Support sending a sliced file in chromium....

net/base/upload_data_stream.h

 // Copyright (c) 2010 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.
 
 #ifndef NET_BASE_UPLOAD_DATA_STREAM_H_
 #define NET_BASE_UPLOAD_DATA_STREAM_H_
 
 #include "net/base/file_stream.h"
 #include "net/base/upload_data.h"
 
 namespace net {
 
 class IOBuffer;
 
 class UploadDataStream {
  public:
-  explicit UploadDataStream(const UploadData* data);
+  // Returns a new instance of UploadDataStream if it can be created and
+  // initialized successfully. If not, NULL will be returned and the error
+  // code will be set if the output parameter error_code is not empty.
+  static UploadDataStream* Create(const UploadData* data, int* error_code);
+
   ~UploadDataStream();
 
   // Returns the stream's buffer and buffer length.
   IOBuffer* buf() const { return buf_; }
   size_t buf_len() const { return buf_len_; }
 
   // Call to indicate that a portion of the stream's buffer was consumed.  This
   // call modifies the stream's buffer so that it contains the next segment of
   // the upload data to be consumed.
   void DidConsume(size_t num_bytes);
 
   // Returns the total size of the data stream and the current position.
   // size() is not to be used to determine whether the stream has ended
   // because it is possible for the stream to end before its size is reached,
   // for example, if the file is truncated.
   uint64 size() const { return total_size_; }
   uint64 position() const { return current_position_; }
 
   // Returns whether there is no more data to read, regardless of whether
   // position < size.
   bool eof() const { return eof_; }
 
  private:
+  // Protects from public access since now we have a static creator function
+  // which will do both creation and initialization and might return an error.
+  explicit UploadDataStream(const UploadData* data);
+
   // Fills the buffer with any remaining data and sets eof_ if there was nothing
   // left to fill the buffer with.
-  void FillBuf();
+  // Returns OK if the operation succeeds. Otherwise error code is returned.
+  int FillBuf();
 
   const UploadData* data_;
 
   // This buffer is filled with data to be uploaded.  The data to be sent is
   // always at the front of the buffer.  If we cannot send all of the buffer at
   // once, then we memmove the remaining portion and back-fill the buffer for
   // the next "write" call.  buf_len_ indicates how much data is in the buffer.
   enum { kBufSize = 16384 };
   scoped_refptr<IOBuffer> buf_;
   size_t buf_len_;
@@ skipping 19 matching lines @@
 
   // Whether there is no data left to read.
   bool eof_;
 
   DISALLOW_EVIL_CONSTRUCTORS(UploadDataStream);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_UPLOAD_DATA_STREAM_H_