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