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devname.c revision 1.8 
      1 /*	$NetBSD: devname.c,v 1.8 2000/01/22 22:19:09 mycroft Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 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[] = "@(#)devname.c	8.2 (Berkeley) 4/29/95";
     40 #else
     41 __RCSID("$NetBSD: devname.c,v 1.8 2000/01/22 22:19:09 mycroft Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include "namespace.h"
     46 #include <sys/types.h>
     47 
     48 #include <db.h>
     49 #include <errno.h>
     50 #include <fcntl.h>
     51 #include <paths.h>
     52 #include <stdio.h>
     53 #include <string.h>
     54 #include <stdlib.h>
     55 #include <err.h>
     56 
     57 #ifdef __weak_alias
     58 __weak_alias(devname,_devname)
     59 #endif
     60 
     61 char *
     62 devname(dev, type)
     63 	dev_t dev;
     64 	mode_t type;
     65 {
     66 	struct {
     67 		mode_t type;
     68 		dev_t dev;
     69 	} bkey;
     70 	static DB *db;
     71 	static int failure;
     72 	DBT data, key;
     73 
     74 	if (!db && !failure &&
     75 	    !(db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL))) {
     76 		warn("warning: %s", _PATH_DEVDB);
     77 		failure = 1;
     78 	}
     79 	if (failure)
     80 		return (NULL);
     81 
     82 	/*
     83 	 * Keys are a mode_t followed by a dev_t.  The former is the type of
     84 	 * the file (mode & S_IFMT), the latter is the st_rdev field.  Be
     85 	 * sure to clear any padding that may be found in bkey.
     86 	 */
     87 	memset(&bkey, 0, sizeof(bkey));
     88 	bkey.dev = dev;
     89 	bkey.type = type;
     90 	key.data = &bkey;
     91 	key.size = sizeof(bkey);
     92 	return ((db->get)(db, &key, &data, 0) ? NULL : (char *)data.data);
     93 }
     94