UploadDataStream now returns errors on failures

net/base/elements_upload_data_stream.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/base/elements_upload_data_stream.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "net/base/completion_callback.h"
 #include "net/base/io_buffer.h"
@@ skipping 107 matching lines @@
         buf.get(),
         buf->BytesRemaining(),
         base::Bind(&ElementsUploadDataStream::OnReadElementCompleted,
                    weak_ptr_factory_.GetWeakPtr(),
                    buf));
     if (result == ERR_IO_PENDING)
       return ERR_IO_PENDING;
     ProcessReadResult(buf, result);
   }
 
-  if (read_failed_) {
-    // If an error occured during read operation, then pad with zero.
-    // Otherwise the server will hang waiting for the rest of the data.
-    int num_bytes_to_fill =
-        static_cast<int>(std::min(static_cast<uint64_t>(buf->BytesRemaining()),
-                                  size() - position() - buf->BytesConsumed()));
-    DCHECK_GE(num_bytes_to_fill, 0);
-    memset(buf->data(), 0, num_bytes_to_fill);
-    buf->DidConsume(num_bytes_to_fill);
-  }
+  if (read_failed_)
+    return ERR_FAILED;
 
   return buf->BytesConsumed();
 }
 
 void ElementsUploadDataStream::OnReadElementCompleted(
     const scoped_refptr<DrainableIOBuffer>& buf,
     int result) {
   ProcessReadResult(buf, result);
 
   result = ReadElements(buf);
   if (result != ERR_IO_PENDING)
     OnReadCompleted(result);
 }
 
 void ElementsUploadDataStream::ProcessReadResult(
     const scoped_refptr<DrainableIOBuffer>& buf,
     int result) {
   DCHECK_NE(ERR_IO_PENDING, result);
   DCHECK(!read_failed_);
 
   if (result >= 0) {
     buf->DidConsume(result);
   } else {
     read_failed_ = true;

[mmenke, 2016/06/06 16:22:33]

Instead of just setting read_failed_ to true, can we replace read_failed_ with
an integer (That's net::OK by default), and set it to the error code stored in
result here, and then return that error code in
ElementsUploadDataStream::ReadElements?

[maksims (do not use this acc), 2016/06/21 11:09:25]

Done.

   }
 }
 
 }  // namespace net