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