chromeos/dbus/pipe_reader.h

   1 // Copyright 2014 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 CHROMEOS_DBUS_PIPE_READER_H_
   6 #define CHROMEOS_DBUS_PIPE_READER_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "base/files/file.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/memory/weak_ptr.h"
  15
  16 namespace base {
  17 class TaskRunner;
  18 }
  19
  20 namespace net {
  21 class FileStream;
  22 class IOBufferWithSize;
  23 }
  24
  25 namespace chromeos {
  26
  27 // Simple class to encapsulate collecting data from a pipe into a
  28 // string.  To use:
  29 //   - Instantiate the appropriate subclass of PipeReader
  30 //   - Call StartIO() which will create the appropriate FDs.
  31 //   - As data is received, the PipeReader will collect this data
  32 //     as appropriate to the subclass.
  33 //   - When the there is no more data to read, the PipeReader calls
  34 //     |callback|.
  35 class PipeReader {
  36  public:
  37   typedef base::Callback<void(void)> IOCompleteCallback;
  38
  39   PipeReader(const scoped_refptr<base::TaskRunner>& task_runner,
  40              const IOCompleteCallback& callback);
  41   virtual ~PipeReader();
  42
  43   // Starts data collection.
  44   // Returns the write end of the pipe if stream was setup correctly.
  45   // On success data will automatically be accumulated into a string that
  46   // can be retrieved with PipeReader::data().  To shutdown collection delete
  47   // the instance and/or use PipeReader::OnDataReady(-1).
  48   base::File StartIO();
  49
  50   // Called when pipe data are available.  Can also be used to shutdown
  51   // data collection by passing -1 for |byte_count|.
  52   void OnDataReady(int byte_count);
  53
  54   // Virtual function that subclasses will override in order to deal
  55   // with incoming data.
  56   virtual void AcceptData(const char *data, int length) = 0;
  57
  58  private:
  59   scoped_ptr<net::FileStream> data_stream_;
  60   scoped_refptr<net::IOBufferWithSize> io_buffer_;
  61   scoped_refptr<base::TaskRunner> task_runner_;
  62   IOCompleteCallback callback_;
  63
  64   // Note: This should remain the last member so it'll be destroyed and
  65   // invalidate its weak pointers before any other members are destroyed.
  66   base::WeakPtrFactory<PipeReader> weak_ptr_factory_;
  67
  68   DISALLOW_COPY_AND_ASSIGN(PipeReader);
  69 };
  70
  71 // PipeReader subclass which accepts incoming data to a string.
  72 class PipeReaderForString : public PipeReader {
  73  public:
  74   PipeReaderForString(const scoped_refptr<base::TaskRunner>& task_runner,
  75                       const IOCompleteCallback& callback);
  76
  77   void AcceptData(const char* data, int length) override;
  78
  79   // Destructively returns collected data, by swapping |data_| with |data|.
  80   void GetData(std::string* data);
  81
  82  private:
  83   std::string data_;
  84
  85   DISALLOW_COPY_AND_ASSIGN(PipeReaderForString);
  86 };
  87
  88 }  // namespace chromeos
  89
  90 #endif  // CHROMEOS_DBUS_PIPE_READER_H_