Backport into build-200911241145-5.1.40sp1

> ------------------------------------------------------------
> revno: 1810.3959.6
> revision-id: joro@sun.com-20091021084345-iki6z0uceieoupey
> parent: ramil@mysql.com-20091023112648-gie6o3odj57cxh1e
> committer: Georgi Kodinov <joro@sun.com>
> branch nick: B47780-5.0-bugteam
> timestamp: Wed 2009-10-21 11:43:45 +0300
> message:
>   Bug #47780: crash when comparing GIS items from subquery
>         
>   If the first argument to GeomFromWKB function is a geometry
>   field then the function just returns its value.
>   However in doing so it's not preserving first argument's 
>   null_value flag and this causes unexpected null value to
>   be returned to the calling function.
>         
>   Fixed by updating the null_value of the GeomFromWKB function
>   in such cases (and all other cases that return a NULL e.g.
>   because of not enough memory for the return buffer).

mysql-test/r/gis.result

@@ -972,6 +972,18 @@ select min(`col002`) from t1 union select `col002` from t1;
 min(`col002`)
 NULL
 drop table t1;
+#
+# Bug #47780: crash when comparing GIS items from subquery
+#
+CREATE TABLE t1(a INT, b MULTIPOLYGON);
+INSERT INTO t1 VALUES 
+(0,
+GEOMFROMTEXT(
+'multipolygon(((1 2,3 4,5 6,7 8,9 8),(7 6,5 4,3 2,1 2,3 4)))'));
+# must not crash
+SELECT 1 FROM t1 WHERE a <> (SELECT GEOMETRYCOLLECTIONFROMWKB(b) FROM t1);
+1
+DROP TABLE t1;
 End of 5.0 tests
 create table t1 (f1 tinyint(1), f2 char(1), f3 varchar(1), f4 geometry, f5 datetime);
 create view v1 as select * from t1;

mysql-test/t/gis.test

@@ -655,6 +655,22 @@ insert into t1 values (),(),();
 select min(`col002`) from t1 union select `col002` from t1;
 drop table t1;
 
+--echo #
+--echo # Bug #47780: crash when comparing GIS items from subquery
+--echo #
+
+CREATE TABLE t1(a INT, b MULTIPOLYGON);
+INSERT INTO t1 VALUES 
+  (0,
+   GEOMFROMTEXT(
+    'multipolygon(((1 2,3 4,5 6,7 8,9 8),(7 6,5 4,3 2,1 2,3 4)))'));
+
+--echo # must not crash
+SELECT 1 FROM t1 WHERE a <> (SELECT GEOMETRYCOLLECTIONFROMWKB(b) FROM t1);
+
+DROP TABLE t1;
+
+
 --echo End of 5.0 tests
 
 

sql/item_geofunc.cc

@@ -84,7 +84,9 @@ String *Item_func_geometry_from_wkb::val_str(String *str)
 
   if (args[0]->field_type() == MYSQL_TYPE_GEOMETRY)
   {
-    return args[0]->val_str(str);
+    String *str_ret= args[0]->val_str(str);
+    null_value= args[0]->null_value;
+    return str_ret;
   }
 
   wkb= args[0]->val_str(&arg_val);
@@ -94,7 +96,10 @@ String *Item_func_geometry_from_wkb::val_str(String *str)
 
   str->set_charset(&my_charset_bin);
   if (str->reserve(SRID_SIZE, 512))
-    return 0;
+  {
+    null_value= TRUE;                           /* purecov: inspected */
+    return 0;                                   /* purecov: inspected */
+  }
   str->length(0);
   str->q_append(srid);
   if ((null_value=