bug 801466 ST_INTERSECTION() returns invalid value on empty intersection in maria-5.3-gis.

    We didn't implement an empty geometry. And returning NULL instead of it is not
    quite correct. So here is the implementation of the empty value as GEOMETRYCOLLECTION().

per-file comments:
  mysql-test/r/gis-precise.result
bug 801466 ST_INTERSECTION() returns invalid value on empty intersection in maria-5.3-gis.
    test result updated.

  mysql-test/r/gis.result
bug 801466 ST_INTERSECTION() returns invalid value on empty intersection in maria-5.3-gis.
    test result updated.

  mysql-test/t/gis-precise.test
bug 801466 ST_INTERSECTION() returns invalid value on empty intersection in maria-5.3-gis.
    test case added.

  mysql-test/t/gis.test
bug 801466 ST_INTERSECTION() returns invalid value on empty intersection in maria-5.3-gis.
    test case added.

  sql/field.cc
bug 801466 ST_INTERSECTION() returns invalid value on empty intersection in maria-5.3-gis.
    store GEOMETRYCOLLECTION() properly.

  sql/gcalc_tools.cc
bug 801466 ST_INTERSECTION() returns invalid value on empty intersection in maria-5.3-gis.
    create the GEOMETRYCOLLECTION() for the empty result.

  sql/gstream.h
bug 801466 ST_INTERSECTION() returns invalid value on empty intersection in maria-5.3-gis.
    next_symbol() added.

  sql/spatial.cc
bug 801466 ST_INTERSECTION() returns invalid value on empty intersection in maria-5.3-gis.
    code modified to handle 0 geometries in the GEOMETRYCOLLECTION properly.

1 files changed, 14 insertions, 12 deletions

diff --git a/sql/spatial.cc b/sql/spatial.cc
index 67ece027141..67e36ccb12b 100644
--- a/sql/spatial.cc
+++ b/sql/spatial.cc
@@ -2075,19 +2075,22 @@ bool Gis_geometry_collection::init_from_wkt(Gis_read_stream *trs, String *wkb)
     return 1;
   wkb->length(wkb->length()+4);			// Reserve space for points
 
-  for (;;)
+  if (trs->next_symbol() != ')')
   {
-    if (!(g= create_from_wkt(&buffer, trs, wkb)))
-      return 1;
-
-    if (g->get_class_info()->m_type_id == wkb_geometrycollection)
+    for (;;)
     {
-      trs->set_error_msg("Unexpected GEOMETRYCOLLECTION");
-      return 1;
+      if (!(g= create_from_wkt(&buffer, trs, wkb)))
+        return 1;
+
+      if (g->get_class_info()->m_type_id == wkb_geometrycollection)
+      {
+        trs->set_error_msg("Unexpected GEOMETRYCOLLECTION");
+        return 1;
+      }
+      n_objects++;
+      if (trs->skip_char(','))			// Didn't find ','
+        break;
     }
-    n_objects++;
-    if (trs->skip_char(','))			// Didn't find ','
-      break;
   }
 
   wkb->write_at_position(no_pos, n_objects);
@@ -2208,10 +2211,9 @@ bool Gis_geometry_collection::get_data_as_wkt(String *txt,
     geom->set_data_ptr(data, (uint) (m_data_end - data));
     if (geom->as_wkt(txt, &data))
       return 1;
-    if (txt->append(STRING_WITH_LEN(","), 512))
+    if (n_objects && txt->append(STRING_WITH_LEN(","), 512))
       return 1;
   }
-  txt->length(txt->length() - 1);
   *end= data;
   return 0;
 }