1 /* vi: set sw=4 ts=4: */
3 * devno.c - find a particular device by its device number (major/minor)
5 * Copyright (C) 2000, 2001, 2003 Theodore Ts'o
6 * Copyright (C) 2001 Andreas Dilger
9 * This file may be redistributed under the terms of the
10 * GNU Lesser General Public License.
21 #ifdef HAVE_SYS_TYPES_H
22 #include <sys/types.h>
29 #ifdef HAVE_SYS_MKDEV_H
30 #include <sys/mkdev.h>
37 struct dir_list *next;
40 char *blkid_strndup(const char *s, int length)
50 ret = xmalloc(length + 1);
51 strncpy(ret, s, length);
56 char *blkid_strdup(const char *s)
58 return blkid_strndup(s, 0);
62 * This function adds an entry to the directory list
64 static void add_to_dirlist(const char *name, struct dir_list **list)
68 dp = xmalloc(sizeof(struct dir_list));
69 dp->name = blkid_strdup(name);
75 * This function frees a directory list
77 static void free_dirlist(struct dir_list **list)
79 struct dir_list *dp, *next;
81 for (dp = *list; dp; dp = next) {
89 static void scan_dir(char *dir_name, dev_t devno, struct dir_list **list,
98 if ((dir = opendir(dir_name)) == NULL)
100 dirlen = strlen(dir_name) + 2;
101 while ((dp = readdir(dir)) != 0) {
102 if (dirlen + strlen(dp->d_name) >= sizeof(path))
105 if (dp->d_name[0] == '.' &&
106 ((dp->d_name[1] == 0) ||
107 ((dp->d_name[1] == '.') && (dp->d_name[2] == 0))))
110 sprintf(path, "%s/%s", dir_name, dp->d_name);
111 if (stat(path, &st) < 0)
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);
119 printf("found 0x%llx at %s (%p)\n", devno,
127 /* Directories where we will try to search for device numbers */
128 const char *blkid_devdirs[] = { "/devices", "/devfs", "/dev", NULL };
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.
135 char *blkid_devno_to_devname(dev_t devno)
137 struct dir_list *list = NULL, *new_list = NULL;
138 char *devname = NULL;
142 * Add the starting directories to search in reverse order of
143 * importance, since we are using a stack...
145 for (dir = blkid_devdirs; *dir; dir++)
146 add_to_dirlist(*dir, &list);
149 struct dir_list *current = list;
152 DBG(DEBUG_DEVNO, printf("directory %s\n", current->name));
153 scan_dir(current->name, devno, &new_list, &devname);
159 * If we're done checking at this level, descend to
160 * the next level of subdirectories. (breadth-first)
168 free_dirlist(&new_list);
172 printf("blkid: cannot find devno 0x%04lx\n",
173 (unsigned long) devno));
176 printf("found devno 0x%04llx as %s\n", devno, devname));
184 int main(int argc, char** argv)
189 const char *errmsg = "Cannot parse %s: %s\n";
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",
199 devno = strtoul(argv[1], &tmp, 0);
201 fprintf(stderr, errmsg, "device number", argv[1]);
205 major = strtoul(argv[1], &tmp, 0);
207 fprintf(stderr, errmsg, "major number", argv[1]);
210 minor = strtoul(argv[2], &tmp, 0);
212 fprintf(stderr, errmsg, "minor number", argv[2]);
215 devno = makedev(major, minor);
217 printf("Looking for device 0x%04Lx\n", devno);
218 devname = blkid_devno_to_devname(devno);