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 209
