openvt,getty,vfork_daemon_rexec,mount: tighten up fd cleanup code

(will close all fd's > 2 on daemonization now)
getty: fix "getty -" support, and also do not try to chown/chmod "-"
telnetd: fix "lost ctty" bug
Yet another attempt on saner function names:
bb_sanitize_server_stdio(0/1) -> bb_sanitize_stdio() + bb_daemonize();

1 files changed, 8 insertions, 4 deletions

diff --git a/networking/telnetd.c b/networking/telnetd.c
index 51bd0c012..25cba3eb0 100644
--- a/networking/telnetd.c
+++ b/networking/telnetd.c
@@ -283,15 +283,19 @@ make_new_session(
 
         /* child */
 
+        /* make new process group */
+        setsid();
+        tcsetpgrp(0, getpid());
+        /* ^^^ strace says: "ioctl(0, TIOCSPGRP, [pid]) = -1 ENOTTY" -- ??! */
+
         /* open the child's side of the tty. */
-        fd = xopen(tty_name, O_RDWR /*| O_NOCTTY*/);
+        /* NB: setsid() disconnects from any previous ctty's. Therefore
+         * we must open child's side of the tty AFTER setsid! */
+        fd = xopen(tty_name, O_RDWR); /* becomes our ctty */
         dup2(fd, 0);
         dup2(fd, 1);
         dup2(fd, 2);
         while (fd > 2) close(fd--);
-        /* make new process group */
-        setsid();
-        tcsetpgrp(0, getpid());
 
         /* The pseudo-terminal allocated to the client is configured to operate in
          * cooked mode, and with XTABS CRMOD enabled (see tty(4)). */