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