1 files changed, 51 insertions, 0 deletions
diff --git a/widget/windows/WindowsConsole.cpp b/widget/windows/WindowsConsole.cpp
new file mode 100644
index 0000000000..16005a642b
--- /dev/null
+++ b/widget/windows/WindowsConsole.cpp
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "WindowsConsole.h"
+
+#include <windows.h>
+#include <fcntl.h>
+
+namespace mozilla {
+
+static void AssignStdHandle(const char* aPath, const char* aMode, FILE* aStream,
+                            DWORD aStdHandle) {
+  // Visual Studio's _fileno() returns -2 for the standard
+  // streams if they aren't associated with an output stream.
+  const int fd = _fileno(aStream);
+  if (fd == -2) {
+    freopen(aPath, aMode, aStream);
+    return;
+  }
+  if (fd < 0) {
+    return;
+  }
+
+  const HANDLE handle = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
+  if (handle == INVALID_HANDLE_VALUE) {
+    return;
+  }
+
+  const HANDLE oldHandle = GetStdHandle(aStdHandle);
+  if (handle == oldHandle) {
+    return;
+  }
+
+  SetStdHandle(aStdHandle, handle);
+}
+
+// This code attaches the process to the appropriate console.
+void UseParentConsole() {
+  if (AttachConsole(ATTACH_PARENT_PROCESS)) {
+    // Redirect the standard streams to the existing console, but
+    // only if they haven't been redirected to a valid file.
+    AssignStdHandle("CONOUT$", "w", stdout, STD_OUTPUT_HANDLE);
+    // There is no CONERR$, so use CONOUT$ for stderr as well.
+    AssignStdHandle("CONOUT$", "w", stderr, STD_ERROR_HANDLE);
+    AssignStdHandle("CONIN$", "r", stdin, STD_INPUT_HANDLE);
+  }
+}
+
+}  // namespace mozilla