1 /* 2 * devno.c - find a particular device by its device number (major/minor) 3 * 4 * Copyright (C) 2000, 2001, 2003 Theodore Ts'o 5 * Copyright (C) 2001 Andreas Dilger 6 * 7 * %Begin-Header% 8 * This file may be redistributed under the terms of the 9 * GNU Lesser General Public License. 10 * %End-Header% 11 */ 12 13 #include <stdio.h> 14 #include <string.h> 15 #if HAVE_UNISTD_H 16 #include <unistd.h> 17 #endif 18 #include <stdlib.h> 19 #include <string.h> 20 #if HAVE_SYS_TYPES_H 21 #include <sys/types.h> 22 #endif 23 #if HAVE_SYS_STAT_H 24 #include <sys/stat.h> 25 #endif 26 #include <dirent.h> 27 #if HAVE_ERRNO_H 28 #include <errno.h> 29 #endif 30 #if HAVE_SYS_MKDEV_H 31 #include <sys/mkdev.h> 32 #endif 33 34 #include "blkidP.h" 35 36 struct dir_list { 37 char *name; 38 struct dir_list *next; 39 }; 40 41 char *blkid_strndup(const char *s, int length) 42 { 43 char *ret; 44 45 if (!s) 46 return NULL; 47 48 if (!length) 49 length = strlen(s); 50 51 ret = malloc(length + 1); 52 if (ret) { 53 strncpy(ret, s, length); 54 ret[length] = '\0'; 55 } 56 return ret; 57 } 58 59 char *blkid_strdup(const char *s) 60 { 61 return blkid_strndup(s, 0); 62 } 63 64 /* 65 * This function adds an entry to the directory list 66 */ 67 static void add_to_dirlist(const char *name, struct dir_list **list) 68 { 69 struct dir_list *dp; 70 71 dp = malloc(sizeof(struct dir_list)); 72 if (!dp) 73 return; 74 dp->name = blkid_strdup(name); 75 if (!dp->name) { 76 free(dp); 77 return; 78 } 79 dp->next = *list; 80 *list = dp; 81 } 82 83 /* 84 * This function frees a directory list 85 */ 86 static void free_dirlist(struct dir_list **list) 87 { 88 struct dir_list *dp, *next; 89 90 for (dp = *list; dp; dp = next) { 91 next = dp->next; 92 free(dp->name); 93 free(dp); 94 } 95 *list = NULL; 96 } 97 98 static void scan_dir(char *dirname, dev_t devno, struct dir_list **list, 99 char **devname) 100 { 101 DIR *dir; 102 struct dirent *dp; 103 char path[1024]; 104 int dirlen; 105 struct stat st; 106 107 if ((dir = opendir(dirname)) == NULL) 108 return; 109 dirlen = strlen(dirname) + 2; 110 while ((dp = readdir(dir)) != 0) { 111 if (dirlen + strlen(dp->d_name) >= sizeof(path)) 112 continue; 113 114 if (dp->d_name[0] == '.' && 115 ((dp->d_name[1] == 0) || 116 ((dp->d_name[1] == '.') && (dp->d_name[2] == 0)))) 117 continue; 118 119 sprintf(path, "%s/%s", dirname, dp->d_name); 120 if (stat(path, &st) < 0) 121 continue; 122 123 if (S_ISBLK(st.st_mode) && st.st_rdev == devno) { 124 *devname = blkid_strdup(path); 125 DBG(DEBUG_DEVNO, 126 printf("found 0x%llx at %s (%p)\n", (long long)devno, 127 path, *devname)); 128 break; 129 } 130 if (S_ISDIR(st.st_mode) && !lstat(path, &st) && 131 S_ISDIR(st.st_mode)) 132 add_to_dirlist(path, list); 133 } 134 closedir(dir); 135 return; 136 } 137 138 /* Directories where we will try to search for device numbers */ 139 const char *blkid_devdirs[] = { "/devices", "/devfs", "/dev", NULL }; 140 141 /* 142 * This function finds the pathname to a block device with a given 143 * device number. It returns a pointer to allocated memory to the 144 * pathname on success, and NULL on failure. 145 */ 146 char *blkid_devno_to_devname(dev_t devno) 147 { 148 struct dir_list *list = NULL, *new_list = NULL; 149 char *devname = NULL; 150 const char **dir; 151 152 /* 153 * Add the starting directories to search in reverse order of 154 * importance, since we are using a stack... 155 */ 156 for (dir = blkid_devdirs; *dir; dir++) 157 add_to_dirlist(*dir, &list); 158 159 while (list) { 160 struct dir_list *current = list; 161 162 list = list->next; 163 DBG(DEBUG_DEVNO, printf("directory %s\n", current->name)); 164 scan_dir(current->name, devno, &new_list, &devname); 165 free(current->name); 166 free(current); 167 if (devname) 168 break; 169 /* 170 * If we're done checking at this level, descend to 171 * the next level of subdirectories. (breadth-first) 172 */ 173 if (list == NULL) { 174 list = new_list; 175 new_list = NULL; 176 } 177 } 178 free_dirlist(&list); 179 free_dirlist(&new_list); 180 181 if (!devname) { 182 DBG(DEBUG_DEVNO, 183 printf("blkid: couldn't find devno 0x%04lx\n", 184 (unsigned long) devno)); 185 } else { 186 DBG(DEBUG_DEVNO, 187 printf("found devno 0x%04llx as %s\n", (long long)devno, devname)); 188 } 189 190 191 return devname; 192 } 193 194 #ifdef TEST_PROGRAM 195 int main(int argc, char** argv) 196 { 197 char *devname, *tmp; 198 int major, minor; 199 dev_t devno; 200 const char *errmsg = "Couldn't parse %s: %s\n"; 201 202 blkid_debug_mask = DEBUG_ALL; 203 if ((argc != 2) && (argc != 3)) { 204 fprintf(stderr, "Usage:\t%s device_number\n\t%s major minor\n" 205 "Resolve a device number to a device name\n", 206 argv[0], argv[0]); 207 exit(1); 208 } 209 if (argc == 2) { 210 devno = strtoul(argv[1], &tmp, 0); 211 if (*tmp) { 212 fprintf(stderr, errmsg, "device number", argv[1]); 213 exit(1); 214 } 215 } else { 216 major = strtoul(argv[1], &tmp, 0); 217 if (*tmp) { 218 fprintf(stderr, errmsg, "major number", argv[1]); 219 exit(1); 220 } 221 minor = strtoul(argv[2], &tmp, 0); 222 if (*tmp) { 223 fprintf(stderr, errmsg, "minor number", argv[2]); 224 exit(1); 225 } 226 devno = makedev(major, minor); 227 } 228 printf("Looking for device 0x%04llx\n", (long long)devno); 229 devname = blkid_devno_to_devname(devno); 230 if (devname) 231 free(devname); 232 return 0; 233 } 234 #endif 235
