gio: add GWin32FileSyncStream

This is a COM object that implements IStream by using a HANDLE
and WinAPI file functions to access the file (only a file; pipes
are not supported). Only supports synchronous access (this is
a feature - the APIs that read from this stream internally will
never return the COM equivalent of EWOULDBLOCK, which greatly
simplifies their use).

gio/gwin32file-sync-stream.h

@@ -0,0 +1,44 @@
+/* GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright (C) 2020 Руслан Ижбулатов <lrn1986@gmail.com>
+ *
+ * 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/>.
+ *
+ */
+#ifndef __G_WIN32_FILE_SYNC_STREAM_H__
+#define __G_WIN32_FILE_SYNC_STREAM_H__
+
+#include <gio/gio.h>
+
+#ifdef G_PLATFORM_WIN32
+
+typedef struct _GWin32FileSyncStream GWin32FileSyncStream;
+
+struct _GWin32FileSyncStream
+{
+  IStream  self;
+  ULONG    ref_count;
+  HANDLE   file_handle;
+  gboolean owns_handle;
+  DWORD    stgm_mode;
+};
+
+IStream *g_win32_file_sync_stream_new (HANDLE    file_handle,
+                                       gboolean  owns_handle,
+                                       DWORD     stgm_mode,
+                                       HRESULT  *output_hresult);
+
+#endif /* G_PLATFORM_WIN32 */
+
+#endif /* __G_WIN32_FILE_SYNC_STREAM_H__ */