Foundation: avoid temporary file leaks on Windows

Correct the implementation of `_NSCleanupTemporaryFile` to use
`MoveFileExW` with `MOVEFILE_COPY_ALLOWED` to prefer to use file renames
rather than copy and delete.  This should improve performance in the
general single volume case and still allow the correct behaviour in the
multi-volume scenarios using `CopyFile` and `DeleteFile`.

Thanks to @darinf for identifying the test case with 65535 temporary
files!

Author: compnerd

Sources/Foundation/FileManager+Win32.swift

@@ -620,7 +620,7 @@ extension FileManager {
                 // case, we need to do a recursive copy & remove.
                 if PathIsSameRootW(wszSource, wszDestination) ||
                         faSourceAttributes.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY == 0 {
-                    if !MoveFileExW(wszSource, wszDestination, DWORD(MOVEFILE_COPY_ALLOWED | MOVEFILE_WRITE_THROUGH)) {
+                    if !MoveFileExW(wszSource, wszDestination, MOVEFILE_COPY_ALLOWED | MOVEFILE_WRITE_THROUGH) {
                         throw _NSErrorWithWindowsError(GetLastError(), reading: false, paths: [srcPath, dstPath])
                     }
                 } else {

Sources/Foundation/NSPathUtilities.swift

@@ -813,7 +813,8 @@ internal func _NSCleanupTemporaryFile(_ auxFilePath: String, _ filePath: String)
 #if os(Windows)
     try withNTPathRepresentation(of: auxFilePath) { pwszSource in
         try withNTPathRepresentation(of: filePath) { pwszDestination in
-            guard CopyFileW(pwszSource, pwszDestination, false) else {
+            guard MoveFileExW(pwszSource, pwszDestination,
+                              MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH) else {
                 let dwErrorCode = GetLastError()
                 try? FileManager.default.removeItem(atPath: auxFilePath)
                 throw _NSErrorWithWindowsError(dwErrorCode, reading: false)

Sources/Foundation/WinSDK+Extensions.swift

@@ -57,6 +57,18 @@ internal var GENERIC_WRITE: DWORD {
     DWORD(WinSDK.GENERIC_WRITE)
 }
 
+internal var MOVEFILE_COPY_ALLOWED: DWORD {
+    DWORD(WinSDK.MOVEFILE_COPY_ALLOWED)
+}
+
+internal var MOVEFILE_REPLACE_EXISTING: DWORD {
+    DWORD(WinSDK.MOVEFILE_REPLACE_EXISTING)
+}
+
+internal var MOVEFILE_WRITE_THROUGH: DWORD {
+    DWORD(WinSDK.MOVEFILE_WRITE_THROUGH)
+}
+
 internal var OPEN_EXISTING: DWORD {
     DWORD(WinSDK.OPEN_EXISTING)
 }