login_manager/subprocess.h

// Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef LOGIN_MANAGER_SUBPROCESS_H_
#define LOGIN_MANAGER_SUBPROCESS_H_

#include <unistd.h>

#include <string>
#include <vector>

#include <base/macros.h>
#include <base/time/time.h>

namespace login_manager {

class SystemUtils;

class SubprocessInterface {
 public:
  virtual ~SubprocessInterface() {}

  // fork(), export |environment_variables|, and exec(argv, env_vars).
  // Returns false if fork() fails, true otherwise.
  virtual bool ForkAndExec(const std::vector<std::string>& args,
                           const std::vector<std::string>& env_vars) = 0;

  // Sends signal to pid_. No-op if there is no subprocess running.
  virtual void Kill(int signal) = 0;

  // Sends signal to pid_'s entire process group.
  // No-op if there is no subprocess running.
  virtual void KillEverything(int signal) = 0;

  virtual pid_t GetPid() const = 0;
  virtual void ClearPid() = 0;
};

// A class that provides functionality for creating/destroying a subprocess.
// Intended to be embedded in an implementation of ChildJobInterface.
class Subprocess : public SubprocessInterface {
 public:
  Subprocess(uid_t desired_uid, SystemUtils* system);
  ~Subprocess() override;

  // SubprocessInterface:
  bool ForkAndExec(const std::vector<std::string>& args,
                   const std::vector<std::string>& env_vars) override;
  void Kill(int signal) override;
  void KillEverything(int signal) override;
  pid_t GetPid() const override;
  void ClearPid() override;

 private:
  // The pid of the managed subprocess, when running. Set to -1 when
  // cleared, or not yet set by ForkAndExec().
  pid_t pid_;
  // The uid the subprocess should be run as.
  const uid_t desired_uid_;
  SystemUtils* const system_;  // weak; owned by embedder.
  DISALLOW_COPY_AND_ASSIGN(Subprocess);
};

}  // namespace login_manager

#endif  // LOGIN_MANAGER_SUBPROCESS_H_