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      1 /*	$NetBSD: ttyname.c,v 1.26 2012/06/12 18:17:04 joerg Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1988, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)ttyname.c	8.2 (Berkeley) 1/27/94";
     36 #else
     37 __RCSID("$NetBSD: ttyname.c,v 1.26 2012/06/12 18:17:04 joerg Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <sys/ioctl.h>
     43 #include <sys/stat.h>
     44 
     45 #include <assert.h>
     46 #include <errno.h>
     47 #include <limits.h>
     48 #include <paths.h>
     49 #include <string.h>
     50 #include <stdlib.h>
     51 #include <termios.h>
     52 #include <unistd.h>
     53 
     54 #ifdef __weak_alias
     55 __weak_alias(ttyname,_ttyname)
     56 __weak_alias(ttyname_r,_ttyname_r)
     57 #endif
     58 
     59 int
     60 ttyname_r(int fd, char *buf, size_t len)
     61 {
     62 	struct stat sb;
     63 	struct termios ttyb;
     64 	struct ptmget ptm;
     65 
     66 	_DIAGASSERT(fd != -1);
     67 
     68 	/* If it is a pty, deal with it quickly */
     69 	if (ioctl(fd, TIOCPTSNAME, &ptm) != -1) {
     70 		if (strlcpy(buf, ptm.sn, len) >= len) {
     71 			return ERANGE;
     72 		}
     73 		return 0;
     74 	}
     75 
     76 	/* Must be a terminal. */
     77 	if (tcgetattr(fd, &ttyb) == -1)
     78 		return errno;
     79 
     80 	if (fstat(fd, &sb))
     81 		return errno;
     82 
     83 	if (strlcpy(buf, _PATH_DEV, len) >= len)
     84 		return ERANGE;
     85 	buf += strlen(_PATH_DEV);
     86 	len -= strlen(_PATH_DEV);
     87 	return devname_r(sb.st_rdev, sb.st_mode & S_IFMT, buf, len);
     88 }
     89 
     90 char *
     91 ttyname(int fd)
     92 {
     93 	static char buf[PATH_MAX];
     94 	int rv;
     95 
     96 	rv = ttyname_r(fd, buf, sizeof(buf));
     97 	if (rv != 0) {
     98 		errno = rv;
     99 		return NULL;
    100 	}
    101 	return buf;
    102 }
    103