/* * devno.c - find a particular device by its device number (major/minor) * * Copyright (C) 2000, 2001, 2003 Theodore Ts'o * Copyright (C) 2001 Andreas Dilger * * %Begin-Header% * This file may be redistributed under the terms of the * GNU Lesser General Public License. * %End-Header% */ #include <stdio.h> #include <string.h> #if HAVE_UNISTD_H #include <unistd.h> #endif #include <stdlib.h> #include <string.h> #if HAVE_SYS_TYPES_H #include <sys/types.h> #endif #if HAVE_SYS_STAT_H #include <sys/stat.h> #endif #include <dirent.h> #if HAVE_ERRNO_H #include <errno.h> #endif #if HAVE_SYS_MKDEV_H #include <sys/mkdev.h> #endif #include "blkidP.h" struct dir_list { char *name; struct dir_list *next; }; char *blkid_strndup(const char *s, int length) { char *ret; if (!s) return NULL; if (!length) length = strlen(s); ret = xmalloc(length + 1); strncpy(ret, s, length); ret[length] = '\0'; return ret; } char *blkid_strdup(const char *s) { return blkid_strndup(s, 0); } /* * This function adds an entry to the directory list */ static void add_to_dirlist(const char *name, struct dir_list **list) { struct dir_list *dp; dp = xmalloc(sizeof(struct dir_list)); dp->name = blkid_strdup(name); dp->next = *list; *list = dp; } /* * This function frees a directory list */ static void free_dirlist(struct dir_list **list) { struct dir_list *dp, *next; for (dp = *list; dp; dp = next) { next = dp->next; free(dp->name); free(dp); } *list = NULL; } static void scan_dir(char *dir_name, dev_t devno, struct dir_list **list, char **devname) { DIR *dir; struct dirent *dp; char path[1024]; int dirlen; struct stat st; if ((dir = opendir(dir_name)) == NULL) return; dirlen = strlen(dir_name) + 2; while ((dp = readdir(dir)) != 0) { if (dirlen + strlen(dp->d_name) >= sizeof(path)) continue; if (dp->d_name[0] == '.' && ((dp->d_name[1] == 0) || ((dp->d_name[1] == '.') && (dp->d_name[2] == 0)))) continue; sprintf(path, "%s/%s", dir_name, dp->d_name); if (stat(path, &st) < 0) continue; if (S_ISDIR(st.st_mode)) add_to_dirlist(path, list); else if (S_ISBLK(st.st_mode) && st.st_rdev == devno) { *devname = blkid_strdup(path); DBG(DEBUG_DEVNO, printf("found 0x%llx at %s (%p)\n", devno, path, *devname)); break; } } closedir(dir); return; } /* Directories where we will try to search for device numbers */ const char *blkid_devdirs[] = { "/devices", "/devfs", "/dev", NULL }; /* * This function finds the pathname to a block device with a given * device number. It returns a pointer to allocated memory to the * pathname on success, and NULL on failure. */ char *blkid_devno_to_devname(dev_t devno) { struct dir_list *list = NULL, *new_list = NULL; char *devname = NULL; const char **dir; /* * Add the starting directories to search in reverse order of * importance, since we are using a stack... */ for (dir = blkid_devdirs; *dir; dir++) add_to_dirlist(*dir, &list); while (list) { struct dir_list *current = list; list = list->next; DBG(DEBUG_DEVNO, printf("directory %s\n", current->name)); scan_dir(current->name, devno, &new_list, &devname); free(current->name); free(current); if (devname) break; /* * If we're done checking at this level, descend to * the next level of subdirectories. (breadth-first) */ if (list == NULL) { list = new_list; new_list = NULL; } } free_dirlist(&list); free_dirlist(&new_list); if (!devname) { DBG(DEBUG_DEVNO, printf("blkid: couldn't find devno 0x%04lx\n", (unsigned long) devno)); } else { DBG(DEBUG_DEVNO, printf("found devno 0x%04llx as %s\n", devno, devname)); } return devname; } #ifdef TEST_PROGRAM int main(int argc, char** argv) { char *devname, *tmp; int major, minor; dev_t devno; const char *errmsg = "Couldn't parse %s: %s\n"; blkid_debug_mask = DEBUG_ALL; if ((argc != 2) && (argc != 3)) { fprintf(stderr, "Usage:\t%s device_number\n\t%s major minor\n" "Resolve a device number to a device name\n", argv[0], argv[0]); exit(1); } if (argc == 2) { devno = strtoul(argv[1], &tmp, 0); if (*tmp) { fprintf(stderr, errmsg, "device number", argv[1]); exit(1); } } else { major = strtoul(argv[1], &tmp, 0); if (*tmp) { fprintf(stderr, errmsg, "major number", argv[1]); exit(1); } minor = strtoul(argv[2], &tmp, 0); if (*tmp) { fprintf(stderr, errmsg, "minor number", argv[2]); exit(1); } devno = makedev(major, minor); } printf("Looking for device 0x%04Lx\n", devno); devname = blkid_devno_to_devname(devno); free(devname); return 0; } #endif