Add g_win32_handle_is_console_output()

Private function that checks whether a HANDLE refers to a console
screen buffer.

glib/gwin32.c

@@ -1453,6 +1453,31 @@ g_win32_find_helper_executable_path (const gchar *executable_name, void *dll_han
   return executable_path;
 }
 
+bool
+g_win32_handle_is_console_output (HANDLE handle,
+                                  bool   log_errors)
+{
+  /* MSDN suggests using GetConsoleMode() to check if a HANDLE refers to
+   * the console. However, GetConsoleMode() requires read access rights
+   * (FILE_READ_DATA | FILE_READ_ATTRIBUTES | FILE_READ_EA on Windows 10)
+   * and output HANDLEs may be opened with write rights only. To overcome
+   * that we use WriteConsole() with a zero characters count.
+   */
+  const wchar_t *dummy = L"";
+  if (!WriteConsole (handle, dummy, 0, NULL, NULL))
+    {
+      if (log_errors &&
+          GetLastError () != ERROR_INVALID_HANDLE)
+        {
+          WIN32_API_FAILED ("WriteConsole");
+        }
+
+      return false;
+    }
+
+  return true;
+}
+
 /*
  * g_win32_handle_is_socket:
  * @h: a win32 HANDLE

glib/gwin32private.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright © 2025 Luca Bacci
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Luca Bacci <luca.bacci@outlook.com>
+ */
+
+#ifndef __G_WIN32PRIVATE_H__
+#define __G_WIN32PRIVATE_H__
+
+#ifdef G_PLATFORM_WIN32
+
+#include "config.h"
+
+/** < private >
+ *
+ * g_win32_handle_is_console_output:
+ *
+ * @handle: the given HANDLE
+ * @log_errors: whether to log unexpected errors
+ *
+ * Checks if the given HANDLE refers to a Win32 console screen
+ * buffer (output HANDLE).
+ */
+bool
+g_win32_handle_is_console_output (HANDLE handle,
+                                  bool   log_errors);
+
+#endif /* G_PLATFORM_WIN32 */
+
+#endif /* __G_WIN32PRIVATE_H__ */