Implement MoveFileEx or other atomic rename

pywincffi/core/cdefs/headers/constants.h

@@ -114,6 +114,14 @@
 #define PIPE_TYPE_BYTE ...
 #define PIPE_TYPE_MESSAGE ...
 
+// Flags for MoveFileEx
+#define MOVEFILE_COPY_ALLOWED ...
+#define MOVEFILE_CREATE_HARDLINK ...
+#define MOVEFILE_DELAY_UNTIL_REBOOT ...
+#define MOVEFILE_FAIL_IF_NOT_TRACKABLE ...
+#define MOVEFILE_REPLACE_EXISTING ...
+#define MOVEFILE_WRITE_THROUGH ...
+
 // General security
 #define SECURITY_ANONYMOUS ...
 #define SECURITY_CONTEXT_TRACKING ...
@@ -131,6 +139,7 @@
 #define ERROR_INVALID_PARAMETER ...
 #define ERROR_ACCESS_DENIED ...
 #define ERROR_ALREADY_EXISTS ...
+#define ERROR_NOT_SAME_DEVICE ...
 
 // For the moment, we can't define this here.  When cffi
 // parses the header this returns -1 and cffi seems to

pywincffi/core/cdefs/headers/functions.h

@@ -21,6 +21,7 @@ BOOL SetNamedPipeHandleState(HANDLE, LPDWORD, LPDWORD, LPDWORD);
 // Files
 BOOL WriteFile(HANDLE, LPCVOID, DWORD, LPDWORD, LPOVERLAPPED);
 BOOL ReadFile(HANDLE, LPVOID, DWORD, LPDWORD, LPOVERLAPPED);
+BOOL MoveFileEx(LPCTSTR, LPCTSTR, DWORD);
 
 // Handles
 HANDLE handle_from_fd(int);

pywincffi/kernel32/__init__.py

@@ -9,7 +9,7 @@
 # Our kernel32 package is broken into several submodules.  The functions
 # we're wrapping are imported here so it's easier to access and because
 # it's close to the way Windows would present them (as a single module)
-from pywincffi.kernel32.file import ReadFile, WriteFile
+from pywincffi.kernel32.file import ReadFile, WriteFile, MoveFileEx
 from pywincffi.kernel32.handle import (
     CloseHandle, GetStdHandle, WaitForSingleObject, handle_from_file)
 from pywincffi.kernel32.pipe import (

pywincffi/kernel32/file.py

@@ -5,10 +5,11 @@
 A module containing common Windows file functions for working with files.
 """
 
-from six import integer_types
+from six import integer_types, string_types
 
 from pywincffi.core import dist
 from pywincffi.core.checks import Enums, input_check, error_check
+from pywincffi.util import string_to_cdata
 
 
 def WriteFile(hFile, lpBuffer, lpOverlapped=None):
@@ -119,3 +120,47 @@ def ReadFile(hFile, nNumberOfBytesToRead, lpOverlapped=None):
     )
     error_check("ReadFile", code=code, expected=Enums.NON_ZERO)
     return ffi.string(lpBuffer)
+
+
+def MoveFileEx(lpExistingFileName, lpNewFileName, dwFlags=None):
+    """
+    Moves an existing file or directory, including its children,
+    see the MSDN documentation for full options.
+
+    .. seealso::
+
+        https://msdn.microsoft.com/en-us/library/aa365240
+
+    :param str lpExistingFileName:
+        Name of the file or directory to perform the operation on.
+
+    :param str lpNewFileName:
+        Optional new name of the path or directory.  This value may be
+        ``None``.
+
+    :keyword int dwFlags:
+        Parameters which control the operation of :func:`MoveFileEx`.  See
+        the MSDN documentation for full details.  By default
+        ``MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH`` is used.
+    """
+    ffi, library = dist.load()
+
+    if dwFlags is None:
+        dwFlags = \
+            library.MOVEFILE_REPLACE_EXISTING | library.MOVEFILE_WRITE_THROUGH
+
+    input_check("lpExistingFileName", lpExistingFileName, string_types)
+    input_check("dwFlags", dwFlags, integer_types)
+
+    if lpNewFileName is not None:
+        input_check("lpNewFileName", lpNewFileName, string_types)
+        lpNewFileName = string_to_cdata(lpNewFileName)
+    else:
+        lpNewFileName = ffi.NULL
+
+    code = library.MoveFileEx(
+        string_to_cdata(lpExistingFileName),
+        lpNewFileName,
+        ffi.cast("DWORD", dwFlags)
+    )
+    error_check("MoveFileEx", code=code, expected=Enums.NON_ZERO)

tests/test_kernel32/test_file.py

@@ -0,0 +1,68 @@
+import os
+import ctypes
+import tempfile
+from os.path import isfile
+
+from pywincffi.core import dist
+from pywincffi.dev.testutil import TestCase
+from pywincffi.exceptions import WindowsAPIError
+from pywincffi.kernel32 import MoveFileEx
+
+
+class TestMoveFileEx(TestCase):
+    """
+    Tests for :func:`pywincffi.kernel32.MoveFileEx`
+    """
+    def test_replaces_file(self):
+        # Destination file exists, this should replace it.
+        file_contents = self.random_string(12)
+        fd, path1 = tempfile.mkstemp()
+
+        with os.fdopen(fd, "w") as file_:
+            file_.write(file_contents)
+
+        fd, path2 = tempfile.mkstemp()
+        self.addCleanup(os.remove, path2)
+        os.close(fd)
+
+        MoveFileEx(path1, path2)
+
+        with open(path2, "r") as file_:
+            self.assertEqual(file_.read(), file_contents)
+
+        self.assertFalse(isfile(path1))
+
+    def test_renames_file(self):
+        # Destination file does not exist, this should create it.
+        file_contents = self.random_string(12)
+        fd, path1 = tempfile.mkstemp()
+        path2 = path1 + ".new"
+
+        with os.fdopen(fd, "w") as file_:
+            file_.write(file_contents)
+
+        MoveFileEx(path1, path2)
+
+        with open(path2, "r") as file_:
+            self.assertEqual(file_.read(), file_contents)
+
+        self.assertFalse(isfile(path1))
+
+    def test_run_delete_after_reboot(self):
+        fd, path = tempfile.mkstemp()
+        os.close(fd)
+
+        _, library = dist.load()
+        try:
+            MoveFileEx(path, None, dwFlags=library.MOVEFILE_DELAY_UNTIL_REBOOT)
+        except WindowsAPIError as error:
+            # If we're not an administrator then we don't
+            # have the permissions to perform this kind of
+            # action.
+            if error.errno == library.ERROR_ACCESS_DENIED:
+                self.assertFalse(ctypes.windll.shell32.IsUserAnAdmin())
+                return
+
+            raise
+        else:
+            self.assertTrue(isfile(path))