1 files changed, 90 insertions, 0 deletions
diff --git a/scripts/vhd.py b/scripts/vhd.py
new file mode 100755
index 0000000..6a26892
--- /dev/null
+++ b/scripts/vhd.py
@@ -0,0 +1,90 @@
+#!/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())