/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__SCCSID("@(#)ttyname.c	8.2 (Berkeley) 1/27/94");
#include "namespace.h"
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/filio.h>
#include <fcntl.h>
#include <dirent.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <paths.h>
#include <errno.h>
#include "reentrant.h"
#include "un-namespace.h"

#include "libc_private.h"

static char ttyname_buf[sizeof(_PATH_DEV) + MAXNAMLEN];

static once_t		ttyname_init_once = ONCE_INITIALIZER;
static thread_key_t	ttyname_key;
static int		ttyname_keycreated = 0;

int
ttyname_r(int fd, char *buf, size_t len)
{
	size_t used;

	/* Don't write off the end of a zero-length buffer. */
	if (len < 1)
		return (ERANGE);

	*buf = '\0';

	/* Must be a terminal. */
	if (!isatty(fd))
		return (errno);
	/* Must have enough room */
	if (len <= sizeof(_PATH_DEV))
		return (ERANGE);

	strcpy(buf, _PATH_DEV);
	used = strlen(buf);
	if (fdevname_r(fd, buf + used, len - used) == NULL)
		return (errno == EINVAL ? ERANGE : errno);
	return (0);
}

static void
ttyname_keycreate(void)
{
	ttyname_keycreated = (thr_keycreate(&ttyname_key, free) == 0);
}

char *
ttyname(int fd)
{
	char	*buf;

	if (thr_main() != 0)
		buf = ttyname_buf;
	else {
		if (thr_once(&ttyname_init_once, ttyname_keycreate) != 0 ||
		    !ttyname_keycreated)
			return (NULL);
		if ((buf = thr_getspecific(ttyname_key)) == NULL) {
			if ((buf = malloc(sizeof ttyname_buf)) == NULL)
				return (NULL);
			if (thr_setspecific(ttyname_key, buf) != 0) {
				free(buf);
				return (NULL);
			}
		}
	}

	if (ttyname_r(fd, buf, sizeof ttyname_buf) != 0)
		return (NULL);
	return (buf);
}
