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HTML5 asynchronous file download, downloaded stream is always invalid

I am trying to debug an asynchronous file loader that I created some time ago, which no longer works, I have already spent a lot of time without success.

The stream that the server receives is always corrupted, in fact, the file (image) that I save cannot be opened.

To simplify debugging, I created a new ASP.NET project with two main files, an HTML file with a form field and an ASP.NET handler.

Despite the fact that the code here is very trivial, I'm still out of luck !: (

Any help is greatly appreciated, thank you very much!

<!DOCTYPE html> <html> <head> <title>Upload Files using XMLHttpRequest - Minimal</title> <script type="text/javascript"> function uploadFile() { var fd = new FormData(); fd.append("fileToUpload", document.getElementById('fileToUpload').files[0]); var xhr = new XMLHttpRequest(); xhr.addEventListener("load", uploadComplete, false); xhr.addEventListener("error", uploadFailed, false); xhr.addEventListener("abort", uploadCanceled, false); xhr.open("POST", "Handler1.ashx"); xhr.send(fd); } function uploadComplete(evt) { /* This event is raised when the server send back a response */ alert(evt.target.responseText); } function uploadFailed(evt) { alert("There was an error attempting to upload the file."); } function uploadCanceled(evt) { alert("The upload has been canceled by the user or the browser dropped the connection."); } </script> </head> <body> <form id="form1" enctype="multipart/form-data" method="post" action="Handler1.ashx"> <input type="file" name="fileToUpload" id="fileToUpload"/> <input type="button" onclick="uploadFile()" value="Upload" /> </form> </body> </html>

and here is the ashx handler:

 using System; using System.Collections.Generic; using System.Web.Extensions; using System.Linq; using System.Web; using System.Web.Services; using System.IO; namespace MultipleFileUploadTest { [WebService(Namespace = "http://tempuri.org/")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] public class Handler1 : IHttpHandler { public void ProcessRequest(HttpContext context) { var stream = context.Request.InputStream; MemoryStream memoryStream; ReadFully(stream, out memoryStream); Byte[] ba = memoryStream.ToArray(); var path = @"C:\Users\giuseppe.JHP\Desktop\Image upload test\uploaded.gif"; using (FileStream fs = new FileStream(path, FileMode.OpenOrCreate)) { fs.Write(ba, 0, ba.Length); } //DEBUGGING CODE //I'm opening the same file that was originally picked by the input form field and I'm now comparing the original file with the one received within the context stream. They always differ! Byte[] ba2 = File.ReadAllBytes(@"C:\Users\giuseppe.JHP\Desktop\Image upload test\a.gif"); //equal evaluates always to false bool equal = ba.Length == ba2.Length; if (equal) { for (var i = 0; i < ba2.Length; i++) { if (ba[i] != ba2[i]) { equal = false; i = ba2.Length; } } } //equal is always false //if (!equal) //{ // throw Exception("Stream is not valid"); //} //The code below will throw a Parameter is invalid exception //System.Drawing.Image mediaObject = System.Drawing.Image.FromStream(memoryStream); memoryStream.Close(); } public static void ReadFully(Stream input, out MemoryStream ms) { ms = new MemoryStream(); byte[] buffer = new byte[16 * 1024]; int read; while ((read = input.Read(buffer, 0, buffer.Length)) > 0) { ms.Write(buffer, 0, read); } } public bool IsReusable { get { return false; } } } }
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If this helped someone else, I have code to work, here is what he changed:

  public void ProcessRequest(HttpContext context) { if (context.Request.Files != null && context.Request.Files.Count > 0) { var file = context.Request.Files[0]; file.SaveAs(@"C:\Users\giuseppe.JHP\Desktop\Image upload test\uploaded.gif"); } }
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Source: https://habr.com/ru/post/910102/

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