chromeos/process_proxy/process_output_watcher.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 CHROMEOS_PROCESS_PROXY_PROCESS_OUTPUT_WATCHER_H_
   6 #define CHROMEOS_PROCESS_PROXY_PROCESS_OUTPUT_WATCHER_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "base/files/file.h"
  12 #include "base/memory/weak_ptr.h"
  13 #include "base/message_loop/message_loop.h"
  14 #include "chromeos/chromeos_export.h"
  15
  16 namespace chromeos {
  17
  18 enum ProcessOutputType {
  19   PROCESS_OUTPUT_TYPE_OUT,
  20   PROCESS_OUTPUT_TYPE_EXIT
  21 };
  22
  23 typedef base::Callback<void(ProcessOutputType, const std::string&)>
  24       ProcessOutputCallback;
  25
  26 // Observes output on |out_fd| and invokes |callback| when some output is
  27 // detected. It assumes UTF8 output.
  28 class CHROMEOS_EXPORT ProcessOutputWatcher
  29     : public base::MessageLoopForIO::Watcher {
  30  public:
  31   ProcessOutputWatcher(int out_fd, const ProcessOutputCallback& callback);
  32   ~ProcessOutputWatcher() override;
  33
  34   void Start();
  35
  36  private:
  37   // MessageLoopForIO::Watcher overrides:
  38   void OnFileCanReadWithoutBlocking(int fd) override;
  39   void OnFileCanWriteWithoutBlocking(int fd) override;
  40
  41   // Listens to output from fd passed to the constructor.
  42   void WatchProcessOutput();
  43
  44   // Reads data from fd and invokes callback |on_read_callback_| with read data.
  45   void ReadFromFd(int fd);
  46
  47   // Checks if the read buffer has any trailing incomplete UTF8 characters and
  48   // returns the read buffer size without them.
  49   size_t OutputSizeWithoutIncompleteUTF8();
  50
  51   // Processes new |read_buffer_| state and notifies observer about new process
  52   // output.
  53   void ReportOutput(ProcessOutputType type, size_t new_bytes_count);
  54
  55   char read_buffer_[256];
  56   // Maximum read buffer content size.
  57   size_t read_buffer_capacity_;
  58   // Current read bufferi content size.
  59   size_t read_buffer_size_;
  60
  61   // Contains file descsriptor to which watched process output is written.
  62   base::File process_output_file_;
  63   base::MessageLoopForIO::FileDescriptorWatcher output_file_watcher_;
  64
  65   // Callback that will be invoked when some output is detected.
  66   ProcessOutputCallback on_read_callback_;
  67
  68   base::WeakPtrFactory<ProcessOutputWatcher> weak_factory_;
  69
  70   DISALLOW_COPY_AND_ASSIGN(ProcessOutputWatcher);
  71 };
  72
  73 }  // namespace chromeos
  74
  75 #endif  // CHROMEOS_PROCESS_PROXY_PROCESS_OUTPUT_WATCHER_H_