mirror of https://github.com/vitalif/e2fsprogs
297 lines
5.9 KiB
C
297 lines
5.9 KiB
C
/*
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* devno.c - find a particular device by its device number (major/minor)
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*
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* Copyright (C) 2000, 2001 Theodore Ts'o
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* Copyright (C) 2001 Andreas Dilger
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the
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* GNU Lesser General Public License.
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* %End-Header%
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*/
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#include <stdio.h>
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#include <string.h>
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <stdlib.h>
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#include <string.h>
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#if HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#if HAVE_SYS_STAT_H
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#include <sys/stat.h>
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#endif
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#include <dirent.h>
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#if HAVE_ERRNO_H
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#include <errno.h>
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#endif
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#if HAVE_SYS_MKDEV_H
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#include <sys/mkdev.h>
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#endif
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#include "blkid/blkid.h"
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#ifdef DEBUG_DEVNO
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#define DEB_DEVNO(fmt, arg...) printf("devno: " fmt, ## arg)
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#else
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#define DEB_DEVNO(fmt, arg...) do {} while (0)
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#endif
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struct dir_list {
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char *name;
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struct dir_list *next;
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};
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char *stringn_copy(const char *s, const int length)
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{
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char *ret;
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if (!s)
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return NULL;
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ret = malloc(length + 1);
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if (ret) {
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strncpy(ret, s, length);
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ret[length] = '\0';
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}
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return ret;
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}
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char *string_copy(const char *s)
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{
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if (!s)
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return NULL;
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return stringn_copy(s, strlen(s));
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}
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void string_free(char *s)
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{
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if (s)
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free(s);
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}
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/*
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* This function adds an entry to the directory list
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*/
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static void add_to_dirlist(const char *name, struct dir_list **list)
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{
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struct dir_list *dp;
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dp = malloc(sizeof(struct dir_list));
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if (!dp)
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return;
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dp->name = string_copy(name);
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if (!dp->name) {
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free(dp);
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return;
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}
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dp->next = *list;
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*list = dp;
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}
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/*
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* This function frees a directory list
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*/
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static void free_dirlist(struct dir_list **list)
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{
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struct dir_list *dp, *next;
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for (dp = *list; dp; dp = next) {
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next = dp->next;
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string_free(dp->name);
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free(dp);
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}
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*list = NULL;
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}
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static int scan_dir(char *dirname, dev_t devno, struct dir_list **list,
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char **devname)
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{
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DIR *dir;
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struct dirent *dp;
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char path[1024];
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int dirlen;
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struct stat st;
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int ret = 0;
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dirlen = strlen(dirname);
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if ((dir = opendir(dirname)) == NULL)
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return errno;
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dp = readdir(dir);
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while (dp) {
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if (dirlen + strlen(dp->d_name) + 2 >= sizeof(path))
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goto skip_to_next;
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if (dp->d_name[0] == '.' &&
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((dp->d_name[1] == 0) ||
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((dp->d_name[1] == '.') && (dp->d_name[2] == 0))))
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goto skip_to_next;
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sprintf(path, "%s/%s", dirname, dp->d_name);
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if (stat(path, &st) < 0)
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goto skip_to_next;
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if (S_ISDIR(st.st_mode))
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add_to_dirlist(path, list);
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else if (S_ISBLK(st.st_mode) && st.st_rdev == devno) {
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*devname = string_copy(path);
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DEB_DEVNO("found 0x%Lx at %s (%p)\n", devno,
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*devname, *devname);
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if (!*devname)
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ret = -BLKID_ERR_MEM;
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break;
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}
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skip_to_next:
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dp = readdir(dir);
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}
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closedir(dir);
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return ret;
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}
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/* Directories where we will try to search for device numbers */
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const char *devdirs[] = { "/dev", "/devfs", "/devices", NULL };
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/*
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* This function finds the pathname to a block device with a given
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* device number. It returns a pointer to allocated memory to the
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* pathname on success, and NULL on failure.
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*/
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char *blkid_devno_to_devname(dev_t devno)
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{
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struct dir_list *list = NULL, *new_list = NULL;
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char *devname = NULL;
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const char **dir;
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/*
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* Add the starting directories to search in reverse order of
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* importance, since we are using a stack...
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*/
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for (dir = devdirs; *dir; dir++)
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/* go to end of list */;
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do {
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--dir;
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add_to_dirlist(*dir, &list);
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} while (dir != devdirs);
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while (list) {
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struct dir_list *current = list;
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list = list->next;
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DEB_DEVNO("directory %s\n", current->name);
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scan_dir(current->name, devno, &new_list, &devname);
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string_free(current->name);
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free(current);
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if (devname)
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break;
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/*
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* If we're done checking at this level, descend to
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* the next level of subdirectories. (breadth-first)
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*/
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if (list == NULL) {
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list = new_list;
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new_list = NULL;
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}
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}
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free_dirlist(&list);
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free_dirlist(&new_list);
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if (!devname)
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fprintf(stderr, "blkid: couldn't find devno 0x%04Lx\n", devno);
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else
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DEB_DEVNO("found devno 0x%04Lx as %s\n", devno, devname);
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return devname;
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}
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blkid_dev *blkid_find_devno(blkid_cache *cache, dev_t devno)
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{
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blkid_dev *dev = NULL;
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struct list_head *p, *n;
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if (!cache)
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return NULL;
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/* This cannot be a standard list_for_each() because we may be
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* deleting the referenced struct in blkid_verify_devname() and
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* pointing to another one that was probed from disk, and "p"
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* would point to freed memory.
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*/
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list_for_each_safe(p, n, &cache->bic_devs) {
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blkid_dev *tmp = list_entry(p, blkid_dev, bid_devs);
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if (tmp->bid_devno != devno)
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continue;
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tmp = blkid_verify_devname(cache, tmp);
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if (!tmp || tmp->bid_devno != devno)
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continue;
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dev = tmp;
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break;
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}
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if (dev)
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DEB_DEVNO("found devno 0x%04LX in cache as %s\n",
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devno, dev->bid_name);
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return dev;
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}
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blkid_dev *blkid_get_devno(blkid_cache *cache, dev_t devno)
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{
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char *devname;
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blkid_dev *dev;
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if (!(dev = blkid_find_devno(cache, devno)) &&
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(devname = blkid_devno_to_devname(devno))) {
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dev = blkid_get_devname(cache, devname);
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string_free(devname);
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}
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return dev;
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}
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#ifdef TEST_PROGRAM
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int main(int argc, char** argv)
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{
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char *devname, *tmp;
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int major, minor;
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dev_t devno;
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const char *errmsg = "Couldn't parse %s: %s\n";
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if ((argc != 2) && (argc != 3)) {
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fprintf(stderr, "Usage:\t%s device_number\n\t%s major minor\n"
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"Resolve a device number to a device name\n",
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argv[0], argv[0]);
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exit(1);
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}
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if (argc == 2) {
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devno = strtoul(argv[1], &tmp, 0);
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if (*tmp) {
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fprintf(stderr, errmsg, "device number", argv[1]);
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exit(1);
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}
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} else {
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major = strtoul(argv[1], &tmp, 0);
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if (*tmp) {
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fprintf(stderr, errmsg, "major number", argv[1]);
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exit(1);
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}
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minor = strtoul(argv[2], &tmp, 0);
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if (*tmp) {
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fprintf(stderr, errmsg, "minor number", argv[2]);
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exit(1);
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}
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devno = makedev(major, minor);
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}
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printf("Looking for device 0x%04Lx\n", devno);
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devname = blkid_devno_to_devname(devno);
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if (devname)
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string_free(devname);
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return 0;
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}
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#endif
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