From 9f5d50ef18a56ed2b290044bfc170b9d248583e5 Mon Sep 17 00:00:00 2001
From: rouault <rouault@f0d54148-0727-0410-94bb-9a71ac55c965>
Date: Thu, 7 Jan 2016 20:10:03 +0000
Subject: [PATCH] WMS: determine a resolution that will not result in a number
 that is larger than the maximum size of an integer.  Any value that exceeds
 the maximum size of an integer will raise an invalid dataset dimensions
 error. (patch by Tim Astle, https://github.com/OSGeo/gdal/pull/89)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@32806 f0d54148-0727-0410-94bb-9a71ac55c965
---
 frmts/wms/wmsdriver.cpp | 40 ++++++++++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 8 deletions(-)

diff --git a/frmts/wms/wmsdriver.cpp b/frmts/wms/wmsdriver.cpp
index 4f8507d0b1..f307f39fb2 100644
--- a/frmts/wms/wmsdriver.cpp
+++ b/frmts/wms/wmsdriver.cpp
@@ -42,6 +42,8 @@
 #include "minidriver_arcgis_server.h"
 #include "minidriver_iip.h"
 
+#include <limits>
+
 /************************************************************************/
 /*              GDALWMSDatasetGetConfigFromURL()                        */
 /************************************************************************/
@@ -160,6 +162,7 @@ CPLXMLNode * GDALWMSDatasetGetConfigFromURL(GDALOpenInfo *poOpenInfo)
         nTileSize = 1024;
 
     int nXSize, nYSize;
+    double dXSize, dYSize;
 
     int nOverviewCount = (osOverviewCount.size()) ? atoi(osOverviewCount) : 20;
 
@@ -173,30 +176,51 @@ CPLXMLNode * GDALWMSDatasetGetConfigFromURL(GDALOpenInfo *poOpenInfo)
             dfMinResolution *= 2;
         }
 
-        nXSize = (int) ((dfMaxX - dfMinX) / dfMinResolution + 0.5);
-        nYSize = (int) ((dfMaxY - dfMinY) / dfMinResolution + 0.5);
+        // Determine a suitable size that doesn't overflow max int.
+        dXSize = ((dfMaxX - dfMinX) / dfMinResolution + 0.5);
+        dYSize = ((dfMaxY - dfMinY) / dfMinResolution + 0.5);
+
+        while (dXSize > (std::numeric_limits<int>::max)() || 
+               dYSize > (std::numeric_limits<int>::max)())
+        {
+            dfMinResolution *= 2;
+
+            dXSize = ((dfMaxX - dfMinX) / dfMinResolution + 0.5);
+            dYSize = ((dfMaxY - dfMinY) / dfMinResolution + 0.5);
+        }
     }
     else
     {
         double dfRatio = (dfMaxX - dfMinX) / (dfMaxY - dfMinY);
         if (dfRatio > 1)
         {
-            nXSize = nTileSize;
-            nYSize = (int) (nXSize / dfRatio);
+            dXSize = nTileSize;
+            dYSize = dXSize / dfRatio;
         }
         else
         {
-            nYSize = nTileSize;
-            nXSize = (int) (nYSize * dfRatio);
+            dYSize = nTileSize;
+            dXSize = dYSize * dfRatio;
         }
 
         if (nOverviewCount < 0 || nOverviewCount > 20)
             nOverviewCount = 20;
 
-        nXSize = nXSize * (1 << nOverviewCount);
-        nYSize = nYSize * (1 << nOverviewCount);
+        dXSize = dXSize * (1 << nOverviewCount);
+        dYSize = dYSize * (1 << nOverviewCount);
+
+        // Determine a suitable size that doesn't overflow max int.
+        while (dXSize > (std::numeric_limits<int>::max)() || 
+               dYSize > (std::numeric_limits<int>::max)())
+        {
+            dXSize /= 2;
+            dYSize /= 2;
+        }
     }
 
+    nXSize = (int) dXSize;
+    nYSize = (int) dYSize;
+
     int bTransparent = osTransparent.size() ? CSLTestBoolean(osTransparent) : FALSE;
 
     if (osFormat.size() == 0)