[hackers] [ubase] Check if 0, 1, 2 are valid tty file descriptors || sin

[git]

commit 2d45a04b92df641158ca400873a522fede1d9a01
Author: sin <s...@2f30.org>
Date:   Sun Nov 30 13:04:47 2014 +0000

    Check if 0, 1, 2 are valid tty file descriptors

diff --git a/login.c b/login.c
index e0930c5..45b69ea 100644
--- a/login.c
+++ b/login.c
@@ -71,8 +71,8 @@ main(int argc, char *argv[])
        if (argc < 1)
                usage();
 
-       if (isatty(STDIN_FILENO) == 0)
-               eprintf("stdin is not a tty\n");
+       if (isatty(0) == 0 || isatty(1) == 0 || isatty(2) == 0)
+               eprintf("no tty");
 
        user = argv[0];
        errno = 0;