Add HttpPostedFile*.

src/Microsoft.AspNetCore.SystemWebAdapters/Generated/Ref.Standard.cs

@@ -135,13 +135,37 @@ public sealed partial class HttpFileCollection : System.Collections.Specialized.
         internal HttpFileCollection() { }
         public string[] AllKeys { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override int Count { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public System.Web.HttpPostedFile this[int index] { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public System.Web.HttpPostedFile this[string name] { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         [System.ObsoleteAttribute("Retrieving Keys is not supported on .NET 6+. Please use the enumerator instead.")]
         public override System.Collections.Specialized.NameObjectCollectionBase.KeysCollection Keys { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public System.Web.HttpPostedFile Get(int index) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
         public System.Web.HttpPostedFile Get(string name) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
         public override System.Collections.IEnumerator GetEnumerator() { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
         public System.Collections.Generic.IList<System.Web.HttpPostedFile> GetMultiple(string name) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
     }
+    public abstract partial class HttpFileCollectionBase : System.Collections.Specialized.NameObjectCollectionBase
+    {
+        protected HttpFileCollectionBase() { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public virtual string[] AllKeys { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public virtual System.Web.HttpPostedFileBase this[int index] { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public virtual System.Web.HttpPostedFileBase this[string name] { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public virtual System.Web.HttpPostedFileBase Get(int index) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public virtual System.Web.HttpPostedFileBase Get(string name) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public virtual System.Collections.Generic.IList<System.Web.HttpPostedFileBase> GetMultiple(string name) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+    }
+    public partial class HttpFileCollectionWrapper : System.Web.HttpFileCollectionBase
+    {
+        public HttpFileCollectionWrapper(System.Web.HttpFileCollection httpFileCollection) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public override string[] AllKeys { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override int Count { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override System.Web.HttpPostedFileBase this[int index] { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override System.Web.HttpPostedFileBase this[string name] { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override System.Web.HttpPostedFileBase Get(int index) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public override System.Web.HttpPostedFileBase Get(string name) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public override System.Collections.IEnumerator GetEnumerator() { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public override System.Collections.Generic.IList<System.Web.HttpPostedFileBase> GetMultiple(string name) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+    }
     public sealed partial class HttpPostedFile
     {
         internal HttpPostedFile() { }
@@ -150,6 +174,22 @@ internal HttpPostedFile() { }
         public string FileName { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public System.IO.Stream InputStream { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
     }
+    public abstract partial class HttpPostedFileBase
+    {
+        protected HttpPostedFileBase() { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public virtual int ContentLength { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public virtual string ContentType { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public virtual string FileName { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public virtual System.IO.Stream InputStream { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+    }
+    public partial class HttpPostedFileWrapper : System.Web.HttpPostedFileBase
+    {
+        public HttpPostedFileWrapper(System.Web.HttpPostedFile httpPostedFile) { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");}
+        public override int ContentLength { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override string ContentType { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override string FileName { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override System.IO.Stream InputStream { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+    }
     public partial class HttpRequest
     {
         internal HttpRequest() { }
@@ -202,6 +242,7 @@ public abstract partial class HttpRequestBase
         public virtual int ContentLength { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual string ContentType { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} set { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.Web.HttpCookieCollection Cookies { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public virtual System.Web.HttpFileCollectionBase Files { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.Collections.Specialized.NameValueCollection Headers { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual string HttpMethod { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public virtual System.IO.Stream InputStream { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
@@ -239,6 +280,7 @@ public partial class HttpRequestWrapper : System.Web.HttpRequestBase
         public override int ContentLength { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override string ContentType { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} set { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.Web.HttpCookieCollection Cookies { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public override System.Web.HttpFileCollectionBase Files { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.Collections.Specialized.NameValueCollection Headers { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override string HttpMethod { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public override System.IO.Stream InputStream { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }

src/Microsoft.AspNetCore.SystemWebAdapters/Generated/TypeForwards.Framework.cs

@@ -26,7 +26,11 @@
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpCookieCollection))]
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpException))]
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpFileCollection))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpFileCollectionBase))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpFileCollectionWrapper))]
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpPostedFile))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpPostedFileBase))]
+[assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpPostedFileWrapper))]
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpRequest))]
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpRequestBase))]
 [assembly:System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.Web.HttpRequestWrapper))]

src/Microsoft.AspNetCore.SystemWebAdapters/HttpFileCollection.cs

@@ -43,10 +43,14 @@ public override IEnumerator GetEnumerator()
 
     public HttpPostedFile? Get(string name) => FormFiles.GetFile(name) is { } file ? new(file) : null;
 
+    public HttpPostedFile? Get(int index) => FormFiles[index] is { } file ? new(file) : null;
+
     public IList<HttpPostedFile> GetMultiple(string name) => FormFiles.GetFiles(name) is { Count: > 0 } files ? new ReadOnlyPostedFileCollection(files) : Array.Empty<HttpPostedFile>();
 
     public HttpPostedFile? this[string name] => Get(name);
 
+    public HttpPostedFile? this[int index] => Get(index);
+
     private string[] GetKeys()
     {
         if (FormFiles.Count == 0)
@@ -86,7 +90,7 @@ public HttpPostedFile this[int index]
             set => throw new NotSupportedException(Message);
         }
 
-        private static HttpPostedFile Create(IFormFile file) => new(file);
+        private static HttpPostedFile Create(IFormFile file) => new HttpPostedFile(file);
 
         public int Count => _other.Count;
 

src/Microsoft.AspNetCore.SystemWebAdapters/HttpFileCollectionBase.cs

@@ -0,0 +1,22 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Generic;
+using System.Collections.Specialized;
+
+namespace System.Web;
+
+public abstract class HttpFileCollectionBase : NameObjectCollectionBase
+{
+    public virtual string[] AllKeys => throw new NotImplementedException();
+
+    public virtual HttpPostedFileBase? this[string name] => throw new NotImplementedException();
+
+    public virtual HttpPostedFileBase? this[int index] => throw new NotImplementedException();
+
+    public virtual HttpPostedFileBase? Get(int index) => throw new NotImplementedException();
+
+    public virtual HttpPostedFileBase? Get(string name) => throw new NotImplementedException();
+
+    public virtual IList<HttpPostedFileBase> GetMultiple(string name) => throw new NotImplementedException();
+}

src/Microsoft.AspNetCore.SystemWebAdapters/HttpFileCollectionWrapper.cs

@@ -0,0 +1,45 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace System.Web;
+
+public class HttpFileCollectionWrapper: HttpFileCollectionBase
+{
+    private readonly HttpFileCollection _collection;
+
+    public HttpFileCollectionWrapper(HttpFileCollection httpFileCollection)
+    {
+        if (httpFileCollection == null)
+        {
+            throw new ArgumentNullException(nameof(httpFileCollection));
+        }
+
+        _collection = httpFileCollection;
+    }
+
+    public override string[] AllKeys => _collection.AllKeys;
+
+    public override int Count => _collection.Count;
+
+    public override HttpPostedFileBase? this[string name] => Get(name);
+
+    public override HttpPostedFileBase? this[int index] => Get(index);
+
+    public override HttpPostedFileBase? Get(string name) =>
+        _collection[name] is { } file ? new HttpPostedFileWrapper(file) : null;
+
+    public override HttpPostedFileBase? Get(int index) =>
+        _collection[index] is { } file ? new HttpPostedFileWrapper(file) : null;
+
+    public override IList<HttpPostedFileBase> GetMultiple(string name)
+         => _collection.GetMultiple(name)
+            .Select(x=> (HttpPostedFileBase)new HttpPostedFileWrapper(x))
+            .ToList()
+            .AsReadOnly();
+
+    public override IEnumerator GetEnumerator() => _collection.GetEnumerator();
+}

src/Microsoft.AspNetCore.SystemWebAdapters/HttpPostedFileBase.cs

@@ -0,0 +1,17 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.IO;
+
+namespace System.Web;
+
+public abstract class HttpPostedFileBase
+{
+    public virtual string FileName => throw new NotImplementedException();
+
+    public virtual string ContentType => throw new NotImplementedException();
+
+    public virtual int ContentLength => throw new NotImplementedException();
+
+    public virtual Stream InputStream => throw new NotImplementedException();
+}

src/Microsoft.AspNetCore.SystemWebAdapters/HttpPostedFileWrapper.cs

@@ -0,0 +1,29 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.IO;
+
+namespace System.Web;
+
+public class HttpPostedFileWrapper : HttpPostedFileBase
+{
+    private readonly HttpPostedFile _file;
+
+    public HttpPostedFileWrapper(HttpPostedFile httpPostedFile)
+    {
+        if (httpPostedFile == null)
+        {
+            throw new ArgumentNullException(nameof(httpPostedFile));
+        }
+
+        _file = httpPostedFile;
+    }
+
+    public override int ContentLength => _file.ContentLength;
+
+    public override string ContentType => _file.ContentType;
+
+    public override string FileName => _file.FileName;
+
+    public override Stream InputStream => _file.InputStream;
+}

src/Microsoft.AspNetCore.SystemWebAdapters/HttpRequestBase.cs

@@ -38,6 +38,8 @@ public abstract class HttpRequestBase
 
         public virtual HttpCookieCollection Cookies => throw new NotImplementedException();
 
+        public virtual HttpFileCollectionBase Files => throw new NotImplementedException();
+
         public virtual string? this[string key] => throw new NotImplementedException();
 
         public virtual NameValueCollection Params => throw new NotImplementedException();

src/Microsoft.AspNetCore.SystemWebAdapters/HttpRequestWrapper.cs

@@ -37,6 +37,8 @@ public override string? ContentType
 
         public override NameValueCollection Headers => _request.Headers;
 
+        public override HttpFileCollectionBase Files => new HttpFileCollectionWrapper(_request.Files);
+
         public override string HttpMethod => _request.HttpMethod;
 
         public override Stream InputStream => _request.InputStream;