From b43ee6dd0494b31965946fa5a21149202a7c12a8 Mon Sep 17 00:00:00 2001
From: artemp <artem@mapnik.org>
Date: Thu, 18 Feb 2016 11:44:39 +0100
Subject: [PATCH] beef up `has_index` method to check if *.index file is valid
 (has expected header) (ref #3300)

---
 plugins/input/shape/shape_io.hpp | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/plugins/input/shape/shape_io.hpp b/plugins/input/shape/shape_io.hpp
index c2fd3a564..1828ebd54 100644
--- a/plugins/input/shape/shape_io.hpp
+++ b/plugins/input/shape/shape_io.hpp
@@ -23,16 +23,16 @@
 #ifndef SHAPE_IO_HPP
 #define SHAPE_IO_HPP
 
+// stl
+#include <memory>
+#include <ios>
 // mapnik
 #include <mapnik/box2d.hpp>
 #include <mapnik/util/noncopyable.hpp>
-
+#include <mapnik/util/spatial_index.hpp>
 // boost
 #include <boost/optional.hpp>
-
-// stl
-#include <memory>
-
+//
 #include "dbfile.hpp"
 #include "shapefile.hpp"
 
@@ -72,7 +72,13 @@ public:
 
     inline bool has_index() const
     {
-        return (index_ && index_->is_open());
+        if (index_ && index_->is_open())
+        {
+            bool status = mapnik::util::check_spatial_index(index_->file());
+            index_->seek(0);// rewind
+            return status;
+        }
+        return false;
     }
 
     inline int id() const { return id_;}