GetCentroid on empty polygons crashes

[dpinte@…]

After our discussion on the irc, here is the bug report.

Calling GetCentroid() on a OGRPolygon wich is empty, crashes.

It seems to be a bug in the geos api geos::WkbReader.

Here is the traceback given by Frank Warmerdam

(gdb) where
#0  geos::Geometry::hasNonEmptyElements (geometries=0x0) at stl_iterator.h:593
#1  0x0016e77d in Polygon (this=0x852ec80, newShell=0x85563b0, newHoles=0x0, 
    newFactory=0x8556318) at stl_alloc.h:656
#2  0x00167f99 in geos::GeometryFactory::createPolygon (this=0x8556318, 
    shell=0x85563b0, holes=0x0) at GeometryFactory.cpp:554
#3  0x001a11a5 in geos::WKBReader::readPolygon (this=0xfef0f520)
    at ../io/WKBReader.cpp:163
#4  0x001a0ee7 in geos::WKBReader::readGeometry (this=0xfef0f520)
    at ../io/WKBReader.cpp:103
#5  0x001a0d76 in geos::WKBReader::read (this=0x1, is=@0x0)
    at ../io/WKBReader.cpp:56
#6  0x00200516 in GEOSGeomFromWKB_buf (wkb=0x852eb78 "\001\003", size=9)
    at geos_c.cpp:628
#7  0x0131a4c0 in OGRGeometry::exportToGEOS (this=0x852eba8)
    at ogrgeometry.cpp:1375
#8  0x013184c3 in OGRPolygon::Centroid (this=0x852eba8, poPoint=0x852ebc0)
    at ogrpolygon.cpp:836
#9  0x0131867e in OGR_G_Centroid (hPolygon=0x852eba8, hCentroidPoint=0x852ebc0)
    at ogrpolygon.cpp:916
#10 0x00e76018 in _wrap_OGR_G_Centroid (self=0x0, args=0xf7003b6c)
    at gdal_wrap.c:8587
#11 0x080ea4dd in PyCFunction_Call ()
#12 0x080ab36d in PyEval_GetFuncDesc ()
#13 0x080a9059 in PyEval_EvalCode ()
#14 0x080a9c3e in PyEval_EvalCodeEx ()
#15 0x080ab42c in PyEval_GetFuncDesc ()
#16 0x080ab27a in PyEval_GetFuncDesc ()
#17 0x080a9059 in PyEval_EvalCode ()
#18 0x080a9c3e in PyEval_EvalCodeEx ()
#19 0x080a6c37 in PyEval_EvalCode ()
#20 0x080c99d9 in PyRun_FileExFlags ()
#21 0x080c850c in PyRun_InteractiveOneFlags ()
#22 0x080c82a6 in PyRun_InteractiveLoopFlags ()
#23 0x080c81a7 in PyRun_AnyFileExFlags ()
#24 0x080553c7 in Py_Main ()
#25 0x08054de9 in main ()

[dpinte@…]

I need to write a little C test program before reporting it as a GEOS bug

Didrik

[warmerdam]

The problem was the WKBReader in GEOS wasn't handling polygons with no
rings.  I have fixed this in GEOS-CVS.