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223 lines
4.6 KiB
C
223 lines
4.6 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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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, 2003 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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#ifdef 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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#ifdef HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#include <sys/stat.h>
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#include <dirent.h>
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#ifdef HAVE_ERRNO_H
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#include <errno.h>
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#endif
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#ifdef HAVE_SYS_MKDEV_H
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#include <sys/mkdev.h>
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#endif
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#include "blkidP.h"
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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 *blkid_strndup(const char *s, 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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if (!length)
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length = strlen(s);
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ret = xmalloc(length + 1);
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strncpy(ret, s, length);
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ret[length] = '\0';
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return ret;
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}
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char *blkid_strdup(const char *s)
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{
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return blkid_strndup(s, 0);
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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 = xmalloc(sizeof(struct dir_list));
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dp->name = blkid_strdup(name);
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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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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 void scan_dir(char *dir_name, 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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if ((dir = opendir(dir_name)) == NULL)
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return;
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dirlen = strlen(dir_name) + 2;
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while ((dp = readdir(dir)) != 0) {
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if (dirlen + strlen(dp->d_name) >= sizeof(path))
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continue;
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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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continue;
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sprintf(path, "%s/%s", dir_name, dp->d_name);
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if (stat(path, &st) < 0)
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continue;
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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 = blkid_strdup(path);
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DBG(DEBUG_DEVNO,
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printf("found 0x%llx at %s (%p)\n", devno,
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path, *devname));
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break;
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}
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}
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closedir(dir);
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}
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/* Directories where we will try to search for device numbers */
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const char *blkid_devdirs[] = { "/devices", "/devfs", "/dev", 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 = blkid_devdirs; *dir; dir++)
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add_to_dirlist(*dir, &list);
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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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DBG(DEBUG_DEVNO, printf("directory %s\n", current->name));
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scan_dir(current->name, devno, &new_list, &devname);
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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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DBG(DEBUG_DEVNO,
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printf("blkid: cannot find devno 0x%04lx\n",
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(unsigned long) devno));
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} else {
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DBG(DEBUG_DEVNO,
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printf("found devno 0x%04llx as %s\n", devno, devname));
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}
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return devname;
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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 = "Cannot parse %s: %s\n";
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blkid_debug_mask = DEBUG_ALL;
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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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free(devname);
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return 0;
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}
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#endif
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