*: shrink: use Vladimir's "o+" specifier instead of xatou(opt_param)

function                                             old     new   delta
getopt32                                            1370    1385     +15
sulogin_main                                         490     494      +4
realpath_main                                         84      86      +2
sleep_main                                            76      77      +1
mt_main                                              256     257      +1
printenv_main                                         75      74      -1
fdformat_main                                        546     545      -1
usleep_main                                           44      42      -2
setlogcons_main                                       77      75      -2
ed_main                                             2654    2649      -5
deallocvt_main                                        69      64      -5
addgroup_main                                        373     368      -5
mkfs_minix_main                                     2989    2982      -7
tail_main                                           1221    1213      -8
sv_main                                             1254    1241     -13
du_main                                              348     328     -20
tftp_main                                            325     302     -23
split_main                                           581     558     -23
nc_main                                             1000     977     -23
diff_main                                            891     868     -23
arping_main                                         1797    1770     -27
ls_main                                              893     847     -46
od_main                                             2797    2750     -47
readprofile_main                                    1944    1895     -49
tcpudpsvd_main                                      1973    1922     -51
udhcpc_main                                         2590    2513     -77
grep_main                                            824     722    -102
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 5/22 up/down: 23/-560)         Total: -537 bytes
   text    data     bss     dec     hex filename
 796973     658    7428  805059   c48c3 busybox_old
 796479     662    7420  804561   c46d1 busybox_unstripped

1 files changed, 4 insertions, 3 deletions

diff --git a/loginutils/login.c b/loginutils/login.c
index d7eb8d35b..e8fe74e16 100644
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -221,7 +221,7 @@ static void alarm_handler(int sig ATTRIBUTE_UNUSED)
 }
 
 int login_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int login_main(int argc, char **argv)
+int login_main(int argc ATTRIBUTE_UNUSED, char **argv)
 {
         enum {
                 LOGIN_OPT_f = (1<<0),
@@ -269,8 +269,9 @@ int login_main(int argc, char **argv)
                         bb_error_msg_and_die("-f is for root only");
                 safe_strncpy(username, opt_user, sizeof(username));
         }
-        if (optind < argc) /* user from command line (getty) */
-                safe_strncpy(username, argv[optind], sizeof(username));
+        argv += optind;
+        if (argv[0]) /* user from command line (getty) */
+                safe_strncpy(username, argv[0], sizeof(username));
 
         /* Let's find out and memorize our tty */
         if (!isatty(0) || !isatty(1) || !isatty(2))