Fixed: Prevent root folders from being added under the startup folder

src/NzbDrone.Core/Validation/Paths/StartupFolderValidator.cs

@@ -0,0 +1,25 @@
+using FluentValidation.Validators;
+using NzbDrone.Common.EnvironmentInfo;
+using NzbDrone.Common.Extensions;
+
+namespace NzbDrone.Core.Validation.Paths
+{
+    public class StartupFolderValidator : PropertyValidator
+    {
+        private readonly IAppFolderInfo _appFolderInfo;
+        
+
+        public StartupFolderValidator(IAppFolderInfo appFolderInfo)
+            : base("Path cannot be an ancestor of the start up folder")
+        {
+            _appFolderInfo = appFolderInfo;
+        }
+
+        protected override bool IsValid(PropertyValidatorContext context)
+        {
+            if (context.PropertyValue == null) return true;
+
+            return !_appFolderInfo.StartUpFolder.IsParentPath(context.PropertyValue.ToString());
+        }
+    }
+}