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#!/usr/bin/python
#
# Python library for reading and writing Windows shortcut files (.lnk)
# Copyright 2011 Tim-Christian Mundt
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 3 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, see
# <http://www.gnu.org/licenses/>.
#
# hardly cannibalized from https://sourceforge.net/p/pylnk/home/Home/
# not as clean as i wished
# cannibal: @theguly

from __future__ import print_function
from future import standard_library
standard_library.install_aliases()
from builtins import chr
from builtins import str
from builtins import range
from builtins import object
import sys, os, time, re
from struct import pack, unpack
from pprint import pformat,PrettyPrinter
from datetime import datetime
from io import StringIO
pp = PrettyPrinter(indent=4)

#---- constants

_SIGNATURE = b'L\x00\x00\x00'
_GUID = b'\x01\x14\x02\x00\x00\x00\x00\x00\xc0\x00\x00\x00\x00\x00\x00F'
_LINK_INFO_HEADER_DEFAULT = 0x1C
_LINK_INFO_HEADER_OPTIONAL = 0x24

_LINK_FLAGS = ('has_shell_item_id_list', 'has_link_info', 'has_description',
              'has_relative_path', 'has_work_directory', 'has_arguments',
              'has_icon', 'is_unicode', 'force_no_link_info')

_FILE_ATTRIBUTES_FLAGS = ('read_only', 'hidden', 'system_file', 'reserved1',
                         'directory', 'archive', 'reserved2', 'normal',
                         'temporary', 'sparse_file', 'reparse_point',
                         'compressed', 'offline', 'not_content_indexed',
                         'encrypted')

_MODIFIER_KEYS = ('SHIFT', 'CONTROL', 'ALT')

WINDOW_NORMAL = "Normal"
WINDOW_MAXIMIZED = "Maximized"
WINDOW_MINIMIZED = "Minimized"
_SHOW_COMMANDS = {1:WINDOW_NORMAL, 3:WINDOW_MAXIMIZED, 7:WINDOW_MINIMIZED}
_SHOW_COMMAND_IDS = dict((v, k) for k, v in _SHOW_COMMANDS.items())

DRIVE_UNKNOWN = "Unknown"
DRIVE_NO_ROOT_DIR = "No root directory"
DRIVE_REMOVABLE = "Removable"
DRIVE_FIXED = "Fixed (Hard disk)"
DRIVE_REMOTE = "Remote (Network drive)"
DRIVE_CDROM = "CD-ROM"
DRIVE_RAMDISK = "Ram disk"
_DRIVE_TYPES = {0: DRIVE_UNKNOWN,
                1: DRIVE_NO_ROOT_DIR,
                2: DRIVE_REMOVABLE,
                3: DRIVE_FIXED,
                4: DRIVE_REMOTE,
                5: DRIVE_CDROM,
                6: DRIVE_RAMDISK}
_DRIVE_TYPE_IDS = dict((v, k) for k, v in _DRIVE_TYPES.items())

_KEYS = {0x30: '0', 0x31: '1', 0x32: '2', 0x33: '3', 0x34: '4', 0x35: '5', 0x36: '6',
        0x37: '7', 0x38: '8', 0x39: '9', 0x41: 'A', 0x42: 'B', 0x43: 'C', 0x44: 'D',
        0x45: 'E', 0x46: 'F', 0x47: 'G', 0x48: 'H', 0x49: 'I', 0x4A: 'J', 0x4B: 'K',
        0x4C: 'L', 0x4D: 'M', 0x4E: 'N', 0x4F: 'O', 0x50: 'P', 0x51: 'Q', 0x52: 'R',
        0x53: 'S', 0x54: 'T', 0x55: 'U', 0x56: 'V', 0x57: 'W', 0x58: 'X', 0x59: 'Y',
        0x5A: 'Z', 0x70: 'F1', 0x71: 'F2', 0x72: 'F3', 0x73: 'F4', 0x74: 'F5',
        0x75: 'F6', 0x76: 'F7', 0x77: 'F8', 0x78: 'F9', 0x79: 'F10', 0x7A: 'F11',
        0x7B: 'F12', 0x7C: 'F13', 0x7D: 'F14', 0x7E: 'F15', 0x7F: 'F16', 0x80: 'F17',
        0x81: 'F18', 0x82: 'F19', 0x83: 'F20', 0x84: 'F21', 0x85: 'F22', 0x86: 'F23',
        0x87: 'F24', 0x90: 'NUM LOCK', 0x91: 'SCROLL LOCK'}
_KEY_CODES = dict((v, k) for k, v in _KEYS.items())

ROOT_MY_COMPUTER = 'MY_COMPUTER'
ROOT_MY_DOCUMENTS = 'MY_DOCUMENTS'
ROOT_NETWORK_SHARE = 'NETWORK_SHARE'
ROOT_NETWORK_SERVER = 'NETWORK_SERVER'
ROOT_NETWORK_PLACES = 'NETWORK_PLACES'
ROOT_NETWORK_DOMAIN = 'NETWORK_DOMAIN'
ROOT_INTERNET = 'INTERNET'
ROOT_RECYLCE_BIN = 'RECYLCE_BIN'
ROOT_CONTROL_PANEL = 'CONTROL_PANEL'

_ROOT_LOCATIONS = {'{20D04FE0-3AEA-1069-A2D8-08002B30309D}': ROOT_MY_COMPUTER,
                  '{450D8FBA-AD25-11D0-98A8-0800361B1103}': ROOT_MY_DOCUMENTS,
                  '{54a754c0-4bf1-11d1-83ee-00a0c90dc849}': ROOT_NETWORK_SHARE,
                  '{c0542a90-4bf0-11d1-83ee-00a0c90dc849}': ROOT_NETWORK_SERVER,
                  '{208D2C60-3AEA-1069-A2D7-08002B30309D}': ROOT_NETWORK_PLACES,
                  '{46e06680-4bf0-11d1-83ee-00a0c90dc849}': ROOT_NETWORK_DOMAIN,
                  '{871C5380-42A0-1069-A2EA-08002B30309D}': ROOT_INTERNET,
                  '{645FF040-5081-101B-9F08-00AA002F954E}': ROOT_RECYLCE_BIN,
                  '{21EC2020-3AEA-1069-A2DD-08002B30309D}': ROOT_CONTROL_PANEL}
_ROOT_LOCATION_GUIDS = dict((v, k) for k, v in _ROOT_LOCATIONS.items())

TYPE_FOLDER = 'FOLDER'
TYPE_FILE = 'FILE'
_ENTRY_TYPES = {0x31: 'FOLDER', 0x32: 'FILE',
               0x35: 'FOLDER (UNICODE)', 0x36: 'FILE (UNICODE)'}
_ENTRY_TYPE_IDS = dict((v, k) for k, v in _ENTRY_TYPES.items())

_DRIVE_PATTERN = re.compile("(\w)[:/\\\\]*$")

#---- read and write binary data

def read_byte(buf):
    return unpack('<B', buf.read(1))[0]

def read_short(buf):
    return unpack('<H', buf.read(2))[0]

def read_int(buf):
    return unpack('<I', buf.read(4))[0]

def read_double(buf):
    return unpack('<Q', buf.read(8))[0]

def read_cunicode(buf):
    s = ""
    b = buf.read(2)
    while b!= '\x00\x00':
        s += b
        b = buf.read(2)
    return s.decode('utf-16-le')

def read_cstring(buf, padding=False):
    s = ""
    b = buf.read(1)
    while b != '\x00':
        s += b
        b = buf.read(1)
    if padding and not len(s) % 2:
        buf.read(1) # make length + terminator even
    #TODO: encoding is not clear, unicode-escape has been necessary sometimes
    return s.decode('cp1252')

def read_sized_string(buf, str=True):
    size = read_short(buf)
    if str:
        return buf.read(size*2).decode('utf-16-le')
    else:
        return buf.read(size)

def get_bits(value, start, count, length=16):
    mask = 0
    for i in range(count):
        mask = mask | 1 << i
    shift = length - start - count
    return value >> shift & mask

def read_dos_datetime(buf):
    date = read_short(buf)
    time = read_short(buf)
    year = get_bits(date, 0, 7) + 1980
    month = get_bits(date, 7, 4)
    day = get_bits(date, 11, 5)
    hour = get_bits(time, 0, 5)
    minute = get_bits(time, 5, 6)
    second = get_bits(time, 11, 5)
    return datetime(year, month, day, hour, minute, second)

def write_byte(val, buf):
    buf.write(pack('<B', val).decode('UTF-8'))

def write_short(val, buf):
    buf.write(pack('<H', val).decode('latin-1'))

def write_int(val, buf):
    buf.write(pack('<I', val).decode('UTF-8'))

def write_double(val, buf):
    buf.write(pack('<Q', val).decode('UTF-8'))

def write_cstring(val, buf, padding=False):
    #val = val.encode('unicode-escape').replace('\\\\', '\\')
    val = val.encode('cp1252')
    buf.write((val + b'\x00').decode('UTF-8'))
    if padding and not len(val) % 2:
        buf.write('\x00')

def write_cunicode(val, buf):
    uni = val.encode('utf-16-le')
    buf.write((uni + b'\x00\x00').decode('UTF-8'))

def write_sized_string(val, buf, str=True):
    size = len(val)
    write_short(size, buf)
    if str:
        buf.write(val.encode('utf-16-le'))
    else:
        buf.write(val)

def ret_sized_string(val, str=True):
    size = len(val)
    ret = pack('<H', size)
    if str:
        ret += val.encode('utf-16-le')
    else:
        ret += val.encode('UTF-8')
    return ret

def put_bits(bits, target, start, count, length=16):
    return target | bits << (length - start - count)

def write_dos_datetime(val, buf):
    date = time = 0
    date = put_bits(val.year-1980, date, 0, 7)
    date = put_bits(val.month, date, 7, 4)
    date = put_bits(val.day, date, 11, 5)
    time = put_bits(val.hour, time, 0, 5)
    time = put_bits(val.minute, time, 5, 6)
    time = put_bits(val.second, time, 11, 5)
    write_short(date, buf)
    write_short(time, buf)

#---- helpers

def convert_time_to_unix(windows_time):
    # Windows time is specified as the number of 0.1 nanoseconds since January 1, 1601.
    # UNIX time is specified as the number of seconds since January 1, 1970.
    # There are 134774 days (or 11644473600 seconds) between these dates.
    unix_time = windows_time / 10000000.0 - 11644473600
    return datetime.fromtimestamp(unix_time)

def convert_time_to_windows(unix_time):
    if isinstance(unix_time, datetime):
        unix_time = time.mktime(unix_time.timetuple())
    return int((unix_time + 11644473600) * 10000000)

class FormatException(Exception):
    pass

class MissingInformationException(Exception):
    pass

class InvalidKeyException(Exception):
    pass

#---- data structures

class Flags(object):
    
    def __init__(self, flag_names, flags_bytes=0):
        self._flag_names = flag_names
        self._flags = dict([(name, None) for name in flag_names])
        self.set_flags(flags_bytes)
    
    def set_flags(self, flags_bytes):
        for pos in range(len(self._flag_names)):
            self._flags[self._flag_names[pos]] = flags_bytes >> pos & 0x1 and True or False
    
    def bytes(self):
        bytes = 0
        for pos in range(len(self._flag_names)):
            bytes = (self._flags[self._flag_names[pos]] and 1 or 0) << pos | bytes
        return bytes
    bytes = property(bytes)
    
    def __getitem__(self, key):
        return object.__getattribute__(self, '_flags')[key]
    
    def __setitem__(self, key, value):
        if key not in self._flags:
            raise KeyError("The key '%s' is not defined for those flags." % key)
        self._flags[key] = value
    
    def __getattr__(self, key):
        return object.__getattribute__(self, '_flags')[key]
    
    def __setattr__(self, key, value):
        if '_flags' not in self.__dict__:
            object.__setattr__(self, key, value)
        elif key in self.__dict__:
            object.__setattr__(self, key, value)
        else:
            self.__setitem__(key, value)

    def __str__(self):
        return pformat(self._flags, indent=2)


class ModifierKeys(Flags):
    
    def __init__(self, flags_bytes=0):
        Flags.__init__(self, _MODIFIER_KEYS, flags_bytes)
    
    def __str__(self):
        s = ""
        s += self.CONTROL and "CONTROL+" or ""
        s += self.SHIFT and "SHIFT+" or ""
        s += self.ALT and "ALT+" or ""
        return s


class RootEntry(object):
    
    def __init__(self, root):
        if root is not None:
            if root in list(_ROOT_LOCATION_GUIDS.keys()):
                self.root = root
                self.guid = _ROOT_LOCATION_GUIDS[root]
            else:
                bytes = root
                if len(bytes) == 18: # and bytes[:2] == '\x1F\x50':
                    # '\x1F\x50' for MY_COMPUTER
                    # '\x1FX' for NETWORK
                    bytes = bytes[2:]
                if len(bytes) != 16:
                    raise FormatException("This is no valid _GUID: %s" % bytes)
                ordered = [bytes[3], bytes[2], bytes[1], bytes[0], bytes[5], bytes[4],
                           bytes[7], bytes[6], bytes[8], bytes[9], bytes[10], bytes[11],
                           bytes[12], bytes[13], bytes[14], bytes[15]]
                self.guid = "{%02X%02X%02X%02X-%02X%02X-%02X%02X-%02X%02X-%02X%02X%02X%02X%02X%02X}" % tuple(
                       [ord(x) for x in ordered])
                self.root = _ROOT_LOCATIONS.get(self.guid, "UNKNOWN")

    def bytes(self):
        guid = self.guid[1:-1].replace('-', '')
        chars = [chr(int(x, 16)) for x in [guid[i:i+2] for i in range(0, 32, 2)]]
        return '\x1F\x50' + chars[3] + chars[2] + chars[1] + chars[0] + chars[5] + chars[4] \
               + chars[7] + chars[6] + ''.join(chars[8:])
    bytes = property(bytes)
    
    def __str__(self):
        return "<RootEntry: %s>" % self.root


class DriveEntry(object):
    
    def __init__(self, drive):
        if len(drive) == 23:
            self.drive = drive[1:3]
        else:
            m = _DRIVE_PATTERN.match(drive.strip())
            if m:
                self.drive = m.groups()[0].upper() + ':'
            else:
                raise FormatException("This is not a valid drive: " + drive)
    
    def bytes(self):
        return '/' + self.drive + '\\' + '\x00' * 19
    bytes = property(bytes)
    
    def __str__(self):
        return "<DriveEntry: %s>" % self.drive


class PathSegmentEntry(object):
    
    def __init__(self, bytes=None):
        self.type = None
        self.file_size = None
        self.modified = None
        self.short_name = None
        self.created = None
        self.accessed = None
        self.full_name = None
        if bytes is not None:
            buf = StringIO(bytes)
            self.type = _ENTRY_TYPES.get(read_short(buf), 'UNKNOWN')
            short_name_is_unicode = self.type.endswith('(UNICODE)')
            self.file_size = read_int(buf)
            self.modified = read_dos_datetime(buf)
            unknown = read_short(buf) # should be 0x10
            if short_name_is_unicode:
                self.short_name = read_cunicode(buf)
            else:
                self.short_name = read_cstring(buf, padding=True)
            indicator_1 = read_short(buf) # see below
            only_83 = read_short(buf) < 0x03
            unknown = read_short(buf) # 0x04
            self.is_unicode = read_short(buf) == 0xBeef
            self.created = read_dos_datetime(buf)
            self.accessed = read_dos_datetime(buf)
            offset_unicode = read_short(buf)
            only_83_2 = offset_unicode >= indicator_1 or offset_unicode < 0x14
            offset_ansi = read_short(buf)
            self.full_name = read_cunicode(buf)
            offset_part2 = read_short(buf) # offset to byte after short name
    
    def create_for_path(cls, path):
        entry = cls()
        entry.type = 'FILE'
        entry.file_size = 473600
        entry.short_name = path
        entry.modified = datetime.fromtimestamp(1444297518)
        entry.created = datetime.fromtimestamp(1444297518)
        entry.accessed = datetime.fromtimestamp(1503493813)
        entry.full_name = entry.short_name
        return entry
    
    create_for_path = classmethod(create_for_path)
    
    def _validate(self):
        if self.type is None:
            raise MissingInformationException("Type is missing, choose either TYPE_FOLDER or TYPE_FILE.")
        if self.file_size is None:
            if self.type.startswith('FOLDER'):
                self.file_size = 0
            else:
                raise MissingInformationException("File size missing")
        if self.modified is None or self.accessed is None or self.created is None:
            raise MissingInformationException("Date information missing")
        if self.full_name is None:
            raise MissingInformationException("A full name is missing")
        if self.short_name is None:
            self.short_name = self.full_name
    
    def bytes(self):
        self._validate()
        out = StringIO()
        entry_type = self.type
        short_name_len = len(self.short_name) + 1
        try:
            if isinstance(self.short_name, bytes):
                self.short_name.decode("ascii")
            short_name_is_unicode = False
            short_name_len += short_name_len % 2 # padding
        except (UnicodeEncodeError, UnicodeDecodeError):
            short_name_is_unicode = True
            short_name_len = short_name_len * 2
            self.type += " (UNICODE)"
        write_short(_ENTRY_TYPE_IDS[entry_type], out)
        write_int(self.file_size, out)
        write_dos_datetime(self.modified, out)
        write_short(0x10, out)
        if short_name_is_unicode:
            write_cunicode(self.short_name, out)
        else:
            write_cstring(self.short_name, out, padding=True)
        indicator = 24 + 2 * len(self.short_name)
        write_short(indicator, out)
        write_short(0x03, out)
        write_short(0x04, out)
        write_short(0xBeef, out)
        write_dos_datetime(self.created, out)
        write_dos_datetime(self.accessed, out)
        offset_unicode = 0x14 # fixed data structure, always the same
        write_short(offset_unicode, out)
        offset_ansi = 0 # we always write unicode
        write_short(offset_ansi, out)
        write_cunicode(self.full_name, out)
        offset_part2 = 0x0E + short_name_len
        write_short(offset_part2, out)
        return out.getvalue()
    bytes = property(bytes)
    
    def __str__(self):
        return "<PathSegmentEntry: %s>" % self.full_name


class LinkTargetIDList(object):

    def __init__(self, bytes=None):
        self.items = []
        if bytes is not None:
            buf = StringIO(bytes)
            raw = []
            entry_len = read_short(buf)
            while entry_len > 0:
                raw.append(buf.read(entry_len - 2)) # the length includes the size
                entry_len = read_short(buf)
            self._interpret(raw)

    def _interpret(self, raw):
        if len(raw[0]) == 0x12:
            self.items.append(RootEntry(raw[0]))
            if self.items[0].root == ROOT_MY_COMPUTER:
                if not len(raw[1]) == 0x17:
                    raise ValueError("This seems to be an absolute link which requires a drive as second element.")
                self.items.append(DriveEntry(raw[1]))
                items = raw[2:]
            elif self.items[0].root == ROOT_NETWORK_PLACES:
                raise NotImplementedError("""Parsing network lnks has not yet been implemented.
                     If you need it just contact me and we'll see...""")
            else:
                items = raw[1:]
        else:
            items = raw
        for item in items:
            self.items.append(PathSegmentEntry(item))

    def _validate(self):
        if type(self.items[0]) == RootEntry:
            if self.items[0].root == ROOT_MY_COMPUTER \
            and type(self.items[1]) != DriveEntry:
                raise ValueError("A drive is required for absolute lnks")
    
    def bytes(self):
        self._validate()
        out = StringIO()
        for item in self.items:
            bytes = item.bytes
            write_short(len(bytes) + 2, out) # len + terminator
            out.write(bytes)
        out.write('\x00\x00')
        return out.getvalue()
    bytes = property(bytes)
    
    def __str__(self):
        return "<LinkTargetIDList:\n%s>" % pformat([str(item) for item in self.items])


class LinkInfo(object):

    def __init__(self, lnk=None):
        if lnk is not None:
            self.start = lnk.tell()
            self.size = read_int(lnk)
            self.header_size = read_int(lnk)
            link_info_flags = read_int(lnk)
            self.local = link_info_flags & 1
            self.remote = link_info_flags & 2
            self.offs_local_volume_table = read_int(lnk)
            self.offs_local_base_path = read_int(lnk)
            self.offs_network_volume_table = read_int(lnk)
            self.offs_base_name = read_int(lnk)
            if self.header_size >= _LINK_INFO_HEADER_OPTIONAL:
                print("TODO: read the unicode stuff") # TODO: read the unicode stuff
            self._parse_path_elements(lnk)
        else:
            self.size = None
            self.header_size = _LINK_INFO_HEADER_DEFAULT
            self.remote = None
            self.offs_local_volume_table = 0
            self.offs_local_base_path = 0
            self.offs_network_volume_table = 0
            self.offs_base_name = 0
            self.drive_type = None
            self.drive_serial = None
            self.volume_label = None
            self.local_base_path = None
            self.network_share_name = None
            self.base_name = None
            self._path = None


class Lnk(object):

    def __init__(self, f=None):
        self.file = None
        if type(f) == str or type(f) == str:
            self.file = f
            try:
                f = open(self.file, 'rb')
            except IOError:
                self.file += ".lnk"
                f = open(self.file, 'rb')
        # defaults
        self.link_flags = Flags(_LINK_FLAGS)
        self.file_flags = Flags(_FILE_ATTRIBUTES_FLAGS)
        self.creation_time = datetime.now()
        self.access_time = datetime.now()
        self.modification_time = datetime.now()
        self.file_size = 0
        self.icon_index = 0
        self._show_command = WINDOW_NORMAL
        self.hot_key = None
        self._link_info = LinkInfo()
        self.description = None
        self.relative_path = None
        self.work_dir = None
        self.arguments = None
        self.icon = None
    
    def _write_hot_key(self, hot_key, lnk):
        if hot_key is None:
            low = high = 0
        else:
            hot_key = hot_key.split('+')
            try:
                low = _KEY_CODES[hot_key[-1]]
            except KeyError:
                raise InvalidKeyException("Cannot find key code for %s" % hot_key[1])
            modifiers = ModifierKeys()
            for modifier in hot_key[:-1]:
                modifiers[modifier.upper()] = True
            high = modifiers.bytes
        write_byte(low, lnk)
        write_byte(high, lnk)

    def save(self, f=None, force_ext=False):
        if f is None:
            f = self.file
        if f is None:
            raise ValueError("File (name) missing for saveing the lnk")
        is_file = hasattr(f, 'write')
        if not is_file:
            if not type(f) == str and not type(f) == str:
                raise ValueError("Need a writeable object or a file name to save to, got %s" % f)
            if force_ext:
                if not f.lower().endswith('.lnk'):
                    f += '.lnk'
            f = open(f, 'wb')
        self.write(f)
        # only close the stream if it's our own
        if not is_file:
            f.close()

    def ret(self):
        ret  = _SIGNATURE
        ret += _GUID
        ret += pack('<I',self.link_flags.bytes)
        ret += pack('<I',self.file_flags.bytes)
        ret += pack('<Q',convert_time_to_windows(self.creation_time))
        ret += pack('<Q',convert_time_to_windows(self.access_time))
        ret += pack('<Q',convert_time_to_windows(self.modification_time))
        ret += pack('<I',self.file_size)
        ret += pack('<I',self.icon_index)
        ret += pack('<I',_SHOW_COMMAND_IDS[self._show_command])
        ret += pack('<B',0) #hotkey
        ret += pack('<B',0) #hotkey
        ret += (b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00') # reserved

        if self.link_flags.has_shell_item_id_list:
            siil = self.shell_item_id_list.bytes
            ret += pack('<H',len(siil))
            ret += siil.encode('UTF-8')
        # TOFIX / TOINVESTIGATE
        #if self.link_flags.has_link_info:
            #self._link_info.write(lnk)
        if self.link_flags.has_description:
            ret += ret_sized_string(self.description, self.link_flags.is_unicode)
        if self.link_flags.has_relative_path:
            ret += ret_sized_string(self.relative_path, self.link_flags.is_unicode)
        if self.link_flags.has_work_directory:
            ret += ret_sized_string(self.work_dir, self.link_flags.is_unicode)
        if self.link_flags.has_arguments:
            ret += ret_sized_string(self.arguments, self.link_flags.is_unicode)
        if self.link_flags.has_icon:
            ret += ret_sized_string(self.icon, self.link_flags.is_unicode)

        ret += (b'\x00\x00\x00\x00') # header_size
        return ret

    def write(self, lnk):
        lnk.write(_SIGNATURE)
        lnk.write(_GUID)
        write_int(self.link_flags.bytes, lnk)
        write_int(self.file_flags.bytes, lnk)
        write_double(convert_time_to_windows(self.creation_time), lnk)
        write_double(convert_time_to_windows(self.access_time), lnk)
        write_double(convert_time_to_windows(self.modification_time), lnk)
        write_int(self.file_size, lnk)
        write_int(self.icon_index, lnk)
        write_int(_SHOW_COMMAND_IDS[self._show_command], lnk)
        self._write_hot_key(self.hot_key, lnk)
        lnk.write('\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00') # reserved
        if self.link_flags.has_shell_item_id_list:
            siil = self.shell_item_id_list.bytes
            write_short(len(siil), lnk)
            lnk.write(siil)
        if self.link_flags.has_link_info:
            self._link_info.write(lnk)
        if self.link_flags.has_description:
            write_sized_string(self.description, lnk, self.link_flags.is_unicode)
        if self.link_flags.has_relative_path:
            write_sized_string(self.relative_path, lnk, self.link_flags.is_unicode)
        if self.link_flags.has_work_directory:
            write_sized_string(self.work_dir, lnk, self.link_flags.is_unicode)
        if self.link_flags.has_arguments:
            write_sized_string(self.arguments, lnk, self.link_flags.is_unicode)
        if self.link_flags.has_icon:
            write_sized_string(self.icon, lnk, self.link_flags.is_unicode)
        lnk.write('\x00\x00\x00\x00') # header_size

    def _get_shell_item_id_list(self):
        return self._shell_item_id_list

    def _set_shell_item_id_list(self, shell_item_id_list):
        self._shell_item_id_list = shell_item_id_list
        self.link_flags.has_shell_item_id_list = shell_item_id_list != None
    shell_item_id_list = property(_get_shell_item_id_list, _set_shell_item_id_list)

    def _get_link_info(self):
        return self._link_info

    def _set_link_info(self, link_info):
        self._link_info = link_info
        self.link_flags.force_no_link_info = link_info == None
        self.link_flags.has_link_info = link_info != None
    link_info = property(_get_link_info, _set_link_info)

    def _get_description(self):
        return self._description

    def _set_description(self, description):
        self._description = description
        self.link_flags.has_description = description != None
    description = property(_get_description, _set_description)

    def _get_relative_path(self):
        return self._relative_path
    def _set_relative_path(self, relative_path):
        self._relative_path = relative_path
        self.link_flags.has_relative_path = relative_path != None
    relative_path = property(_get_relative_path, _set_relative_path)

    def _get_work_dir(self):
        return self._work_dir
    def _set_work_dir(self, work_dir):
        self._work_dir = work_dir
        self.link_flags.has_work_directory = work_dir != None
    work_dir = working_dir = property(_get_work_dir, _set_work_dir)

    def _get_arguments(self):
        return self._arguments
    def _set_arguments(self, arguments):
        self._arguments = arguments
        self.link_flags.has_arguments = arguments != None
    arguments = property(_get_arguments, _set_arguments)

    def _get_icon(self):
        return self._icon
    def _set_icon(self, icon):
        self._icon = icon
        self.link_flags.has_icon = icon != None
    icon = property(_get_icon, _set_icon)
    
    def _get_window_mode(self):
        return self._show_command
    def _set_window_mode(self, value):
        if not value in list(_SHOW_COMMANDS.values()):
            raise ValueError("Not a valid window mode: %s. Choose any of pylnk.WINDOW_*" % value)
        self._show_command = value
    window_mode = show_command = property(_get_window_mode, _set_window_mode)

    def _get_path(self):
        return self._shell_item_id_list.get_path()
    path = property(_get_path)
    
    def __str__(self):
        s = "Target file:\n"
        s += str(self.file_flags)
        s += "\nCreation Time: %s" % self.creation_time
        s += "\nModification Time: %s" % self.modification_time
        s += "\nAccess Time: %s" % self.access_time
        s += "\nFile size: %s" % self.file_size
        s += "\nWindow mode: %s" % self._show_command
        s += "\nHotkey: %s\n" % self.hot_key
        s += str(self._link_info)
        if self.link_flags.has_shell_item_id_list:
            s += "\n%s" % self.shell_item_id_list
        if self.link_flags.has_description:
            s += "\nDescription: %s" % self.description
        if self.link_flags.has_relative_path:
            s += "\nRelative Path: %s" % self.relative_path
        if self.link_flags.has_work_directory:
            s += "\nWorking Directory: %s" % self.work_dir
        if self.link_flags.has_arguments:
            s += "\nCommandline Arguments: %s" % self.arguments
        if self.link_flags.has_icon:
            s += "\nIcon: %s" % self.icon
        s += "\nUsed Path: %s" % self.shell_item_id_list.get_path()
        return s

#---- convenience functions

def create(f=None):
    lnk = Lnk()
    lnk.file = f
    return lnk

def for_file(target_file, arguments, lnkname, lnkicon=None, description=None):
    drive, full_path = target_file.split(':',1)
    full_path = full_path.lstrip('\\')
    lnk = create()
    lnk.link_info = None
    level = full_path
    elements = [RootEntry(ROOT_MY_COMPUTER),
                DriveEntry(drive)]
    segment = PathSegmentEntry.create_for_path(level)
    elements.append(segment)
    lnk.shell_item_id_list = LinkTargetIDList()
    lnk.shell_item_id_list.items = elements
    lnk.description = description
    lnk.arguments = arguments
    lnk.icon = lnkicon
    #if lnkname:
    #    lnk.save()
    return lnk