From c32166c71fa970b409630c3efe40dd35154abf43 Mon Sep 17 00:00:00 2001
From: artemp <artem@mapnik.org>
Date: Mon, 23 Nov 2015 09:58:27 +0000
Subject: [PATCH] move loop terminatiion condition to the top and avoid
 potential infinite loop when `if (content_length != shp.read_xdr_integer())`
 + Track `empty` shapes and don't create *.index when there is no non-empty
 geometries (#3184)

---
 utils/shapeindex/shapeindex.cpp | 44 +++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/utils/shapeindex/shapeindex.cpp b/utils/shapeindex/shapeindex.cpp
index 5555c203b..e6ce36bee 100644
--- a/utils/shapeindex/shapeindex.cpp
+++ b/utils/shapeindex/shapeindex.cpp
@@ -162,7 +162,7 @@ int main (int argc,char** argv)
         mapnik::quad_tree<int> tree(extent, depth, ratio);
         int count = 0;
 
-        while (true)
+        while (shx.is_good() && pos <= file_length + 4)
         {
             int offset = shx.read_xdr_integer();
             int content_length = shx.read_xdr_integer();
@@ -189,34 +189,40 @@ int main (int argc,char** argv)
             {
                 shp.read_envelope(item_ext);
             }
-
-            tree.insert(offset * 2,item_ext);
-
             if (verbose)
             {
                 std::clog << "record number " << record_number << " box=" << item_ext << std::endl;
             }
-            ++count;
-            if (pos >= file_length) break;
+            if (item_ext.valid())
+            {
+                tree.insert(offset * 2,item_ext);
+                ++count;
+            }
         }
 
-        std::clog << " number shapes=" << count << std::endl;
-
-        std::fstream file((shapename+".index").c_str(),
-                          std::ios::in | std::ios::out | std::ios::trunc | std::ios::binary);
-        if (!file)
+        if (count > 0)
         {
-            std::clog << "cannot open index file for writing file \""
-                 << (shapename+".index") << "\"" << std::endl;
+            std::clog << " number shapes=" << count << std::endl;
+            std::fstream file((shapename+".index").c_str(),
+                              std::ios::in | std::ios::out | std::ios::trunc | std::ios::binary);
+            if (!file)
+            {
+                std::clog << "cannot open index file for writing file \""
+                          << (shapename+".index") << "\"" << std::endl;
+            }
+            else
+            {
+                tree.trim();
+                std::clog << " number nodes=" << tree.count() << std::endl;
+                file.exceptions(std::ios::failbit | std::ios::badbit);
+                tree.write(file);
+                file.flush();
+                file.close();
+            }
         }
         else
         {
-            tree.trim();
-            std::clog << " number nodes=" << tree.count() << std::endl;
-            file.exceptions(std::ios::failbit | std::ios::badbit);
-            tree.write(file);
-            file.flush();
-            file.close();
+            std::clog << "No non-empty geometries in shapefile" << std::endl;
         }
     }