xref: /freebsd/lib/libc/gen/ttyname.c (revision d201fe46e355212750b727061e6a7ac005267852)

/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 *
 * $FreeBSD$
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)ttyname.c	8.2 (Berkeley) 1/27/94";
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <paths.h>
#include <pthread.h>
#include "un-namespace.h"

#include <db.h>
#include "libc_private.h"

static char buf[sizeof(_PATH_DEV) + MAXNAMLEN] = _PATH_DEV;
static char *oldttyname __P((int, struct stat *));
static char *ttyname_threaded(int fd);
static char *ttyname_unthreaded(int fd);

static pthread_mutex_t	ttyname_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_key_t	ttyname_key;
static int		ttyname_init = 0;

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

	if (__isthreaded == 0)
		ret = ttyname_unthreaded(fd);
	else
		ret = ttyname_threaded(fd);
	return (ret);
}

char *
ttyname_r(int fd, char *buf, size_t len)
{
	struct dirent	*dirp;
	DIR		*dp;
	struct stat	dsb;
	struct stat	sb;
	char		*rval;
	int		minlen;

	rval = NULL;

	/* Must be a terminal. */
	if (!isatty(fd))
		return (rval);
	/* Must be a character device. */
	if (_fstat(fd, &sb) || !S_ISCHR(sb.st_mode))
		return (rval);
	/* Must have enough room */
	if (len <= sizeof(_PATH_DEV))
		return (rval);

	if ((dp = opendir(_PATH_DEV)) != NULL) {
		memcpy(buf, _PATH_DEV, sizeof(_PATH_DEV));
		for (rval = NULL; (dirp = readdir(dp)) != NULL;) {
			if (dirp->d_fileno != sb.st_ino)
				continue;
			minlen = (len - (sizeof(_PATH_DEV) - 1)) < (dirp->d_namlen + 1) ?
				(len - (sizeof(_PATH_DEV) - 1)) : (dirp->d_namlen + 1);
			memcpy(buf + sizeof(_PATH_DEV) - 1, dirp->d_name, minlen);
			if (stat(buf, &dsb) || sb.st_dev != dsb.st_dev ||
			    sb.st_ino != dsb.st_ino)
				continue;
			rval = buf;
			break;
		}
		(void) closedir(dp);
	}
	return (rval);
}

static char *
ttyname_threaded(int fd)
{
	char	*buf;

	if (ttyname_init == 0) {
		_pthread_mutex_lock(&ttyname_lock);
		if (ttyname_init == 0) {
			if (_pthread_key_create(&ttyname_key, free)) {
				_pthread_mutex_unlock(&ttyname_lock);
				return (NULL);
			}
			ttyname_init = 1;
		}
		_pthread_mutex_unlock(&ttyname_lock);
	}

	/* Must have thread specific data field to put data */
	if ((buf = _pthread_getspecific(ttyname_key)) == NULL) {
		if ((buf = malloc(sizeof(_PATH_DEV) + MAXNAMLEN)) != NULL) {
			if (_pthread_setspecific(ttyname_key, buf) != 0) {
				free(buf);
				return (NULL);
			}
		} else {
			return (NULL);
		}
	}
	return (ttyname_r(fd, buf, sizeof(_PATH_DEV) + MAXNAMLEN));
}

static char *
ttyname_unthreaded(int fd)
{
	struct stat	sb;
	struct termios	ttyb;
	DB		*db;
	DBT		data, key;
	struct {
		mode_t type;
		dev_t dev;
	} bkey;

	/* Must be a terminal. */
	if (tcgetattr(fd, &ttyb) < 0)
		return (NULL);
	/* Must be a character device. */
	if (_fstat(fd, &sb) || !S_ISCHR(sb.st_mode))
		return (NULL);

	if ( (db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL)) ) {
		memset(&bkey, 0, sizeof(bkey));
		bkey.type = S_IFCHR;
		bkey.dev = sb.st_rdev;
		key.data = &bkey;
		key.size = sizeof(bkey);
		if (!(db->get)(db, &key, &data, 0)) {
			bcopy(data.data,
			    buf + sizeof(_PATH_DEV) - 1, data.size);
			(void)(db->close)(db);
			return (buf);
		}
		(void)(db->close)(db);
	}
	return (oldttyname(fd, &sb));
}

static char *
oldttyname(int fd, struct stat *sb)
{
	struct dirent	*dirp;
	struct stat	dsb;
	DIR 		*dp;

	if ((dp = opendir(_PATH_DEV)) == NULL)
		return (NULL);

	while ( (dirp = readdir(dp)) ) {
		if (dirp->d_fileno != sb->st_ino)
			continue;
		bcopy(dirp->d_name, buf + sizeof(_PATH_DEV) - 1,
		    dirp->d_namlen + 1);
		if (stat(buf, &dsb) || sb->st_dev != dsb.st_dev ||
		    sb->st_ino != dsb.st_ino)
			continue;
		(void)closedir(dp);
		return (buf);
	}
	(void)closedir(dp);
	return (NULL);
}