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ttyname.c revision 1.17 
      1 /*	$NetBSD: ttyname.c,v 1.17 1999/09/20 04:39:06 lukem 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. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)ttyname.c	8.2 (Berkeley) 1/27/94";
     40 #else
     41 __RCSID("$NetBSD: ttyname.c,v 1.17 1999/09/20 04:39:06 lukem Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include "namespace.h"
     46 #include <sys/types.h>
     47 #include <sys/stat.h>
     48 
     49 #include <assert.h>
     50 #include <db.h>
     51 #include <dirent.h>
     52 #include <errno.h>
     53 #include <fcntl.h>
     54 #include <paths.h>
     55 #include <string.h>
     56 #include <termios.h>
     57 #include <unistd.h>
     58 
     59 #ifdef __weak_alias
     60 __weak_alias(ttyname,_ttyname);
     61 #endif
     62 
     63 static char buf[sizeof(_PATH_DEV) + MAXNAMLEN] = _PATH_DEV;
     64 static char *oldttyname __P((struct stat *));
     65 
     66 char *
     67 ttyname(fd)
     68 	int fd;
     69 {
     70 	struct stat sb;
     71 	struct termios ttyb;
     72 	DB *db;
     73 	DBT data, key;
     74 	struct {
     75 		mode_t type;
     76 		dev_t dev;
     77 	} bkey;
     78 
     79 	_DIAGASSERT(fd != -1);
     80 
     81 	/* Must be a terminal. */
     82 	if (tcgetattr(fd, &ttyb) < 0)
     83 		return (NULL);
     84 	/* Must be a character device. */
     85 	if (fstat(fd, &sb) || !S_ISCHR(sb.st_mode))
     86 		return (NULL);
     87 
     88 	if ((db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL)) != NULL) {
     89 		memset(&bkey, 0, sizeof(bkey));
     90 		bkey.type = S_IFCHR;
     91 		bkey.dev = sb.st_rdev;
     92 		key.data = &bkey;
     93 		key.size = sizeof(bkey);
     94 		if (!(db->get)(db, &key, &data, 0)) {
     95 			memmove(buf + sizeof(_PATH_DEV) - 1, data.data,
     96 			    data.size);
     97 			(void)(db->close)(db);
     98 			return (buf);
     99 		}
    100 		(void)(db->close)(db);
    101 	}
    102 	return (oldttyname(&sb));
    103 }
    104 
    105 static char *
    106 oldttyname(sb)
    107 	struct stat *sb;
    108 {
    109 	struct dirent *dirp;
    110 	DIR *dp;
    111 	struct stat dsb;
    112 
    113 	_DIAGASSERT(sb != NULL);
    114 
    115 	if ((dp = opendir(_PATH_DEV)) == NULL)
    116 		return (NULL);
    117 
    118 	while ((dirp = readdir(dp)) != NULL) {
    119 		if (dirp->d_fileno != sb->st_ino)
    120 			continue;
    121 		memmove(buf + sizeof(_PATH_DEV) - 1, dirp->d_name,
    122 		    (size_t)(dirp->d_namlen + 1));
    123 		if (stat(buf, &dsb) || sb->st_dev != dsb.st_dev ||
    124 		    sb->st_ino != dsb.st_ino)
    125 			continue;
    126 		(void)closedir(dp);
    127 		return (buf);
    128 	}
    129 	(void)closedir(dp);
    130 	return (NULL);
    131 }
    132