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devname.c revision 1.9
      1 /*	$NetBSD: devname.c,v 1.9 2000/06/05 06:12:49 simonb Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2000 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Simon Burge.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 /*-
     40  * Copyright (c) 1992 Keith Muller.
     41  * Copyright (c) 1989, 1993
     42  *	The Regents of the University of California.  All rights reserved.
     43  *
     44  * This code is derived from software contributed to Berkeley by
     45  * Keith Muller of the University of California, San Diego.
     46  *
     47  * Redistribution and use in source and binary forms, with or without
     48  * modification, are permitted provided that the following conditions
     49  * are met:
     50  * 1. Redistributions of source code must retain the above copyright
     51  *    notice, this list of conditions and the following disclaimer.
     52  * 2. Redistributions in binary form must reproduce the above copyright
     53  *    notice, this list of conditions and the following disclaimer in the
     54  *    documentation and/or other materials provided with the distribution.
     55  * 3. All advertising materials mentioning features or use of this software
     56  *    must display the following acknowledgement:
     57  *	This product includes software developed by the University of
     58  *	California, Berkeley and its contributors.
     59  * 4. Neither the name of the University nor the names of its contributors
     60  *    may be used to endorse or promote products derived from this software
     61  *    without specific prior written permission.
     62  *
     63  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     64  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     65  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     66  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     67  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     68  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     69  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     70  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     71  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     72  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     73  * SUCH DAMAGE.
     74  */
     75 
     76 #include <sys/cdefs.h>
     77 #if defined(LIBC_SCCS) && !defined(lint)
     78 #if 0
     79 static char sccsid[] = "@(#)devname.c	8.2 (Berkeley) 4/29/95";
     80 #else
     81 __RCSID("$NetBSD: devname.c,v 1.9 2000/06/05 06:12:49 simonb Exp $");
     82 #endif
     83 #endif /* LIBC_SCCS and not lint */
     84 
     85 #include "namespace.h"
     86 #include <sys/types.h>
     87 
     88 #include <db.h>
     89 #include <fcntl.h>
     90 #include <paths.h>
     91 #include <stdio.h>
     92 #include <string.h>
     93 #include <stdlib.h>
     94 #include <err.h>
     95 
     96 #ifdef __weak_alias
     97 __weak_alias(devname,_devname)
     98 #endif
     99 
    100 #define	DEV_SZ		317	/* show be prime for best results */
    101 #define	VALID		1	/* entry and devname are valid */
    102 #define	INVALID		2	/* entry valid, devname NOT valid */
    103 
    104 typedef struct devc {
    105 	int valid;		/* entry valid? */
    106 	dev_t dev;		/* cached device */
    107 	mode_t type;		/* cached file type */
    108 	char name[NAME_MAX];	/* device name */
    109 } DEVC;
    110 
    111 char *
    112 devname(dev, type)
    113 	dev_t dev;
    114 	mode_t type;
    115 {
    116 	struct {
    117 		mode_t type;
    118 		dev_t dev;
    119 	} bkey;
    120 	static DB *db;
    121 	static int failure;
    122 	DBT data, key;
    123 	DEVC *ptr, **pptr;
    124 	static DEVC **devtb = NULL;
    125 
    126 	if (!db && !failure &&
    127 	    !(db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL))) {
    128 		warn("warning: %s", _PATH_DEVDB);
    129 		failure = 1;
    130 	}
    131 	/* initialise dev cache */
    132 	if (!failure && devtb == NULL) {
    133 		devtb = (DEVC **)calloc(DEV_SZ, sizeof(DEVC *));
    134 		if (devtb == NULL)
    135 			failure= 1;
    136 	}
    137 	if (failure)
    138 		return (NULL);
    139 
    140 	/* see if we have this dev/type cached */
    141 	pptr = devtb + ((dev + type) % DEV_SZ);
    142 	ptr = *pptr;
    143 
    144 	if (ptr && ptr->valid > 0 && ptr->dev == dev && ptr->type == type) {
    145 		if (ptr->valid == VALID)
    146 			return (ptr->name);
    147 		return (NULL);
    148 	}
    149 
    150 	if (ptr == NULL)
    151 		*pptr = ptr = (DEVC *)malloc(sizeof(DEVC));
    152 
    153 	/*
    154 	 * Keys are a mode_t followed by a dev_t.  The former is the type of
    155 	 * the file (mode & S_IFMT), the latter is the st_rdev field.  Be
    156 	 * sure to clear any padding that may be found in bkey.
    157 	 */
    158 	memset(&bkey, 0, sizeof(bkey));
    159 	bkey.dev = dev;
    160 	bkey.type = type;
    161 	key.data = &bkey;
    162 	key.size = sizeof(bkey);
    163 	if ((db->get)(db, &key, &data, 0) == 0) {
    164 		if (ptr == NULL)
    165 			return (char *)data.data;
    166 		ptr->dev = dev;
    167 		ptr->type = type;
    168 		strncpy(ptr->name, (char *)data.data, NAME_MAX);
    169 		ptr->name[NAME_MAX - 1] = '\0';
    170 		ptr->valid = VALID;
    171 		return (ptr->name);
    172 	} else {
    173 		if (ptr == NULL)
    174 			return (NULL);
    175 		ptr->dev = dev;
    176 		ptr->type = type;
    177 		ptr->valid = INVALID;
    178 		return (NULL);
    179 	}
    180 }
    181