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