busybox/coreutils/tty.c

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/* vi: set sw=4 ts=4: */
/*
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* tty implementation for busybox
*
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* Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
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/* BB_AUDIT SUSv3 compliant */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/tty.html */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "busybox.h"
int tty_main(int argc, char **argv)
{
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const char *s;
int silent; /* Note: No longer relevant in SUSv3. */
int retval;
bb_default_error_retval = 2; /* SUSv3 requires > 1 for error. */
silent = bb_getopt_ulflags(argc, argv, "s");
/* gnu tty outputs a warning that it is ignoring all args. */
bb_warn_ignoring_args(argc - optind);
retval = 0;
if ((s = ttyname(0)) == 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;
}
if (!silent) {
puts(s);
}
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bb_fflush_stdout_and_exit(retval);
}