polybar/include/utils/command.hpp

#pragma once

#include <mutex>

#include "common.hpp"
#include "components/logger.hpp"
#include "errors.hpp"
#include "utils/factory.hpp"
#include "utils/functional.hpp"

POLYBAR_NS

DEFINE_ERROR(command_error);

/**
 * Wrapper used to execute command in a subprocess.
 * In-/output streams are opened to enable ipc.
 *
 * Example usage:
 *
 * @code cpp
 *   auto cmd = command_util::make_command("cat /etc/rc.local");
 *   cmd->exec();
 *   cmd->tail([](string s) { std::cout << s << std::endl; });
 * @endcode
 *
 * @code cpp
 *   auto cmd = command_util::make_command(
 *    "while read -r line; do echo data from parent process: $line; done");
 *   cmd->exec(false);
 *   cmd->writeline("Test");
 *   cout << cmd->readline();
 *   cmd->wait();
 * @endcode
 *
 * @code cpp
 *   auto cmd = command_util::make_command("for i in 1 2 3; do echo $i; done");
 *   cmd->exec();
 *   cout << cmd->readline(); // 1
 *   cout << cmd->readline() << cmd->readline(); // 23
 * @endcode
 */
class command {
 public:
  explicit command(const logger& logger, string cmd);

  ~command();

  int exec(bool wait_for_completion = true);
  void terminate();
  bool is_running();
  int wait();

  void tail(callback<string> cb);
  int writeline(string data);
  string readline();

  int get_stdout(int c);
  int get_stdin(int c);
  pid_t get_pid();
  int get_exit_status();

 protected:
  const logger& m_log;

  string m_cmd;

  int m_stdout[2]{};
  int m_stdin[2]{};

  pid_t m_forkpid{};
  int m_forkstatus{};

  std::mutex m_pipelock{};
};

namespace command_util {
  template <typename... Args>
  unique_ptr<command> make_command(Args&&... args) {
    return factory_util::unique<command>(logger::make(), forward<Args>(args)...);
  }
}

POLYBAR_NS_END