net/base/upload_element_reader.h

   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
  12 namespace net {
  13
  14 class IOBuffer;
  15 class UploadBytesElementReader;
  16 class UploadFileElementReader;
  17
  18 // An interface to read an upload data element.
  19 class 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_