lib/ext2fs/finddev.c

   1 /*
   2  * finddev.c -- this routine attempts to find a particular device in
   3  *      /dev
   4  *
   5  * Copyright (C) 2000 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Library
   9  * General Public License, version 2.
  10  * %End-Header%
  11  */
  12
  13 #include "config.h"
  14 #include <stdio.h>
  15 #include <string.h>
  16 #if HAVE_UNISTD_H
  17 #include <unistd.h>
  18 #endif
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #if HAVE_SYS_TYPES_H
  22 #include <sys/types.h>
  23 #endif
  24 #if HAVE_SYS_STAT_H
  25 #include <sys/stat.h>
  26 #endif
  27 #include <dirent.h>
  28 #if HAVE_ERRNO_H
  29 #include <errno.h>
  30 #endif
  31 #if HAVE_SYS_MKDEV_H
  32 #include <sys/mkdev.h>
  33 #endif
  34 #ifdef HAVE_SYS_SYSMACROS_H
  35 #include <sys/sysmacros.h>
  36 #endif
  37
  38 #include "ext2_fs.h"
  39 #include "ext2fs.h"
  40 #include "ext2fsP.h"
  41
  42 struct dir_list {
  43         char    *name;
  44         struct dir_list *next;
  45 };
  46
  47 /*
  48  * This function adds an entry to the directory list
  49  */
  50 static void add_to_dirlist(const char *name, struct dir_list **list)
  51 {
  52         struct dir_list *dp;
  53
  54         dp = malloc(sizeof(struct dir_list));
  55         if (!dp)
  56                 return;
  57         dp->name = malloc(strlen(name)+1);
  58         if (!dp->name) {
  59                 free(dp);
  60                 return;
  61         }
  62         strcpy(dp->name, name);
  63         dp->next = *list;
  64         *list = dp;
  65 }
  66
  67 /*
  68  * This function frees a directory list
  69  */
  70 static void free_dirlist(struct dir_list **list)
  71 {
  72         struct dir_list *dp, *next;
  73
  74         for (dp = *list; dp; dp = next) {
  75                 next = dp->next;
  76                 free(dp->name);
  77                 free(dp);
  78         }
  79         *list = 0;
  80 }
  81
  82 static int scan_dir(char *dirname, dev_t device, struct dir_list **list,
  83                     char **ret_path)
  84 {
  85         DIR     *dir;
  86         struct dirent *dp;
  87         char    path[1024], *cp;
  88         int     dirlen;
  89         struct stat st;
  90
  91         dirlen = strlen(dirname);
  92         if ((dir = opendir(dirname)) == NULL)
  93                 return errno;
  94         dp = readdir(dir);
  95         while (dp) {
  96                 if (dirlen + strlen(dp->d_name) + 2 >= sizeof(path))
  97                         goto skip_to_next;
  98                 if (dp->d_name[0] == '.' &&
  99                     ((dp->d_name[1] == 0) ||
 100                      ((dp->d_name[1] == '.') && (dp->d_name[2] == 0))))
 101                         goto skip_to_next;
 102                 sprintf(path, "%s/%s", dirname, dp->d_name);
 103                 if (stat(path, &st) < 0)
 104                         goto skip_to_next;
 105                 if (S_ISDIR(st.st_mode))
 106                         add_to_dirlist(path, list);
 107                 if (ext2fsP_is_disk_device(st.st_mode) &&
 108                     st.st_rdev == device) {
 109                         cp = malloc(strlen(path)+1);
 110                         if (!cp) {
 111                                 closedir(dir);
 112                                 return ENOMEM;
 113                         }
 114                         strcpy(cp, path);
 115                         *ret_path = cp;
 116                         goto success;
 117                 }
 118         skip_to_next:
 119                 dp = readdir(dir);
 120         }
 121 success:
 122         closedir(dir);
 123         return 0;
 124 }
 125
 126 /*
 127  * This function finds the pathname to a block device with a given
 128  * device number.  It returns a pointer to allocated memory to the
 129  * pathname on success, and NULL on failure.
 130  */
 131 char *ext2fs_find_block_device(dev_t device)
 132 {
 133         struct dir_list *list = 0, *new_list = 0;
 134         struct dir_list *current;
 135         char    *ret_path = 0;
 136         int    level = 0;
 137
 138         /*
 139          * Add the starting directories to search...
 140          */
 141         add_to_dirlist("/devices", &list);
 142         add_to_dirlist("/devfs", &list);
 143         add_to_dirlist("/dev", &list);
 144
 145         while (list) {
 146                 current = list;
 147                 list = list->next;
 148 #ifdef DEBUG
 149                 printf("Scanning directory %s\n", current->name);
 150 #endif
 151                 scan_dir(current->name, device, &new_list, &ret_path);
 152                 free(current->name);
 153                 free(current);
 154                 if (ret_path)
 155                         break;
 156                 /*
 157                  * If we're done checking at this level, descend to
 158                  * the next level of subdirectories. (breadth-first)
 159                  */
 160                 if (list == 0) {
 161                         list = new_list;
 162                         new_list = 0;
 163                         /* Avoid infinite loop */
 164                         if (++level >= EXT2FS_MAX_NESTED_LINKS)
 165                                 break;
 166                 }
 167         }
 168         free_dirlist(&list);
 169         free_dirlist(&new_list);
 170         return ret_path;
 171 }
 172
 173
 174 #ifdef DEBUG
 175 int main(int argc, char** argv)
 176 {
 177         char    *devname, *tmp;
 178         int     major, minor;
 179         dev_t   device;
 180         const char *errmsg = "Couldn't parse %s: %s\n";
 181
 182         if ((argc != 2) && (argc != 3)) {
 183                 fprintf(stderr, "Usage: %s device_number\n", argv[0]);
 184                 fprintf(stderr, "\t: %s major minor\n", argv[0]);
 185                 exit(1);
 186         }
 187         if (argc == 2) {
 188                 device = strtoul(argv[1], &tmp, 0);
 189                 if (*tmp) {
 190                         fprintf(stderr, errmsg, "device number", argv[1]);
 191                         exit(1);
 192                 }
 193         } else {
 194                 major = strtoul(argv[1], &tmp, 0);
 195                 if (*tmp) {
 196                         fprintf(stderr, errmsg, "major number", argv[1]);
 197                         exit(1);
 198                 }
 199                 minor = strtoul(argv[2], &tmp, 0);
 200                 if (*tmp) {
 201                         fprintf(stderr, errmsg, "minor number", argv[2]);
 202                         exit(1);
 203                 }
 204                 device = makedev(major, minor);
 205                 printf("Looking for device 0x%04x (%d:%d)\n", device,
 206                        major, minor);
 207         }
 208         devname = ext2fs_find_block_device(device);
 209         if (devname) {
 210                 printf("Found device!  %s\n", devname);
 211                 free(devname);
 212         } else {
 213                 printf("Couldn't find device.\n");
 214         }
 215         return 0;
 216 }
 217
 218 #endif