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/*
* 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
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