add checks to make sure given nodepath pointers are not null before working with them

(bzr r1560)

2 files changed, 25 insertions, 1 deletions

diff --git a/src/node-context.cpp b/src/node-context.cpp
index f213b58aa..3142e5b0e 100644
--- a/src/node-context.cpp
+++ b/src/node-context.cpp
@@ -527,6 +527,11 @@ sp_node_context_root_handler(SPEventContext *event_context, GdkEvent *event)
     SPDesktop *desktop = event_context->desktop;
     Inkscape::Selection *selection = sp_desktop_selection (desktop);
 
+    // fixme:  nc->nodepath can potentially become NULL after retrieving nc.
+    // A general method for handling this possibility should be created.
+    // For now, the number of checks for a NULL nc->nodepath have been
+    // increased, both here and in the called sp_nodepath_* functions.
+
     SPNodeContext *nc = SP_NODE_CONTEXT(event_context);
     double const nudge = prefs_get_double_attribute_limited("options.nudgedistance", "value", 2, 0, 1000); // in px
     event_context->tolerance = prefs_get_int_attribute_limited("options.dragtolerance", "value", 0, 0, 100); // read every time, to make prefs changes really live
@@ -560,6 +565,13 @@ sp_node_context_root_handler(SPEventContext *event_context, GdkEvent *event)
                      && ( abs( (gint) event->motion.y - event_context->yp ) < event_context->tolerance ) ) {
                     break; // do not drag if we're within tolerance from origin
                 }
+                
+                // The path went away while dragging; throw away any further motion
+                // events until the mouse pointer is released.
+                if (nc->hit && (nc->nodepath == NULL)) {                  
+                  break;
+                }
+                
                 // Once the user has moved farther than tolerance from the original location
                 // (indicating they intend to move the object, not click), then always process the
                 // motion notify coordinates as given (no snapping back to origin)
@@ -625,7 +637,9 @@ sp_node_context_root_handler(SPEventContext *event_context, GdkEvent *event)
                 NR::Maybe<NR::Rect> b = Inkscape::Rubberband::get()->getRectangle();
 
                 if (nc->hit && !event_context->within_tolerance) { //drag curve
-                    sp_nodepath_update_repr (nc->nodepath, _("Drag curve"));
+                    if (nc->nodepath) {
+                        sp_nodepath_update_repr (nc->nodepath, _("Drag curve"));
+                    }
                 } else if (b != NR::Nothing() && !event_context->within_tolerance) { // drag to select
                     if (nc->nodepath) {
                         sp_nodepath_select_rect(nc->nodepath, b.assume(), event->button.state & GDK_SHIFT_MASK);
diff --git a/src/nodepath.cpp b/src/nodepath.cpp
index d4aada20c..e3681f59a 100644
--- a/src/nodepath.cpp
+++ b/src/nodepath.cpp
@@ -479,6 +479,9 @@ static void update_repr_internal(Inkscape::NodePath::Path *np)
  */
 void sp_nodepath_update_repr(Inkscape::NodePath::Path *np, const gchar *annotation)
 {
+    //fixme: np can be NULL, so check before proceeding
+    g_return_if_fail(np != NULL);
+
     if (np->livarot_path) {
         delete np->livarot_path;
         np->livarot_path = NULL;
@@ -1551,6 +1554,9 @@ sp_nodepath_select_segment_near_point(Inkscape::NodePath::Path *nodepath, NR::Po
     //find segment to segment
     Inkscape::NodePath::Node *e = sp_nodepath_get_node_by_index(position.piece);
 
+    //fixme: this can return NULL, so check before proceeding.
+    g_return_if_fail(e != NULL);
+    
     gboolean force = FALSE;
     if (!(e->selected && (!e->p.other || e->p.other->selected))) {
         force = TRUE;
@@ -1604,6 +1610,10 @@ sp_nodepath_add_node_near_point(Inkscape::NodePath::Path *nodepath, NR::Point p)
 void
 sp_nodepath_curve_drag(Inkscape::NodePath::Node * e, double t, NR::Point delta)
 {
+    //fixme: e and e->p can be NULL, so check for those before proceeding
+    g_return_if_fail(e != NULL);
+    g_return_if_fail(&e->p != NULL);
+    
     /* feel good is an arbitrary parameter that distributes the delta between handles
      * if t of the drag point is less than 1/6 distance form the endpoint only
      * the corresponding hadle is adjusted. This matches the behavior in GIMP