Bug#1101703: rlogind immediately disconnects

[Andy Spiegl <spiegl.rsh_debian@bfw-online.de>]

Removing the vhangup() call from "login.c" of the "util-linux" package helps.
But I'm hesitant to patch "login" because of possible security issues.

Instead I took a look at "rlogin.c" from the "rsh-redone-server" package.
The following patch makes rlogin ignore the signal which is sent by the
login process using the vhangup() call:

*** rlogind.c   Wed Oct  1 19:16:13 2025
--- rlogind.c.ORIG      Wed Oct  1 19:10:53 2025
***************
*** 500,510 ****
                asprintf(&envp[0], "TERM=%s", term);
                envp[1] = NULL;
  
-               syslog(LOG_NOTICE, "Ignoring SIGHUP (login calls vhangup which kills rlogin)");
-               struct sigaction sa;
-               sa.sa_handler = SIG_IGN;
-               sigaction(SIGHUP, &sa, NULL);
- 
                /* Spawn login process */
  
                execle("/bin/login", "login", "-p", "-h", host, "-f", pamuser, NULL, envp);
--- 500,505 ----


For some reason it did not suffice to just add this:
  signal(SIGHUP, SIG_IGN);

What do you think?  Is this a viable way to make rlogin work with again
with a modern version of login?

Thanks,
 Andy