Add support for cloud placeholder on Windows (Such as OneDrive)

game_backuper/cfapi.py

@@ -0,0 +1,35 @@
+from ctypes import HRESULT, byref, c_uint, windll
+from ctypes.wintypes import (
+    DWORD, HANDLE, LARGE_INTEGER, LPCWSTR, LPVOID, PHANDLE
+)
+
+
+dll = windll.CldApi
+CF_OPEN_FILE_FLAG_NONE = 0
+CF_OPEN_FILE_FLAG_EXCLUSIVE = 1
+CF_OPEN_FILE_FLAG_WRITE_ACCESS = 2
+CF_OPEN_FILE_FLAG_DELETE_ACCESS = 3
+CF_OPEN_FILE_FLAG_FOREGROUND = 4
+CfOpenFileWithOplock = dll.CfOpenFileWithOplock
+CfOpenFileWithOplock.argtypes = [LPCWSTR, c_uint, PHANDLE]
+CfOpenFileWithOplock.restype = HRESULT
+CfHydratePlaceholder = dll.CfHydratePlaceholder
+CfHydratePlaceholder.argtypes = [HANDLE, LARGE_INTEGER, LARGE_INTEGER, c_uint, LPVOID]  # noqa: E501
+CfHydratePlaceholder.restype = HRESULT
+CfCloseHandle = dll.CfCloseHandle
+CfCloseHandle.argtypes = [HANDLE]
+ERROR_INVALID_FUNCTION = 1
+GetLastError = windll.Kernel32.GetLastError
+GetLastError.restype = DWORD
+
+
+def hydrate_file(s: str):
+    h = HANDLE()
+    try:
+        CfOpenFileWithOplock(s, CF_OPEN_FILE_FLAG_NONE, byref(h))
+        CfHydratePlaceholder(h, 0, -1, 0, LPVOID())
+    except OSError as e:
+        if GetLastError() != ERROR_INVALID_FUNCTION:
+            CfCloseHandle(h)
+            raise e
+    CfCloseHandle(h)