[Fixes #4876] ContentResult forcing chunked encoding

src/Microsoft.AspNetCore.Mvc.Core/ContentResult.cs

@@ -2,24 +2,14 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Text;
 using System.Threading.Tasks;
-using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Mvc.Internal;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Logging;
-using Microsoft.Net.Http.Headers;
 
 namespace Microsoft.AspNetCore.Mvc
 {
     public class ContentResult : ActionResult
     {
-        private readonly string DefaultContentType = new MediaTypeHeaderValue("text/plain")
-        {
-            Encoding = Encoding.UTF8
-        }.ToString();
-
         /// <summary>
         /// Gets or set the content representing the body of the response.
         /// </summary>
@@ -42,38 +32,8 @@ namespace Microsoft.AspNetCore.Mvc
                 throw new ArgumentNullException(nameof(context));
             }
 
-            var loggerFactory = context.HttpContext.RequestServices.GetRequiredService<ILoggerFactory>();
+            var executor = context.HttpContext.RequestServices.GetRequiredService<ContentResultExecutor>();
-            var logger = loggerFactory.CreateLogger<ContentResult>();
+            return executor.ExecuteAsync(context, this);
-
-            var response = context.HttpContext.Response;
-
-            string resolvedContentType;
-            Encoding resolvedContentTypeEncoding;
-            ResponseContentTypeHelper.ResolveContentTypeAndEncoding(
-                ContentType,
-                response.ContentType,
-                DefaultContentType,
-                out resolvedContentType,
-                out resolvedContentTypeEncoding);
-
-            response.ContentType = resolvedContentType;
-
-            if (StatusCode != null)
-            {
-                response.StatusCode = StatusCode.Value;
-            }
-
-            logger.ContentResultExecuting(resolvedContentType);
-
-            if (Content != null)
-            {
-                var bufferingFeature = response.HttpContext.Features.Get<IHttpBufferingFeature>();
-                bufferingFeature?.DisableResponseBuffering();
-
-                return response.WriteAsync(Content, resolvedContentTypeEncoding);
-            }
-
-            return TaskCache.CompletedTask;
         }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/DependencyInjection/MvcCoreServiceCollectionExtensions.cs

@@ -215,6 +215,7 @@ namespace Microsoft.Extensions.DependencyInjection
             services.TryAddSingleton<LocalRedirectResultExecutor>();
             services.TryAddSingleton<RedirectToActionResultExecutor>();
             services.TryAddSingleton<RedirectToRouteResultExecutor>();
+            services.TryAddSingleton<ContentResultExecutor>();
 
             //
             // Route Handlers

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

@@ -0,0 +1,72 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.AspNetCore.Mvc.Internal
+{
+    public class ContentResultExecutor
+    {
+        private const string DefaultContentType = "text/plain; charset=utf-8";
+        private readonly ILogger<ContentResultExecutor> _logger;
+        private readonly IHttpResponseStreamWriterFactory _httpResponseStreamWriterFactory;
+
+        public ContentResultExecutor(ILogger<ContentResultExecutor> logger, IHttpResponseStreamWriterFactory httpResponseStreamWriterFactory)
+        {
+            _logger = logger;
+            _httpResponseStreamWriterFactory = httpResponseStreamWriterFactory;
+        }
+
+        public async Task ExecuteAsync(ActionContext context, ContentResult result)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            if (result == null)
+            {
+                throw new ArgumentNullException(nameof(result));
+            }
+
+            var response = context.HttpContext.Response;
+
+            string resolvedContentType;
+            Encoding resolvedContentTypeEncoding;
+            ResponseContentTypeHelper.ResolveContentTypeAndEncoding(
+                result.ContentType,
+                response.ContentType,
+                DefaultContentType,
+                out resolvedContentType,
+                out resolvedContentTypeEncoding);
+
+            response.ContentType = resolvedContentType;
+
+            if (result.StatusCode != null)
+            {
+                response.StatusCode = result.StatusCode.Value;
+            }
+
+            _logger.ContentResultExecuting(resolvedContentType);
+
+            if (result.Content != null)
+            {
+                response.ContentLength = resolvedContentTypeEncoding.GetByteCount(result.Content);
+
+                using (var textWriter = _httpResponseStreamWriterFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
+                {
+                    await textWriter.WriteAsync(result.Content);
+
+                    // Flushing the HttpResponseStreamWriter does not flush the underlying stream. This just flushes
+                    // the buffered text in the writer.
+                    // We do this rather than letting dispose handle it because dispose would call Write and we want
+                    // to call WriteAsync.
+                    await textWriter.FlushAsync();
+                }
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.Core.Test/ContentResultTest.cs

@@ -1,14 +1,17 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Buffers;
 using System.IO;
 using System.Text;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Abstractions;
+using Microsoft.AspNetCore.Mvc.Internal;
 using Microsoft.AspNetCore.Mvc.TestCommon;
 using Microsoft.AspNetCore.Mvc.ViewComponents;
 using Microsoft.AspNetCore.Routing;
+using Microsoft.AspNetCore.WebUtilities;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Testing;
@@ -20,6 +23,8 @@ namespace Microsoft.AspNetCore.Mvc
 {
     public class ContentResultTest
     {
+        private const int DefaultCharacterChunkSize = HttpResponseStreamWriter.DefaultBufferSize;
+
         [Fact]
         public async Task ContentResult_Response_NullContent_SetsContentTypeAndEncoding()
         {
@@ -137,6 +142,110 @@ namespace Microsoft.AspNetCore.Mvc
             var finalResponseContentType = httpContext.Response.ContentType;
             Assert.Equal(expectedContentType, finalResponseContentType);
             Assert.Equal(expectedContentData, memoryStream.ToArray());
+            Assert.Equal(expectedContentData.Length, httpContext.Response.ContentLength);
+        }
+
+        public static TheoryData<string, string> ContentResult_WritesDataCorrectly_ForDifferentContentSizesData
+        {
+            get
+            {
+                // content, contentType
+                return new TheoryData<string, string>
+                {
+                    {  string.Empty, "text/plain; charset=utf-8" },
+                    {  new string('a', DefaultCharacterChunkSize), "text/plain; charset=utf-8" },
+                    {  new string('a', DefaultCharacterChunkSize - 1), "text/plain; charset=utf-8" },
+                    {  new string('a', DefaultCharacterChunkSize + 1), "text/plain; charset=utf-8" },
+                    {  new string('a', DefaultCharacterChunkSize - 2), "text/plain; charset=utf-8" },
+                    {  new string('a', DefaultCharacterChunkSize + 2), "text/plain; charset=utf-8" },
+                    {  new string('a', DefaultCharacterChunkSize - 3), "text/plain; charset=utf-8" },
+                    {  new string('a', DefaultCharacterChunkSize + 3), "text/plain; charset=utf-8" },
+                    {  new string('a', DefaultCharacterChunkSize * 2), "text/plain; charset=utf-8" },
+                    {  new string('a', DefaultCharacterChunkSize * 3), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 2) - 1), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 2) - 2), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 2) - 3), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 2) + 1), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 2) + 2), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 2) + 3), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 3) - 1), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 3) - 2), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 3) - 3), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 3) + 1), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 3) + 2), "text/plain; charset=utf-8" },
+                    {  new string('a', (DefaultCharacterChunkSize * 3) + 3), "text/plain; charset=utf-8" },
+
+                    {  new string('色', DefaultCharacterChunkSize), "text/plain; charset=utf-16" },
+                    {  new string('色', DefaultCharacterChunkSize - 1), "text/plain; charset=utf-16" },
+                    {  new string('色', DefaultCharacterChunkSize + 1), "text/plain; charset=utf-16" },
+                    {  new string('色', DefaultCharacterChunkSize - 2), "text/plain; charset=utf-16" },
+                    {  new string('色', DefaultCharacterChunkSize + 2), "text/plain; charset=utf-16" },
+                    {  new string('色', DefaultCharacterChunkSize - 3), "text/plain; charset=utf-16" },
+                    {  new string('色', DefaultCharacterChunkSize + 3), "text/plain; charset=utf-16" },
+                    {  new string('色', DefaultCharacterChunkSize * 2), "text/plain; charset=utf-16" },
+                    {  new string('色', DefaultCharacterChunkSize * 3), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) - 1), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) - 2), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) - 3), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) + 1), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) + 2), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) + 3), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) - 1), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) - 2), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) - 3), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) + 1), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) + 2), "text/plain; charset=utf-16" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) + 3), "text/plain; charset=utf-16" },
+
+                    {  new string('色', DefaultCharacterChunkSize), "text/plain; charset=utf-32" },
+                    {  new string('色', DefaultCharacterChunkSize - 1), "text/plain; charset=utf-32" },
+                    {  new string('色', DefaultCharacterChunkSize + 1), "text/plain; charset=utf-32" },
+                    {  new string('色', DefaultCharacterChunkSize - 2), "text/plain; charset=utf-32" },
+                    {  new string('色', DefaultCharacterChunkSize + 2), "text/plain; charset=utf-32" },
+                    {  new string('色', DefaultCharacterChunkSize - 3), "text/plain; charset=utf-32" },
+                    {  new string('色', DefaultCharacterChunkSize + 3), "text/plain; charset=utf-32" },
+                    {  new string('色', DefaultCharacterChunkSize * 2), "text/plain; charset=utf-32" },
+                    {  new string('色', DefaultCharacterChunkSize * 3), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) - 1), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) - 2), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) - 3), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) + 1), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) + 2), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 2) + 3), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) - 1), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) - 2), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) - 3), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) + 1), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) + 2), "text/plain; charset=utf-32" },
+                    {  new string('色', (DefaultCharacterChunkSize * 3) + 3), "text/plain; charset=utf-32" },
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(ContentResult_WritesDataCorrectly_ForDifferentContentSizesData))]
+        public async Task ContentResult_WritesDataCorrectly_ForDifferentContentSizes(string content, string contentType)
+        {
+            // Arrange
+            var contentResult = new ContentResult
+            {
+                Content = content,
+                ContentType = contentType
+            };
+            var httpContext = GetHttpContext();
+            var memoryStream = new MemoryStream();
+            httpContext.Response.Body = memoryStream;
+            var actionContext = GetActionContext(httpContext);
+            var encoding = MediaTypeHeaderValue.Parse(contentType).Encoding;
+
+            // Act
+            await contentResult.ExecuteResultAsync(actionContext);
+
+            // Assert
+            memoryStream.Seek(0, SeekOrigin.Begin);
+            var streamReader = new StreamReader(memoryStream, encoding);
+            var actualContent = await streamReader.ReadToEndAsync();
+            Assert.Equal(content, actualContent);
         }
 
         private static ActionContext GetActionContext(HttpContext httpContext)
@@ -151,8 +260,18 @@ namespace Microsoft.AspNetCore.Mvc
 
         private static IServiceCollection CreateServices(params ViewComponentDescriptor[] descriptors)
         {
+            // An array pool could return a buffer which is greater or equal to the size of the default character
+            // chunk size. Since the tests here depend on a specifc character buffer size to test boundary conditions,
+            // make sure to only return a buffer of that size.
+            var charArrayPool = new Mock<ArrayPool<char>>();
+            charArrayPool
+                .Setup(ap => ap.Rent(DefaultCharacterChunkSize))
+                .Returns(new char[DefaultCharacterChunkSize]);
+
             var services = new ServiceCollection();
-            services.AddSingleton<ILoggerFactory>(NullLoggerFactory.Instance);
+            services.AddSingleton(new ContentResultExecutor(
+                new Logger<ContentResultExecutor>(NullLoggerFactory.Instance),
+                new MemoryPoolHttpResponseStreamWriterFactory(ArrayPool<byte>.Shared, charArrayPool.Object)));
             return services;
         }
 
@@ -166,4 +285,4 @@ namespace Microsoft.AspNetCore.Mvc
             return httpContext;
         }
     }
-}
+}

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/ControllerActionInvokerTest.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Buffers;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Diagnostics;
@@ -2726,9 +2727,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
 
             httpContext.SetupGet(c => c.Request).Returns(httpRequest);
             httpContext.SetupGet(c => c.Response).Returns(httpResponse);
-            httpContext
-                .Setup(o => o.RequestServices.GetService(typeof(ILoggerFactory)))
-                .Returns(NullLoggerFactory.Instance);
 
             httpResponse.Body = new MemoryStream();
 
@@ -2752,6 +2750,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 .SetupGet(o => o.Value)
                 .Returns(options);
 
+            httpContext
+                .Setup(o => o.RequestServices.GetService(typeof(ILoggerFactory)))
+                .Returns(NullLoggerFactory.Instance);
+
             httpContext
                 .Setup(o => o.RequestServices.GetService(typeof(IOptions<MvcOptions>)))
                 .Returns(optionsAccessor.Object);
@@ -2765,6 +2767,12 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     new TestHttpResponseStreamWriterFactory(),
                     NullLoggerFactory.Instance));
 
+            httpContext
+                .Setup(o => o.RequestServices.GetService(typeof(ContentResultExecutor)))
+                .Returns(new ContentResultExecutor(
+                    new Logger<ContentResultExecutor>(NullLoggerFactory.Instance),
+                   new MemoryPoolHttpResponseStreamWriterFactory(ArrayPool<byte>.Shared, ArrayPool<char>.Shared)));
+
             if (routeData == null)
             {
                 routeData = new RouteData();