#include <sys/stat.h>

#include <fcntl.h>

/* Bit-mask values for 'flags' argument of becomeDaemon() */

#define BD_NO_CHDIR           01    /* Don't chdir("/") */

#define BD_NO_CLOSE_FILES     02    /* Don't close all open files */

#define BD_NO_REOPEN_STD_FDS  04    /* Don't reopen stdin, stdout, and

                                       stderr to /dev/null */

#define BD_NO_UMASK0         010    /* Don't do a umask(0) */

#define BD_MAX_CLOSE  8192          /* Maximum file descriptors to close if

                                       sysconf(_SC_OPEN_MAX) is indeterminate */

int becomeDaemon(int flags)         /* Returns 0 on success, -1 on error */

{

    int maxfd, fd;

    switch (fork())                        /* Become background process */

    {

    case -: return -;

    case :  break;                     /* Child falls through... */

    default: _exit(EXIT_SUCCESS);       /* while parent terminates */

    }

    if (setsid() == -)                 /* Become leader of new session */

        return -;

    switch (fork()) {                   /* Ensure we are not session leader */

    case -: return -;

    case :  break;

    default: _exit(EXIT_SUCCESS);

    }

    if (!(flags & BD_NO_UMASK0))

        umask();                       /* Clear file mode creation mask */

    if (!(flags & BD_NO_CHDIR))

        chdir("/");                     /* Change to root directory */

    if (!(flags & BD_NO_CLOSE_FILES)) { /* Close all open files */

        maxfd = sysconf(_SC_OPEN_MAX);

        if (maxfd == -)                /* Limit is indeterminate... */

            maxfd = BD_MAX_CLOSE;       /* so take a guess */

        for (fd = ; fd < maxfd; fd++)

            close(fd);

    }

    if (!(flags & BD_NO_REOPEN_STD_FDS)) {

        close(STDIN_FILENO);            /* Reopen standard fd's to /dev/null */

        fd = open("/dev/null", O_RDWR);

        if (fd != STDIN_FILENO)         /* 'fd' should be 0 */

            return -;

        if (dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO)

            return -;

        if (dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO)

            return -;

    }

    return ;

}