Check response code before writing blob to file.

webkit/fileapi/file_writer_delegate.cc

 // Copyright (c) 2011 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 "webkit/fileapi/file_writer_delegate.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/file_util_proxy.h"
 #include "base/message_loop.h"
@@ skipping 151 matching lines @@
                                                bool is_hsts_host) {
   NOTREACHED();
   OnError(base::PLATFORM_FILE_ERROR_SECURITY);
 }
 
 void FileWriterDelegate::OnResponseStarted(net::URLRequest* request) {
   DCHECK_EQ(request_, request);
   // file_stream_->Seek() blocks the IO thread.
   // See http://crbug.com/75548.
   base::ThreadRestrictions::ScopedAllowIO allow_io;
-  if (!request->status().is_success()) {
+  if (!request->status().is_success() || request->GetResponseCode() != 200) {

[ericu, 2012/01/05 05:47:20]

Why is is_success true here, if the blob wasn't valid?
[Sorry--I'm away from my workstation and can't easily look that up.]

[tzik, 2012/01/05 06:59:45]

Looking at other use of URLRequestStatus, !is_success() seems to mean error on
lower layer. e.g. failed to connect to server.
Errors on upper layer (like 404) should be caught in response code.

If blob is invalid, status code is set to 404 and content of the response is
empty in current impl.
(In case of HTTP, if a resource is not found, response code is set to 404 and
content of response can be non empty error page.)

     OnError(base::PLATFORM_FILE_ERROR_FAILED);
     return;
   }
   int64 error = file_stream_->Seek(net::FROM_BEGIN, offset_);
   if (error != offset_) {
     OnError(base::PLATFORM_FILE_ERROR_FAILED);
     return;
   }
   Read();
 }
 
 void FileWriterDelegate::OnReadCompleted(net::URLRequest* request,
                                          int bytes_read) {
   DCHECK_EQ(request_, request);
   if (!request->status().is_success()) {

[ericu, 2012/01/05 05:47:20]

Is it possible to get is_success == true, but request->GetResponseCode() != 200
here?  What if it's a write of a large File that goes away halfway through the
operation?

[tzik, 2012/01/05 06:59:45]

The response code is invariant after header of the blob protocol reached, so
it's enough to check response code in start time.
If we encounter an error on reading blob, we'll get !is_success().

     OnError(base::PLATFORM_FILE_ERROR_FAILED);
     return;
   }
   OnDataReceived(bytes_read);
 }
 
 void FileWriterDelegate::Read() {
   bytes_written_ = 0;
   bytes_read_ = 0;
   if (request_->Read(io_buffer_.get(), io_buffer_->size(), &bytes_read_)) {
@@ skipping 120 matching lines @@
 
 FileSystemQuotaUtil* FileWriterDelegate::quota_util() const {
   DCHECK(file_system_operation_);
   DCHECK(file_system_operation_->file_system_context());
   DCHECK(file_system_operation_->file_system_operation_context());
   return file_system_operation_->file_system_context()->GetQuotaUtil(
       file_system_operation_context()->src_type());
 }
 
 }  // namespace fileapi