1 files changed, 217 insertions, 0 deletions

diff --git a/platform_utils_win32.py b/platform_utils_win32.py
new file mode 100644
index 00000000..fe76b3d6
--- /dev/null
+++ b/platform_utils_win32.py
@@ -0,0 +1,217 @@
+#
+# Copyright (C) 2016 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import errno
+
+from ctypes import WinDLL, get_last_error, FormatError, WinError, addressof
+from ctypes import c_buffer
+from ctypes.wintypes import BOOL, LPCWSTR, DWORD, HANDLE, POINTER, c_ubyte
+from ctypes.wintypes import WCHAR, USHORT, LPVOID, Structure, Union, ULONG
+from ctypes.wintypes import byref
+
+kernel32 = WinDLL('kernel32', use_last_error=True)
+
+LPDWORD = POINTER(DWORD)
+UCHAR = c_ubyte
+
+# Win32 error codes
+ERROR_SUCCESS = 0
+ERROR_NOT_SUPPORTED = 50
+ERROR_PRIVILEGE_NOT_HELD = 1314
+
+# Win32 API entry points
+CreateSymbolicLinkW = kernel32.CreateSymbolicLinkW
+CreateSymbolicLinkW.restype = BOOL
+CreateSymbolicLinkW.argtypes = (LPCWSTR,  # lpSymlinkFileName In
+                                LPCWSTR,  # lpTargetFileName In
+                                DWORD)    # dwFlags In
+
+# Symbolic link creation flags
+SYMBOLIC_LINK_FLAG_FILE = 0x00
+SYMBOLIC_LINK_FLAG_DIRECTORY = 0x01
+
+GetFileAttributesW = kernel32.GetFileAttributesW
+GetFileAttributesW.restype = DWORD
+GetFileAttributesW.argtypes = (LPCWSTR,)  # lpFileName In
+
+INVALID_FILE_ATTRIBUTES = 0xFFFFFFFF
+FILE_ATTRIBUTE_REPARSE_POINT = 0x00400
+
+CreateFileW = kernel32.CreateFileW
+CreateFileW.restype = HANDLE
+CreateFileW.argtypes = (LPCWSTR,  # lpFileName In
+                        DWORD,    # dwDesiredAccess In
+                        DWORD,    # dwShareMode In
+                        LPVOID,   # lpSecurityAttributes In_opt
+                        DWORD,    # dwCreationDisposition In
+                        DWORD,    # dwFlagsAndAttributes In
+                        HANDLE)   # hTemplateFile In_opt
+
+CloseHandle = kernel32.CloseHandle
+CloseHandle.restype = BOOL
+CloseHandle.argtypes = (HANDLE,)  # hObject In
+
+INVALID_HANDLE_VALUE = HANDLE(-1).value
+OPEN_EXISTING = 3
+FILE_FLAG_BACKUP_SEMANTICS = 0x02000000
+FILE_FLAG_OPEN_REPARSE_POINT = 0x00200000
+
+DeviceIoControl = kernel32.DeviceIoControl
+DeviceIoControl.restype = BOOL
+DeviceIoControl.argtypes = (HANDLE,   # hDevice In
+                            DWORD,    # dwIoControlCode In
+                            LPVOID,   # lpInBuffer In_opt
+                            DWORD,    # nInBufferSize In
+                            LPVOID,   # lpOutBuffer Out_opt
+                            DWORD,    # nOutBufferSize In
+                            LPDWORD,  # lpBytesReturned Out_opt
+                            LPVOID)   # lpOverlapped Inout_opt
+
+# Device I/O control flags and options
+FSCTL_GET_REPARSE_POINT = 0x000900A8
+IO_REPARSE_TAG_MOUNT_POINT = 0xA0000003
+IO_REPARSE_TAG_SYMLINK = 0xA000000C
+MAXIMUM_REPARSE_DATA_BUFFER_SIZE = 0x4000
+
+
+class GENERIC_REPARSE_BUFFER(Structure):
+  _fields_ = (('DataBuffer', UCHAR * 1),)
+
+
+class SYMBOLIC_LINK_REPARSE_BUFFER(Structure):
+  _fields_ = (('SubstituteNameOffset', USHORT),
+              ('SubstituteNameLength', USHORT),
+              ('PrintNameOffset', USHORT),
+              ('PrintNameLength', USHORT),
+              ('Flags', ULONG),
+              ('PathBuffer', WCHAR * 1))
+
+  @property
+  def PrintName(self):
+    arrayt = WCHAR * (self.PrintNameLength // 2)
+    offset = type(self).PathBuffer.offset + self.PrintNameOffset
+    return arrayt.from_address(addressof(self) + offset).value
+
+
+class MOUNT_POINT_REPARSE_BUFFER(Structure):
+  _fields_ = (('SubstituteNameOffset', USHORT),
+              ('SubstituteNameLength', USHORT),
+              ('PrintNameOffset', USHORT),
+              ('PrintNameLength', USHORT),
+              ('PathBuffer', WCHAR * 1))
+
+  @property
+  def PrintName(self):
+    arrayt = WCHAR * (self.PrintNameLength // 2)
+    offset = type(self).PathBuffer.offset + self.PrintNameOffset
+    return arrayt.from_address(addressof(self) + offset).value
+
+
+class REPARSE_DATA_BUFFER(Structure):
+  class REPARSE_BUFFER(Union):
+    _fields_ = (('SymbolicLinkReparseBuffer', SYMBOLIC_LINK_REPARSE_BUFFER),
+                ('MountPointReparseBuffer', MOUNT_POINT_REPARSE_BUFFER),
+                ('GenericReparseBuffer', GENERIC_REPARSE_BUFFER))
+  _fields_ = (('ReparseTag', ULONG),
+              ('ReparseDataLength', USHORT),
+              ('Reserved', USHORT),
+              ('ReparseBuffer', REPARSE_BUFFER))
+  _anonymous_ = ('ReparseBuffer',)
+
+
+def create_filesymlink(source, link_name):
+  """Creates a Windows file symbolic link source pointing to link_name."""
+  _create_symlink(source, link_name, SYMBOLIC_LINK_FLAG_FILE)
+
+
+def create_dirsymlink(source, link_name):
+  """Creates a Windows directory symbolic link source pointing to link_name.
+  """
+  _create_symlink(source, link_name, SYMBOLIC_LINK_FLAG_DIRECTORY)
+
+
+def _create_symlink(source, link_name, dwFlags):
+  # Note: Win32 documentation for CreateSymbolicLink is incorrect.
+  # On success, the function returns "1".
+  # On error, the function returns some random value (e.g. 1280).
+  # The best bet seems to use "GetLastError" and check for error/success.
+  CreateSymbolicLinkW(link_name, source, dwFlags)
+  code = get_last_error()
+  if code != ERROR_SUCCESS:
+    error_desc = FormatError(code).strip()
+    if code == ERROR_PRIVILEGE_NOT_HELD:
+      raise OSError(errno.EPERM, error_desc, link_name)
+    _raise_winerror(
+        code,
+        'Error creating symbolic link \"%s\"'.format(link_name))
+
+
+def islink(path):
+  result = GetFileAttributesW(path)
+  if result == INVALID_FILE_ATTRIBUTES:
+    return False
+  return bool(result & FILE_ATTRIBUTE_REPARSE_POINT)
+
+
+def readlink(path):
+  reparse_point_handle = CreateFileW(path,
+                                     0,
+                                     0,
+                                     None,
+                                     OPEN_EXISTING,
+                                     FILE_FLAG_OPEN_REPARSE_POINT |
+                                     FILE_FLAG_BACKUP_SEMANTICS,
+                                     None)
+  if reparse_point_handle == INVALID_HANDLE_VALUE:
+    _raise_winerror(
+        get_last_error(),
+        'Error opening symblic link \"%s\"'.format(path))
+  target_buffer = c_buffer(MAXIMUM_REPARSE_DATA_BUFFER_SIZE)
+  n_bytes_returned = DWORD()
+  io_result = DeviceIoControl(reparse_point_handle,
+                              FSCTL_GET_REPARSE_POINT,
+                              None,
+                              0,
+                              target_buffer,
+                              len(target_buffer),
+                              byref(n_bytes_returned),
+                              None)
+  CloseHandle(reparse_point_handle)
+  if not io_result:
+    _raise_winerror(
+        get_last_error(),
+        'Error reading symblic link \"%s\"'.format(path))
+  rdb = REPARSE_DATA_BUFFER.from_buffer(target_buffer)
+  if rdb.ReparseTag == IO_REPARSE_TAG_SYMLINK:
+    return _preserve_encoding(path, rdb.SymbolicLinkReparseBuffer.PrintName)
+  elif rdb.ReparseTag == IO_REPARSE_TAG_MOUNT_POINT:
+    return _preserve_encoding(path, rdb.MountPointReparseBuffer.PrintName)
+  # Unsupported reparse point type
+  _raise_winerror(
+      ERROR_NOT_SUPPORTED,
+      'Error reading symblic link \"%s\"'.format(path))
+
+
+def _preserve_encoding(source, target):
+  """Ensures target is the same string type (i.e. unicode or str) as source."""
+  if isinstance(source, unicode):
+    return unicode(target)
+  return str(target)
+
+
+def _raise_winerror(code, error_desc):
+  win_error_desc = FormatError(code).strip()
+  error_desc = "%s: %s".format(error_desc, win_error_desc)
+  raise WinError(code, error_desc)