From 3113a946ef38e9430f7fc3d53c2b9957373badc0 Mon Sep 17 00:00:00 2001
From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Wed, 31 Jul 2019 21:42:20 +0000
Subject: [PATCH] Handle POINT EMPTY in shape loader/dumper Closes #4437

git-svn-id: http://svn.osgeo.org/postgis/trunk@17653 b70326c6-7e19-0410-871a-916f4a2858ee
---
 NEWS                    |  1 +
 loader/pgsql2shp-core.c | 20 +++++++++++-
 loader/shp2pgsql-core.c | 67 +++++++++++++++++++++++------------------
 3 files changed, 58 insertions(+), 30 deletions(-)

diff --git a/NEWS b/NEWS
index a728f4d8f..dd959d87b 100644
--- a/NEWS
+++ b/NEWS
@@ -20,6 +20,7 @@ Additional features enabled if you are running Proj6+ and PostgreSQL 12
   - #4466, Fix undefined behaviour in _postgis_gserialized_stats (Raúl Marín)
   - #4209, Handle NULL geometry values in pgsql2shp (Paul Ramsey)
   - #4419, Use protobuf version to enable/disable mvt/geobuf (Paul Ramsey)
+  - #4437, Handle POINT EMPTY in shape loader/dumper (Paul Ramsey)
 
 PostGIS 3.0.0alpha3
 2019/07/01
diff --git a/loader/pgsql2shp-core.c b/loader/pgsql2shp-core.c
index 1b0a650c1..d486edc94 100644
--- a/loader/pgsql2shp-core.c
+++ b/loader/pgsql2shp-core.c
@@ -67,6 +67,17 @@ static char * goodDBFValue(char *in, char fieldType);
 /** @brief Binary to hexewkb conversion function */
 char *convert_bytes_to_hex(uint8_t *ewkb, size_t size);
 
+static SHPObject *
+create_point_empty(SHPDUMPERSTATE *state, LWPOINT *lwpoint)
+{
+	SHPObject *obj;
+	const uint8_t ndr_nan[8] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf8, 0x7f};
+	double double_nan;
+
+	memcpy(&double_nan, ndr_nan, 8);
+	obj = SHPCreateObject(state->outshptype, -1, 0, NULL, NULL, 1, &double_nan, &double_nan, &double_nan, &double_nan);
+	return obj;
+}
 
 static SHPObject *
 create_point(SHPDUMPERSTATE *state, LWPOINT *lwpoint)
@@ -2112,7 +2123,14 @@ int ShpLoaderGenerateShapeRow(SHPDUMPERSTATE *state)
 			switch (lwgeom->type)
 			{
 			case POINTTYPE:
-				obj = create_point(state, lwgeom_as_lwpoint(lwgeom));
+				if (lwgeom_is_empty(lwgeom))
+				{
+					obj = create_point_empty(state, lwgeom_as_lwpoint(lwgeom));
+				}
+				else
+				{
+					obj = create_point(state, lwgeom_as_lwpoint(lwgeom));
+				}
 				break;
 
 			case MULTIPOINTTYPE:
diff --git a/loader/shp2pgsql-core.c b/loader/shp2pgsql-core.c
index dc71310eb..c37e3509e 100644
--- a/loader/shp2pgsql-core.c
+++ b/loader/shp2pgsql-core.c
@@ -240,41 +240,50 @@ GeneratePointGeometry(SHPLOADERSTATE *state, SHPObject *obj, char **geometry, in
 	FLAGS_SET_Z(dims, state->has_z);
 	FLAGS_SET_M(dims, state->has_m);
 
-	/* Allocate memory for our array of LWPOINTs and our dynptarrays */
-	lwmultipoints = malloc(sizeof(LWPOINT *) * obj->nVertices);
-
-	/* We need an array of pointers to each of our sub-geometries */
-	for (u = 0; u < obj->nVertices; u++)
+	/* POINT EMPTY encoded as POINT(NaN NaN) */
+	if (obj->nVertices == 1 && isnan(obj->padfX[0]) && isnan(obj->padfY[0]))
+	{
+		lwgeom = lwpoint_as_lwgeom(lwpoint_construct_empty(state->from_srid, state->has_z, state->has_m));
+	}
+	/* Not empty */
+	else
 	{
-		/* Create a ptarray containing a single point */
-		POINTARRAY *pa = ptarray_construct_empty(state->has_z, state->has_m, 1);
+		/* Allocate memory for our array of LWPOINTs and our dynptarrays */
+		lwmultipoints = malloc(sizeof(LWPOINT *) * obj->nVertices);
 
-		/* Generate the point */
-		point4d.x = obj->padfX[u];
-		point4d.y = obj->padfY[u];
+		/* We need an array of pointers to each of our sub-geometries */
+		for (u = 0; u < obj->nVertices; u++)
+		{
+			/* Create a ptarray containing a single point */
+			POINTARRAY *pa = ptarray_construct_empty(state->has_z, state->has_m, 1);
 
-		if (state->has_z)
-			point4d.z = obj->padfZ[u];
-		if (state->has_m)
-			point4d.m = obj->padfM[u];
+			/* Generate the point */
+			point4d.x = obj->padfX[u];
+			point4d.y = obj->padfY[u];
 
-		/* Add in the point! */
-		ptarray_append_point(pa, &point4d, LW_TRUE);
+			if (state->has_z)
+				point4d.z = obj->padfZ[u];
+			if (state->has_m)
+				point4d.m = obj->padfM[u];
 
-		/* Generate the LWPOINT */
-		lwmultipoints[u] = lwpoint_as_lwgeom(lwpoint_construct(state->from_srid, NULL, pa));
-	}
+			/* Add in the point! */
+			ptarray_append_point(pa, &point4d, LW_TRUE);
 
-	/* If we have more than 1 vertex then we are working on a MULTIPOINT and so generate a MULTIPOINT
-	rather than a POINT */
-	if ((obj->nVertices > 1) || force_multi)
-	{
-		lwgeom = lwcollection_as_lwgeom(lwcollection_construct(MULTIPOINTTYPE, state->from_srid, NULL, obj->nVertices, lwmultipoints));
-	}
-	else
-	{
-		lwgeom = lwmultipoints[0];
-		lwfree(lwmultipoints);
+			/* Generate the LWPOINT */
+			lwmultipoints[u] = lwpoint_as_lwgeom(lwpoint_construct(state->from_srid, NULL, pa));
+		}
+
+		/* If we have more than 1 vertex then we are working on a MULTIPOINT and so generate a MULTIPOINT
+		rather than a POINT */
+		if ((obj->nVertices > 1) || force_multi)
+		{
+			lwgeom = lwcollection_as_lwgeom(lwcollection_construct(MULTIPOINTTYPE, state->from_srid, NULL, obj->nVertices, lwmultipoints));
+		}
+		else
+		{
+			lwgeom = lwmultipoints[0];
+			lwfree(lwmultipoints);
+		}
 	}
 
 	if (state->config->use_wkt)
-- 
2.40.0