util.c

#include "util.h"

int daemonize(int nochdir, int noclose)
{
    int fd;

    switch (fork())
    {
    case -1:
        return (-1);

    case 0:
        break;

    default:
        _exit(EXIT_SUCCESS);
    }

    if (setsid() == -1)
        return (-1);

    if (nochdir == 0)
    {
        if(chdir("/") != 0)
        {
            perror("chdir");
            return (-1);
        }
    }

    if (noclose == 0 && (fd = open("/dev/null", O_RDWR, 0)) != -1)
    {
        if (dup2(fd, STDIN_FILENO) < 0)
        {
            perror("dup2 stdin");
            return (-1);
        }
        if (dup2(fd, STDOUT_FILENO) < 0)
        {
            perror("dup2 stdout");
            return (-1);
        }
        if (dup2(fd, STDERR_FILENO) < 0)
        {
            perror("dup2 stderr");
            return (-1);
        }

        if (fd > STDERR_FILENO)
        {
            if (close(fd) < 0)
            {
                perror("close");
                return (-1);
            }
        }
    }

    return(0);
}

static void signal_handler(int signo)
{
    fprintf(stderr, "Get one signal: %d. man sigaction.\n", signo);
    return;
}

void signal_setup(void)
{
    static int signo[] = {
        SIGHUP,
        SIGINT,     /* ctrl + c */
        SIGCHLD,    /* 僵死进程或线程的信号 */
        SIGPIPE,
        SIGALRM,
        SIGUSR1,
        SIGUSR2,
        SIGTERM,
        //SIGCLD,

#ifdef  SIGTSTP
        /* background tty read */
        SIGTSTP,
#endif
#ifdef  SIGTTIN
        /* background tty read */
        SIGTTIN,
#endif
#ifdef SIGTTOU
        SIGTTOU,
#endif
        SIGNO_END
    };

    int i = 0;
    struct sigaction sa;
    //sa.sa_handler = SIG_IGN;    //设定接受到指定信号后的动作为忽略
    sa.sa_handler = signal_handler;
    sa.sa_flags   = SA_SIGINFO;

    if (-1 == sigemptyset(&sa.sa_mask))   //初始化信号集为空
    {
        fprintf(stderr, "failed to init sa_mask.\n");
        exit(EXIT_FAILURE);
    }

    for (i = 0; SIGNO_END != signo[i]; i++)
    {
        //屏蔽信号
        if (-1 == sigaction(signo[i], &sa, NULL))
        {
            fprintf(stderr, "failed to ignore: %d\n", signo[i]);
            exit(EXIT_FAILURE);
        }
    }

    return (void)0;
}