1 /* $NetBSD: devname.c,v 1.22 2012/06/03 21:42:46 joerg 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 1.22 2012/06/03 21:42:46 joerg Exp $");
34
35 #include "namespace.h"
36 #include "reentrant.h"
37 #include <sys/stat.h>
38
39 #include <cdbr.h>
40 #include <errno.h>
41 #include <fts.h>
42 #include <limits.h>
43 #include <paths.h>
44 #include <stdio.h>
45 #include <string.h>
46 #include <stdlib.h>
47
48 #ifdef __minix
49 #include <minix/dmap.h> /* for UNIX98_MINOR */
50 #endif /* __minix */
51
52 #ifdef __weak_alias
53 __weak_alias(devname_r,_devname_r)
54 #endif
55
56 static once_t db_opened = ONCE_INITIALIZER;
57 static struct cdbr *db;
58 static devmajor_t pts;
59
60 static void
devname_dbopen(void)61 devname_dbopen(void)
62 {
63 db = cdbr_open(_PATH_DEVCDB, CDBR_DEFAULT);
64 pts = getdevmajor("pts", S_IFCHR);
65 }
66
67 __CTASSERT(sizeof(dev_t) == 8);
68
69 static int
devname_dblookup(dev_t dev,mode_t type,char * path,size_t len)70 devname_dblookup(dev_t dev, mode_t type, char *path, size_t len)
71 {
72 const void *data;
73 size_t datalen;
74 uint8_t key[10];
75
76 le64enc(key, dev);
77 le16enc(key + 8, type);
78 if (cdbr_find(db, key, sizeof(key), &data, &datalen) != 0)
79 return ENOENT;
80 if (datalen <= sizeof(key))
81 return ENOENT;
82 if (memcmp(key, data, sizeof(key)) != 0)
83 return ENOENT;
84 data = (const char *)data + sizeof(key);
85 datalen -= sizeof(key);
86 if (memchr(data, '\0', datalen) != (const char *)data + datalen - 1)
87 return ENOENT;
88 if (datalen > len)
89 return ERANGE;
90 memcpy(path, data, datalen);
91 return 0;
92 }
93
94 static int
devname_ptslookup(dev_t dev,mode_t type,char * path,size_t len)95 devname_ptslookup(dev_t dev, mode_t type, char *path, size_t len)
96 {
97 int rv;
98
99 if (type != S_IFCHR || pts == NODEVMAJOR || major(dev) != pts)
100 return ENOENT;
101 #ifdef __minix
102 /*
103 * MINIX3 does not use an identity mapping for /dev/pts, because the
104 * same major number is also used for PTY masters and legacy PTYs.
105 */
106 if (minor(dev) < UNIX98_MINOR || !(minor(dev) & 1))
107 return ENOENT;
108 #endif /* __minix */
109
110 rv = snprintf(path, len, "%s%d", _PATH_DEV_PTS + sizeof(_PATH_DEV) - 1,
111 #ifndef __minix
112 minor(dev));
113 #else /* __minix */
114 (minor(dev) - UNIX98_MINOR) >> 1);
115 #endif /* __minix */
116 if (rv < 0 || (size_t)rv >= len)
117 return ERANGE;
118 return 0;
119 }
120
121 static int
devname_fts(dev_t dev,mode_t type,char * path,size_t len)122 devname_fts(dev_t dev, mode_t type, char *path, size_t len)
123 {
124 FTS *ftsp;
125 FTSENT *fe;
126 static const char path_dev[] = _PATH_DEV;
127 static char * const dirs[2] = { __UNCONST(path_dev), NULL };
128 const size_t len_dev = strlen(path_dev);
129 int rv;
130
131 if ((ftsp = fts_open(dirs, FTS_NOCHDIR | FTS_PHYSICAL, NULL)) == NULL)
132 return ENOENT;
133
134 rv = ENOENT;
135 while ((fe = fts_read(ftsp)) != NULL) {
136 if (fe->fts_info != FTS_DEFAULT)
137 continue;
138 if (fe->fts_statp->st_rdev != dev)
139 continue;
140 if ((type & S_IFMT) != (fe->fts_statp->st_mode & S_IFMT))
141 continue;
142 if (strncmp(fe->fts_path, path_dev, len_dev))
143 continue;
144 if (strlcpy(path, fe->fts_path + len_dev, len) < len) {
145 rv = 0;
146 break;
147 }
148 }
149
150 fts_close(ftsp);
151 return rv;
152 }
153
154 int
devname_r(dev_t dev,mode_t type,char * path,size_t len)155 devname_r(dev_t dev, mode_t type, char *path, size_t len)
156 {
157 int rv;
158
159 thr_once(&db_opened, devname_dbopen);
160
161 if (db != NULL) {
162 rv = devname_dblookup(dev, type, path, len);
163 if (rv == 0 || rv == ERANGE)
164 return rv;
165 }
166
167 rv = devname_ptslookup(dev, type, path, len);
168 if (rv == 0 || rv == ERANGE)
169 return rv;
170
171 if (db != NULL)
172 return ENOENT;
173 rv = devname_fts(dev, type, path, len);
174 return rv;
175 }
176
177 char *
devname(dev_t dev,mode_t type)178 devname(dev_t dev, mode_t type)
179 {
180 static char path[PATH_MAX];
181
182 return devname_r(dev, type, path, sizeof(path)) == 0 ? path : NULL;
183 }
184