IndexedDB: Fixed support for empty blobs.

storage/browser/fileapi/file_writer_delegate.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 "storage/browser/fileapi/file_writer_delegate.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_util_proxy.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 13 matching lines @@
 
 FileWriterDelegate::FileWriterDelegate(
     scoped_ptr<FileStreamWriter> file_stream_writer,
     FlushPolicy flush_policy)
     : file_stream_writer_(file_stream_writer.Pass()),
       writing_started_(false),
       flush_policy_(flush_policy),
       bytes_written_backlog_(0),
       bytes_written_(0),
       bytes_read_(0),
+      total_bytes_read_(0),
       io_buffer_(new net::IOBufferWithSize(kReadBufSize)),
       weak_factory_(this) {
 }
 
 FileWriterDelegate::~FileWriterDelegate() {
 }
 
 void FileWriterDelegate::Start(scoped_ptr<net::URLRequest> request,
                                const DelegateWriteCallback& write_callback) {
   write_callback_ = write_callback;
@@ skipping 84 matching lines @@
         FROM_HERE,
         base::Bind(&FileWriterDelegate::OnDataReceived,
                    weak_factory_.GetWeakPtr(), bytes_read_));
   } else if (!request_->status().is_io_pending()) {
     OnError(base::File::FILE_ERROR_FAILED);
   }
 }
 
 void FileWriterDelegate::OnDataReceived(int bytes_read) {
   bytes_read_ = bytes_read;
+  total_bytes_read_ += bytes_read;
   if (!bytes_read_) {  // We're done.
+    if (total_bytes_read_ == 0) {
+      // Need to call Write (even though no data was received). This is because
+      // the file is created lazily upon first receipt of data, so without it
+      // no empty file would be created.
+      Write();
+    }
     OnProgress(0, true);
   } else {
     // This could easily be optimized to rotate between a pool of buffers, so
     // that we could read and write at the same time.  It's not yet clear that
     // it's necessary.
     cursor_ = new net::DrainableIOBuffer(io_buffer_.get(), bytes_read_);
     Write();
   }
 }
 
@@ skipping 78 matching lines @@
     base::File::Error error,
     int bytes_written,
     WriteProgressStatus progress_status) {
   if (flush_policy_ == FlushPolicy::NO_FLUSH_ON_COMPLETION) {
     write_callback_.Run(error, bytes_written, progress_status);
     return;
   }
   // DCHECK_EQ on enum classes is not supported.
   DCHECK(flush_policy_ == FlushPolicy::FLUSH_ON_COMPLETION);
 
-  int flush_error = file_stream_writer_->Flush(
-      base::Bind(&FileWriterDelegate::OnFlushed, weak_factory_.GetWeakPtr(),
-                 error, bytes_written, progress_status));
+  int flush_error = 0;
+  if (bytes_written) {
+    flush_error = file_stream_writer_->Flush(
+        base::Bind(&FileWriterDelegate::OnFlushed, weak_factory_.GetWeakPtr(),
+                   error, bytes_written, progress_status));
+  }
   if (flush_error != net::ERR_IO_PENDING)
     OnFlushed(error, bytes_written, progress_status, flush_error);
 }
 
 void FileWriterDelegate::OnFlushed(base::File::Error error,
                                    int bytes_written,
                                    WriteProgressStatus progress_status,
                                    int flush_error) {
   if (error == base::File::FILE_OK && flush_error != net::OK) {
     // If the Flush introduced an error, overwrite the status.
     // Otherwise, keep the original error status.
     error = NetErrorToFileError(flush_error);
     progress_status = GetCompletionStatusOnError();
   }
   write_callback_.Run(error, bytes_written, progress_status);
 }
 
 }  // namespace storage