[configs/releng] Fixed and improved serial console support.

Current implementation fails if console=ttyS0 (without more options).

Tested with:
console=ttyS0
console=ttyS0,9600
console=ttyS0,38400
console=ttyS0,9600n8
console=ttyS0,38400n8r

Closing FS#16232

Signed-off-by: Gerardo Exequiel Pozzi <vmlinuz386@yahoo.com.ar>

configs/releng/root-image/etc/rc.d/archiso

@@ -16,20 +16,24 @@ do_locale_gen ()
 # start agetty on it too.
 do_special_console()
 {
-    cmdline_console="$(kernel_cmdline console)"
-    [ $? -ne 0 ] && return
-
-    dev="${cmdline_console%%,*}"
-    args="${cmdline_console##*,}"
-    baud="${args%%[neo]*}" && baud="${baud:-"9600"}"
-    [ "x${args}" != "x${args%%r}" ] && rts="-h"
-
-
+    local cmdline_console
+    if cmdline_console=$(kernel_cmdline console); then
         stat_busy "Starting agetty on console: ${cmdline_console}"
-    echo "${dev}" >> /etc/securetty
-    echo "z0:2345:respawn:/sbin/agetty ${rts} ${baud} ${dev} linux" >> /etc/inittab
+            local port options baud rts
+            port=${cmdline_console%%,*}
+            options=${cmdline_console#${port}}
+            options=${options#,}
+            baud=${options%%[neo]*}
+            [[ ${options} =~ r$ ]] && rts="-h"
+            if ! grep -q "^${port}" /etc/securetty; then
+                echo ${port} >> /etc/securetty
+            fi
+            if ! grep -q "^z0:" /etc/inittab; then
+                echo "z0:2345:respawn:/sbin/agetty -8 -s ${rts} ${baud:-9600} ${port} linux" >> /etc/inittab
+            fi
             /sbin/telinit q
         stat_done
+    fi
 }
 
 case "$1" in