Determine which wrapper binary to use based on the available JREs

Note: this code assumes a 64-bit wrapper binary is available, which is
true on new installs but may not be true on all installations until
updates can be pushed out through fred

CommandsMenu.cs

@@ -101,6 +101,15 @@ private void FindNode()
                     // dialog.
                     Log.Error(strings.MalformedConfig, e.Filename, e.Value);
                     MessageBox.Show(String.Format(strings.MalformedConfig, e.Filename, e.Value), "", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                } 
+                catch (MissingJRE e)
+                {
+                    // No JRE was found
+                    FNLog.Error(strings.JRENotFound);
+                    MessageBox.Show(strings.JRENotFound, "", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                    /* Cannot continue for now */
+                    Application.Exit();
+                    return;
                 }
                 // TODO: Explain what happened to prompt a custom location?
                 try

NodeController.cs

@@ -53,10 +53,25 @@ public MissingConfigValueException(string filename, string value)
         public int FProxyPort { get { return _config.FProxyPort; } }
         public string DownloadsDir { get { return _config.DownloadsDir; } }
 
-        public const string WrapperFilename = @"wrapper\freenetwrapper.exe";
         private const string FreenetIniFilename = @"freenet.ini";
         private const string WrapperConfFilename = "wrapper.conf";
 
+        public static string WrapperFilename {
+            get {
+                switch (MachineConfig.GetBestAvailableJRE) {
+                    case JREType.JRE64Bit:
+                        return @"wrapper\freenetwrapper-64.exe";
+                    case JREType.JRE32Bit:
+                        return @"wrapper\freenetwrapper.exe";
+                    case JREType.None:
+                        // there is no JRE installed at all
+                        throw new MissingJRE();
+                    default:
+                        throw new MissingJRE();
+                }
+            }
+        }
+
         // TODO: Where to document? Thows FileNotFound; DirectoryNotFound
         public NodeController()
         {

strings.resx

@@ -126,6 +126,9 @@
   <data name="FreenetStarting" xml:space="preserve">
     <value>Freenet is starting.</value>
   </data>
+  <data name="JRENotFound" xml:space="preserve">
+    <value>No Java runtime is available</value>
+  </data>
   <data name="MalformedConfig" xml:space="preserve">
     <value>The configuration file '{0}' does not contain a valid value for '{1}'.</value>
   </data>