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      1 /*	$NetBSD: devname.c,v 1.24 2025/12/16 12:39:02 nia Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2012 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  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __RCSID("$NetBSD: devname.c,v 1.24 2025/12/16 12:39:02 nia Exp $");
     34 
     35 #include "namespace.h"
     36 #include "reentrant.h"
     37 #include <sys/stat.h>
     38 #include <sys/endian.h>
     39 
     40 #include <cdbr.h>
     41 #include <errno.h>
     42 #include <fts.h>
     43 #include <limits.h>
     44 #include <paths.h>
     45 #include <stdio.h>
     46 #include <string.h>
     47 #include <stdlib.h>
     48 
     49 #ifdef __weak_alias
     50 __weak_alias(devname_r,_devname_r)
     51 #endif
     52 
     53 static once_t db_opened = ONCE_INITIALIZER;
     54 static struct cdbr *db;
     55 static devmajor_t pts;
     56 
     57 static void
     58 devname_dbopen(void)
     59 {
     60 	db = cdbr_open(_PATH_DEVCDB, CDBR_DEFAULT);
     61 	pts = getdevmajor("pts", S_IFCHR);
     62 }
     63 
     64 __CTASSERT(sizeof(dev_t) == 8);
     65 
     66 static int
     67 devname_dblookup(dev_t dev, mode_t type, char *path, size_t len)
     68 {
     69 	const void *data;
     70 	size_t datalen;
     71 	uint8_t key[10];
     72 
     73 	le64enc(key, dev);
     74 	le16enc(key + 8, type);
     75 	if (cdbr_find(db, key, sizeof(key), &data, &datalen) != 0)
     76 		return ENOENT;
     77 	if (datalen <= sizeof(key))
     78 		return ENOENT;
     79 	if (memcmp(key, data, sizeof(key)) != 0)
     80 		return ENOENT;
     81 	data = (const char *)data + sizeof(key);
     82 	datalen -= sizeof(key);
     83 	if (memchr(data, '\0', datalen) != (const char *)data + datalen - 1)
     84 		return ENOENT;
     85 	if (datalen > len)
     86 		return ERANGE;
     87 	memcpy(path, data, datalen);
     88 	return 0;
     89 }
     90 
     91 static int
     92 devname_ptslookup(dev_t dev, mode_t type, char *path, size_t len)
     93 {
     94 	int rv;
     95 
     96 	if (type != S_IFCHR || pts == NODEVMAJOR || major(dev) != pts)
     97 		return ENOENT;
     98 
     99 	rv = snprintf(path, len, "%s%d", &_PATH_DEV_PTS[sizeof(_PATH_DEV) - 1],
    100 	    minor(dev));
    101 	if (rv < 0 || (size_t)rv >= len)
    102 		return ERANGE;
    103 	return 0;
    104 }
    105 
    106 static int
    107 devname_fts(dev_t dev, mode_t type, char *path, size_t len)
    108 {
    109 	FTS *ftsp;
    110 	FTSENT *fe;
    111 	static const char path_dev[] = _PATH_DEV;
    112 	static char * const dirs[2] = { __UNCONST(path_dev), NULL };
    113 	const size_t len_dev = strlen(path_dev);
    114 	int rv;
    115 
    116 	if ((ftsp = fts_open(dirs, FTS_NOCHDIR | FTS_PHYSICAL, NULL)) == NULL)
    117 		return ENOENT;
    118 
    119 	rv = ENOENT;
    120 	while ((fe = fts_read(ftsp)) != NULL) {
    121 		if (fe->fts_info != FTS_DEFAULT)
    122 			continue;
    123 		if (fe->fts_statp->st_rdev != dev)
    124 			continue;
    125 		if ((type & S_IFMT) != (fe->fts_statp->st_mode & S_IFMT))
    126 			continue;
    127 		if (strncmp(fe->fts_path, path_dev, len_dev))
    128 			continue;
    129 		if (strlcpy(path, fe->fts_path + len_dev, len) < len) {
    130 			rv = 0;
    131 			break;
    132 		}
    133 	}
    134 
    135 	fts_close(ftsp);
    136 	return rv;
    137 }
    138 
    139 int
    140 devname_r(dev_t dev, mode_t type, char *path, size_t len)
    141 {
    142 	int rv;
    143 
    144 	thr_once(&db_opened, devname_dbopen);
    145 
    146 	if (db != NULL) {
    147 		rv = devname_dblookup(dev, type, path, len);
    148 		if (rv == 0 || rv == ERANGE)
    149 			return rv;
    150 	}
    151 
    152 	rv = devname_ptslookup(dev, type, path, len);
    153 	if (rv == 0 || rv == ERANGE)
    154 		return rv;
    155 
    156 	if (db != NULL)
    157 		return ENOENT;
    158 	rv = devname_fts(dev, type, path, len);
    159 	return rv;
    160 }
    161 
    162 char *
    163 devname(dev_t dev, mode_t type)
    164 {
    165 	static char path[PATH_MAX];
    166 
    167 	return devname_r(dev, type, path, sizeof(path)) == 0 ? path : NULL;
    168 }
    169