From 952147e245b51a34463e31fbef4e14ed9e4f8058 Mon Sep 17 00:00:00 2001
From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Wed, 24 Jun 2015 22:40:57 +0000
Subject: [PATCH] #3177, gserialized_is_empty cannot handle nested empty cases

git-svn-id: http://svn.osgeo.org/postgis/trunk@13700 b70326c6-7e19-0410-871a-916f4a2858ee
---
 liblwgeom/cunit/cu_libgeom.c | 52 +++++++++++++++++++++++++++++++++---
 liblwgeom/g_serialized.c     | 45 ++++++++++++++++++++++---------
 2 files changed, 80 insertions(+), 17 deletions(-)

diff --git a/liblwgeom/cunit/cu_libgeom.c b/liblwgeom/cunit/cu_libgeom.c
index 1d8e1fa5e..99119f7f7 100644
--- a/liblwgeom/cunit/cu_libgeom.c
+++ b/liblwgeom/cunit/cu_libgeom.c
@@ -306,6 +306,49 @@ static void test_lwgeom_from_gserialized(void)
 
 }
 
+
+static void test_gserialized_is_empty(void)
+{
+	int i = 0;
+	struct gserialized_empty_cases {
+		const char* wkt;
+		int isempty;
+	};
+	
+	struct gserialized_empty_cases cases[] = {
+		{ "POINT EMPTY", 1 },
+		{ "POINT(1 1)", 0 },
+		{ "LINESTRING EMPTY", 1 },
+		{ "MULTILINESTRING EMPTY", 1 },
+		{ "MULTILINESTRING(EMPTY)", 1 },
+		{ "MULTILINESTRING(EMPTY,EMPTY)", 1 },
+		{ "MULTILINESTRING(EMPTY,(0 0,1 1))", 0 },
+		{ "MULTILINESTRING((0 0,1 1),EMPTY)", 0 },
+		{ "MULTILINESTRING(EMPTY,(0 0,1 1),EMPTY)", 0 },
+		{ "MULTILINESTRING(EMPTY,EMPTY,EMPTY)", 1 },
+		{ "GEOMETRYCOLLECTION(POINT EMPTY,MULTILINESTRING(EMPTY,EMPTY,EMPTY))", 1 },
+		{ "GEOMETRYCOLLECTION(POINT EMPTY,MULTILINESTRING(EMPTY),POINT(1 1))", 0 },
+		{ "GEOMETRYCOLLECTION(POINT EMPTY,MULTILINESTRING(EMPTY, (0 0)),POINT EMPTY)", 0 },
+		{ "GEOMETRYCOLLECTION(POLYGON EMPTY,POINT EMPTY,MULTILINESTRING(EMPTY,EMPTY),POINT EMPTY)", 1 },
+		{ "GEOMETRYCOLLECTION(POLYGON EMPTY,GEOMETRYCOLLECTION(POINT EMPTY),MULTILINESTRING(EMPTY,EMPTY),POINT EMPTY)", 1 },
+		{ NULL, 0 }
+	};
+	
+	while( cases[i].wkt )
+	{
+		// i = 11;
+		LWGEOM *lw = lwgeom_from_wkt(cases[i].wkt, LW_PARSER_CHECK_NONE);
+		GSERIALIZED *g = gserialized_from_lwgeom(lw, 0, 0);
+		int ie = gserialized_is_empty(g);
+		// printf("%s: we say %d, they say %d\n", cases[i].wkt, cases[i].isempty, ie);
+		CU_ASSERT_EQUAL(ie, cases[i].isempty);
+		lwgeom_free(lw);
+		lwfree(g);
+		i++;
+	}
+}
+	
+
 static void test_geometry_type_from_string(void)
 {
 	int rv;
@@ -597,8 +640,8 @@ static void test_lwgeom_flip_coordinates(void)
 
 
 	/*
-	     * Srid
-	     */
+	* Srid
+	*/
 
 	do_lwgeom_flip_coordinates(
 	    "SRID=4326;POINT(1 2)",
@@ -974,9 +1017,9 @@ static void test_lwgeom_scale(void)
 
 	geom = lwgeom_from_wkt("SRID=4326;GEOMETRYCOLLECTION(POINT(0 1 2 3),POLYGON((-1 -1 0 1,-1 2.5 0 1,2 2 0 1,2 -1 0 1,-1 -1 0 1),(0 0 1 2,0 1 1 2,1 1 1 2,1 0 2 3,0 0 1 2)),LINESTRING(0 0 0 0, 1 2 3 4))", LW_PARSER_CHECK_NONE);
 	factor.x = 2; factor.y = 3; factor.z = 4; factor.m = 5;
-  lwgeom_scale(geom, &factor);
+	lwgeom_scale(geom, &factor);
 	out_ewkt = lwgeom_to_ewkt(geom);
-  ASSERT_STRING_EQUAL(out_ewkt, "SRID=4326;GEOMETRYCOLLECTION(POINT(0 3 8 15),POLYGON((-2 -3 0 5,-2 7.5 0 5,4 6 0 5,4 -3 0 5,-2 -3 0 5),(0 0 4 10,0 3 4 10,2 3 4 10,2 0 8 15,0 0 4 10)),LINESTRING(0 0 0 0,2 6 12 20))");
+	ASSERT_STRING_EQUAL(out_ewkt, "SRID=4326;GEOMETRYCOLLECTION(POINT(0 3 8 15),POLYGON((-2 -3 0 5,-2 7.5 0 5,4 6 0 5,4 -3 0 5,-2 -3 0 5),(0 0 4 10,0 3 4 10,2 3 4 10,2 0 8 15,0 0 4 10)),LINESTRING(0 0 0 0,2 6 12 20))");
 	lwgeom_free(geom);
 	lwfree(out_ewkt);
 
@@ -1024,4 +1067,5 @@ void libgeom_suite_setup(void)
 	PG_ADD_TEST(suite, test_lwline_from_lwmpoint);
 	PG_ADD_TEST(suite, test_lwgeom_as_curve);
 	PG_ADD_TEST(suite, test_lwgeom_scale);
+	PG_ADD_TEST(suite, test_gserialized_is_empty);
 }
diff --git a/liblwgeom/g_serialized.c b/liblwgeom/g_serialized.c
index 01bda61c4..ced4177b2 100644
--- a/liblwgeom/g_serialized.c
+++ b/liblwgeom/g_serialized.c
@@ -108,27 +108,46 @@ GSERIALIZED* gserialized_copy(const GSERIALIZED *g)
 	return g_out;
 }
 
+static size_t gserialized_is_empty_recurse(const uint8_t *p, int *isempty);
+static size_t gserialized_is_empty_recurse(const uint8_t *p, int *isempty)
+{
+	int i;
+	int32_t type, num;
+
+	memcpy(&type, p, 4);
+	memcpy(&num, p+4, 4);
+	
+	if ( lwtype_is_collection(type) )
+	{
+		size_t lz = 8;
+		for ( i = 0; i < num; i++ )
+		{
+			lz += gserialized_is_empty_recurse(p+lz, isempty);
+			if ( ! *isempty )
+				return lz;
+		}
+		*isempty = LW_TRUE;
+		return lz;
+	}
+	else
+	{
+		*isempty = (num == 0 ? LW_TRUE : LW_FALSE);
+		return 8;
+	}
+}
+
 int gserialized_is_empty(const GSERIALIZED *g)
 {
 	uint8_t *p = (uint8_t*)g;
-	int i;
+	int isempty = 0;
 	assert(g);
 
 	p += 8; /* Skip varhdr and srid/flags */
 	if( FLAGS_GET_BBOX(g->flags) )
 		p += gbox_serialized_size(g->flags); /* Skip the box */
-	p += 4; /* Skip type number */
-	
-	/* For point/line/circstring this is npoints */
-	/* For polygons this is nrings */
-	/* For collections this is ngeoms */
-	memcpy(&i, p, sizeof(int));
-	
-	/* If it is non-zero, it's not empty */
-	if ( i > 0 )
-		return LW_FALSE;
-	else
-		return LW_TRUE;	
+
+	gserialized_is_empty_recurse(p, &isempty);
+	return isempty;
 }
 
 char* gserialized_to_string(const GSERIALIZED *g)
-- 
2.50.0