From 83f72567d319768cdd04755b7bd7f9201cb63403 Mon Sep 17 00:00:00 2001
From: Jonathon Jongsma <jjongsma@redhat.com>
Date: Wed, 19 Jul 2017 15:59:46 -0500
Subject: [PATCH] Screenshot: reject unknown image type filenames

If the image format cannot be determined for a screenshot filename,
simply return an error informing the user that this is not a valid image
format.

In the past, if we couldn't determine the file type, we simply saved it
as a PNG, and appended a ".png" file extension to the filename. This has
several problems. First, it can result in some oddly-named files (e.g. a
screenshot named 'Screenshot.pdf.png').

Second, modifying the filename that is returned from the GtkFileChooser
undermines the overwrite-confirmation functionality that is built into
the gtk file chooser. When the user specifies a filename in the file
chooser dialog, the chooser will automatically check whether a file of
that name exists, and if it does, it will display a dialog asking
whether the user wants to overwrite it. But if we then append a ".png"
extension to the filename and save it, we may be overwriting an existing
file without warning. By returning an error for unrecognized file types,
we avoid this problem.

Resolves: rhbz#1455832
---
 src/virt-viewer-window.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/src/virt-viewer-window.c b/src/virt-viewer-window.c
index 41794a6..a796685 100644
--- a/src/virt-viewer-window.c
+++ b/src/virt-viewer-window.c
@@ -947,17 +947,9 @@ virt_viewer_window_save_screenshot(VirtViewerWindow *self,
     gboolean result;
 
     if (format == NULL) {
-        g_debug("unknown file extension, falling back to png");
-        if (!g_str_has_suffix(file, ".png")) {
-            char *png_filename;
-            png_filename = g_strconcat(file, ".png", NULL);
-            result = gdk_pixbuf_save(pix, png_filename, "png", error,
-                                     "tEXt::Generator App", PACKAGE, NULL);
-            g_free(png_filename);
-        } else {
-            result = gdk_pixbuf_save(pix, file, "png", error,
-                                     "tEXt::Generator App", PACKAGE, NULL);
-        }
+        g_set_error(error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
+                    _("Unable to determine image format for file '%s'"), file);
+        result = FALSE;
     } else {
         char *type = gdk_pixbuf_format_get_name(format);
         g_debug("saving to %s", type);
-- 
2.13.6