moving win10 app, bringing back uploader

clients/winuploader/Microbit.Uploader/KnownFolders.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Management;
+using System.Runtime.InteropServices;
+using System.Security;
+
+namespace Microsoft.MicroBit
+{
+    /// <summary>
+    /// Class containing methods to retrieve specific file system paths.
+    /// </summary>
+    internal static class KnownFoldersNativeMethods
+    {
+        [SecurityCritical]
+        [SuppressMessage("Microsoft.Design", "CA1024:UsePropertiesWhereAppropriate")]
+        public static string GetDownloadPath()
+        {
+            IntPtr outPath;
+            int result = SHGetKnownFolderPath(new Guid("{374DE290-123F-4565-9164-39C4925E467B}"), 0x00004000, new IntPtr(0), out outPath);
+            if (result >= 0)
+                return Marshal.PtrToStringUni(outPath);
+            else return null;
+        }
+
+        [SuppressMessage("Microsoft.Security", "CA5122:PInvokesShouldNotBeSafeCriticalFxCopRule")]
+        [DllImport("Shell32.dll")]
+        [SecurityCritical]
+        private static extern int SHGetKnownFolderPath(
+            [MarshalAs(UnmanagedType.LPStruct)]Guid rfid, uint dwFlags, IntPtr hToken,
+            out IntPtr ppszPath);
+    }
+
+}