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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright: 2015 Bastian Blank
# License: MIT, see LICENSE.txt for details.
import array
import struct
import time
import sys
import os
from uuid import uuid4
class VHDFooter:
_struct = struct.Struct('>8sLLQL4sL4sQQ4sLL16sB427x')
size = _struct.size
vhd_timestamp_base = 946684800
def __init__(self, size, uuid=None, timestamp=None):
self.size = size
self.timestamp = timestamp or (int(time.time()) - self.vhd_timestamp_base)
self.uuid = uuid or uuid4()
@staticmethod
def _checksum(msg):
return 0x100000000 + ~sum(array.array("B", msg))
def _pack_geometry(self):
sectors = self.size // 512
if sectors > 65535 * 16 * 255:
sectors = 65535 * 16 * 255
if sectors >= 65535 * 16 * 63:
sectorsPerTrack = 255
heads = 16
cylinderTimesHeads = sectors // sectorsPerTrack
else:
sectorsPerTrack = 17
cylinderTimesHeads = sectors // sectorsPerTrack
heads = (cylinderTimesHeads + 1023) // 1024
if heads < 4:
heads = 4
if cylinderTimesHeads >= (heads * 1024) or heads > 16:
sectorsPerTrack = 31
heads = 16
cylinderTimesHeads = sectors // sectorsPerTrack
if cylinderTimesHeads >= (heads * 1024):
sectorsPerTrack = 63
heads = 16
cylinderTimesHeads = sectors // sectorsPerTrack
cylinders = cylinderTimesHeads // heads
return struct.pack('>HBB', cylinders, heads, sectorsPerTrack)
def _pack(self, checksum):
return self._struct.pack(
b'conectix', # Cookie
0x00000002, # Features
0x00010000, # File Format Version
0xffffffffffffffff, # Data Offset
self.timestamp, # Time Stamp
b'qemu', # Creator Application
0x00010000, # Creator Version
b'Wi2k', # Creator Host OS
self.size, # Original Size
self.size, # Current Size
self._pack_geometry(), # Disk Geometry
2, # Disk Type
checksum, # Checksum
self.uuid.bytes, # Unique Id
0, # Saved State
)
def pack(self):
c = self._checksum(self._pack(0))
return self._pack(c)
with open(sys.argv[1], 'rb+') as f:
f.seek(0, 2)
image_size = f.tell()
image_size_complete = image_size + VHDFooter.size
footer = VHDFooter(image_size)
f.write(footer.pack())
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