#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
grml2usb
~~~~~~~~

This script installs a grml system (either a running system or ISO[s]) to a USB device

:copyright: (c) 2009 by Michael Prokop <mika@grml.org>
:license: GPL v2 or any later version
:bugreports: http://grml.org/bugs/

"""

from __future__ import with_statement
from optparse import OptionParser
from inspect import isroutine, isclass
import datetime, logging, os, re, subprocess, sys, tempfile, time

# global variables
PROG_VERSION = "0.9.2(pre1)"
MOUNTED = set()  # register mountpoints
TMPFILES = set() # register tmpfiles
DATESTAMP = time.mktime(datetime.datetime.now().timetuple()) # unique identifier for syslinux.cfg

# cmdline parsing
USAGE = "Usage: %prog [options] <[ISO[s] | /live/image]> </dev/sdX#>\n\
\n\
%prog installs a grml ISO to an USB device to be able to boot from it.\n\
Make sure you have at least one grml ISO or a running grml system (/live/image),\n\
syslinux (just run 'aptitude install syslinux' on Debian-based systems)\n\
and root access. Further information can be found in: man grml2usb"

# pylint: disable-msg=C0103
parser = OptionParser(usage=USAGE)
parser.add_option("--bootoptions", dest="bootoptions",
                  action="store", type="string",
                  help="use specified bootoptions as default")
parser.add_option("--bootloader-only", dest="bootloaderonly", action="store_true",
                  help="do not copy files but just install a bootloader")
parser.add_option("--copy-only", dest="copyonly", action="store_true",
                  help="copy files only but do not install bootloader")
parser.add_option("--dry-run", dest="dryrun", action="store_true",
                  help="avoid executing commands")
parser.add_option("--fat16", dest="fat16", action="store_true",
                  help="format specified partition with FAT16")
parser.add_option("--force", dest="force", action="store_true",
                  help="force any actions requiring manual interaction")
parser.add_option("--grub", dest="grub", action="store_true",
                  help="install grub bootloader instead of syslinux")
parser.add_option("--initrd", dest="initrd", action="store", type="string",
                  help="install specified initrd instead of the default [TODO]")
parser.add_option("--kernel", dest="kernel", action="store", type="string",
                  help="install specified kernel instead of the default [TODO]")
parser.add_option("--lilo", dest="lilo",  action="store", type="string",
                  help="lilo executable to be used for installing MBR")
parser.add_option("--quiet", dest="quiet", action="store_true",
                  help="do not output anything but just errors on console")
parser.add_option("--skip-addons", dest="skipaddons", action="store_true",
                  help="do not install /boot/addons/ files")
parser.add_option("--skip-mbr", dest="skipmbr", action="store_true",
                  help="do not install a master boot record (MBR) on the device")
parser.add_option("--squashfs", dest="squashfs", action="store", type="string",
                  help="install specified squashfs file instead of the default [TODO]")
parser.add_option("--uninstall", dest="uninstall", action="store_true",
                  help="remove grml ISO files from specified device [TODO]")
parser.add_option("--verbose", dest="verbose", action="store_true",
                  help="enable verbose mode")
parser.add_option("-v", "--version", dest="version", action="store_true",
                  help="display version and exit")
(options, args) = parser.parse_args()


class CriticalException(Exception):
    """Throw critical exception if the exact error is not known but fatal."

    @Exception: message"""
    pass


def cleanup():
    """Cleanup function to make sure there aren't any mounted devices left behind.
    """

    logging.info("Cleaning up before exiting...")
    proc = subprocess.Popen(["sync"])
    proc.wait()

    try:
        for device in MOUNTED:
            unmount(device, "")
    # ignore: RuntimeError: Set changed size during iteration
    except RuntimeError:
        logging.debug('caught expection RuntimeError, ignoring')


def register_tmpfile(path):
    """TODO
    """

    TMPFILES.add(path)


def unregister_tmpfile(path):
    """TODO
    """

    if path in TMPFILES:
        TMPFILES.remove(path)


def register_mountpoint(target):
    """TODO
    """

    MOUNTED.add(target)


def unregister_mountpoint(target):
    """TODO
    """

    if target in MOUNTED:
        MOUNTED.remove(target)


def get_function_name(obj):
    """Helper function for use in execute() to retrive name of a function

    @obj: the function object
    """
    if not (isroutine(obj) or isclass(obj)):
        obj = type(obj)
    return obj.__module__ + '.' + obj.__name__


def execute(f, *exec_arguments):
    """Wrapper for executing a command. Either really executes
    the command (default) or when using --dry-run commandline option
    just displays what would be executed."""
    # usage: execute(subprocess.Popen, (["ls", "-la"]))
    # TODO: doesn't work for proc = execute(subprocess.Popen...() -> any ideas?
    if options.dryrun:
        # pylint: disable-msg=W0141
        logging.debug('dry-run only: %s(%s)' % (get_function_name(f), ', '.join(map(repr, exec_arguments))))
    else:
        # pylint: disable-msg=W0142
        return f(*exec_arguments)


def is_exe(fpath):
    """Check whether a given file can be executed

    @fpath: full path to file
    @return:"""
    return os.path.exists(fpath) and os.access(fpath, os.X_OK)


def which(program):
    """Check whether a given program is available in PATH

    @program: name of executable"""
    fpath = os.path.split(program)[0]
    if fpath:
        if is_exe(program):
            return program
    else:
        for path in os.environ["PATH"].split(os.pathsep):
            exe_file = os.path.join(path, program)
            if is_exe(exe_file):
                return exe_file

    return None


def search_file(filename, search_path='/bin' + os.pathsep + '/usr/bin'):
    """Given a search path, find file

    @filename: name of file to search for
    @search_path: path where searching for the specified filename"""
    file_found = 0
    paths = search_path.split(os.pathsep)
    current_dir = '' # make pylint happy :)
    for path in paths:
        # pylint: disable-msg=W0612
        for current_dir, directories, files in os.walk(path):
            if os.path.exists(os.path.join(current_dir, filename)):
                file_found = 1
                break
    if file_found:
        return os.path.abspath(os.path.join(current_dir, filename))
    else:
        return None


def check_uid_root():
    """Check for root permissions"""
    if not os.geteuid()==0:
        sys.exit("Error: please run this script with uid 0 (root).")


def mkfs_fat16(device):
    """Format specified device with VFAT/FAT16 filesystem.

    @device: partition that should be formated"""

    # syslinux -d boot/isolinux /dev/sdb1
    logging.info("Formating partition with fat16 filesystem")
    logging.debug("mkfs.vfat -F 16 %s" % device)
    proc = subprocess.Popen(["mkfs.vfat", "-F", "16", device])
    proc.wait()
    if proc.returncode != 0:
        raise Exception("error executing mkfs.vfat")


def generate_main_grub2_config(grml_flavour, install_partition, bootoptions):
    """Generate grub2 configuration for use via grub.cfg

    TODO

    @grml_flavour: name of grml flavour the configuration should be generated for"""

    local_datestamp = DATESTAMP

    return("""\
set default=0
set timeout=5

insmod fat

insmod png
if background_image (hd0, %(install_partition)s)/boot/grub/grml.png ; then
  set color_normal=black/black
  set color_highlight=magenta/black
else
  set menu_color_normal=cyan/blue
  set menu_color_highlight=white/blue
fi

## main grub2 configuration - generated by grml2usb [main config generated at: %(local_datestamp)s]
menuentry "%(grml_flavour)s (default)" {
    set root=(hd0,%(install_partition)s)
    linux   /boot/release/%(grml_flavour)s/linux26 apm=power-off lang=us vga=791 quiet boot=live nomce module=%(grml_flavour)s %(bootoptions)s
    initrd  /boot/release/%(grml_flavour)s/initrd.gz
}

menuentry "Memory test (memtest86+)" {
   linux   /boot/addons/memtest
}

menuentry "Grub - all in one image" {
   linux   /boot/addons/memdisk
   initrd  /boot/addons/allinone.img
}

menuentry "FreeDOS" {
   linux   /boot/addons/memdisk
   initrd  /boot/addons/balder10.imz
}

#menuentry "Operating System on first partition of first disk" {
#    set root=(hd0,1)
#    chainloader +1
#}
#
#menuentry "Operating System on second partition of first disk" {
#    set root=(hd0,2)
#    chainloader +1
#}
#
#menuentry "Operating System on first partition of second disk" {
#    set root=(hd1,1)
#    chainloader +1
#}
#menuentry "Operating System on second partition of second disk" {
#    set root=(hd1,2)
#    chainloader +1
#}

""" % {'grml_flavour': grml_flavour, 'local_datestamp': local_datestamp, 'bootoptions': bootoptions, 'install_partition': install_partition } )


def generate_flavour_specific_grub2_config(grml_flavour, install_partition, bootoptions):
    """Generate grub2 configuration for use via grub.cfg

    TODO

    @grml_flavour: name of grml flavour the configuration should be generated for"""

    local_datestamp = DATESTAMP

    return("""\
# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
menuentry "%(grml_flavour)s" {
    set root=(hd0,%(install_partition)s)
    linux  /boot/release/%(grml_flavour)s/linux26 apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s %(bootoptions)s
    initrd /boot/release/%(grml_flavour)s/initrd.gz
}

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
menuentry "%(grml_flavour)s2ram" {
    set root=(hd0,%(install_partition)s)
    linux  /boot/release/%(grml_flavour)s/linux26 apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s toram=%(grml_flavour)s %(bootoptions)s
    initrd /boot/release/%(grml_flavour)s/initrd.gz

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
menuentry "%(grml_flavour)s-debug" {
    set root=(hd0,%(install_partition)s)
    linux /boot/release/%(grml_flavour)s/linux26
    initrd /boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s debug boot=live initcall_debug%(bootoptions)s
}

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
menuentry "%(grml_flavour)s-x" {
    set root=(hd0,%(install_partition)s)
    linux  /boot/release/%(grml_flavour)s/linux26
    initrd /boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s startx=wm-ng %(bootoptions)s
}

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
menuentry "%(grml_flavour)s-nofb" {
    set root=(hd0,%(install_partition)s)
    linux  /boot/release/%(grml_flavour)s/linux26
    initrd /boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce quiet module=%(grml_flavour)s vga=normal video=ofonly %(bootoptions)s
}

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
menuentry "%(grml_flavour)s-failsafe" {
    set root=(hd0,%(install_partition)s)
    linux /boot/release/%(grml_flavour)s/linux26
    initrd /boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce quiet module=%(grml_flavour)s vga=normal lang=us boot=live noautoconfig atapicd noacpi acpi=off nomodules nofirewire noudev nousb nohotplug noapm nopcmcia maxcpus=1 noscsi noagp nodma ide=nodma noswap nofstab nosound nogpm nosyslog nodhcp nocpu nodisc nomodem xmodule=vesa noraid nolvm %(bootoptions)s
}

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
menuentry "%(grml_flavour)s-forensic" {
    set root=(hd0,%(install_partition)s)
    linux /boot/release/%(grml_flavour)s/linux26
    initrd /boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s nofstab noraid nolvm noautoconfig noswap raid=noautodetect %(bootoptions)s
}

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
menuentry "%(grml_flavour)s-serial" {
    set root=(hd0,%(install_partition)s)
    linux /boot/release/%(grml_flavour)s/linux26
    initrd /boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce quiet module=%(grml_flavour)s vga=normal video=vesafb:off console=tty1 console=ttyS0,9600n8 %(bootoptions)s
}

""" % {'grml_flavour': grml_flavour, 'local_datestamp': local_datestamp, 'bootoptions': bootoptions, 'install_partition': install_partition } )


def generate_grub1_config(grml_flavour, install_partition, bootoptions):
    """Generate grub1 configuration for use via menu.lst

    @grml_flavour: name of grml flavour the configuration should be generated for"""

    local_datestamp = DATESTAMP

    return("""\
# misc options:
timeout 30
# color red/blue green/black
splashimage=/boot/grub/splash.xpm.gz
foreground  = 000000
background  = FFCC33

# define entries:
title %(grml_flavour)s  - Default boot (using 1024x768 framebuffer)
kernel /boot/release/%(grml_flavour)s/linux26 apm=power-off lang=us vga=791 quiet boot=live nomce module=%(grml_flavour)s
initrd /boot/release/%(grml_flavour)s/initrd.gz

""" % {'grml_flavour': grml_flavour, 'local_datestamp': local_datestamp, 'bootoptions': bootoptions} )


def generate_isolinux_splash(grml_flavour):
    """Generate bootsplash for isolinux/syslinux

    @grml_flavour: name of grml flavour the configuration should be generated for"""

    # TODO: adjust last bootsplash line (the one following the "Some information and boot ...")

    grml_name = grml_flavour

    return("""\
17/boot/syslinux/logo.16

Some information and boot options available via keys F2 - F10. http://grml.org/
%(grml_name)s
""" % {'grml_name': grml_name} )


def generate_main_syslinux_config(grml_flavour, bootoptions):
    """Generate main configuration for use in syslinux.cfg

    @grml_flavour: name of grml flavour the configuration should be generated for
    @bootoptions: bootoptions that should be used as a default"""

    local_datestamp = DATESTAMP

    return("""\
## main syslinux configuration - generated by grml2usb [main config generated at: %(local_datestamp)s]
# use this to control the bootup via a serial port
# SERIAL 0 9600
DEFAULT grml
TIMEOUT 300
PROMPT 1
DISPLAY /boot/syslinux/boot.msg
F1 /boot/syslinux/boot.msg
F2 /boot/syslinux/f2
F3 /boot/syslinux/f3
F4 /boot/syslinux/f4
F5 /boot/syslinux/f5
F6 /boot/syslinux/f6
F7 /boot/syslinux/f7
F8 /boot/syslinux/f8
F9 /boot/syslinux/f9
F10 /boot/syslinux/f10
## end of main configuration

## global configuration
# the default option (using %(grml_flavour)s)
LABEL  grml
KERNEL /boot/release/%(grml_flavour)s/linux26
APPEND initrd=/boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s %(bootoptions)s

# memtest
LABEL  memtest
KERNEL /boot/addons/memtest

# grub
LABEL grub
MENU LABEL grub
KERNEL /boot/addons/memdisk
APPEND initrd=/boot/addons/allinone.img

# dos
LABEL dos
MENU LABEL dos
KERNEL /boot/addons/memdisk
APPEND initrd=/boot/addons/balder10.imz

## end of global configuration
""" % {'grml_flavour': grml_flavour, 'local_datestamp': local_datestamp, 'bootoptions': bootoptions} )


def generate_flavour_specific_syslinux_config(grml_flavour, bootoptions):
    """Generate flavour specific configuration for use in syslinux.cfg

    @grml_flavour: name of grml flavour the configuration should be generated for
    @bootoptions: bootoptions that should be used as a default"""

    local_datestamp = DATESTAMP

    return("""\

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
LABEL  %(grml_flavour)s
KERNEL /boot/release/%(grml_flavour)s/linux26
APPEND initrd=/boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s %(bootoptions)s

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
LABEL  %(grml_flavour)s2ram
KERNEL /boot/release/%(grml_flavour)s/linux26
APPEND initrd=/boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s toram=%(grml_flavour)s %(bootoptions)s

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
LABEL  %(grml_flavour)s-debug
KERNEL /boot/release/%(grml_flavour)s/linux26
APPEND initrd=/boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s debug boot=live initcall_debug%(bootoptions)s

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
LABEL  %(grml_flavour)s-x
KERNEL /boot/release/%(grml_flavour)s/linux26
APPEND initrd=/boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s startx=wm-ng %(bootoptions)s

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
LABEL  %(grml_flavour)s-nofb
KERNEL /boot/release/%(grml_flavour)s/linux26
APPEND initrd=/boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce quiet module=%(grml_flavour)s vga=normal video=ofonly %(bootoptions)s

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
LABEL  %(grml_flavour)s-failsafe
KERNEL /boot/release/%(grml_flavour)s/linux26
APPEND initrd=/boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce quiet module=%(grml_flavour)s vga=normal lang=us boot=live noautoconfig atapicd noacpi acpi=off nomodules nofirewire noudev nousb nohotplug noapm nopcmcia maxcpus=1 noscsi noagp nodma ide=nodma noswap nofstab nosound nogpm nosyslog nodhcp nocpu nodisc nomodem xmodule=vesa noraid nolvm %(bootoptions)s

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
LABEL  %(grml_flavour)s-forensic
KERNEL /boot/release/%(grml_flavour)s/linux26
APPEND initrd=/boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce vga=791 quiet module=%(grml_flavour)s nofstab noraid nolvm noautoconfig noswap raid=noautodetect %(bootoptions)s

# flavour specific configuration for %(grml_flavour)s [grml2usb for %(grml_flavour)s: %(local_datestamp)s]
LABEL  %(grml_flavour)s-serial
KERNEL /boot/release/%(grml_flavour)s/linux26
APPEND initrd=/boot/release/%(grml_flavour)s/initrd.gz apm=power-off boot=live nomce quiet module=%(grml_flavour)s vga=normal video=vesafb:off console=tty1 console=ttyS0,9600n8 %(bootoptions)s
""" % {'grml_flavour': grml_flavour, 'local_datestamp': local_datestamp, 'bootoptions': bootoptions} )


def install_grub(device):
    """Install grub on specified device.

    @mntpoint: mountpoint of device where grub should install its files to
    @device: partition where grub should be installed to"""

    if options.dryrun:
        logging.info("Would execute grub-install [--root-directory=mount_point] %s now.", device)
    else:
        device_mountpoint = tempfile.mkdtemp()
        register_tmpfile(device_mountpoint)
        try:
            mount(device, device_mountpoint, "")
            logging.debug("grub-install --root-directory=%s %s", device_mountpoint, device)
            proc = subprocess.Popen(["grub-install", "--root-directory=%s" % device_mountpoint, device])
            proc.wait()
            if proc.returncode != 0:
                raise Exception("error executing grub-install")
        except CriticalException, error:
            logging.critical("Fatal: %s" % error)
            cleanup()
            sys.exit(1)

        finally:
            unmount(device_mountpoint, "")
            os.rmdir(device_mountpoint)
            unregister_tmpfile(device_mountpoint)


def install_syslinux(device):
    """Install syslinux on specified device.

    @device: partition where syslinux should be installed to"""

    if options.dryrun:
        logging.info("Would install syslinux as bootloader on %s", device)
        return 0

    # syslinux -d boot/isolinux /dev/sdb1
    logging.info("Installing syslinux as bootloader")
    logging.debug("syslinux -d boot/syslinux %s" % device)
    proc = subprocess.Popen(["syslinux", "-d", "boot/syslinux", device])
    proc.wait()
    if proc.returncode != 0:
        raise CriticalException("Error executing syslinux (either try --fat16 or --grub?)")


def install_bootloader(device):
    """Install bootloader on specified device.

    @device: partition where bootloader should be installed to"""

    # Install bootloader on the device (/dev/sda),
    # not on the partition itself (/dev/sda1)?
    #if partition[-1:].isdigit():
    #    device = re.match(r'(.*?)\d*$', partition).group(1)
    #else:
    #    device = partition

    if options.grub:
        install_grub(device)
    else:
        try:
            install_syslinux(device)
        except CriticalException, error:
            logging.critical("Fatal: %s" % error)
            cleanup()
            sys.exit(1)


def install_lilo_mbr(lilo, device):
    """TODO"""

    # TODO: check out the *real* difference between:
    # * mbr-install /dev/ice
    # * lilo -S /dev/null -M /dev/ice ext && lilo -S /dev/null -A /dev/ice 1
    # * cat /usr/lib/syslinux/mbr.bin > /dev/ice
    # * syslinux -sf /dev/iceX
    # * ...?

    # to support -A for extended partitions:
    logging.info("Installing MBR")
    logging.debug("%s -S /dev/null -M %s ext" % (lilo, device))
    proc = subprocess.Popen([lilo, "-S", "/dev/null", "-M", device, "ext"])
    proc.wait()
    if proc.returncode != 0:
        raise Exception("error executing lilo")

    # activate partition:
    logging.debug("%s -S /dev/null -A %s 1" % (lilo, device))
    proc = subprocess.Popen([lilo, "-S", "/dev/null", "-A", device, "1"])
    proc.wait()
    if proc.returncode != 0:
        raise Exception("error executing lilo")


def install_syslinux_mbr(device):
    """TODO"""

    # lilo's mbr is broken, use the one from syslinux instead:
    if not os.path.isfile("/usr/lib/syslinux/mbr.bin"):
        raise Exception("/usr/lib/syslinux/mbr.bin can not be read")

    logging.debug("cat /usr/lib/syslinux/mbr.bin > %s" % device)
    try:
        # TODO -> use Popen instead?
        retcode = subprocess.call("cat /usr/lib/syslinux/mbr.bin > "+ device, shell=True)
        if retcode < 0:
            logging.critical("Error copying MBR to device (%s)" % retcode)
    except OSError, error:
        logging.critical("Execution failed:", error)


def install_mbr(device):
    """Install a default master boot record on given device

    @device: device where MBR should be installed to"""

    if not is_writeable(device):
        raise IOError("device not writeable for user")

    # try to use system's lilo
    if which("lilo"):
        lilo = which("lilo")
    else:
        # otherwise fall back to our static version
        from platform import architecture
        if architecture()[0] == '64bit':
            lilo = '/usr/share/grml2usb/lilo/lilo.static.amd64'
        else:
            lilo = '/usr/share/grml2usb/lilo/lilo.static.i386'
    # finally prefer a specified lilo executable
    if options.lilo:
        lilo = options.lilo

    if not is_exe(lilo):
        raise Exception("lilo executable can not be execute")

    if options.dryrun:
        logging.info("Would install MBR running lilo and using syslinux.")
        return 0

    install_lilo_mbr(lilo, device)
    install_syslinux_mbr(device)


def is_writeable(device):
    """Check if the device is writeable for the current user

    @device: partition where bootloader should be installed to"""

    if not device:
        return False
        #raise Exception("no device for checking write permissions")

    if not os.path.exists(device):
        return False

    return os.access(device, os.W_OK) and os.access(device, os.R_OK)


def mount(source, target, mount_options):
    """Mount specified source on given target

    @source: name of device/ISO that should be mounted
    @target: directory where the ISO should be mounted to
    @options: mount specific options"""

    # notice: options.dryrun does not work here, as we have to
    # locate files and identify the grml flavour
    logging.debug("mount %s %s %s" % (mount_options, source, target))
    proc = subprocess.Popen(["mount"] + list(mount_options) + [source, target])
    proc.wait()
    if proc.returncode != 0:
        raise CriticalException("Error executing mount")
    else:
        logging.debug("register_mountpoint(%s)" % target)
        register_mountpoint(target)


def unmount(target, unmount_options):
    """Unmount specified target

    @target: target where something is mounted on and which should be unmounted
    @options: options for umount command"""

    # make sure we unmount only already mounted targets
    target_unmount = False
    mounts = open('/proc/mounts').readlines()
    mountstring = re.compile(".*%s.*" % re.escape(target))
    for line in mounts:
        if re.match(mountstring, line):
            target_unmount = True

    if not target_unmount:
        logging.debug("%s not mounted anymore" % target)
    else:
        logging.debug("umount %s %s" % (list(unmount_options), target))
        proc = subprocess.Popen(["umount"] + list(unmount_options) + [target])
        proc.wait()
        if proc.returncode != 0:
            raise Exception("Error executing umount")
        else:
            logging.debug("unregister_mountpoint(%s)" % target)
            unregister_mountpoint(target)


def check_for_usbdevice(device):
    """Check whether the specified device is a removable USB device

    @device: device name, like /dev/sda1 or /dev/sda
    """

    usbdevice = re.match(r'/dev/(.*?)\d*$', device).group(1)
    usbdevice = os.path.realpath('/sys/class/block/' + usbdevice + '/removable')
    if os.path.isfile(usbdevice):
        is_usb = open(usbdevice).readline()
        if is_usb == "1":
            return 0
        else:
            return 1


def check_for_fat(partition):
    """Check whether specified partition is a valid VFAT/FAT16 filesystem

    @partition: device name of partition"""

    try:
        udev_info = subprocess.Popen(["/lib/udev/vol_id", "-t", partition],
                    stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        filesystem = udev_info.communicate()[0].rstrip()

        if udev_info.returncode == 2:
            raise CriticalException("Failed to read device %s"
                                    "(wrong UID/permissions or device not present?)" % partition)

        if filesystem != "vfat":
            raise CriticalException("Device %s does not contain a FAT16 partition." % partition)

    except OSError:
        raise CriticalException("Sorry, /lib/udev/vol_id not available.")


def mkdir(directory):
    """Simple wrapper around os.makedirs to get shell mkdir -p behaviour"""

    # just silently pass as it's just fine it the directory exists
    if not os.path.isdir(directory):
        try:
            os.makedirs(directory)
        # pylint: disable-msg=W0704
        except OSError:
            pass


def copy_system_files(grml_flavour, iso_mount, target):
    """TODO"""

    squashfs = search_file(grml_flavour + '.squashfs', iso_mount)
    if squashfs is None:
        logging.critical("Fatal: squashfs file not found")
    else:
        squashfs_target = target + '/live/'
        execute(mkdir, squashfs_target)
        # use install(1) for now to make sure we can write the files afterwards as normal user as well
        logging.debug("cp %s %s" % (squashfs, target + '/live/' + grml_flavour + '.squashfs'))
        proc = subprocess.Popen(["install", "--mode=664", squashfs, squashfs_target + grml_flavour + ".squashfs"])
        proc.wait()

    filesystem_module = search_file('filesystem.module', iso_mount)
    if filesystem_module is None:
        logging.critical("Fatal: filesystem.module not found")
    else:
        logging.debug("cp %s %s" % (filesystem_module, squashfs_target + grml_flavour + '.module'))
        proc = subprocess.Popen(["install", "--mode=664", filesystem_module,
                                squashfs_target + grml_flavour + '.module'])
        proc.wait()

    release_target = target + '/boot/release/' + grml_flavour
    execute(mkdir, release_target)

    kernel = search_file('linux26', iso_mount)
    if kernel is None:
        logging.critical("Fatal kernel not found")
    else:
        logging.debug("cp %s %s" % (kernel, release_target + '/linux26'))
        proc = subprocess.Popen(["install", "--mode=664", kernel, release_target + '/linux26'])
        proc.wait()

    initrd = search_file('initrd.gz', iso_mount)
    if initrd is None:
        logging.critical("Fatal: initrd not found")
    else:
        logging.debug("cp %s %s" % (initrd, release_target + '/initrd.gz'))
        proc = subprocess.Popen(["install", "--mode=664", initrd, release_target + '/initrd.gz'])
        proc.wait()


def copy_grml_files(iso_mount, target):
    """TODO"""

    grml_target = target + '/grml/'
    execute(mkdir, grml_target)

    for myfile in 'grml-cheatcodes.txt', 'grml-version', 'LICENSE.txt', 'md5sums', 'README.txt':
        grml_file = search_file(myfile, iso_mount)
        if grml_file is None:
            logging.warn("Warning: myfile %s could not be found - can not install it", myfile)
        else:
            logging.debug("cp %s %s" % (grml_file, grml_target + grml_file))
            proc = subprocess.Popen(["install", "--mode=664", grml_file, grml_target + myfile])
            proc.wait()

    grml_web_target = grml_target + '/web/'
    execute(mkdir, grml_web_target)

    for myfile in 'index.html', 'style.css':
        grml_file = search_file(myfile, iso_mount)
        if grml_file is None:
            logging.warn("Warning: myfile %s could not be found - can not install it")
        else:
            logging.debug("cp %s %s" % (grml_file, grml_web_target + grml_file))
            proc = subprocess.Popen(["install", "--mode=664", grml_file, grml_web_target + myfile])
            proc.wait()

    grml_webimg_target = grml_web_target + '/images/'
    execute(mkdir, grml_webimg_target)

    for myfile in 'button.png', 'favicon.png', 'linux.jpg', 'logo.png':
        grml_file = search_file(myfile, iso_mount)
        if grml_file is None:
            logging.warn("Warning: myfile %s could not be found - can not install it")
        else:
            logging.debug("cp %s %s" % (grml_file, grml_webimg_target + grml_file))
            proc = subprocess.Popen(["install", "--mode=664", grml_file, grml_webimg_target + myfile])
            proc.wait()


def copy_addons(iso_mount, target):
    """TODO"""
    addons = target + '/boot/addons/'
    execute(mkdir, addons)

    # grub all-in-one image
    allinoneimg = search_file('allinone.img', iso_mount)
    if allinoneimg is None:
        logging.warn("Warning: allinone.img not found - can not install it")
    else:
        logging.debug("cp %s %s" % (allinoneimg, addons + '/allinone.img'))
        proc = subprocess.Popen(["install", "--mode=664", allinoneimg, addons + 'allinone.img'])
        proc.wait()

    # freedos image
    balderimg = search_file('balder10.imz', iso_mount)
    if balderimg is None:
        logging.warn("Warning: balder10.imz not found - can not install it")
    else:
        logging.debug("cp %s %s" % (balderimg, addons + '/balder10.imz'))
        proc = subprocess.Popen(["install", "--mode=664", balderimg, addons + 'balder10.imz'])
        proc.wait()

    # memdisk image
    memdiskimg = search_file('memdisk', iso_mount)
    if memdiskimg is None:
        logging.warn("Warning: memdisk not found - can not install it")
    else:
        logging.debug("cp %s %s" % (memdiskimg, addons + '/memdisk'))
        proc = subprocess.Popen(["install", "--mode=664", memdiskimg, addons + 'memdisk'])
        proc.wait()

    # memtest86+ image
    memtestimg = search_file('memtest', iso_mount)
    if memtestimg is None:
        logging.warn("Warning: memtest not found - can not install it")
    else:
        logging.debug("cp %s %s" % (memtestimg, addons + '/memtest'))
        proc = subprocess.Popen(["install", "--mode=664", memtestimg, addons + 'memtest'])
        proc.wait()


def copy_bootloader_files(iso_mount, target):
    """"TODO"""

    syslinux_target = target + '/boot/syslinux/'
    execute(mkdir, syslinux_target)

    logo = search_file('logo.16', iso_mount)
    logging.debug("cp %s %s" % (logo, syslinux_target + 'logo.16'))
    proc = subprocess.Popen(["install", "--mode=664", logo, syslinux_target + 'logo.16'])
    proc.wait()

    for ffile in 'f2', 'f3', 'f4', 'f5', 'f6', 'f7', 'f8', 'f9', 'f10':
        bootsplash = search_file(ffile, iso_mount)
        logging.debug("cp %s %s" % (bootsplash, syslinux_target + ffile))
        proc = subprocess.Popen(["install", "--mode=664", bootsplash, syslinux_target + ffile])
        proc.wait()

    grub_target = target + '/boot/grub/'
    execute(mkdir, grub_target)

    if not os.path.isfile("/usr/share/grml2usb/grub/splash.xpm.gz"):
        logging.critical("Error: /usr/share/grml2usb/grub/splash.xpm.gz can not be read.")
        raise
    else:
        logging.debug("cp /usr/share/grml2usb/grub/splash.xpm.gz %s" % grub_target + 'splash.xpm.gz')
        proc = subprocess.Popen(["install", "--mode=664", '/usr/share/grml2usb/grub/splash.xpm.gz',
                                grub_target + 'splash.xpm.gz'])
        proc.wait()

    if not os.path.isfile("/usr/share/grml2usb/grub/stage2_eltorito"):
        logging.critical("Error: /usr/share/grml2usb/grub/stage2_eltorito can not be read.")
        raise
    else:
        logging.debug("cp /usr/share/grml2usb/grub/stage2_eltorito to %s" % grub_target + 'stage2_eltorito')
        proc = subprocess.Popen(["install", "--mode=664", '/usr/share/grml2usb/grub/stage2_eltorito',
                                grub_target + 'stage2_eltorito'])
        proc.wait()


def install_iso_files(grml_flavour, iso_mount, device, target):
    """Copy files from ISO on given target"""

    # TODO
    # * make sure grml_flavour, iso_mount, target are set when the function is called, otherwise raise exception
    # * provide alternative search_file() if file information is stored in a config.ini file?
    # * catch "install: .. No space left on device" & CO
    # * abstract copy logic to make the code shorter and get rid of spaghettis ;)

    if options.dryrun:
        logging.info("Would copy files to %s", iso_mount)
        return 0
    elif not options.bootloaderonly:
        logging.info("Copying files. This might take a while....")
        copy_system_files(grml_flavour, iso_mount, target)
        copy_grml_files(iso_mount, target)

    if not options.skipaddons:
        copy_addons(iso_mount, target)

    if not options.copyonly:
        copy_bootloader_files(iso_mount, target)

        if not options.dryrun:
            handle_bootloader_config(grml_flavour, device, target) # FIXME

    # make sure we sync filesystems before returning
    proc = subprocess.Popen(["sync"])
    proc.wait()


def uninstall_files(device):
    """Get rid of all grml files on specified device

    @device: partition where grml2usb files should be removed from"""

    # TODO
    logging.critical("TODO: uninstalling files from %s not yet implement, sorry." % device)


def identify_grml_flavour(mountpath):
    """Get name of grml flavour

    @mountpath: path where the grml ISO is mounted to
    @return: name of grml-flavour"""

    version_file = search_file('grml-version', mountpath)

    if version_file == "":
        logging.critical("Error: could not find grml-version file.")
        raise

    try:
        tmpfile = open(version_file, 'r')
        grml_info = tmpfile.readline()
        grml_flavour = re.match(r'[\w-]*', grml_info).group()
    except TypeError:
        raise
    except:
        logging.critical("Unexpected error:", sys.exc_info()[0])
        raise

    return grml_flavour


def handle_bootloader_config(grml_flavour, device, target):
    """TODO"""

    logging.debug("Generating grub configuration")
    #with open("...", "w") as f:
    #f.write("bla bla bal")

    grub_target = target + '/boot/grub/'
    # should be present via copy_bootloader_files(), but make sure it exists:
    execute(mkdir, grub_target)
    # we have to adjust root() inside grub configuration
    if device[-1:].isdigit():
        install_partition = device[-1:]

    # grub1 config
    logging.debug("Creating grub1 configuration file")
    grub_config_file = open(grub_target + 'menu.lst', 'w')
    grub_config_file.write(generate_grub1_config(grml_flavour, install_partition, options.bootoptions))
    grub_config_file.close()

    # TODO => generate_main_grub1_config() && generate_flavour_specific_grub1_config()

    # grub2 config
    grub2_cfg = grub_target + 'grub.cfg'
    logging.debug("Creating grub2 configuration file")

    # install main configuration only *once*, no matter how many ISOs we have:
    if os.path.isfile(grub2_cfg):
        string = open(grub2_cfg).readline()
        main_identifier = re.compile(".*main config generated at: %s.*" % re.escape(str(DATESTAMP)))
        if not re.match(main_identifier, string):
            grub2_config_file = open(grub2_cfg, 'w')
            logging.info("Notice: grml flavour %s is being installed as the default booting system." % grml_flavour)
            grub2_config_file.write(generate_main_grub2_config(grml_flavour, install_partition, options.bootoptions))
            grub2_config_file.close()
    else:
        grub2_config_file = open(grub2_cfg, 'w')
        grub2_config_file.write(generate_main_grub2_config(grml_flavour, install_partition, options.bootoptions))
        grub2_config_file.close()

    grub_flavour_config = True
    if os.path.isfile(grub2_cfg):
        string = open(grub2_cfg).readlines()
        logging.info("Notice: you can boot flavour %s using '%s' on the commandline." % (grml_flavour, grml_flavour))
        flavour = re.compile("grml2usb for %s: %s" % (re.escape(grml_flavour), re.escape(str(DATESTAMP))))
        for line in string:
            if flavour.match(line):
                grub_flavour_config = False

    if grub_flavour_config:
        grub2_config_file = open(grub2_cfg, 'a')
        grub2_config_file.write(generate_flavour_specific_grub2_config(grml_flavour, install_partition, options.bootoptions))
        grub2_config_file.close( )


    logging.info("Generating syslinux configuration")
    syslinux_target = target + '/boot/syslinux/'
    # should be present via  copy_bootloader_files(), but make sure it exits:
    execute(mkdir, syslinux_target)
    syslinux_cfg = syslinux_target + 'syslinux.cfg'

    # install main configuration only *once*, no matter how many ISOs we have:
    if os.path.isfile(syslinux_cfg):
        string = open(syslinux_cfg).readline()
        main_identifier = re.compile(".*main config generated at: %s.*" % re.escape(str(DATESTAMP)))
        if not re.match(main_identifier, string):
            syslinux_config_file = open(syslinux_cfg, 'w')
            logging.info("Notice: grml flavour %s is being installed as the default booting system." % grml_flavour)
            syslinux_config_file.write(generate_main_syslinux_config(grml_flavour, options.bootoptions))
            syslinux_config_file.close()
    else:
        syslinux_config_file = open(syslinux_cfg, 'w')
        syslinux_config_file.write(generate_main_syslinux_config(grml_flavour, options.bootoptions))
        syslinux_config_file.close()

    # install flavour specific configuration only *once* as well
    # kind of ugly - I'm pretty sure this could be smoother...
    syslinux_flavour_config = True
    if os.path.isfile(syslinux_cfg):
        string = open(syslinux_cfg).readlines()
        logging.info("Notice: you can boot flavour %s using '%s' on the commandline." % (grml_flavour, grml_flavour))
        flavour = re.compile("grml2usb for %s: %s" % (re.escape(grml_flavour), re.escape(str(DATESTAMP))))
        for line in string:
            if flavour.match(line):
                syslinux_flavour_config = False

    if syslinux_flavour_config:
        syslinux_config_file = open(syslinux_cfg, 'a')
        syslinux_config_file.write(generate_flavour_specific_syslinux_config(grml_flavour, options.bootoptions))
        syslinux_config_file.close( )

    logging.debug("Generating isolinux/syslinux splash %s" % syslinux_target + 'boot.msg')
    isolinux_splash = open(syslinux_target + 'boot.msg', 'w')
    isolinux_splash.write(generate_isolinux_splash(grml_flavour))
    isolinux_splash.close( )


def handle_iso(iso, device):
    """Main logic for mounting ISOs and copying files.

    @iso: full path to the ISO that should be installed to the specified device
    @device: partition where the specified ISO should be installed to"""

    logging.info("Using ISO %s" % iso)

    if os.path.isdir(iso):
        logging.critical("TODO: /live/image handling not yet implemented - sorry") # TODO
        sys.exit(1)

    iso_mountpoint = tempfile.mkdtemp()
    register_tmpfile(iso_mountpoint)
    remove_iso_mountpoint = True

    if not os.path.isfile(iso):
        logging.critical("Fatal: specified ISO %s could not be read" % iso)
        cleanup()
        sys.exit(1)

    try:
        mount(iso, iso_mountpoint, ["-o", "loop", "-t", "iso9660"])
    except CriticalException, error:
        logging.critical("Fatal: %s" % error)
        sys.exit(1)

    if os.path.isdir(device):
        logging.info("Specified target is a directory, not mounting therefor.")
        device_mountpoint = device
        remove_device_mountpoint = False
        # skip_mbr = True
    else:
        device_mountpoint = tempfile.mkdtemp()
        register_tmpfile(device_mountpoint)
        remove_device_mountpoint = True
        try:
            mount(device, device_mountpoint, "")
        except CriticalException, error:
            logging.critical("Fatal: %s" % error)
            cleanup()
            sys.exit(1)

    try:
        grml_flavour = identify_grml_flavour(iso_mountpoint)
        logging.info("Identified grml flavour \"%s\"." % grml_flavour)
        install_iso_files(grml_flavour, iso_mountpoint, device, device_mountpoint)
    except TypeError:
        logging.critical("Fatal: a critical error happend during execution (not a grml ISO?), giving up")
        sys.exit(1)
    finally:
        if os.path.isdir(iso_mountpoint) and remove_iso_mountpoint:
            unmount(iso_mountpoint, "")
            os.rmdir(iso_mountpoint)
            unregister_tmpfile(iso_mountpoint)
        if remove_device_mountpoint:
            unmount(device_mountpoint, "")
            if os.path.isdir(device_mountpoint):
                os.rmdir(device_mountpoint)
                unregister_tmpfile(device_mountpoint)


def handle_mbr(device):
    """TODO"""

    # install MBR
    # if not options.mbr:
    #     logging.info("You are NOT using the --mbr option. Consider using it if your device does not boot.")
    # else:
    # make sure we install MBR on /dev/sdX and not /dev/sdX#

    # make sure we have syslinux available
    # if options.mbr:
    if not options.skipmbr:
        if not which("syslinux") and not options.copyonly and not options.dryrun:
            logging.critical('Sorry, syslinux not available. Exiting.')
            logging.critical('Please install syslinux or consider using the --grub option.')
            sys.exit(1)

    if not options.skipmbr:
        if device[-1:].isdigit():
            mbr_device = re.match(r'(.*?)\d*$', device).group(1)

        try:
            install_mbr(mbr_device)
        except IOError, error:
            logging.critical("Execution failed: %s", error)
            sys.exit(1)
        except Exception, error:
            logging.critical("Execution failed: %s", error)
            sys.exit(1)


def handle_vfat(device):
    """TODO"""

    # make sure we have mkfs.vfat available
    if options.fat16 and not options.force:
        if not which("mkfs.vfat") and not options.copyonly and not options.dryrun:
            logging.critical('Sorry, mkfs.vfat not available. Exiting.')
            logging.critical('Please make sure to install dosfstools.')
            sys.exit(1)

        # make sure the user is aware of what he is doing
        f = raw_input("Are you sure you want to format the device with a fat16 filesystem? y/N ")
        if f == "y" or f == "Y":
            logging.info("Note: you can skip this question using the option --force")
            mkfs_fat16(device)
        else:
            sys.exit(1)

    # check for vfat filesystem
    if device is not None and not os.path.isdir(device):
        try:
            check_for_fat(device)
        except CriticalException, error:
            logging.critical("Execution failed: %s", error)
            sys.exit(1)

    if not check_for_usbdevice(device):
        print "Warning: the specified device %s does not look like a removable usb device." % device
        f = raw_input("Do you really want to continue? y/N ")
        if f == "y" or f == "Y":
            pass
        else:
            sys.exit(1)


def handle_compat_warning(device):
    """TODO"""

    # make sure we can replace old grml2usb script and warn user when using old way of life:
    if device.startswith("/mnt/external") or device.startswith("/mnt/usb") and not options.force:
        print "Warning: the semantics of grml2usb has changed."
        print "Instead of using grml2usb /path/to/iso %s you might" % device
        print "want to use grml2usb /path/to/iso /dev/... instead."
        print "Please check out the grml2usb manpage for details."
        f = raw_input("Do you really want to continue? y/N ")
        if f == "y" or f == "Y":
            pass
        else:
            sys.exit(1)


def handle_logging():
    """TODO"""

    if options.verbose:
        FORMAT = "%(asctime)-15s %(message)s"
        logging.basicConfig(level=logging.DEBUG, format=FORMAT)
    elif options.quiet:
        FORMAT = "Critial: %(message)s"
        logging.basicConfig(level=logging.CRITICAL, format=FORMAT)
    else:
        FORMAT = "Info: %(message)s"
        logging.basicConfig(level=logging.INFO, format=FORMAT)


def handle_bootloader(device):
    """TODO"""
    # Install bootloader only if not using the --copy-only option
    if options.copyonly:
        logging.info("Not installing bootloader and its files as requested via option copyonly.")
    else:
        install_bootloader(device)


def main():
    """Main function [make pylint happy :)]"""

    if options.version:
        print os.path.basename(sys.argv[0]) + " " + PROG_VERSION
        sys.exit(0)

    if len(args) < 2:
        parser.error("invalid usage")

    # log handling
    handle_logging()

    # make sure we have the appropriate permissions
    check_uid_root()

    if options.dryrun:
        logging.info("Running in simulate mode as requested via option dry-run.")

    # specified arguments
    device = args[len(args) - 1]
    isos = args[0:len(args) - 1]

    # provide upgrade path
    handle_compat_warning(device)

    # check for vfat partition
    handle_vfat(device)

    # main operation (like installing files)
    for iso in isos:
        handle_iso(iso, device)

    # install mbr
    handle_mbr(device)

    handle_bootloader(device)

    # finally be politely :)
    logging.info("Finished execution of grml2usb (%s). Have fun with your grml system." % PROG_VERSION)


if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        logging.info("Received KeyboardInterrupt")
        cleanup()

## END OF FILE #################################################################
# vim:foldmethod=indent expandtab ai ft=python tw=120 fileencoding=utf-8