usr/src/lib/libc/gen/ttyname.c

/*
 * 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)ttyname.c   8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <sgtty.h>
#include <db.h>
#include <string.h>
#include <paths.h>

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

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

        /* Must be a terminal. */
        if (ioctl(fd, TIOCGETP, &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)) {
                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(fd, sb)
        int fd;
        struct stat *sb;
{
        register struct dirent *dirp;
        register DIR *dp;
        struct stat dsb;

        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);
}