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.

4 files changed, 28 insertions, 17 deletions

diff --git a/sql/field.cc b/sql/field.cc
index 50f66363c1f..42324674838 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -8008,7 +8008,7 @@ int Field_geom::store(const char *from, uint length, CHARSET_INFO *cs)
       goto err;
     // Check given WKB
     uint32 wkb_type;
-    if (length < SRID_SIZE + WKB_HEADER_SIZE + SIZEOF_STORED_DOUBLE*2)
+    if (length < SRID_SIZE + WKB_HEADER_SIZE + 4)
       goto err;
     wkb_type= uint4korr(from + SRID_SIZE + 1);
     if (wkb_type < (uint32) Geometry::wkb_point ||
diff --git a/sql/gcalc_tools.cc b/sql/gcalc_tools.cc
index ab173803323..0d5c1c52d61 100644
--- a/sql/gcalc_tools.cc
+++ b/sql/gcalc_tools.cc
@@ -137,6 +137,8 @@ int Gcalc_function::count_internal()
   cur_func+= 4;
   if (next_func == op_shape)
     return i_states[c_op & ~(op_any | op_not)] ^ mask;
+  if (n_ops == 0)
+    return mask;
 
   result= count_internal();
 
@@ -442,11 +444,9 @@ void Gcalc_result_receiver::reset()
 
 int Gcalc_result_receiver::get_result_typeid()
 {
-  if (!n_shapes)
-    return 0;
-
-  if (collection_result)
+  if (!n_shapes || collection_result)
     return Geometry::wkb_geometrycollection;
+
   switch (common_shapetype)
   {
     case Gcalc_function::shape_polygon:
@@ -1186,6 +1186,7 @@ int Gcalc_operation_reducer::get_result(Gcalc_result_receiver *storage)
   poly_instance *polygons= NULL;
 
   *m_res_hook= NULL;
+
   while (m_result)
   {
     Gcalc_function::shape_type shape= m_result->type;
diff --git a/sql/gstream.h b/sql/gstream.h
index 1ef90ad5bf0..a1850e9a333 100644
--- a/sql/gstream.h
+++ b/sql/gstream.h
@@ -57,6 +57,14 @@ public:
     m_cur++;
     return 0;
   }
+  /* Returns the next notempty character. */
+  char next_symbol() 
+  {
+    skip_space();
+    if (m_cur >= m_limit)
+      return 0;                                 /* EOL meet. */
+    return *m_cur;
+  }
   void set_error_msg(const char *msg);
 
   // caller should free this pointer
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;
 }