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