release/src/router/ntfs-3g/libntfs-3g/realpath.c

   1 /*
   2  * realpath.c - realpath() aware of device mapper
   3  * Originated from the util-linux project.
   4  */
   5
   6 #ifdef HAVE_CONFIG_H
   7 #include "config.h"
   8 #endif
   9
  10 #include <stdlib.h>
  11 #include <stdio.h>
  12 #include <string.h>
  13
  14 #ifdef HAVE_LIMITS_H
  15 #include <limits.h>
  16 #endif
  17 #ifdef HAVE_CTYPE_H
  18 #include <ctype.h>
  19 #endif
  20
  21 #include "param.h"
  22 #include "realpath.h"
  23
  24 /* If there is no realpath() on the system, provide a dummy one. */
  25 #ifndef HAVE_REALPATH
  26 char *ntfs_realpath(const char *path, char *resolved_path)
  27 {
  28        strncpy(resolved_path, path, PATH_MAX);
  29        resolved_path[PATH_MAX] = '\0';
  30        return resolved_path;
  31 }
  32 #endif
  33
  34
  35 #ifdef linux
  36
  37 /*
  38  * Converts private "dm-N" names to "/dev/mapper/<name>"
  39  *
  40  * Since 2.6.29 (patch 784aae735d9b0bba3f8b9faef4c8b30df3bf0128) kernel sysfs
  41  * provides the real DM device names in /sys/block/<ptname>/dm/name
  42  */
  43 static char *
  44 canonicalize_dm_name(const char *ptname, char *canonical)
  45 {
  46         FILE    *f;
  47         size_t  sz;
  48         char    path[MAPPERNAMELTH + 24];
  49         char    name[MAPPERNAMELTH + 16];
  50         char    *res = NULL;
  51
  52         snprintf(path, sizeof(path), "/sys/block/%s/dm/name", ptname);
  53         if (!(f = fopen(path, "r")))
  54                 return NULL;
  55
  56         /* read "<name>\n" from sysfs */
  57         if (fgets(name, sizeof(name), f) && (sz = strlen(name)) > 1) {
  58                 name[sz - 1] = '\0';
  59                 snprintf(path, sizeof(path), "/dev/mapper/%s", name);
  60                 res = strcpy(canonical, path);
  61         }
  62         fclose(f);
  63         return res;
  64 }
  65
  66 /*
  67  *              Canonicalize a device path
  68  *
  69  *      Workaround from "basinilya" for fixing device mapper paths.
  70  *
  71  *  Background (Phillip Susi, 2011-04-09)
  72  *      - ntfs-3g canonicalizes the device name so that if you mount with
  73  *        /dev/mapper/foo, the device name listed in mtab is /dev/dm-n,
  74  *        so you can not umount /dev/mapper/foo
  75  *      - umount won't even recognize and translate /dev/dm-n to the mount
  76  *        point, apparently because of the '-' involved. Editing mtab and
  77  *        removing the '-' allows you to umount /dev/dmn successfully.
  78  *
  79  *      This code restores the devmapper name after canonicalization,
  80  *      until a proper fix is implemented.
  81  */
  82
  83 char *ntfs_realpath_canonicalize(const char *path, char *canonical)
  84 {
  85         char *p;
  86
  87         if (path == NULL)
  88                 return NULL;
  89
  90         if (!ntfs_realpath(path, canonical))
  91                 return NULL;
  92
  93         p = strrchr(canonical, '/');
  94         if (p && strncmp(p, "/dm-", 4) == 0 && isdigit(*(p + 4))) {
  95                 p = canonicalize_dm_name(p+1, canonical);
  96                 if (p)
  97                         return p;
  98         }
  99
 100         return canonical;
 101 }
 102
 103 #endif