Treat names with slashes that do not end in .cshtml as paths

Fixes #6672

src/Microsoft.AspNetCore.Mvc.Core/Internal/ViewEnginePath.cs

@@ -11,9 +11,24 @@ namespace Microsoft.AspNetCore.Mvc.Internal
 {
     public static class ViewEnginePath
     {
+        public static readonly char[] PathSeparators = new[] { '/', '\\' };
         private const string CurrentDirectoryToken = ".";
         private const string ParentDirectoryToken = "..";
-        private static readonly char[] _pathSeparators = new[] { '/', '\\' };
+        private static readonly string[] TokensRequiringNormalization = new string[]
+        {
+            // ./
+            CurrentDirectoryToken + PathSeparators[0],
+            // .\
+            CurrentDirectoryToken + PathSeparators[1],
+            // ../
+            ParentDirectoryToken + PathSeparators[0],
+            // ..\
+            ParentDirectoryToken + PathSeparators[1],
+            // //
+            "" + PathSeparators[0] + PathSeparators[0],
+            // \\
+            "" + PathSeparators[1] + PathSeparators[1],
+        };
 
         public static string CombinePath(string first, string second)
         {
@@ -42,18 +57,18 @@ public static string CombinePath(string first, string second)
                 result = first.Substring(0, index + 1) + second;
             }
 
-            return ResolvePath(result);
+            return NormalizePath(result);
         }
 
-        public static string ResolvePath(string path)
+        public static string NormalizePath(string path)
         {
-            if (!RequiresPathResolution(path))
+            if (!RequiresPathNormalization(path))
             {
                 return path;
             }
 
             var pathSegments = new List<StringSegment>();
-            var tokenizer = new StringTokenizer(path, _pathSeparators);
+            var tokenizer = new StringTokenizer(path, PathSeparators);
             foreach (var segment in tokenizer)
             {
                 if (segment.Length == 0)
@@ -93,10 +108,17 @@ public static string ResolvePath(string path)
             return builder.ToString();
         }
 
-        private static bool RequiresPathResolution(string path)
+        private static bool RequiresPathNormalization(string path)
         {
-            return path.IndexOf(ParentDirectoryToken, StringComparison.Ordinal) != -1 ||
-                path.IndexOf(CurrentDirectoryToken, StringComparison.Ordinal) != -1;
+            for (var i = 0; i < TokensRequiringNormalization.Length; i++)
+            {
+                if (path.IndexOf(TokensRequiringNormalization[i]) != -1)
+                {
+                    return true;
+                }
+            }
+
+            return false;
         }
     }
 }

src/Microsoft.AspNetCore.Mvc.Razor/RazorViewEngine.cs

@@ -142,7 +142,7 @@ public RazorPageResult GetPage(string executingFilePath, string pagePath)
                 throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, nameof(pagePath));
             }
 
-            if (!(IsApplicationRelativePath(pagePath) || IsRelativePath(pagePath)))
+            if (!LooksLikePath(pagePath))
             {
                 // Not a path this method can handle.
                 return new RazorPageResult(pagePath, Enumerable.Empty<string>());
@@ -191,7 +191,7 @@ public ViewEngineResult GetView(string executingFilePath, string viewPath, bool
                 throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, nameof(viewPath));
             }
 
-            if (!(IsApplicationRelativePath(viewPath) || IsRelativePath(viewPath)))
+            if (!LooksLikePath(viewPath))
             {
                 // Not a path this method can handle.
                 return ViewEngineResult.NotFound(viewPath, Enumerable.Empty<string>());
@@ -205,8 +205,7 @@ private ViewLocationCacheResult LocatePageFromPath(string executingFilePath, str
         {
             var applicationRelativePath = GetAbsolutePath(executingFilePath, pagePath);
             var cacheKey = new ViewLocationCacheKey(applicationRelativePath, isMainPage);
-            ViewLocationCacheResult cacheResult;
-            if (!ViewLookupCache.TryGetValue(cacheKey, out cacheResult))
+            if (!ViewLookupCache.TryGetValue(cacheKey, out ViewLocationCacheResult cacheResult))
             {
                 var expirationTokens = new HashSet<IChangeToken>();
                 cacheResult = CreateCacheResult(expirationTokens, applicationRelativePath, isMainPage);
@@ -300,11 +299,19 @@ public string GetAbsolutePath(string executingFilePath, string pagePath)
 
             if (IsApplicationRelativePath(pagePath))
             {
-                // An absolute path already; no change required.
-                return pagePath;
+                // An absolute path already; no need to concat it with executingFilePath.
+                return ViewEnginePath.NormalizePath(pagePath);
             }
 
-            if (!IsRelativePath(pagePath))
+            if (pagePath.IndexOfAny(ViewEnginePath.PathSeparators) != -1)
+            {
+                // A name that looks like a path (e.g. Shared/_Partial). Add an extension to it and treat it like one.
+                if (!pagePath.EndsWith(ViewExtension, StringComparison.OrdinalIgnoreCase))
+                {
+                    pagePath = pagePath + ViewExtension;
+                }
+            }
+            else if (!IsRelativePath(pagePath))
             {
                 // A page name; no change required.
                 return pagePath;
@@ -316,7 +323,7 @@ public string GetAbsolutePath(string executingFilePath, string pagePath)
                 // path relative to currently-executing view, if any.
                 // Not yet executing a view. Start in app root.
                 var absolutePath = "/" + pagePath;
-                return ViewEnginePath.ResolvePath(absolutePath);
+                return ViewEnginePath.NormalizePath(absolutePath);
             }
 
             return ViewEnginePath.CombinePath(executingFilePath, pagePath);
@@ -492,5 +499,27 @@ private static bool IsRelativePath(string name)
             // Though ./ViewName looks like a relative path, framework searches for that view using view locations.
             return name.EndsWith(ViewExtension, StringComparison.OrdinalIgnoreCase);
         }
+
+        private static bool LooksLikePath(string name)
+        {
+            Debug.Assert(!string.IsNullOrEmpty(name));
+
+            if (IsApplicationRelativePath(name))
+            {
+                return true;
+            }
+
+            if (IsRelativePath(name))
+            {
+                return true;
+            }
+
+            if (name.IndexOfAny(ViewEnginePath.PathSeparators) != -1)
+            {
+                return true;
+            }
+
+            return false;
+        }
     }
 }

test/Microsoft.AspNetCore.Mvc.FunctionalTests/ViewEngineTests.cs

@@ -493,5 +493,18 @@ public async Task ViewEngine_NormalizesPathsReturnedByViewLocationExpanders()
             // Assert
             Assert.Equal(expected, responseContent.Trim());
         }
+
+        [Fact]
+        public async Task ViewEngine_ResolvesPathsWithSlashesThatDoNotHaveExtensions()
+        {
+            // Arrange
+            var expected = @"<embdedded-layout>Hello from EmbeddedHome\EmbeddedPartial</embdedded-layout>";
+
+            // Act
+            var responseContent = await Client.GetStringAsync("/EmbeddedViews/RelativeNonPath");
+
+            // Assert
+            Assert.Equal(expected, responseContent.Trim());
+        }
     }
 }

test/Microsoft.AspNetCore.Mvc.Razor.Test/RazorViewEngineTest.cs

@@ -24,7 +24,7 @@
 using Moq;
 using Xunit;
 
-namespace Microsoft.AspNetCore.Mvc.Razor.Test
+namespace Microsoft.AspNetCore.Mvc.Razor
 {
     public class RazorViewEngineTest
     {
@@ -1486,13 +1486,10 @@ public void GetPage_ResolvesRelativeToAppRoot_WithRelativePath_IfNoPageExecuting
         [InlineData(null, null)]
         [InlineData(null, "")]
         [InlineData(null, "Page")]
-        [InlineData(null, "Folder/Page")]
-        [InlineData(null, "Folder1/Folder2/Page")]
         [InlineData("/Home/Index.cshtml", null)]
         [InlineData("/Home/Index.cshtml", "")]
         [InlineData("/Home/Index.cshtml", "Page")]
-        [InlineData("/Home/Index.cshtml", "Folder/Page")]
-        [InlineData("/Home/Index.cshtml", "Folder1/Folder2/Page")]
+
         public void GetAbsolutePath_ReturnsPagePathUnchanged_IfNotAPath(string executingFilePath, string pagePath)
         {
             // Arrange
@@ -1505,6 +1502,23 @@ public void GetAbsolutePath_ReturnsPagePathUnchanged_IfNotAPath(string executing
             Assert.Same(pagePath, result);
         }
 
+        [Theory]
+        [InlineData(null, "Folder/Page", "/Folder/Page.cshtml")]
+        [InlineData(null, "Folder1/Folder2/Page", "/Folder1/Folder2/Page.cshtml")]
+        [InlineData("/Home/Index.cshtml", "Folder/Page", "/Home/Folder/Page.cshtml")]
+        [InlineData("/Home/Index.cshtml", "Folder1/Folder2/Page", "/Home/Folder1/Folder2/Page.cshtml")]
+        public void GetAbsolutePath_ResolvesNamesThatLookLikePaths(string executingFilePath, string pagePath, string expected)
+        {
+            // Arrange
+            var viewEngine = CreateViewEngine();
+
+            // Act
+            var result = viewEngine.GetAbsolutePath(executingFilePath, pagePath);
+
+            // Assert
+            Assert.Equal(expected, result);
+        }
+
         [Theory]
         [InlineData("/Views/Home/Index.cshtml", "../Shared/_Partial.cshtml")]
         [InlineData("/Views/Home/Index.cshtml", "..\\Shared\\_Partial.cshtml")]

test/WebSites/RazorWebSite/Controllers/EmbeddedViewsController.cs

@@ -8,5 +8,6 @@ namespace RazorWebSite.Controllers
     public class EmbeddedViewsController : Controller
     {
         public IActionResult Index() => View("/Views/EmbeddedHome/Index.cshtml");
+        public IActionResult RelativeNonPath() => View("/Views/EmbeddedHome/RelativeNonPath.cshtml");
     }
 }

test/WebSites/RazorWebSite/EmbeddedViews/Views/EmbeddedHome/EmbeddedPartial.cshtml

@@ -0,0 +1 @@
+Hello from EmbeddedHome\EmbeddedPartial

test/WebSites/RazorWebSite/EmbeddedViews/Views/EmbeddedHome/RelativeNonPath.cshtml

@@ -0,0 +1,2 @@
+@{ Layout = "../EmbeddedShared/_Layout"; }
+@Html.Partial("./EmbeddedPartial")