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ttyname.c revision 1.5 
      1 /*
      2  * Copyright (c) 1988 The Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 /*static char *sccsid = "from: @(#)ttyname.c	5.10 (Berkeley) 5/6/91";*/
     36 static char *rcsid = "$Id: ttyname.c,v 1.5 1993/08/26 00:45:19 jtc Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include <sys/types.h>
     40 #include <sys/stat.h>
     41 #include <fcntl.h>
     42 #include <dirent.h>
     43 #include <sgtty.h>
     44 #include <db.h>
     45 #include <unistd.h>
     46 #include <paths.h>
     47 
     48 static char buf[sizeof(_PATH_DEV) + MAXNAMLEN] = _PATH_DEV;
     49 
     50 char *
     51 ttyname(fd)
     52 	int fd;
     53 {
     54 	struct stat sb;
     55 	struct sgttyb ttyb;
     56 	DB *db;
     57 	DBT data, key;
     58 	struct {
     59 		mode_t type;
     60 		dev_t dev;
     61 	} bkey;
     62 	static char *__oldttyname();
     63 
     64 	/* Must be a terminal. */
     65 	if (ioctl(fd, TIOCGETP, &ttyb) < 0)
     66 		return(NULL);
     67 	/* Must be a character device. */
     68 	if (fstat(fd, &sb) || !S_ISCHR(sb.st_mode))
     69 		return(NULL);
     70 
     71 	if (db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL)) {
     72 		bkey.type = S_IFCHR;
     73 		bkey.dev = sb.st_rdev;
     74 		key.data = &bkey;
     75 		key.size = sizeof(bkey);
     76 		if (!(db->get)(db, &key, &data, 0)) {
     77 			bcopy(data.data,
     78 			    buf + sizeof(_PATH_DEV) - 1, data.size);
     79 			return(buf);
     80 		}
     81 	}
     82 	return(__oldttyname(fd, &sb));
     83 }
     84 
     85 static char *
     86 __oldttyname(fd, sb)
     87 	int fd;
     88 	struct stat *sb;
     89 {
     90 	register struct dirent *dirp;
     91 	register DIR *dp;
     92 	struct stat dsb;
     93 	char *rval, *strcpy();
     94 
     95 	if ((dp = opendir(_PATH_DEV)) == NULL)
     96 		return(NULL);
     97 
     98 	for (rval = NULL; dirp = readdir(dp);) {
     99 		if (dirp->d_fileno != sb->st_ino)
    100 			continue;
    101 		bcopy(dirp->d_name, buf + sizeof(_PATH_DEV) - 1,
    102 		    dirp->d_namlen + 1);
    103 		if (stat(buf, &dsb) || sb->st_dev != dsb.st_dev ||
    104 		    sb->st_ino != dsb.st_ino)
    105 			continue;
    106 		rval = buf;
    107 		break;
    108 	}
    109 	(void)closedir(dp);
    110 	return(rval);
    111 }
    112