daemon_lin.cpp

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#include "daemon.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <syslog.h>
#include <string.h>

#include <mutex>
#include <condition_variable>
#include <iostream>
#include <signal.h>

namespace
{

  OpcUa::Daemon* DaemonInstance = 0;

  void TerminateSignal(int signum)
  {
    std::cout << "terminating.." << std::endl;
    if (DaemonInstance)
    {
      DaemonInstance->Terminate();
      DaemonInstance = nullptr;
    }
  }

}

namespace OpcUa
{
  void Daemon::SetTerminateHandlers()
  {
    if (signal(SIGTERM, TerminateSignal) == SIG_ERR)
    {
      std::cerr << "unable to set SIGTERM handler" << std::endl;
    }
    if (signal(SIGINT, TerminateSignal) == SIG_ERR)
    {
      std::cerr << "unable to set SIGINT handler" << std::endl;
    }
    if (signal(SIGSTOP, TerminateSignal) == SIG_ERR)
    {
      std::cerr << "unable to set SIGSTOP handler" << std::endl;
    }
    DaemonInstance = this;
  }

  void Daemon::Daemonize(const std::string& logFile)
  {
    pid_t pid, sid;

    pid = fork();
    if (pid < 0)
    {
      std::cerr << "Failed to fork: " << strerror(errno) << std::endl;
      exit(EXIT_FAILURE);
    }
    if (pid > 0)
    {
      exit(EXIT_SUCCESS);
    }

    umask(0);

    sid = setsid();
    if (sid < 0)
    {
      std::cerr << "setsid() failed: " << strerror(errno) << std::endl;
      exit(EXIT_FAILURE);
    }

    if ((chdir("/")) < 0)
    {
      std::cerr << "Cannot change dir. " << strerror(errno) << std::endl;
      exit(EXIT_FAILURE);
    }

    if (!logFile.empty())
    {
      FILE* tmp = fopen(logFile.c_str(), "w");
      if (!tmp)
      {
        std::cerr << "Cannot open log file " << logFile << ". " << strerror(errno) << std::endl;
        exit(EXIT_FAILURE);
      }

      close(STDIN_FILENO);
      close(STDOUT_FILENO);
      close(STDERR_FILENO);

      dup2(fileno(tmp), STDOUT_FILENO);
      dup2(fileno(tmp), STDERR_FILENO);
    }
  }
}