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