Fix crash in drawQuery for layers with labelitem (#5281)

Author: szekerest

mapdraw.c

@@ -1568,7 +1568,7 @@ int pointLayerDrawShape(mapObj *map, imageObj *image, layerObj *layer, shapeObj
       }
       if(MS_DRAW_LABELS(drawmode)) {
         if (layer->labelcache) {
-          if (msAddLabelGroup(map, image, layer->index, c, shape, point, -1) != MS_SUCCESS) return (MS_FAILURE);
+          if (msAddLabelGroup(map, image, layer, c, shape, point, -1) != MS_SUCCESS) return (MS_FAILURE);
         } else {
           for (l = 0; l < layer->class[c]->numlabels; l++)
             if(msGetLabelStatus(map,layer,shape,layer->class[c]->labels[l]) == MS_ON) {
@@ -1765,7 +1765,7 @@ int polygonLayerDrawShape(mapObj *map, imageObj *image, layerObj *layer,
         for (i = 0; i < layer->class[c]->numlabels; i++)
           if (layer->class[c]->labels[i]->angle != 0) layer->class[c]->labels[i]->angle -= map->gt.rotation_angle; /* TODO: is this correct ??? */
         if (layer->labelcache) {
-          if (msAddLabelGroup(map, image, layer->index, c, anno_shape, &annopnt,
+          if (msAddLabelGroup(map, image, layer, c, anno_shape, &annopnt,
                               MS_MIN(shape->bounds.maxx - shape->bounds.minx, shape->bounds.maxy - shape->bounds.miny)) != MS_SUCCESS) {
             return MS_FAILURE;
           }

maplabel.c

@@ -273,7 +273,7 @@ void msPopulateTextSymbolForLabelAndString(textSymbolObj *ts, labelObj *l, char
   ts->rotation = l->angle * MS_DEG_TO_RAD;
 }
 
-int msAddLabelGroup(mapObj *map, imageObj *image, int layerindex, int classindex, shapeObj *shape, pointObj *point, double featuresize)
+int msAddLabelGroup(mapObj *map, imageObj *image, layerObj* layer, int classindex, shapeObj *shape, pointObj *point, double featuresize)
 {
   int l,s, priority;
   labelCacheSlotObj *cacheslot;
@@ -283,8 +283,11 @@ int msAddLabelGroup(mapObj *map, imageObj *image, int layerindex, int classindex
   classObj *classPtr=NULL;
   int numtextsymbols = 0;
   textSymbolObj **textsymbols, *ts;
+  int layerindex = layer->index;
 
-  layerPtr = (GET_LAYER(map, layerindex)); /* set up a few pointers for clarity */
+  // We cannot use GET_LAYER here because in drawQuery the drawing may happen
+  // on a temp layer only.
+  layerPtr = layer;
   classPtr = GET_LAYER(map, layerindex)->class[classindex];
 
   if(classPtr->numlabels == 0) return MS_SUCCESS; /* not an error just nothing to do */

mapserver.h

@@ -2308,7 +2308,7 @@ void msPopulateTextSymbolForLabelAndString(textSymbolObj *ts, labelObj *l, char
   MS_DLL_EXPORT int WARN_UNUSED msGetStringSize(mapObj *map, labelObj *label, int size, char *string, rectObj *r);
 
   MS_DLL_EXPORT int WARN_UNUSED msAddLabel(mapObj *map, imageObj *image, labelObj *label, int layerindex, int classindex, shapeObj *shape, pointObj *point, double featuresize, textSymbolObj *ts);
-  MS_DLL_EXPORT int WARN_UNUSED msAddLabelGroup(mapObj *map, imageObj *image, int layerindex, int classindex, shapeObj *shape, pointObj *point, double featuresize);
+  MS_DLL_EXPORT int WARN_UNUSED msAddLabelGroup(mapObj *map, imageObj *image, layerObj *layer, int classindex, shapeObj *shape, pointObj *point, double featuresize);
   MS_DLL_EXPORT void insertRenderedLabelMember(mapObj *map, labelCacheMemberObj *cachePtr);
   MS_DLL_EXPORT int msTestLabelCacheCollisions(mapObj *map, labelCacheMemberObj *cachePtr, label_bounds *lb, int current_priority, int current_label);
   MS_DLL_EXPORT int msTestLabelCacheLeaderCollision(mapObj *map, pointObj *lp1, pointObj *lp2);