111 lines
3.4 KiB
Python
111 lines
3.4 KiB
Python
# Copyright 2012 Cloudbase Solutions Srl
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import ctypes
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from ctypes import windll
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from ctypes import wintypes
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from cloudbaseinit import exception
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kernel32 = windll.kernel32
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class Win32_DiskGeometry(ctypes.Structure):
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FixedMedia = 12
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_fields_ = [
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('Cylinders', wintypes.LARGE_INTEGER),
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('MediaType', wintypes.DWORD),
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('TracksPerCylinder', wintypes.DWORD),
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('SectorsPerTrack', wintypes.DWORD),
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('BytesPerSector', wintypes.DWORD),
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]
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class PhysicalDisk(object):
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GENERIC_READ = 0x80000000
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FILE_SHARE_READ = 1
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OPEN_EXISTING = 3
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FILE_ATTRIBUTE_READONLY = 1
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INVALID_HANDLE_VALUE = -1
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IOCTL_DISK_GET_DRIVE_GEOMETRY = 0x70000
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FILE_BEGIN = 0
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INVALID_SET_FILE_POINTER = 0xFFFFFFFF
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def __init__(self, path):
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self._path = path
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self._handle = 0
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self._geom = None
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def open(self):
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if self._handle:
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self.close()
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handle = kernel32.CreateFileW(
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ctypes.c_wchar_p(self._path),
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self.GENERIC_READ,
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self.FILE_SHARE_READ,
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0,
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self.OPEN_EXISTING,
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self.FILE_ATTRIBUTE_READONLY,
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0)
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if handle == self.INVALID_HANDLE_VALUE:
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raise exception.CloudbaseInitException('Cannot open file')
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self._handle = handle
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def close(self):
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kernel32.CloseHandle(self._handle)
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self._handle = 0
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self._geom = None
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def get_geometry(self):
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if not self._geom:
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geom = Win32_DiskGeometry()
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bytes_returned = wintypes.DWORD()
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ret_val = kernel32.DeviceIoControl(
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self._handle,
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self.IOCTL_DISK_GET_DRIVE_GEOMETRY,
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0,
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0,
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ctypes.byref(geom),
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ctypes.sizeof(geom),
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ctypes.byref(bytes_returned),
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0)
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if not ret_val:
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raise exception.WindowsCloudbaseInitException(
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"Cannot get disk geometry: %r")
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self._geom = geom
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return self._geom
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def seek(self, offset):
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high = wintypes.DWORD(offset >> 32)
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low = wintypes.DWORD(offset & 0xFFFFFFFF)
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ret_val = kernel32.SetFilePointer(self._handle, low,
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ctypes.byref(high),
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self.FILE_BEGIN)
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if ret_val == self.INVALID_SET_FILE_POINTER:
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raise exception.CloudbaseInitException("Seek error")
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def read(self, bytes_to_read):
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buf = ctypes.create_string_buffer(bytes_to_read)
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bytes_read = wintypes.DWORD()
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ret_val = kernel32.ReadFile(self._handle, buf, bytes_to_read,
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ctypes.byref(bytes_read), 0)
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if not ret_val:
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raise exception.WindowsCloudbaseInitException(
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"Read exception: %r")
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return (buf, bytes_read.value)
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