[Swan-dev] use vfork/exec

[Andrew Cagney]

I'd like to float the idea of simplifying pluto a little by
unconditionally using vfork/exec. For instance, in
programs/pluto/server.c, there is:

#ifdef HAVE_NO_FORK
                addconn_child_pid = vfork(); /* for better, for worse,
in sickness and health..... */
#else
                addconn_child_pid = fork();
#endif
                if (addconn_child_pid == 0) {
                        /* child */
                        sleep(1);
                        DBG(DBG_CONTROLMORE,
                            DBG_log("calling addconn helper using execve"));
                        execve(addconn_path, newargv, newenv);
                        _exit(42);
                }

I'd simplify it to just use vfork.  That way, we're always testing a
single code path (and increasing the odds that on systems that don't
have fork, e.x., systems without an mmu) everything still works.

I should note that vfork() comes with caveats.  Other than exec() and
exit() there's really not much else that is allowed between the
vfork() and exec() calls.  The above, which calls sleep() and printf()
is likely wrong and I'd need to fix it.

Andrew