mapscript crashes on getFeature

[Sean Gillies]

Hi all,

My tests of the Python module include a test of query result set  
members and getFeature. See mapscript/python/tests/cases/ 
resultcachetest.py. I have not been routinely building or testing  
mapscript with the --with-geos option, but I reconfigured today and  
the tests pass as usual. This seems to point to this being a Java  
specific problem.

Now that I look at your Java code, I see a potential problem. You  
shouldn't make the assumption that the tileindex of your  
resultCacheMemberObj is always -1. I'm not sure that figures into the  
current issue, but is something you'll want to beware of in the future.

Sean

On Nov 17, 2005, at 9:25 PM, Steve Lime wrote:

> Hmmm.... The geometry member is initialized to NULL and not used  
> unless =
> you do something like a buffer or a convex hull. The code to free  
> the =
> geometry does check to make sure the geometry is not NULL before  
> unallocati=
> ng it. This leads me to believe the problem is not GEOS per se but =
> elsewhere in the query or MapScript code- perhaps someplace that  
> doesn't =
> use msInitShape() to initialize a shapeObj structure, which could  
> lead to =
> an unitialized geometry pointer. I guess we should try the same code =
> snippet in another MapScript flavor to make sure it's not a java  
> specific =
> issue.
>
> Steve
>
>>>> Donovan <donovan at FUNCTIONFOUR.CA> 11/16/05 12:07 PM >>>
>> You've got my attention. Donovan do you have any more specific  
>> information=
>
> regarding the GEOS crash?   --Steve
>
> Sure,
>
> I'm using mapserver 4.8.0beta - but 4.6.0 breaks too
> --geos-2.1.1 from rpm (gdal-1.2.6 and proj-4.4.9 also)
> --FedoraCore3 with java1.5 (glibc-2.3.5)
>
> I think the crash occurs any time a shapeObj is returned.
>
> I modified the java mapscript example class DrawMap from the mapserver
> source tree to demonstrate the problem - Query.java is attached.
>
> Without GEOS, Query.java generates the png but with GEOS, it looks  
> like =
> this:
> # cd ~/mapserver-4.8.0-beta1/mapscript/java
> # javac -classpath ./:examples/:./mapscript.jar -d examples/  
> examples/*.jav=
> a
> # java -classpath ./:examples/:./mapscript.jar - 
> Djava.library.path=3D. =
> Query
> ../../tests/test.map ./map.png
>
>> The map will be drawn to:./map.png
>> *** glibc detected *** malloc(): memory corruption: 0xb1c11ee8 ***
>> Aborted
>
> From poking around in the source i think the crash happens while  
> freeing =
> the
> geometry pointer in the shape obj but i didn't get any further.
>
> If there is anything else i can provide or if some testing is  
> required i'd
> be happy to help...
>
> Thanks for your attention
>
>
> ----mapscript/java/examples/Query.java----cut-here--
> import edu.umn.gis.mapscript.*;
>
> public class Query {
>
>   public static void usage() {
>     System.err.println("Usage: Query {mapfile} {outfile}");
>     System.exit(-1);
>   }
>
>   public static void main(String[] args) {
>     if (args.length !=3D 2) usage();
>         try
>         {
>           System.loadLibrary("mapscript");
>         }
>         catch(UnsatisfiedLinkError ule)
>         {
>           System.err.println(ule);
>           System.exit(-1);
>         }
>
>     mapObj map =3D new mapObj(args[0]);
>     map.getImagecolor().setRGB(153, 153, 204);
>     styleObj st =3D map.getLayer(1).getClass(0).getStyle(0);
>     st.getColor().setHex("#000000");
>     imageObj img =3D map.draw();
>     System.out.println("The map will be drawn to:"+args[1]);
>
>     layerObj layer =3D map.getLayerByName("POLYGON");
>     layer.setTemplate("dummy.template");
>     layer.queryByPoint(map,new pointObj(0.10,51.4,0),
>         mapscriptConstants.MS_MULTIPLE,-1);
>     resultCacheObj results =3D layer.getResults();
>     layer.open();
>     for (int i=3D0;i<results.getNumresults();i++) {
>        resultCacheMemberObj result =3D results.getResult(i);
>        //CRASH HAPPENS ON NEXT LINE
>        shapeObj feature =3D layer.getFeature(result.getShapeindex 
> (),-1);
>     }
>     layer.close();
>
>     img.save(args[1], map);
>   }
> }
> -----End of Query.java----------

---
Sean Gillies
sgillies at frii dot com
http://zcologia.com/news