release/src/router/busybox/e2fsprogs/blkid/devno.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * devno.c - find a particular device by its device number (major/minor)
   4  *
   5  * Copyright (C) 2000, 2001, 2003 Theodore Ts'o
   6  * Copyright (C) 2001 Andreas Dilger
   7  *
   8  * %Begin-Header%
   9  * This file may be redistributed under the terms of the
  10  * GNU Lesser General Public License.
  11  * %End-Header%
  12  */
  13
  14 #include <stdio.h>
  15 #include <string.h>
  16 #ifdef HAVE_UNISTD_H
  17 #include <unistd.h>
  18 #endif
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #ifdef HAVE_SYS_TYPES_H
  22 #include <sys/types.h>
  23 #endif
  24 #include <sys/stat.h>
  25 #include <dirent.h>
  26 #ifdef HAVE_ERRNO_H
  27 #include <errno.h>
  28 #endif
  29 #ifdef HAVE_SYS_MKDEV_H
  30 #include <sys/mkdev.h>
  31 #endif
  32
  33 #include "blkidP.h"
  34
  35 struct dir_list {
  36         char    *name;
  37         struct dir_list *next;
  38 };
  39
  40 char *blkid_strndup(const char *s, int length)
  41 {
  42         char *ret;
  43
  44         if (!s)
  45                 return NULL;
  46
  47         if (!length)
  48                 length = strlen(s);
  49
  50         ret = xmalloc(length + 1);
  51         strncpy(ret, s, length);
  52         ret[length] = '\0';
  53         return ret;
  54 }
  55
  56 char *blkid_strdup(const char *s)
  57 {
  58         return blkid_strndup(s, 0);
  59 }
  60
  61 /*
  62  * This function adds an entry to the directory list
  63  */
  64 static void add_to_dirlist(const char *name, struct dir_list **list)
  65 {
  66         struct dir_list *dp;
  67
  68         dp = xmalloc(sizeof(struct dir_list));
  69         dp->name = blkid_strdup(name);
  70         dp->next = *list;
  71         *list = dp;
  72 }
  73
  74 /*
  75  * This function frees a directory list
  76  */
  77 static void free_dirlist(struct dir_list **list)
  78 {
  79         struct dir_list *dp, *next;
  80
  81         for (dp = *list; dp; dp = next) {
  82                 next = dp->next;
  83                 free(dp->name);
  84                 free(dp);
  85         }
  86         *list = NULL;
  87 }
  88
  89 static void scan_dir(char *dir_name, dev_t devno, struct dir_list **list,
  90                             char **devname)
  91 {
  92         DIR     *dir;
  93         struct dirent *dp;
  94         char    path[1024];
  95         int     dirlen;
  96         struct stat st;
  97
  98         if ((dir = opendir(dir_name)) == NULL)
  99                 return;
 100         dirlen = strlen(dir_name) + 2;
 101         while ((dp = readdir(dir)) != 0) {
 102                 if (dirlen + strlen(dp->d_name) >= sizeof(path))
 103                         continue;
 104
 105                 if (dp->d_name[0] == '.' &&
 106                     ((dp->d_name[1] == 0) ||
 107                      ((dp->d_name[1] == '.') && (dp->d_name[2] == 0))))
 108                         continue;
 109
 110                 sprintf(path, "%s/%s", dir_name, dp->d_name);
 111                 if (stat(path, &st) < 0)
 112                         continue;
 113
 114                 if (S_ISDIR(st.st_mode))
 115                         add_to_dirlist(path, list);
 116                 else if (S_ISBLK(st.st_mode) && st.st_rdev == devno) {
 117                         *devname = blkid_strdup(path);
 118                         DBG(DEBUG_DEVNO,
 119                             printf("found 0x%llx at %s (%p)\n", devno,
 120                                    path, *devname));
 121                         break;
 122                 }
 123         }
 124         closedir(dir);
 125 }
 126
 127 /* Directories where we will try to search for device numbers */
 128 const char *blkid_devdirs[] = { "/devices", "/devfs", "/dev", NULL };
 129
 130 /*
 131  * This function finds the pathname to a block device with a given
 132  * device number.  It returns a pointer to allocated memory to the
 133  * pathname on success, and NULL on failure.
 134  */
 135 char *blkid_devno_to_devname(dev_t devno)
 136 {
 137         struct dir_list *list = NULL, *new_list = NULL;
 138         char *devname = NULL;
 139         const char **dir;
 140
 141         /*
 142          * Add the starting directories to search in reverse order of
 143          * importance, since we are using a stack...
 144          */
 145         for (dir = blkid_devdirs; *dir; dir++)
 146                 add_to_dirlist(*dir, &list);
 147
 148         while (list) {
 149                 struct dir_list *current = list;
 150
 151                 list = list->next;
 152                 DBG(DEBUG_DEVNO, printf("directory %s\n", current->name));
 153                 scan_dir(current->name, devno, &new_list, &devname);
 154                 free(current->name);
 155                 free(current);
 156                 if (devname)
 157                         break;
 158                 /*
 159                  * If we're done checking at this level, descend to
 160                  * the next level of subdirectories. (breadth-first)
 161                  */
 162                 if (list == NULL) {
 163                         list = new_list;
 164                         new_list = NULL;
 165                 }
 166         }
 167         free_dirlist(&list);
 168         free_dirlist(&new_list);
 169
 170         if (!devname) {
 171                 DBG(DEBUG_DEVNO,
 172                     printf("blkid: cannot find devno 0x%04lx\n",
 173                            (unsigned long) devno));
 174         } else {
 175                 DBG(DEBUG_DEVNO,
 176                     printf("found devno 0x%04llx as %s\n", devno, devname));
 177         }
 178
 179
 180         return devname;
 181 }
 182
 183 #ifdef TEST_PROGRAM
 184 int main(int argc, char** argv)
 185 {
 186         char    *devname, *tmp;
 187         int     major, minor;
 188         dev_t   devno;
 189         const char *errmsg = "Cannot parse %s: %s\n";
 190
 191         blkid_debug_mask = DEBUG_ALL;
 192         if ((argc != 2) && (argc != 3)) {
 193                 fprintf(stderr, "Usage:\t%s device_number\n\t%s major minor\n"
 194                         "Resolve a device number to a device name\n",
 195                         argv[0], argv[0]);
 196                 exit(1);
 197         }
 198         if (argc == 2) {
 199                 devno = strtoul(argv[1], &tmp, 0);
 200                 if (*tmp) {
 201                         fprintf(stderr, errmsg, "device number", argv[1]);
 202                         exit(1);
 203                 }
 204         } else {
 205                 major = strtoul(argv[1], &tmp, 0);
 206                 if (*tmp) {
 207                         fprintf(stderr, errmsg, "major number", argv[1]);
 208                         exit(1);
 209                 }
 210                 minor = strtoul(argv[2], &tmp, 0);
 211                 if (*tmp) {
 212                         fprintf(stderr, errmsg, "minor number", argv[2]);
 213                         exit(1);
 214                 }
 215                 devno = makedev(major, minor);
 216         }
 217         printf("Looking for device 0x%04Lx\n", devno);
 218         devname = blkid_devno_to_devname(devno);
 219         free(devname);
 220         return 0;
 221 }
 222 #endif