update .net core startup

src/Emby.Server/ApplicationPathHelper.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Emby.Server
+{
+    public class ApplicationPathHelper
+    {
+        public static string GetProgramDataPath(string applicationPath)
+        {
+            var useDebugPath = false;
+
+#if DEBUG
+            useDebugPath = true;
+#endif
+
+            var programDataPath = useDebugPath ?
+                "programdata" :
+                "programdata";
+
+            programDataPath = programDataPath
+                .Replace('/', Path.DirectorySeparatorChar)
+                .Replace('\\', Path.DirectorySeparatorChar);
+
+            // If it's a relative path, e.g. "..\"
+            if (!Path.IsPathRooted(programDataPath))
+            {
+                var path = Path.GetDirectoryName(applicationPath);
+
+                if (string.IsNullOrEmpty(path))
+                {
+                    throw new Exception("Unable to determine running assembly location");
+                }
+
+                programDataPath = Path.Combine(path, programDataPath);
+
+                programDataPath = Path.GetFullPath(programDataPath);
+            }
+
+            Directory.CreateDirectory(programDataPath);
+
+            return programDataPath;
+        }
+    }
+}