1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef NET_BASE_UPLOAD_ELEMENT_READER_H_
6#define NET_BASE_UPLOAD_ELEMENT_READER_H_
7
8#include "base/basictypes.h"
9#include "net/base/completion_callback.h"
10#include "net/base/net_export.h"
11
12namespace net {
13
14class IOBuffer;
15class UploadBytesElementReader;
16class UploadFileElementReader;
17
18// An interface to read an upload data element.
19class NET_EXPORT UploadElementReader {
20 public:
21  UploadElementReader() {}
22  virtual ~UploadElementReader() {}
23
24  // Returns this instance's pointer as UploadBytesElementReader when possible,
25  // otherwise returns NULL.
26  virtual const UploadBytesElementReader* AsBytesReader() const;
27
28  // Returns this instance's pointer as UploadFileElementReader when possible,
29  // otherwise returns NULL.
30  virtual const UploadFileElementReader* AsFileReader() const;
31
32  // Initializes the instance synchronously when possible, otherwise does
33  // initialization aynschronously, returns ERR_IO_PENDING and runs callback.
34  // Calling this method again after a Init() success results in resetting the
35  // state.
36  virtual int Init(const CompletionCallback& callback) = 0;
37
38  // Returns the byte-length of the element.  For files that do not exist, 0
39  // is returned.  This is done for consistency with Mozilla.
40  virtual uint64 GetContentLength() const = 0;
41
42  // Returns the number of bytes remaining to read.
43  virtual uint64 BytesRemaining() const = 0;
44
45  // Returns true if the upload element is entirely in memory.
46  // The default implementation returns false.
47  virtual bool IsInMemory() const;
48
49  // Reads up to |buf_length| bytes synchronously and returns the number of
50  // bytes read or error code when possible, otherwise, returns ERR_IO_PENDING
51  // and runs |callback| with the result. |buf_length| must be greater than 0.
52  virtual int Read(IOBuffer* buf,
53                   int buf_length,
54                   const CompletionCallback& callback) = 0;
55
56 private:
57  DISALLOW_COPY_AND_ASSIGN(UploadElementReader);
58};
59
60}  // namespace net
61
62#endif  // NET_BASE_UPLOAD_ELEMENT_READER_H_
63