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