daemonizer.c

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

#include "config.h"
#include "daemonizer.h"

int daemonize()
{
    pid_t pid = fork();
    if(pid < 0)
    {
        return -1;
    }
    else if(pid > 0)
    {
        _exit(0);
    }
    else if(pid == 0)
    {
        int fds;
        setsid();
        for(fds = getdtablesize(); fds >= 3; --fds) 
        {
            if(fds != mediator_lockfd)
                close(fds);
        }
        if (freopen("/dev/null", "r", stdin) == NULL) {
            L_CRITICAL("Failed to reopen stdin to /dev/null: %s", strerror(errno));
            return -1;
        }
        if (freopen("/dev/null", "w", stdout) == NULL) {
            L_CRITICAL("Failed to reopen stdout to /dev/null: %s", strerror(errno));
            return -1;
        }
        if (freopen("/dev/null", "w", stderr) == NULL) {
            L_CRITICAL("Failed to reopen stderr to /dev/null: %s", strerror(errno));
            return -1;
        }
        umask(027);
        if(chdir("/") < 0) {
            L_CRITICAL("Failed to chdir to root: %s", strerror(errno));
            return -1;
        }
    }

    return 0;
}

int write_pid(const char *pidfile)
{
    FILE *pfile = fopen(pidfile, "w");
    if(pfile == NULL)
    {
        L_CRITICAL("Error opening pid file '%s': %s", pidfile, strerror(errno));
        return -1;
    }
    fprintf(pfile, "%d", getpid());
    fclose(pfile);
    return 0;
}