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 (S_ISBLK(st.st_mode) && st.st_rdev == device) { 108 cp = malloc(strlen(path)+1); 109 if (!cp) { 110 closedir(dir); 111 return ENOMEM; 112 } 113 strcpy(cp, path); 114 *ret_path = cp; 115 goto success; 116 } 117 skip_to_next: 118 dp = readdir(dir); 119 } 120 success: 121 closedir(dir); 122 return 0; 123 } 124 125 /* 126 * This function finds the pathname to a block device with a given 127 * device number. It returns a pointer to allocated memory to the 128 * pathname on success, and NULL on failure. 129 */ 130 char *ext2fs_find_block_device(dev_t device) 131 { 132 struct dir_list *list = 0, *new_list = 0; 133 struct dir_list *current; 134 char *ret_path = 0; 135 int level = 0; 136 137 /* 138 * Add the starting directories to search... 139 */ 140 add_to_dirlist("/devices", &list); 141 add_to_dirlist("/devfs", &list); 142 add_to_dirlist("/dev", &list); 143 144 while (list) { 145 current = list; 146 list = list->next; 147 #ifdef DEBUG 148 printf("Scanning directory %s\n", current->name); 149 #endif 150 scan_dir(current->name, device, &new_list, &ret_path); 151 free(current->name); 152 free(current); 153 if (ret_path) 154 break; 155 /* 156 * If we're done checking at this level, descend to 157 * the next level of subdirectories. (breadth-first) 158 */ 159 if (list == 0) { 160 list = new_list; 161 new_list = 0; 162 /* Avoid infinite loop */ 163 if (++level >= EXT2FS_MAX_NESTED_LINKS) 164 break; 165 } 166 } 167 free_dirlist(&list); 168 free_dirlist(&new_list); 169 return ret_path; 170 } 171 172 173 #ifdef DEBUG 174 int main(int argc, char** argv) 175 { 176 char *devname, *tmp; 177 int major, minor; 178 dev_t device; 179 const char *errmsg = "Couldn't parse %s: %s\n"; 180 181 if ((argc != 2) && (argc != 3)) { 182 fprintf(stderr, "Usage: %s device_number\n", argv[0]); 183 fprintf(stderr, "\t: %s major minor\n", argv[0]); 184 exit(1); 185 } 186 if (argc == 2) { 187 device = strtoul(argv[1], &tmp, 0); 188 if (*tmp) { 189 fprintf(stderr, errmsg, "device number", argv[1]); 190 exit(1); 191 } 192 } else { 193 major = strtoul(argv[1], &tmp, 0); 194 if (*tmp) { 195 fprintf(stderr, errmsg, "major number", argv[1]); 196 exit(1); 197 } 198 minor = strtoul(argv[2], &tmp, 0); 199 if (*tmp) { 200 fprintf(stderr, errmsg, "minor number", argv[2]); 201 exit(1); 202 } 203 device = makedev(major, minor); 204 printf("Looking for device 0x%04x (%d:%d)\n", device, 205 major, minor); 206 } 207 devname = ext2fs_find_block_device(device); 208 if (devname) { 209 printf("Found device! %s\n", devname); 210 free(devname); 211 } else { 212 printf("Couldn't find device.\n"); 213 } 214 return 0; 215 } 216 217 #endif 218
