change the wrapped process working directory

set the working directory of the wrapped process with the location of the winsw executable, or the path defined in the configuration file.

Main.cs

@@ -373,6 +373,7 @@ namespace winsw
             var ps = process.StartInfo;
             ps.FileName = executable;
             ps.Arguments = arguments;
+            ps.WorkingDirectory = descriptor.WorkingDirectory;
             ps.CreateNoWindow = false;
             ps.UseShellExecute = false;
             ps.RedirectStandardInput = true; // this creates a pipe for stdin to the new process, instead of having it inherit our stdin.

ServiceDescriptor.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Diagnostics;
+using System.Reflection;
 using System.Runtime.InteropServices;
 using System.ServiceProcess;
 using System.Text;
@@ -69,11 +70,11 @@ namespace winsw
             dom.Load(BasePath + ".xml");
         }
 
-        private string SingleElement(string tagName)
+        private string SingleElement(string tagName, bool optional = false)
         {
             var n = dom.SelectSingleNode("//" + tagName);
-            if (n == null) throw new InvalidDataException("<" + tagName + "> is missing in configuration XML");
-            return Environment.ExpandEnvironmentVariables(n.InnerText);
+            if (n == null && !optional) throw new InvalidDataException("<" + tagName + "> is missing in configuration XML");
+            return n == null ? null : Environment.ExpandEnvironmentVariables(n.InnerText);
         }
 
         private int SingleIntElement(XmlNode parent, string tagName, int defaultValue)
@@ -169,6 +170,16 @@ namespace winsw
             }
         }
 
+        /// <summary>
+        /// Optional working directory.
+        /// </summary>
+        public string WorkingDirectory {
+            get {
+                var wd = SingleElement("workingdirectory", true);
+                return String.IsNullOrEmpty(wd) ? Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) : wd;
+            }
+        }
+
         /// <summary>
         /// Combines the contents of all the elements of the given name,
         /// or return null if no element exists. Handles whitespace quotation.