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ttyname.c revision 1.20 
      1 /*	$NetBSD: ttyname.c,v 1.20 2004/11/11 00:00:15 christos 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 1.20 2004/11/11 00:00:15 christos Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <sys/types.h>
     43 #include <sys/stat.h>
     44 
     45 #include <assert.h>
     46 #include <db.h>
     47 #include <dirent.h>
     48 #include <errno.h>
     49 #include <fcntl.h>
     50 #include <paths.h>
     51 #include <string.h>
     52 #include <termios.h>
     53 #include <unistd.h>
     54 #include <sys/ioctl.h>
     55 
     56 #ifdef __weak_alias
     57 __weak_alias(ttyname,_ttyname)
     58 #endif
     59 
     60 static char buf[sizeof(_PATH_DEV) + MAXNAMLEN] = _PATH_DEV;
     61 static struct ptmget ptm;
     62 static char *oldttyname __P((struct stat *));
     63 
     64 char *
     65 ttyname(fd)
     66 	int fd;
     67 {
     68 	struct stat sb;
     69 	struct termios ttyb;
     70 	DB *db;
     71 	DBT data, key;
     72 	struct {
     73 		mode_t type;
     74 		dev_t dev;
     75 	} bkey;
     76 
     77 	_DIAGASSERT(fd != -1);
     78 
     79 	/* If it is a pty, deal with it quickly */
     80 	if (ioctl(fd, TIOCPTSNAME, &ptm) != -1)
     81 		return ptm.sn;
     82 
     83 	/* Must be a terminal. */
     84 	if (tcgetattr(fd, &ttyb) < 0)
     85 		return (NULL);
     86 	/* Must be a character device. */
     87 	if (fstat(fd, &sb) || !S_ISCHR(sb.st_mode))
     88 		return (NULL);
     89 
     90 	if ((db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL)) != NULL) {
     91 		memset(&bkey, 0, sizeof(bkey));
     92 		bkey.type = S_IFCHR;
     93 		bkey.dev = sb.st_rdev;
     94 		key.data = &bkey;
     95 		key.size = sizeof(bkey);
     96 		if (!(db->get)(db, &key, &data, 0)) {
     97 			memmove(buf + sizeof(_PATH_DEV) - 1, data.data,
     98 			    data.size);
     99 			(void)(db->close)(db);
    100 			return (buf);
    101 		}
    102 		(void)(db->close)(db);
    103 	}
    104 	return (oldttyname(&sb));
    105 }
    106 
    107 static char *
    108 oldttyname(sb)
    109 	struct stat *sb;
    110 {
    111 	struct dirent *dirp;
    112 	DIR *dp;
    113 	struct stat dsb;
    114 
    115 	_DIAGASSERT(sb != NULL);
    116 
    117 	if ((dp = opendir(_PATH_DEV)) == NULL)
    118 		return (NULL);
    119 
    120 	while ((dirp = readdir(dp)) != NULL) {
    121 		if (dirp->d_fileno != sb->st_ino)
    122 			continue;
    123 		memmove(buf + sizeof(_PATH_DEV) - 1, dirp->d_name,
    124 		    (size_t)(dirp->d_namlen + 1));
    125 		if (stat(buf, &dsb) || sb->st_dev != dsb.st_dev ||
    126 		    sb->st_ino != dsb.st_ino)
    127 			continue;
    128 		(void)closedir(dp);
    129 		return (buf);
    130 	}
    131 	(void)closedir(dp);
    132 	return (NULL);
    133 }
    134