Foundation: expose _handle from FileHandle on Windows

Add a SPI for Windows to get the raw `HANDLE` to enable use of `Pipe`
where a raw file descriptor may be needed.

Author: compnerd

Sources/Foundation/FileHandle.swift

@@ -49,10 +49,10 @@ extension NSError {
 
 open class FileHandle : NSObject {
 #if os(Windows)
-    private var _handle: HANDLE
+    internal private(set) var handle: HANDLE
 
-    internal var handle: HANDLE {
-      return _handle
+    public var _handle: HANDLE {
+      return self.handle
     }
 
     @available(Windows, unavailable, message: "Cannot perform non-owning handle to fd conversion")
@@ -61,11 +61,11 @@ open class FileHandle : NSObject {
     }
 
     private func _checkFileHandle() {
-        precondition(_handle != INVALID_HANDLE_VALUE, "Invalid file handle")
+        precondition(self.handle != INVALID_HANDLE_VALUE, "Invalid file handle")
     }
 
     internal var _isPlatformHandleValid: Bool {
-        return _handle != INVALID_HANDLE_VALUE
+        return self.handle != INVALID_HANDLE_VALUE
     }
 #else
     private var _fd: Int32
@@ -228,15 +228,15 @@ open class FileHandle : NSObject {
           return NSData.NSDataReadResult(bytes: nil, length: 0, deallocator: nil)
         }
 
-        if GetFileType(_handle) == FILE_TYPE_DISK {
+        if GetFileType(self.handle) == FILE_TYPE_DISK {
           var fiFileInfo: BY_HANDLE_FILE_INFORMATION = BY_HANDLE_FILE_INFORMATION()
-          if !GetFileInformationByHandle(_handle, &fiFileInfo) {
+          if !GetFileInformationByHandle(self.handle, &fiFileInfo) {
               throw _NSErrorWithWindowsError(GetLastError(), reading: true)
           }
 
           if options.contains(.alwaysMapped) {
             let hMapping: HANDLE =
-                CreateFileMappingA(_handle, nil, DWORD(PAGE_READONLY), 0, 0, nil)
+                CreateFileMappingA(self.handle, nil, DWORD(PAGE_READONLY), 0, 0, nil)
             if hMapping == HANDLE(bitPattern: 0) {
               fatalError("CreateFileMappingA failed")
             }
@@ -272,7 +272,7 @@ open class FileHandle : NSObject {
           }
 
           var BytesRead: DWORD = 0
-          if !ReadFile(_handle, buffer.advanced(by: total), BytesToRead, &BytesRead, nil) {
+          if !ReadFile(self.handle, buffer.advanced(by: total), BytesToRead, &BytesRead, nil) {
             let err = GetLastError()
             if err == ERROR_BROKEN_PIPE {
                 break
@@ -370,7 +370,7 @@ open class FileHandle : NSObject {
 #if os(Windows)
         var BytesRead: DWORD = 0
         let BytesToRead: DWORD = DWORD(length)
-        if !ReadFile(_handle, buffer, BytesToRead, &BytesRead, nil) {
+        if !ReadFile(self.handle, buffer, BytesToRead, &BytesRead, nil) {
             throw _NSErrorWithWindowsError(GetLastError(), reading: true)
         }
         return Int(BytesRead)
@@ -413,7 +413,7 @@ open class FileHandle : NSObject {
 
 #if os(Windows)
     internal init(handle: HANDLE, closeOnDealloc closeopt: Bool) {
-      _handle = handle
+      self.handle = handle
       _closeOnDealloc = closeopt
     }
 
@@ -424,10 +424,10 @@ open class FileHandle : NSObject {
           fatalError("DuplicateHandle() failed: \(GetLastError())")
         }
         _close(fd)
-        _handle = handle!
+        self.handle = handle!
         _closeOnDealloc = true
       } else {
-        _handle = HANDLE(bitPattern: _get_osfhandle(fd))!
+        self.handle = HANDLE(bitPattern: _get_osfhandle(fd))!
         _closeOnDealloc = false
       }
     }
@@ -443,7 +443,7 @@ open class FileHandle : NSObject {
       }), fd > 0 else { return nil }
 
       self.init(fileDescriptor: fd, closeOnDealloc: true)
-      if _handle == INVALID_HANDLE_VALUE { return nil }
+      if self.handle == INVALID_HANDLE_VALUE { return nil }
     }
 #else
     public init(fileDescriptor fd: Int32, closeOnDealloc closeopt: Bool) {
@@ -525,7 +525,7 @@ open class FileHandle : NSObject {
 
         #if os(Windows)
         var liPointer: LARGE_INTEGER = LARGE_INTEGER(QuadPart: 0)
-        guard SetFilePointerEx(_handle, LARGE_INTEGER(QuadPart: 0), &liPointer, DWORD(FILE_CURRENT)) else {
+        guard SetFilePointerEx(self.handle, LARGE_INTEGER(QuadPart: 0), &liPointer, DWORD(FILE_CURRENT)) else {
             throw _NSErrorWithWindowsError(GetLastError(), reading: true)
         }
         return UInt64(liPointer.QuadPart)
@@ -545,7 +545,7 @@ open class FileHandle : NSObject {
 
         #if os(Windows)
         var liPointer: LARGE_INTEGER = LARGE_INTEGER(QuadPart: 0)
-        guard SetFilePointerEx(_handle, LARGE_INTEGER(QuadPart: 0), &liPointer, DWORD(FILE_END)) else {
+        guard SetFilePointerEx(self.handle, LARGE_INTEGER(QuadPart: 0), &liPointer, DWORD(FILE_END)) else {
             throw _NSErrorWithWindowsError(GetLastError(), reading: true)
         }
         return UInt64(liPointer.QuadPart)
@@ -563,7 +563,7 @@ open class FileHandle : NSObject {
         guard _isPlatformHandleValid else { throw NSError(domain: NSCocoaErrorDomain, code: CocoaError.fileReadUnknown.rawValue) }
 
         #if os(Windows)
-        guard SetFilePointerEx(_handle, LARGE_INTEGER(QuadPart: LONGLONG(offset)), nil, DWORD(FILE_BEGIN)) else {
+        guard SetFilePointerEx(self.handle, LARGE_INTEGER(QuadPart: LONGLONG(offset)), nil, DWORD(FILE_BEGIN)) else {
             throw _NSErrorWithWindowsError(GetLastError(), reading: true)
         }
         #else
@@ -578,10 +578,10 @@ open class FileHandle : NSObject {
         guard _isPlatformHandleValid else { throw NSError(domain: NSCocoaErrorDomain, code: CocoaError.fileWriteUnknown.rawValue) }
 
         #if os(Windows)
-        guard SetFilePointerEx(_handle, LARGE_INTEGER(QuadPart: LONGLONG(offset)), nil, DWORD(FILE_BEGIN)) else {
+        guard SetFilePointerEx(self.handle, LARGE_INTEGER(QuadPart: LONGLONG(offset)), nil, DWORD(FILE_BEGIN)) else {
             throw _NSErrorWithWindowsError(GetLastError(), reading: false)
         }
-        guard SetEndOfFile(_handle) else {
+        guard SetEndOfFile(self.handle) else {
             throw _NSErrorWithWindowsError(GetLastError(), reading: false)
         }
         #else
@@ -595,7 +595,7 @@ open class FileHandle : NSObject {
         guard self != FileHandle._nulldeviceFileHandle else { return }
 
         #if os(Windows)
-        guard FlushFileBuffers(_handle) else {
+        guard FlushFileBuffers(self.handle) else {
             throw _NSErrorWithWindowsError(GetLastError(), reading: false)
         }
         #else
@@ -638,10 +638,10 @@ open class FileHandle : NSObject {
         privateAsyncVariablesLock.unlock()
 
         #if os(Windows)
-        guard CloseHandle(_handle) else {
+        guard CloseHandle(self.handle) else {
             throw _NSErrorWithWindowsError(GetLastError(), reading: true)
         }
-        _handle = INVALID_HANDLE_VALUE
+        self.handle = INVALID_HANDLE_VALUE
         #else
         guard _close(_fd) >= 0 else {
             throw _NSErrorWithErrno(errno, reading: true)