[evince/wip/chpe/load-fd: 2/2] previewer: Try sniffing MIME type from FD

[Christian Persch <chpe src gnome org>]

commit 5180032d0035bbed4b390060628f466fa95bd5de
Author: Christian Persch <chpe src gnome org>
Date:   Tue Jan 11 20:42:24 2022 +0100

    previewer: Try sniffing MIME type from FD
    
    When passing a file descriptor, but no MIME type was specified, try
    sniffing the type from data.

 previewer/ev-previewer.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/previewer/ev-previewer.c b/previewer/ev-previewer.c
index 378cbdf80..3e5efc74e 100644
--- a/previewer/ev-previewer.c
+++ b/previewer/ev-previewer.c
@@ -2,7 +2,7 @@
  *  this file is part of evince, a gnome document viewer
  *
  * Copyright (C) 2009 Carlos Garcia Campos <carlosgc gnome org>
- * Copyright © 2012, 2018 Christian Persch
+ * Copyright © 2012, 2018, 2021, 2022 Christian Persch
  *
  * Evince is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by
@@ -195,9 +195,11 @@ check_arguments (int argc,
                         return FALSE;
                 }
                 if (input_mime_type == NULL) {
-                        g_set_error_literal (error, G_OPTION_ERROR, G_OPTION_ERROR_BAD_VALUE,
-                                             "Must specify --mime-type");
-                        return FALSE;
+                        input_mime_type = ev_file_get_mime_type_from_fd (input_fd, error);
+                        if (input_mime_type == NULL) {
+                                g_prefix_error (error, "Must specify --mime-type: ");
+                                return FALSE;
+                        }
                 }
                 if (unlink_temp_file) {
                         g_set_error_literal (error, G_OPTION_ERROR, G_OPTION_ERROR_BAD_VALUE,