usbloadergx/libcustomntfs/source/realpath.c

104 lines
2.3 KiB
C
Raw Permalink Normal View History

/*
* realpath.c - realpath() aware of device mapper
* Originated from the util-linux project.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#ifdef HAVE_CTYPE_H
#include <ctype.h>
#endif
#include "param.h"
#include "realpath.h"
/* If there is no realpath() on the system, provide a dummy one. */
#ifndef HAVE_REALPATH
char *ntfs_realpath(const char *path, char *resolved_path)
{
strncpy(resolved_path, path, PATH_MAX);
resolved_path[PATH_MAX] = '\0';
return resolved_path;
}
#endif
#ifdef linux
/*
* Converts private "dm-N" names to "/dev/mapper/<name>"
*
* Since 2.6.29 (patch 784aae735d9b0bba3f8b9faef4c8b30df3bf0128) kernel sysfs
* provides the real DM device names in /sys/block/<ptname>/dm/name
*/
static char *
canonicalize_dm_name(const char *ptname, char *canonical)
{
FILE *f;
size_t sz;
char path[MAPPERNAMELTH + 24];
char name[MAPPERNAMELTH + 16];
char *res = NULL;
snprintf(path, sizeof(path), "/sys/block/%s/dm/name", ptname);
if (!(f = fopen(path, "r")))
return NULL;
/* read "<name>\n" from sysfs */
if (fgets(name, sizeof(name), f) && (sz = strlen(name)) > 1) {
name[sz - 1] = '\0';
snprintf(path, sizeof(path), "/dev/mapper/%s", name);
res = strcpy(canonical, path);
}
fclose(f);
return res;
}
/*
* Canonicalize a device path
*
* Workaround from "basinilya" for fixing device mapper paths.
*
* Background (Phillip Susi, 2011-04-09)
* - ntfs-3g canonicalizes the device name so that if you mount with
* /dev/mapper/foo, the device name listed in mtab is /dev/dm-n,
* so you can not umount /dev/mapper/foo
* - umount won't even recognize and translate /dev/dm-n to the mount
* point, apparently because of the '-' involved. Editing mtab and
* removing the '-' allows you to umount /dev/dmn successfully.
*
* This code restores the devmapper name after canonicalization,
* until a proper fix is implemented.
*/
char *ntfs_realpath_canonicalize(const char *path, char *canonical)
{
char *p;
if (path == NULL)
return NULL;
if (!ntfs_realpath(path, canonical))
return NULL;
p = strrchr(canonical, '/');
if (p && strncmp(p, "/dm-", 4) == 0 && isdigit(*(p + 4))) {
p = canonicalize_dm_name(p+1, canonical);
if (p)
return p;
}
return canonical;
}
#endif