Fix crash with parentheses in filenames (#204)

* Fix crash with parentheses in filenames

Also free the elements of the wordexp_t struct used.

* Handle the empty string case

Author: dkondor

src/background/background.cpp

@@ -120,15 +120,21 @@ bool WayfireBackground::load_images_from_dir(std::string path)
     wordexp_t exp;
 
     /* Expand path */
-    wordexp(path.c_str(), &exp, 0);
-    if (!exp.we_wordv)
+    if (wordexp(path.c_str(), &exp, 0))
     {
         return false;
     }
 
+    if (!exp.we_wordc)
+    {
+        wordfree(&exp);
+        return false;
+    }
+
     auto dir = opendir(exp.we_wordv[0]);
     if (!dir)
     {
+        wordfree(&exp);
         return false;
     }
 
@@ -158,6 +164,8 @@ bool WayfireBackground::load_images_from_dir(std::string path)
         }
     }
 
+    wordfree(&exp);
+
     if (background_randomize && images.size())
     {
         std::random_device random_device;