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ttyname.c revision 1.19 
      1 /*	$NetBSD: ttyname.c,v 1.19 2003/08/07 16:42:58 agc 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 1.19 2003/08/07 16:42:58 agc 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 
     55 #ifdef __weak_alias
     56 __weak_alias(ttyname,_ttyname)
     57 #endif
     58 
     59 static char buf[sizeof(_PATH_DEV) + MAXNAMLEN] = _PATH_DEV;
     60 static char *oldttyname __P((struct stat *));
     61 
     62 char *
     63 ttyname(fd)
     64 	int fd;
     65 {
     66 	struct stat sb;
     67 	struct termios ttyb;
     68 	DB *db;
     69 	DBT data, key;
     70 	struct {
     71 		mode_t type;
     72 		dev_t dev;
     73 	} bkey;
     74 
     75 	_DIAGASSERT(fd != -1);
     76 
     77 	/* Must be a terminal. */
     78 	if (tcgetattr(fd, &ttyb) < 0)
     79 		return (NULL);
     80 	/* Must be a character device. */
     81 	if (fstat(fd, &sb) || !S_ISCHR(sb.st_mode))
     82 		return (NULL);
     83 
     84 	if ((db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL)) != NULL) {
     85 		memset(&bkey, 0, sizeof(bkey));
     86 		bkey.type = S_IFCHR;
     87 		bkey.dev = sb.st_rdev;
     88 		key.data = &bkey;
     89 		key.size = sizeof(bkey);
     90 		if (!(db->get)(db, &key, &data, 0)) {
     91 			memmove(buf + sizeof(_PATH_DEV) - 1, data.data,
     92 			    data.size);
     93 			(void)(db->close)(db);
     94 			return (buf);
     95 		}
     96 		(void)(db->close)(db);
     97 	}
     98 	return (oldttyname(&sb));
     99 }
    100 
    101 static char *
    102 oldttyname(sb)
    103 	struct stat *sb;
    104 {
    105 	struct dirent *dirp;
    106 	DIR *dp;
    107 	struct stat dsb;
    108 
    109 	_DIAGASSERT(sb != NULL);
    110 
    111 	if ((dp = opendir(_PATH_DEV)) == NULL)
    112 		return (NULL);
    113 
    114 	while ((dirp = readdir(dp)) != NULL) {
    115 		if (dirp->d_fileno != sb->st_ino)
    116 			continue;
    117 		memmove(buf + sizeof(_PATH_DEV) - 1, dirp->d_name,
    118 		    (size_t)(dirp->d_namlen + 1));
    119 		if (stat(buf, &dsb) || sb->st_dev != dsb.st_dev ||
    120 		    sb->st_ino != dsb.st_ino)
    121 			continue;
    122 		(void)closedir(dp);
    123 		return (buf);
    124 	}
    125 	(void)closedir(dp);
    126 	return (NULL);
    127 }
    128