Change SendFileAsync to use a fallback implementation instead of throwing

- If the user wants to use the SendFile API directly then they can access the feature
explicitly.
- Removed SupportsSendFile
- Don't check for existence, let FileStream throw
- Updated Doc comments
- Pass the buffer into StreamCopyOperation
- Using a real using instead of try finally.

src/Microsoft.AspNet.Http.Abstractions/project.json

@@ -36,6 +36,7 @@
         "System.Net.Primitives": "4.0.11-*",
         "System.Net.WebSockets": "4.0.0-*",
         "System.Reflection.TypeExtensions": "4.0.1-*",
+        "System.IO": "4.0.11-*",
         "System.Runtime": "4.0.21-*",
         "System.Runtime.InteropServices": "4.0.21-*",
         "System.Security.Claims": "4.0.1-*",

src/Microsoft.AspNet.Http.Extensions/Properties/Resources.Designer.cs

@@ -1,46 +0,0 @@
-// <auto-generated />
-namespace Microsoft.AspNet.Http.Extensions
-{
-    using System.Globalization;
-    using System.Reflection;
-    using System.Resources;
-
-    internal static class Resources
-    {
-        private static readonly ResourceManager _resourceManager
-            = new ResourceManager("Microsoft.AspNet.Http.Extensions.Resources", typeof(Resources).GetTypeInfo().Assembly);
-
-        /// <summary>
-        /// This server does not support the sendfile.SendAsync extension.
-        /// </summary>
-        internal static string Exception_SendFileNotSupported
-        {
-            get { return GetString("Exception_SendFileNotSupported"); }
-        }
-
-        /// <summary>
-        /// This server does not support the sendfile.SendAsync extension.
-        /// </summary>
-        internal static string FormatException_SendFileNotSupported()
-        {
-            return GetString("Exception_SendFileNotSupported");
-        }
-
-        private static string GetString(string name, params string[] formatterNames)
-        {
-            var value = _resourceManager.GetString(name);
-
-            System.Diagnostics.Debug.Assert(value != null);
-
-            if (formatterNames != null)
-            {
-                for (var i = 0; i < formatterNames.Length; i++)
-                {
-                    value = value.Replace("{" + formatterNames[i] + "}", "{" + i + "}");
-                }
-            }
-
-            return value;
-        }
-    }
-}

src/Microsoft.AspNet.Http.Extensions/Resources.resx

@@ -1,123 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<root>
-  <!-- 
-    Microsoft ResX Schema 
-    
-    Version 2.0
-    
-    The primary goals of this format is to allow a simple XML format 
-    that is mostly human readable. The generation and parsing of the 
-    various data types are done through the TypeConverter classes 
-    associated with the data types.
-    
-    Example:
-    
-    ... ado.net/XML headers & schema ...
-    <resheader name="resmimetype">text/microsoft-resx</resheader>
-    <resheader name="version">2.0</resheader>
-    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
-    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
-    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
-    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
-    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
-        <value>[base64 mime encoded serialized .NET Framework object]</value>
-    </data>
-    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
-        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
-        <comment>This is a comment</comment>
-    </data>
-                
-    There are any number of "resheader" rows that contain simple 
-    name/value pairs.
-    
-    Each data row contains a name, and value. The row also contains a 
-    type or mimetype. Type corresponds to a .NET class that support 
-    text/value conversion through the TypeConverter architecture. 
-    Classes that don't support this are serialized and stored with the 
-    mimetype set.
-    
-    The mimetype is used for serialized objects, and tells the 
-    ResXResourceReader how to depersist the object. This is currently not 
-    extensible. For a given mimetype the value must be set accordingly:
-    
-    Note - application/x-microsoft.net.object.binary.base64 is the format 
-    that the ResXResourceWriter will generate, however the reader can 
-    read any of the formats listed below.
-    
-    mimetype: application/x-microsoft.net.object.binary.base64
-    value   : The object must be serialized with 
-            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
-            : and then encoded with base64 encoding.
-    
-    mimetype: application/x-microsoft.net.object.soap.base64
-    value   : The object must be serialized with 
-            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
-            : and then encoded with base64 encoding.
-
-    mimetype: application/x-microsoft.net.object.bytearray.base64
-    value   : The object must be serialized into a byte array 
-            : using a System.ComponentModel.TypeConverter
-            : and then encoded with base64 encoding.
-    -->
-  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
-    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
-    <xsd:element name="root" msdata:IsDataSet="true">
-      <xsd:complexType>
-        <xsd:choice maxOccurs="unbounded">
-          <xsd:element name="metadata">
-            <xsd:complexType>
-              <xsd:sequence>
-                <xsd:element name="value" type="xsd:string" minOccurs="0" />
-              </xsd:sequence>
-              <xsd:attribute name="name" use="required" type="xsd:string" />
-              <xsd:attribute name="type" type="xsd:string" />
-              <xsd:attribute name="mimetype" type="xsd:string" />
-              <xsd:attribute ref="xml:space" />
-            </xsd:complexType>
-          </xsd:element>
-          <xsd:element name="assembly">
-            <xsd:complexType>
-              <xsd:attribute name="alias" type="xsd:string" />
-              <xsd:attribute name="name" type="xsd:string" />
-            </xsd:complexType>
-          </xsd:element>
-          <xsd:element name="data">
-            <xsd:complexType>
-              <xsd:sequence>
-                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
-                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
-              </xsd:sequence>
-              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
-              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
-              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
-              <xsd:attribute ref="xml:space" />
-            </xsd:complexType>
-          </xsd:element>
-          <xsd:element name="resheader">
-            <xsd:complexType>
-              <xsd:sequence>
-                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
-              </xsd:sequence>
-              <xsd:attribute name="name" type="xsd:string" use="required" />
-            </xsd:complexType>
-          </xsd:element>
-        </xsd:choice>
-      </xsd:complexType>
-    </xsd:element>
-  </xsd:schema>
-  <resheader name="resmimetype">
-    <value>text/microsoft-resx</value>
-  </resheader>
-  <resheader name="version">
-    <value>2.0</value>
-  </resheader>
-  <resheader name="reader">
-    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
-  </resheader>
-  <resheader name="writer">
-    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
-  </resheader>
-  <data name="Exception_SendFileNotSupported" xml:space="preserve">
-    <value>This server does not support the sendfile.SendAsync extension.</value>
-  </data>
-</root>

src/Microsoft.AspNet.Http.Extensions/SendFileResponseExtensions.cs

@@ -2,9 +2,9 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.AspNet.Http.Extensions;
 using Microsoft.AspNet.Http.Features;
 
 namespace Microsoft.AspNet.Http
@@ -14,26 +14,11 @@ namespace Microsoft.AspNet.Http
     /// </summary>
     public static class SendFileResponseExtensions
     {
-        /// <summary>
-        /// Checks if the SendFile extension is supported.
-        /// </summary>
-        /// <param name="response"></param>
-        /// <returns>True if sendfile feature exists in the response.</returns>
-        public static bool SupportsSendFile(this HttpResponse response)
-        {
-            if (response == null)
-            {
-                throw new ArgumentNullException(nameof(response));
-            }
-
-            return response.HttpContext.Features.Get<IHttpSendFileFeature>() != null;
-        }
-
         /// <summary>
         /// Sends the given file using the SendFile extension.
         /// </summary>
         /// <param name="response"></param>
-        /// <param name="fileName"></param>
+        /// <param name="fileName">The full to the file.</param>
         /// <returns></returns>
         public static Task SendFileAsync(this HttpResponse response, string fileName)
         {
@@ -54,7 +39,7 @@ namespace Microsoft.AspNet.Http
         /// Sends the given file using the SendFile extension.
         /// </summary>
         /// <param name="response"></param>
-        /// <param name="fileName">The full or relative path to the file.</param>
+        /// <param name="fileName">The full to the file.</param>
         /// <param name="offset">The offset in the file.</param>
         /// <param name="count">The number of types to send, or null to send the remainder of the file.</param>
         /// <param name="cancellationToken"></param>
@@ -74,10 +59,48 @@ namespace Microsoft.AspNet.Http
             var sendFile = response.HttpContext.Features.Get<IHttpSendFileFeature>();
             if (sendFile == null)
             {
-                throw new NotSupportedException(Resources.Exception_SendFileNotSupported);
+                return SendFileAsync(response.Body, fileName, offset, count, cancellationToken);
             }
 
             return sendFile.SendFileAsync(fileName, offset, count, cancellationToken);
         }
+
+        // Not safe for overlapped writes.
+        private static async Task SendFileAsync(Stream outputStream, string fileName, long offset, long? length, CancellationToken cancel)
+        {
+            cancel.ThrowIfCancellationRequested();
+
+            var fileInfo = new FileInfo(fileName);
+            if (offset < 0 || offset > fileInfo.Length)
+            {
+                throw new ArgumentOutOfRangeException(nameof(offset), offset, string.Empty);
+            }
+
+            if (length.HasValue &&
+                (length.Value < 0 || length.Value > fileInfo.Length - offset))
+            {
+                throw new ArgumentOutOfRangeException(nameof(length), length, string.Empty);
+            }
+
+            int bufferSize = 1024 * 16;
+
+            var fileStream = new FileStream(
+                fileName,
+                FileMode.Open,
+                FileAccess.Read,
+                FileShare.ReadWrite,
+                bufferSize: bufferSize,
+                options: FileOptions.Asynchronous | FileOptions.SequentialScan);
+
+            using (fileStream)
+            {
+                fileStream.Seek(offset, SeekOrigin.Begin);
+
+                // TODO: Use buffer pool
+                var buffer = new byte[bufferSize];
+
+                await StreamCopyOperation.CopyToAsync(fileStream, buffer, outputStream, length, cancel);
+            }
+        }
     }
 }

src/Microsoft.AspNet.Http.Extensions/StreamCopyOperation.cs

@@ -0,0 +1,57 @@
+// 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.Diagnostics;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNet.Http
+{
+    // FYI: In most cases the source will be a FileStream and the destination will be to the network.
+    internal static class StreamCopyOperation
+    {
+        internal static async Task CopyToAsync(Stream source, byte[] buffer, Stream destination, long? length, CancellationToken cancel)
+        {
+            long? bytesRemaining = length;
+            Debug.Assert(source != null);
+            Debug.Assert(destination != null);
+            Debug.Assert(!bytesRemaining.HasValue || bytesRemaining.Value >= 0);
+            Debug.Assert(buffer != null);
+
+            while (true)
+            {
+                // The natural end of the range.
+                if (bytesRemaining.HasValue && bytesRemaining.Value <= 0)
+                {
+                    return;
+                }
+
+                cancel.ThrowIfCancellationRequested();
+
+                int readLength = buffer.Length;
+                if (bytesRemaining.HasValue)
+                {
+                    readLength = (int)Math.Min(bytesRemaining.Value, (long)readLength);
+                }
+                int count = await source.ReadAsync(buffer, 0, readLength, cancel);
+
+                if (bytesRemaining.HasValue)
+                {
+                    bytesRemaining -= count;
+                }
+
+                // End of the source stream.
+                if (count == 0)
+                {
+                    return;
+                }
+
+                cancel.ThrowIfCancellationRequested();
+
+                await destination.WriteAsync(buffer, 0, count, cancel);
+            }
+        }
+    }
+}

test/Microsoft.AspNet.Http.Extensions.Tests/SendFileResponseExtensionsTests.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved. See License.txt in the project root for license information.
 
 using System;
+using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Http.Features;
@@ -12,20 +13,10 @@ namespace Microsoft.AspNet.Http.Extensions.Tests
     public class SendFileResponseExtensionsTests
     {
         [Fact]
-        public void SendFileSupport()
+        public Task SendFileWhenFileNotFoundThrows()
-        {
-            var context = new DefaultHttpContext();
-            var response = context.Response;
-            Assert.False(response.SupportsSendFile());
-            context.Features.Set<IHttpSendFileFeature>(new FakeSendFileFeature());
-            Assert.True(response.SupportsSendFile());
-        }
-
-        [Fact]
-        public Task SendFileWhenNotSupported()
         {
             var response = new DefaultHttpContext().Response;
-            return Assert.ThrowsAsync<NotSupportedException>(() => response.SendFileAsync("foo"));
+            return Assert.ThrowsAsync<FileNotFoundException>(() => response.SendFileAsync("foo"));
         }
 
         [Fact]