From cacc597a8411ddf815c4676acc6c95477c1a49b4 Mon Sep 17 00:00:00 2001
From: Igor Velikorossov <igor.velikorossov@microsoft.com>
Date: Fri, 14 May 2021 21:18:40 +1000
Subject: [PATCH] Validate input in Application.SetHighDpiMode() method

---
 .../src/System/Windows/Forms/Application.cs   | 20 +++++++++++--------
 .../System/Windows/Forms/ApplicationTests.cs  | 10 +++++++++-
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/src/System.Windows.Forms/src/System/Windows/Forms/Application.cs b/src/System.Windows.Forms/src/System/Windows/Forms/Application.cs
index f780907d4f4..b855665ab5f 100644
--- a/src/System.Windows.Forms/src/System/Windows/Forms/Application.cs
+++ b/src/System.Windows.Forms/src/System/Windows/Forms/Application.cs
@@ -303,14 +303,6 @@ public static string ExecutablePath
         public static HighDpiMode HighDpiMode
             => DpiHelper.GetWinformsApplicationDpiAwareness();
 
-        /// <summary>
-        ///  Sets the <see cref="HighDpiMode"/> mode for process.
-        /// </summary>
-        /// <param name="highDpiMode">One of the enumeration values that specifies the high DPI mode to set.</param>
-        /// <returns><see langword="true" /> if the high DPI mode was set; otherwise, <see langword="false" />.</returns>
-        public static bool SetHighDpiMode(HighDpiMode highDpiMode)
-            => !DpiHelper.FirstParkingWindowCreated && DpiHelper.SetWinformsApplicationDpiAwareness(highDpiMode);
-
         /// <summary>
         ///  Gets the path for the application data specific to a local, non-roaming user.
         /// </summary>
@@ -1241,6 +1233,18 @@ public static void SetCompatibleTextRenderingDefault(bool defaultValue)
             Control.UseCompatibleTextRenderingDefault = defaultValue;
         }
 
+        /// <summary>
+        ///  Sets the <see cref="HighDpiMode"/> mode for process.
+        /// </summary>
+        /// <param name="highDpiMode">One of the enumeration values that specifies the high DPI mode to set.</param>
+        /// <returns><see langword="true" /> if the high DPI mode was set; otherwise, <see langword="false" />.</returns>
+        public static bool SetHighDpiMode(HighDpiMode highDpiMode)
+        {
+            SourceGenerated.EnumValidator.Validate(highDpiMode, nameof(highDpiMode));
+
+            return !DpiHelper.FirstParkingWindowCreated && DpiHelper.SetWinformsApplicationDpiAwareness(highDpiMode);
+        }
+
         /// <summary>
         ///  Sets the suspend/hibernate state of the machine.
         ///  Returns true if the call succeeded, else false.
diff --git a/src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/ApplicationTests.cs b/src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/ApplicationTests.cs
index d691ece2a46..1a03bd95d29 100644
--- a/src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/ApplicationTests.cs
+++ b/src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/ApplicationTests.cs
@@ -1,8 +1,9 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Globalization;
 using System.IO;
 using System.Threading;
@@ -150,6 +151,13 @@ public void Application_EnableVisualStyles_ManifestResourceExists()
             Assert.NotNull(stream);
         }
 
+        [WinFormsTheory]
+        [CommonMemberData(nameof(CommonTestHelper.GetEnumTypeTheoryDataInvalid), typeof(HighDpiMode))]
+        public void Application_SetHighDpiMode_SetInvalidValue_ThrowsInvalidEnumArgumentException(HighDpiMode value)
+        {
+            Assert.Throws<InvalidEnumArgumentException>("highDpiMode", () => Application.SetHighDpiMode(value));
+        }
+
         private class CustomLCIDCultureInfo : CultureInfo
         {
             private readonly int _lcid;