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https://git.code.sf.net/p/ntfs-3g/ntfs-3g.git
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571dbc5784
For some reason, when the monted device is "/dev/mapper/*", a record in the form "/dev/dm-*" ends up in /etc/mtab and the device cannot be unmounted. The reason is unclear, the /dev/mapper name is not a symlink, and the function doing the name change is not known. No detailed feedback from the users having met the issue. The patch changes the name back to the /dev/mapper name after realpath() is called, and, if there is an actual change, both the name passed to ntfs-3g and the one passed to fuse and mount are logged in the hope of getting a clue about what is happening. But ntfs-3g is probably not the right place for a fix.
104 lines
2.3 KiB
C
104 lines
2.3 KiB
C
/*
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* realpath.c - realpath() aware of device mapper
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* Originated from the util-linux project.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#ifdef HAVE_LIMITS_H
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#include <limits.h>
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#endif
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#ifdef HAVE_CTYPE_H
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#include <ctype.h>
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#endif
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#include "param.h"
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#include "realpath.h"
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/* If there is no realpath() on the system, provide a dummy one. */
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#ifndef HAVE_REALPATH
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char *ntfs_realpath(const char *path, char *resolved_path)
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{
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strncpy(resolved_path, path, PATH_MAX);
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resolved_path[PATH_MAX] = '\0';
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return resolved_path;
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}
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#endif
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#ifdef linux
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/*
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* Converts private "dm-N" names to "/dev/mapper/<name>"
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*
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* Since 2.6.29 (patch 784aae735d9b0bba3f8b9faef4c8b30df3bf0128) kernel sysfs
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* provides the real DM device names in /sys/block/<ptname>/dm/name
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*/
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static char *
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canonicalize_dm_name(const char *ptname, char *canonical)
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{
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FILE *f;
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size_t sz;
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char path[MAPPERNAMELTH + 24];
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char name[MAPPERNAMELTH + 16];
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char *res = NULL;
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snprintf(path, sizeof(path), "/sys/block/%s/dm/name", ptname);
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if (!(f = fopen(path, "r")))
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return NULL;
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/* read "<name>\n" from sysfs */
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if (fgets(name, sizeof(name), f) && (sz = strlen(name)) > 1) {
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name[sz - 1] = '\0';
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snprintf(path, sizeof(path), "/dev/mapper/%s", name);
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res = strcpy(canonical, path);
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}
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fclose(f);
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return res;
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}
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/*
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* Canonicalize a device path
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*
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* Workaround from "basinilya" for fixing device mapper paths.
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*
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* Background (Phillip Susi, 2011-04-09)
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* - ntfs-3g canonicalizes the device name so that if you mount with
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* /dev/mapper/foo, the device name listed in mtab is /dev/dm-n,
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* so you can not umount /dev/mapper/foo
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* - umount won't even recognize and translate /dev/dm-n to the mount
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* point, apparently because of the '-' involved. Editing mtab and
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* removing the '-' allows you to umount /dev/dmn successfully.
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*
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* This code restores the devmapper name after canonicalization,
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* until a proper fix is implemented.
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*/
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char *ntfs_realpath_canonicalize(const char *path, char *canonical)
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{
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char *p;
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if (path == NULL)
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return NULL;
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if (!ntfs_realpath(path, canonical))
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return NULL;
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p = strrchr(canonical, '/');
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if (p && strncmp(p, "/dm-", 4) == 0 && isdigit(*(p + 4))) {
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p = canonicalize_dm_name(p+1, canonical);
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if (p)
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return p;
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}
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return canonical;
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}
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#endif
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