[BusyBox] vfork_daemon_rexec

[Vladimir N. Oleynik]

Russ,

> This is the behavior with inetd. Thats what the code does. It fails the
> execvp, then proceeds to set argv[0] to /bin/busybox 

If this problem exist - this problem by busybox_main(). Not problem for 
vfork_rexec().

> There are a lot of other problems as well. All the applets using
> vfork_daemon_rexec also call daemon, which returns after a failed fork
> on uclinux (does nothing). A working vfork_daemon_rexec might look like
> this:
> 
> void vfork_daemon_rexec(int nochdir, int noclose,
>                 int argc, char **argv, char *foreground_opt)
> {
>         int fd;
>         char **vfork_args;
>         int a = 0;
>                                                                                                          
>         if (setsid() == -1)
>                 return(-1);
>                                                                                                          
>         if (!nochdir)
>                 chdir("/");
>                                                                                                          
>         if (!noclose && (fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
>                 dup2(fd, STDIN_FILENO);
>                 dup2(fd, STDOUT_FILENO);
>                 dup2(fd, STDERR_FILENO);
>                 if (fd > 2)
>                         close(fd);
>         }

This code present form daemon(3).
vfork_rexec() called after daemon().
 

>         vfork_args = xcalloc(sizeof(char *), argc + 3);
>         vfork_args[a++] = "/bin/busybox";
>         while(*argv) {
>             vfork_args[a++] = *argv;
>             argv++;
>         }
>         vfork_args[a++] = foreground_opt;
>         vfork_args[a] = NULL;

This up line don`t required, xcalloc always set to NULL.

>         switch (vfork()) {
>         case 0: /* child */
>                 /* Make certain we are not a session leader, or else we
>                  * might reacquire a controlling terminal */

Its interesteing only teoreticaly.
Real effect with small code full equivalent you can see from crond:

signal(SIGHUP, SIG_ING);
daemon(); /* this called setsid() */
vfrok_rexec();
signal(SIGHUP, sig_handler);	/* if require */


--w
vodz