINUX = re.compile(r"^\s+linux\s+(.+)")
RE_INITRD = re.compile(r"^\s+initrd\s+(.+)")
RE_CLOSE = re.compile(r"^}")

for line in grub2:
	m = RE_MENUENTRY.match(line)
	if m:
		(name,) = m.groups()
		continue

	m = RE_ROOT.match(line)
	if m and not options.root:
		device, part = m.groups()
		if device.startswith('hd'):
			root = "(%s,%d)" % (device, int(part) - 1)
		elif device.startswith('/dev/'):
			root = "(hd%d,%d)" % (ord(device[-1]) - ord('a'), int(part) - 1)
		else:
			print >>sys.stderr, "Unhandled root=%s" % (line,)
		continue

	m = RE_LINUX.match(line)
	if m:
		(kernel,) = m.groups()
		continue

	m = RE_INITRD.match(line)
	if m:
		(initrd,) = m.groups()
		continue

	m = RE_CLOSE.match(line)
	if m:
		if name and root and kernel:
			print >>out, "title  %s" % (name,)
			print >>out, "root   %s" % (root,)
			print >>out, "kernel %s %s" % (kernel, options.args)
			if initrd:
				print >>out, "initrd %s" % (initrd,)
			print >>out, ""
		name = root = kernel = initrd = None
		root = options.root
		continue

grub2.close()
out.close()