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 source tree.
   8 */
   9//config:config TTY
  10//config:       bool "tty (3.6 kb)"
  11//config:       default y
  12//config:       help
  13//config:       tty is used to print the name of the current terminal to
  14//config:       standard output.
  15
  16//applet:IF_TTY(APPLET_NOFORK(tty, tty, BB_DIR_USR_BIN, BB_SUID_DROP, tty))
  17
  18//kbuild:lib-$(CONFIG_TTY) += tty.o
  19
  20/* BB_AUDIT SUSv4 compliant */
  21/* http://www.opengroup.org/onlinepubs/9699919799/utilities/tty.html */
  22
  23//usage:#define tty_trivial_usage
  24//usage:       "" IF_INCLUDE_SUSv2("[-s]")
  25//usage:#define tty_full_usage "\n\n"
  26//usage:       "Print file name of stdin's terminal"
  27//usage:        IF_INCLUDE_SUSv2( "\n"
  28//usage:     "\n        -s      Print nothing, only return exit status"
  29//usage:        )
  30//usage:
  31//usage:#define tty_example_usage
  32//usage:       "$ tty\n"
  33//usage:       "/dev/tty2\n"
  34
  35#include "libbb.h"
  36
  37int tty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  38int tty_main(int argc UNUSED_PARAM, char **argv)
  39{
  40        const char *s;
  41        IF_INCLUDE_SUSv2(int silent;)  /* Note: No longer relevant in SUSv3. */
  42        int retval;
  43
  44        xfunc_error_retval = 2;  /* SUSv3 requires > 1 for error. */
  45
  46        IF_INCLUDE_SUSv2(silent = getopt32(argv, "s");)
  47        IF_INCLUDE_SUSv2(argv += optind;)
  48        IF_NOT_INCLUDE_SUSv2(argv += 1;)
  49
  50        /* gnu tty outputs a warning that it is ignoring all args. */
  51        bb_warn_ignoring_args(argv[0]);
  52
  53        retval = EXIT_SUCCESS;
  54
  55        s = xmalloc_ttyname(STDIN_FILENO);
  56        if (s == NULL) {
  57        /* According to SUSv3, ttyname can fail with EBADF or ENOTTY.
  58         * We know the file descriptor is good, so failure means not a tty. */
  59                s = "not a tty";
  60                retval = EXIT_FAILURE;
  61        }
  62        IF_INCLUDE_SUSv2(if (!silent) puts(s);)
  63        IF_NOT_INCLUDE_SUSv2(puts(s);)
  64
  65        fflush_stdout_and_exit(retval);
  66}
  67