/* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
* char **argv "vanishes" */
void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
{
int fd;
if (flags & DAEMON_CHDIR_ROOT)
xchdir("/");
if (flags & DAEMON_DEVNULL_STDIO) {
close(0);
close(1);
close(2);
}
fd = open(bb_dev_null, O_RDWR);
if (fd < 0) {
/* NB: we can be called as bb_sanitize_stdio() from init
* or mdev, and there /dev/null may legitimately not (yet) exist!
* Do not use xopen above, but obtain _ANY_ open descriptor,
* even bogus one as below. */
fd = xopen("/", O_RDONLY); /* don't believe this can fail */
}
while ((unsigned)fd < 2)
fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
if (!(flags & DAEMON_ONLY_SANITIZE)) {
if (fork_or_rexec(argv))
exit(EXIT_SUCCESS); /* parent */
/* if daemonizing, detach from stdio & ctty */
setsid();
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
if (flags & DAEMON_DOUBLE_FORK) {
/* On Linux, session leader can acquire ctty
* unknowingly, by opening a tty.
* Prevent this: stop being a session leader.
*/
if (fork_or_rexec(argv))
exit(EXIT_SUCCESS); /* parent */
}
}
while (fd > 2) {
close(fd--);
if (!(flags & DAEMON_CLOSE_EXTRA_FDS))
return;
/* else close everything after fd#2 */
}
}
int setsid_main(int argc UNUSED_PARAM, char **argv)
{
if (!argv[1])
bb_show_usage();
/* setsid() is allowed only when we are not a process group leader.
* Otherwise our PID serves as PGID of some existing process group
* and cannot be used as PGID of a new process group. */
if (getpgrp() == getpid())
if (fork_or_rexec(argv))
exit(EXIT_SUCCESS); /* parent */
setsid(); /* no error possible */
BB_EXECVP(argv[1], argv + 1);
bb_simple_perror_msg_and_die(argv[1]);
}
