0b40f6368b
This patch adds a type of exception for the Windows code, which interpolates the given exception message with the last Windows API error, retrieved with ctypes.GetLastError. This is useful in the case where we have only the log at our disposal for debugging and some API method failed with reasons unknown. Since we can't replicate what the user does everytime, having some additional clue why an API failed could improve our bug detection workflow. Change-Id: I364324ad5a8529b5363be3a7c6dc03ca52eb637c
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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