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