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 */
add_to_dirlist(const char * name,struct dir_list ** list)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 */
free_dirlist(struct dir_list ** list)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
scan_dir(char * dirname,dev_t device,struct dir_list ** list,char ** ret_path)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 */
ext2fs_find_block_device(dev_t device)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
main(int argc,char ** argv)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