replace GetTempFileName (#3639)

* replace GetTempFileName

* replace GetTempFileName

* good app

aspnetcore/includes/GetTempFileName.md

@@ -0,0 +1 @@
+**Warning**: The following code uses `GetTempFileName`, which throws an `IOException` if more than 65535 files are created without deleting previous temporary files. A real app should either delete temporary files or use `GetTempPath` and `GetRandomFileName` to create temporary file names. The 65535 files limit is per server, so another app on the server can use up all 65535 files. 

aspnetcore/mvc/models/file-uploads.md

@@ -1,18 +1,18 @@
 ---
-title: File uploads
+title: File uploads in ASP.NET Core
 author: ardalis
 description: How to use model binding and streaming to upload files in ASP.NET Core MVC.
 keywords: ASP.NET Core, file upload, model binding, IFormFile, streaming
 ms.author: riande
 manager: wpickett
-ms.date: 11/10/2016
+ms.date: 7/5/2017
 ms.topic: article
 ms.assetid: ebc98159-a028-4a94-b06c-43981c79c6be
 ms.technology: aspnet
 ms.prod: asp.net-core
 uid: mvc/models/file-uploads
 ---
-# File uploads
+# File uploads in ASP.NET Core
 
 By [Steve Smith](http://ardalis.com)
 
@@ -66,6 +66,8 @@ public interface IFormFile
 
 When uploading files using model binding and the `IFormFile` interface, the action method can accept either a single `IFormFile` or an `IEnumerable<IFormFile>` (or `List<IFormFile>`) representing several files. The following example loops through one or more uploaded files, saves them to the local file system, and returns the total number and size of files uploaded.
 
+[!INCLUDE [GetTempFileName](../../includes/GetTempFileName.md)]
+
 [!code-csharp[Main](file-uploads/sample/FileUploadSample/Controllers/UploadFilesController.cs?name=snippet1)]
 
 Files uploaded using the `IFormFile` technique are buffered in memory or on disk on the web server before being processed. Inside the action method, the `IFormFile` contents are accessible as a stream. In addition to the local file system, files can be streamed to [Azure Blob storage](https://azure.microsoft.com/documentation/articles/vs-storage-aspnet5-getting-started-blobs) or [Entity Framework](https://docs.microsoft.com/ef/core/index).
@@ -160,6 +162,8 @@ Since model binding is disabled, the `Upload` action method doesn't accept param
 
 The complete `Upload` method is shown below:
 
+[!INCLUDE [GetTempFileName](../../includes/GetTempFileName.md)]
+
 [!code-csharp[Main](file-uploads/sample/FileUploadSample/Controllers/StreamingController.cs?name=snippet1)]
 
 ## Troubleshooting

aspnetcore/mvc/models/file-uploads/sample/FileUploadSample/Controllers/ProfileController.cs

@@ -51,6 +51,11 @@ namespace FileUploadSample.Controllers
             if (model.AvatarFile.Length > 0)
             {
                 // don't rely on or trust the FileName property without validation
+                //**Warning**: The following code uses `GetTempFileName`, which throws
+                // an `IOException` if more than 65535 files are created without 
+                // deleting previous temporary files. A real app should either delete
+                // temporary files or use `GetTempPath` and `GetRandomFileName` 
+                // to create temporary file names.
                 var filePath = Path.GetTempFileName();
                 using (var stream = new FileStream(filePath, FileMode.Create))
                 {