+static int
+stdio_file_fseek (struct ui_file *file, long offset, int whence)
+{
+ struct stdio_file *stdio = ui_file_data (file);
+
+ if (stdio->magic != &stdio_file_magic)
+ internal_error (__FILE__, __LINE__,
+ _("stdio_file_fseek: bad magic number"));
+
+ return fseek (stdio->file, offset, whence);
+}
+
+#ifdef __MINGW32__
+/* This is the implementation of ui_file method to_write for stderr.
+ gdb_stdout is flushed before writing to gdb_stderr. */
+
+static void
+stderr_file_write (struct ui_file *file, const char *buf, long length_buf)
+{
+ gdb_flush (gdb_stdout);
+ stdio_file_write (file, buf, length_buf);
+}
+
+/* This is the implementation of ui_file method to_fputs for stderr.
+ gdb_stdout is flushed before writing to gdb_stderr. */
+
+static void
+stderr_file_fputs (const char *linebuffer, struct ui_file *file)
+{
+ gdb_flush (gdb_stdout);
+ stdio_file_fputs (linebuffer, file);
+}
+#endif
+
+struct ui_file *
+stderr_fileopen (void)
+{
+ struct ui_file *ui_file = stdio_fileopen (stderr);
+
+#ifdef __MINGW32__
+ /* There is no real line-buffering on Windows, see
+ http://msdn.microsoft.com/en-us/library/86cebhfs%28v=vs.71%29.aspx
+ so the stdout is either fully-buffered or non-buffered. We can't
+ make stdout non-buffered, because of two concerns,
+ 1. non-buffering hurts performance,
+ 2. non-buffering may change GDB's behavior when it is interacting
+ with front-end, such as Emacs.
+
+ We decided to leave stdout as fully buffered, but flush it first
+ when something is written to stderr. */
+
+ /* Method 'to_write_async_safe' is not overwritten, because there's
+ no way to flush a stream in an async-safe manner. Fortunately,
+ it doesn't really matter, because:
+ - that method is only used for printing internal debug output
+ from signal handlers.
+ - Windows hosts don't have a concept of async-safeness. Signal
+ handlers run in a separate thread, so they can call
+ the regular non-async-safe output routines freely. */
+ set_ui_file_write (ui_file, stderr_file_write);
+ set_ui_file_fputs (ui_file, stderr_file_fputs);
+#endif
+
+ return ui_file;
+}
+