/*      $OpenBSD: ttyname.c,v 1.22 2026/03/09 12:22:44 deraadt Exp $ */
/*
 * 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/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <db.h>
#include <string.h>
#include <unistd.h>
#include <paths.h>
#include <limits.h>
#include <errno.h>
#include "thread_private.h"

static char buf[TTY_NAME_MAX];
static int oldttyname(struct stat *, char *, size_t);

char *
ttyname(int fd)
{
        _THREAD_PRIVATE_KEY(ttyname);
        char *bufp = (char *) _THREAD_PRIVATE(ttyname, buf, NULL);
        int err;

        if (bufp == NULL)
                return NULL;

        err = ttyname_r(fd, bufp, sizeof buf);
        if (err) {
                errno = err;
                return NULL;
        }

        return bufp;
}
DEF_WEAK(ttyname);

int
ttyname_r(int fd, char *buf, size_t len)
{
        struct stat sb;
        DB *db;
        DBT data, key;
        struct {
                mode_t type;
                dev_t dev;
        } bkey;

        /* Must be a terminal. */
        if (!isatty(fd))
                return (errno);
        /* Must be a character device. */
        if (fstat(fd, &sb))
                return (errno);
        if (!S_ISCHR(sb.st_mode))
                return (ENOTTY);
        if (len < sizeof(_PATH_DEV))
                return (ERANGE);

        memcpy(buf, _PATH_DEV, sizeof(_PATH_DEV));

        if ((db = __hash_open(_PATH_DEVDB, -1, O_RDONLY, 0, NULL, 0))) {
                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)) {
                        if (data.size > len - (sizeof(_PATH_DEV) - 1)) {
                                (void)(db->close)(db);
                                return (ERANGE);
                        }
                        memcpy(buf + sizeof(_PATH_DEV) - 1, data.data,
                            data.size);
                        (void)(db->close)(db);
                        return (0);
                }
                (void)(db->close)(db);
        }
        return (oldttyname(&sb, buf, len));
}
DEF_WEAK(ttyname_r);

static int
oldttyname(struct stat *sb, char *buf, size_t len)
{
        struct dirent *dirp;
        DIR *dp;
        struct stat dsb;
        int error = ENOTTY;

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

        while ((dirp = readdir(dp))) {
                if (dirp->d_type != DT_CHR && dirp->d_type != DT_UNKNOWN)
                        continue;
                if (fstatat(dirfd(dp), dirp->d_name, &dsb, AT_SYMLINK_NOFOLLOW)
                    || !S_ISCHR(dsb.st_mode) || sb->st_rdev != dsb.st_rdev)
                        continue;
                if (dirp->d_namlen > len - sizeof(_PATH_DEV)) {
                        error = ERANGE;
                } else {
                        memcpy(buf + sizeof(_PATH_DEV) - 1, dirp->d_name,
                            dirp->d_namlen + 1);
                        error = 0;
                }
                break;
        }
        (void)closedir(dp);
        return (error);
}