[Dmenu] Fix possible crash.

Don't pass empty string.

Issue: #1083

include/theme.h

@@ -249,6 +249,16 @@ double rofi_theme_get_double (  const widget *widget, const char *property, doub
  */
 void rofi_theme_get_color ( const widget *widget, const char *property, cairo_t *d );
 
+
+/**
+ * @param widget   The widget to query
+ * @param property The property to query.
+ *
+ * Check if a rofi theme has a property set.
+ *
+ */
+gboolean rofi_theme_has_property ( const widget *widget, const char *property );
+
 /**
  * @param widget   The widget to query
  * @param property The property to query.

source/dialogs/script.c

@@ -77,10 +77,11 @@ typedef struct
 void dmenuscript_parse_entry_extras ( G_GNUC_UNUSED Mode *sw, DmenuScriptEntry *entry, char *buffer, size_t length )
 {
     size_t length_key = 0;              //strlen ( line );
-    while ( length_key <= length && buffer[length_key] != '\x1f' ) {
+    while ( length_key < length && buffer[length_key] != '\x1f' ) {
         length_key++;
     }
-    if ( length_key < length ) {
+    // Should be not last character in buffer.
+    if ( length_key < (length-1) ) {
         buffer[length_key] = '\0';
         char *value = buffer + length_key + 1;
         if ( strcasecmp ( buffer, "icon" ) == 0 ) {

source/theme.c

@@ -1158,3 +1158,20 @@ ThemeMediaType rofi_theme_parse_media_type ( const char *type )
     }
     return THEME_MEDIA_TYPE_INVALID;
 }
+
+
+gboolean rofi_theme_has_property ( const widget *widget, const char *property )
+{
+    ThemeWidget *wid = rofi_theme_find_widget ( widget->name, widget->state, FALSE );
+    Property    *p   = rofi_theme_find_property ( wid, P_STRING, property, FALSE );
+    if ( p ) {
+        if ( p->type == P_INHERIT ) {
+            if ( widget->parent ) {
+                return rofi_theme_has_property ( widget->parent, property );
+            }
+            return FALSE;
+        }
+        return TRUE;
+    }
+    return FALSE;
+}