login(1): use setsid() and use given tty

etc/inittab

@@ -2,4 +2,4 @@
 
 init:1:wait:/sbin/rc default
 
-l0:1:once:/bin/login
+l0:1:once:/bin/login /dev/tty0

etc/rc.d/00-mounts

@@ -3,5 +3,9 @@
 echo Mounting /dev
 mount -t devfs /dev
 
+chmod 0666 /dev/tty0
+chown 0:1000 /dev/ttyS0
+chmod 0660 /dev/ttyS0
+
 echo Mounting /sys
 mount -t sysfs /sys

progs/base/bin/login.c

@@ -163,6 +163,28 @@ int main(int argc, char **argv) {
         return -1;
     }
 
+    if (argc != 2) {
+        fprintf(stderr, "usage: login TTY\n");
+        return -1;
+    }
+
+    // Will release 0, 1, 2
+    if (setsid() < 0) {
+        perror("setsid()");
+        return -1;
+    }
+
+    // Open the terminal
+    if (open(argv[1], O_RDONLY, 0) != STDIN_FILENO) {
+        return -1;
+    }
+    if (open(argv[1], O_WRONLY, 0) != STDOUT_FILENO) {
+        return -1;
+    }
+    if (dup(STDOUT_FILENO) != STDERR_FILENO) {
+        return -1;
+    }
+
     signal(SIGINT, signal_handler);
 
     char spnam_buf[128];