LXR busybox/coreutils/tty.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * tty implementation for busybox
   4 *
   5 * Copyright (C) 2003  Manuel Novoa III  <mjn3@codepoet.org>
   6 *
   7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   8 */
   9
  10/* BB_AUDIT SUSv3 compliant */
  11/* http://www.opengroup.org/onlinepubs/007904975/utilities/tty.html */
  12
  13#include "libbb.h"
  14
  15int tty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  16int tty_main(int argc, char **argv SKIP_INCLUDE_SUSv2(UNUSED_PARAM))
  17{
  18        const char *s;
  19        USE_INCLUDE_SUSv2(int silent;)  /* Note: No longer relevant in SUSv3. */
  20        int retval;
  21
  22        xfunc_error_retval = 2; /* SUSv3 requires > 1 for error. */
  23
  24        USE_INCLUDE_SUSv2(silent = getopt32(argv, "s");)
  25        USE_INCLUDE_SUSv2(argc -= optind;)
  26        SKIP_INCLUDE_SUSv2(argc -= 1;)
  27
  28        /* gnu tty outputs a warning that it is ignoring all args. */
  29        bb_warn_ignoring_args(argc);
  30
  31        retval = 0;
  32
  33        s = ttyname(0);
  34        if (s == NULL) {
  35        /* According to SUSv3, ttyname can fail with EBADF or ENOTTY.
  36         * We know the file descriptor is good, so failure means not a tty. */
  37                s = "not a tty";
  38                retval = 1;
  39        }
  40        USE_INCLUDE_SUSv2(if (!silent) puts(s);)
  41        SKIP_INCLUDE_SUSv2(puts(s);)
  42
  43        fflush_stdout_and_exit(retval);
  44}
  45