Add paranoid check to make super-sure no input vertices are dropped by ST_MakeValid...

git-svn-id: http://svn.osgeo.org/postgis/trunk@5357 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/postgis/lwgeom_geos_clean.c b/postgis/lwgeom_geos_clean.c
index 36809d093987c055660b7228fc2b35547f29cc2d..cc316906be763576bee0e4ce8d3a185da38d15bf 100644 (file)
--- a/postgis/lwgeom_geos_clean.c
+++ b/postgis/lwgeom_geos_clean.c
@@ -570,10 +570,21 @@ LWGEOM_GEOS_makeValidPolygon(const GEOSGeometry* gin)
        return gout;
 }
 
+/*
+ * IMPORTANT NOTE:
+ *
+ * This function assumes the caller already checked the geometry given
+ * as argument for validity and ONLY PASSES INVALID geometries.
+ *
+ * Passing a valid geometry here will likely result in a NULL return.
+ *
+ * TODO: change this behaviour (it is so just to save a geometry clone)
+ *
+ */
 static GEOSGeometry*
 LWGEOM_GEOS_makeValid(const GEOSGeometry* gin)
 {
-       GEOSGeometry* ret;
+       GEOSGeometry* gout;
 
        /*
         * Step 3 : make what we got valid
@@ -597,14 +608,14 @@ LWGEOM_GEOS_makeValid(const GEOSGeometry* gin)
        case GEOS_POLYGON:
        case GEOS_MULTIPOLYGON:
        {
-               ret = LWGEOM_GEOS_makeValidPolygon(gin);
-               if ( ! ret )  /* an exception or something */
+               gout = LWGEOM_GEOS_makeValidPolygon(gin);
+               if ( ! gout )  /* an exception or something */
                {
                        /* cleanup and throw */
                        lwerror("%s", loggederror);
                        return NULL;
                }
-               break; /* we've done (geosgeom is the output) */
+               break; /* we've done */
        }
 
        default:
@@ -619,7 +630,37 @@ LWGEOM_GEOS_makeValid(const GEOSGeometry* gin)
        }
        }
 
-       return ret;
+       /*
+        * Now check if every point of input is also found
+        * in output, or abort by returning NULL
+        *
+        * Input geometry was lwgeom_in
+        */
+       const int paranoia = 1;
+       if (paranoia) {
+               int loss;
+               GEOSGeometry *pi, *po, *pd;
+
+               /* TODO: handle some errors here...
+                * Lack of exceptions is annoying indeed,
+                * I'm getting old --strk;
+                */
+               pi = GEOSGeom_extractUniquePoints(gin);
+               po = GEOSGeom_extractUniquePoints(gout);
+               pd = GEOSDifference(pi, po); /* input points - output points */
+               GEOSGeom_destroy(pi);
+               GEOSGeom_destroy(po);
+               loss = !GEOSisEmpty(pd);
+               GEOSGeom_destroy(pd);
+               if ( loss )
+               {
+                       lwnotice("Vertices lost in LWGEOM_GEOS_makeValid");
+                       /* return NULL */
+               }
+       }
+
+
+       return gout;
 }
 
 /* Uses GEOS internally */
@@ -706,13 +747,6 @@ lwgeom_make_valid(LWGEOM* lwgeom_in)
                return NULL;
        }
 
-       /*
-        * Now check if every point of input is also found
-        * in output, or abort by returning NULL
-        *
-        * Input geometry was lwgeom_in
-        */
-
        lwgeom_out = GEOS2LWGEOM(geosout, is3d);
        if ( lwgeom_is_collection(TYPE_GETTYPE(lwgeom_in->type))
                && ! lwgeom_is_collection(TYPE_GETTYPE(lwgeom_out->type)) )