1 /* $OpenBSD: devname.c,v 1.14 2024/01/22 17:22:58 deraadt Exp $ */ 2 /* 3 * Copyright (c) 1989, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/stat.h> 32 #include <sys/types.h> 33 34 #include <db.h> 35 #include <dirent.h> 36 #include <fcntl.h> 37 #include <limits.h> 38 #include <paths.h> 39 #include <stdbool.h> 40 #include <string.h> 41 #include <stdlib.h> 42 43 static char * 44 devname_nodb(dev_t dev, mode_t type) 45 { 46 static char buf[NAME_MAX + 1]; 47 char *name = NULL; 48 struct dirent *dp; 49 struct stat sb; 50 DIR *dirp; 51 52 if ((dirp = opendir(_PATH_DEV)) == NULL) 53 return (NULL); 54 while ((dp = readdir(dirp)) != NULL) { 55 if (dp->d_type != DT_UNKNOWN && DTTOIF(dp->d_type) != type) 56 continue; 57 if (fstatat(dirfd(dirp), dp->d_name, &sb, AT_SYMLINK_NOFOLLOW) 58 || sb.st_rdev != dev || (sb.st_mode & S_IFMT) != type) 59 continue; 60 strlcpy(buf, dp->d_name, sizeof(buf)); 61 name = buf; 62 break; 63 } 64 closedir(dirp); 65 return (name); 66 } 67 68 /* 69 * Keys in dev.db are a mode_t followed by a dev_t. The former is the 70 * type of the file (mode & S_IFMT), the latter is the st_rdev field. 71 * Note that the structure may contain padding. 72 */ 73 char * 74 devname(dev_t dev, mode_t type) 75 { 76 static DB *db; 77 static bool failure; 78 struct { 79 mode_t type; 80 dev_t dev; 81 } bkey; 82 DBT data, key; 83 char *name = NULL; 84 85 if (!db && !failure) { 86 if (!(db = __hash_open(_PATH_DEVDB, O_RDONLY, 0, NULL, 0))) 87 failure = true; 88 } 89 if (!failure) { 90 /* Be sure to clear any padding that may be found in bkey. */ 91 memset(&bkey, 0, sizeof(bkey)); 92 bkey.dev = dev; 93 bkey.type = type; 94 key.data = &bkey; 95 key.size = sizeof(bkey); 96 if ((db->get)(db, &key, &data, 0) == 0) 97 name = data.data; 98 } else { 99 name = devname_nodb(dev, type); 100 } 101 return (name ? name : "??"); 102 } 103 DEF_WEAK(devname); 104