Fix: Prevent creating folders with forbidden names

src/Files.App/Filesystem/FilesystemOperations/FilesystemOperations.cs

@@ -960,4 +960,4 @@ public Task<IStorageHistory> CreateShortcutItemsAsync(IList<IStorageItemWithPath
 			throw new NotImplementedException("Cannot create shortcuts in UWP.");
 		}
 	}
-}
+}

src/Files.App/Filesystem/FilesystemOperations/Helpers/FilesystemHelpers.cs

@@ -96,6 +96,14 @@ public FilesystemHelpers(IShellPage associatedInstance, CancellationToken cancel
 			var progress = new Progress<FileSystemProgress>();
 			progress.ProgressChanged += (s, e) => returnStatus = returnStatus < ReturnResult.Failed ? e.Status!.Value.ToStatus() : returnStatus;
 
+			if (!IsValidForFilename(source.Name))
+			{
+				await DialogDisplayHelper.ShowDialogAsync(
+					"ErrorDialogThisActionCannotBeDone".GetLocalizedResource(),
+					"ErrorDialogNameNotAllowed".GetLocalizedResource());
+				return (ReturnResult.Failed, null);
+			}
+
 			var result = await filesystemOperations.CreateAsync(source, progress, cancellationToken);
 
 			if (registerHistory && !string.IsNullOrWhiteSpace(source.Path))
@@ -538,6 +546,14 @@ public async Task<ReturnResult> RenameAsync(IStorageItemWithPath source, string
 			var progress = new Progress<FileSystemProgress>();
 			progress.ProgressChanged += (s, e) => returnStatus = returnStatus < ReturnResult.Failed ? e.Status!.Value.ToStatus() : returnStatus;
 
+			if (!IsValidForFilename(newName))
+			{
+				await DialogDisplayHelper.ShowDialogAsync(
+					"ErrorDialogThisActionCannotBeDone".GetLocalizedResource(),
+					"ErrorDialogNameNotAllowed".GetLocalizedResource());
+				return ReturnResult.Failed;
+			}
+
 			IStorageHistory history = null;
 
 			switch (source.ItemType)
@@ -632,6 +648,9 @@ public async Task<ReturnResult> RecycleItemsFromClipboard(DataPackageView packag
 
 		#endregion IFilesystemHelpers
 
+		private static bool IsValidForFilename(string name)
+			=> !string.IsNullOrWhiteSpace(name) && !ContainsRestrictedCharacters(name) && !ContainsRestrictedFileName(name);
+
 		private static async Task<(List<FileNameConflictResolveOptionType> collisions, bool cancelOperation, IEnumerable<IFileSystemDialogConflictItemViewModel>)> GetCollision(FilesystemOperationType operationType, IEnumerable<IStorageItemWithPath> source, IEnumerable<string> destination, bool forceDialog)
 		{
 			var incomingItems = new List<BaseFileSystemDialogItemViewModel>();

src/Files.App/Strings/en-US/Resources.resw

@@ -2877,6 +2877,9 @@
   <data name="ReleaseNotes" xml:space="preserve">
     <value>Release Notes</value>
   </data>
+  <data name="ErrorDialogNameNotAllowed" xml:space="preserve">
+    <value>The specified item name is invalid</value>
+  </data>
   <data name="Settings" xml:space="preserve">
     <value>Settings</value>
   </data>