[dart:io] Adds a finalizer to _NativeSocket to avoid socket leaks

runtime/bin/process_win.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #if !defined(DART_IO_DISABLED)
 
 #include "platform/globals.h"
 #if defined(HOST_OS_WINDOWS)
 
 #include "bin/process.h"
@@ skipping 928 matching lines @@
 intptr_t Process::CurrentProcessId() {
   return static_cast<intptr_t>(GetCurrentProcessId());
 }
 
 
 static SignalInfo* signal_handlers = NULL;
 static Mutex* signal_mutex = new Mutex();
 
 
 SignalInfo::~SignalInfo() {
-  reinterpret_cast<FileHandle*>(fd_)->Close();
+  FileHandle* file_handle = reinterpret_cast<FileHandle*>(fd_);
+  file_handle->Close();
+  file_handle->Release();
 }
 
 
 BOOL WINAPI SignalHandler(DWORD signal) {
   MutexLocker lock(signal_mutex);
   const SignalInfo* handler = signal_handlers;
   bool handled = false;
   while (handler != NULL) {
     if (handler->signal() == signal) {
       int value = 0;
@@ skipping 38 matching lines @@
     SetLastError(error_code);
     return -1;
   }
   MutexLocker lock(signal_mutex);
   FileHandle* write_handle = new FileHandle(fds[kWriteHandle]);
   write_handle->EnsureInitialized(EventHandler::delegate());
   intptr_t write_fd = reinterpret_cast<intptr_t>(write_handle);
   if (signal_handlers == NULL) {
     if (SetConsoleCtrlHandler(SignalHandler, true) == 0) {
       int error_code = GetLastError();
-      delete write_handle;
+      // Since SetConsoleCtrlHandler failed, the IO completion port will
+      // never receive an event for this handle, and will therefore never
+      // release the reference Retained by EnsureInitialized(). So, we
+      // have to do a second Release() here.
+      write_handle->Release();
+      write_handle->Release();
       CloseProcessPipe(fds);
       SetLastError(error_code);
       return -1;
     }
   }
   signal_handlers = new SignalInfo(write_fd, signal, signal_handlers);
   return reinterpret_cast<intptr_t>(new FileHandle(fds[kReadHandle]));
 }
 
 
@@ skipping 12 matching lines @@
     }
     handler = handler->next();
   }
   if (handler != NULL) {
     if (signal_handlers == handler) {
       signal_handlers = handler->next();
     }
     if (signal_handlers == NULL) {
       USE(SetConsoleCtrlHandler(SignalHandler, false));
     }
+    FileHandle* file_handle = reinterpret_cast<FileHandle*>(handler->fd());
+    file_handle->Release();
   }
   delete handler;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(HOST_OS_WINDOWS)
 
 #endif  // !defined(DART_IO_DISABLED)