[gvfs] common: Fix possible crash with blank disks

[Ondrej Holy <oholy src gnome org>]

commit 7deded463b8cc148103c55460a84a6b23342c941
Author: Bastien Nocera <hadess hadess net>
Date:   Tue May 12 21:58:09 2015 +0200

    common: Fix possible crash with blank disks
    
    Never call bd_open() with an empty path.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=749093

 common/gvfsmountinfo.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/common/gvfsmountinfo.c b/common/gvfsmountinfo.c
index d206b91..2c36551 100644
--- a/common/gvfsmountinfo.c
+++ b/common/gvfsmountinfo.c
@@ -485,6 +485,14 @@ bdmv_metadata_thread (GSimpleAsyncResult *result,
   file = G_FILE (object);
 
   disc_root = g_file_get_path (file);
+  if (!disc_root)
+    {
+      error = g_error_new_literal (G_IO_ERROR,
+                                   G_IO_ERROR_FAILED,
+                                   "Device is not a Blu-Ray disc");
+      goto error;
+    }
+
   bd = bd_open (disc_root, NULL);
   g_free (disc_root);