setup_environment: code shrink

run_shell: mark as NORETURN
setup_environment, run_shell: add usage comments
login: add FIXME :(

function                                             old     new   delta
UNSPEC_print                                          64      66      +2
sulogin_main                                         509     506      -3
mkfs_minix_main                                     3070    3067      -3
login_main                                          1615    1612      -3
su_main                                              461     448     -13
setup_environment                                    261     206     -55
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/5 up/down: 2/-77)             Total: -75 bytes
   text    data     bss     dec     hex filename
 772578    1051   10724  784353   bf7e1 busybox_old
 772502    1051   10724  784277   bf795 busybox_unstripped

1 files changed, 4 insertions, 3 deletions

diff --git a/loginutils/sulogin.c b/loginutils/sulogin.c
index 5f0a4081d..5c73bda93 100644
--- a/loginutils/sulogin.c
+++ b/loginutils/sulogin.c
@@ -112,14 +112,15 @@ int sulogin_main(int argc, char **argv)
         USE_SELINUX(renew_current_security_context());
 
         shell = getenv("SUSHELL");
-        if (!shell) shell = getenv("sushell");
+        if (!shell)
+                shell = getenv("sushell");
         if (!shell) {
                 shell = "/bin/sh";
                 if (pwd->pw_shell[0])
                         shell = pwd->pw_shell;
         }
-        run_shell(shell, 1, 0, 0);
-        /* never returns */
+        /* Exec login shell with no additional parameters. Never returns. */
+        run_shell(shell, 1, NULL, NULL);
 
 auth_error:
         bb_error_msg_and_die("no password entry for 'root'");