source: MondoRescue/branches/2.2.5/mindi-busybox/coreutils/tty.c

/* vi: set sw=4 ts=4: */
/*
 * tty implementation for busybox
 *
 * Copyright (C) 2003  Manuel Novoa III  <mjn3@codepoet.org>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

/* BB_AUDIT SUSv3 compliant */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/tty.html */

#include "libbb.h"

int tty_main(int argc, char **argv);
int tty_main(int argc, char **argv)
{
    const char *s;
    USE_INCLUDE_SUSv2(int silent;)  /* Note: No longer relevant in SUSv3. */
    int retval;

    xfunc_error_retval = 2; /* SUSv3 requires > 1 for error. */

    USE_INCLUDE_SUSv2(silent = getopt32(argv, "s");)

    /* gnu tty outputs a warning that it is ignoring all args. */
    bb_warn_ignoring_args(argc - optind);

    retval = 0;

    s = ttyname(0);
    if (s == NULL) {
    /* According to SUSv3, ttyname can on fail with EBADF or ENOTTY.
     * We know the file descriptor is good, so failure means not a tty. */
        s = "not a tty";
        retval = 1;
    }
    USE_INCLUDE_SUSv2(if (!silent) puts(s);)
    SKIP_INCLUDE_SUSv2(puts(s);)

    fflush_stdout_and_exit(retval);
}