1 /*
2 * devno.c - find a particular device by its device number (major/minor)
3 *
4 * Copyright (C) 2000, 2001, 2003 Theodore Ts'o
5 * Copyright (C) 2001 Andreas Dilger
6 *
7 * %Begin-Header%
8 * This file may be redistributed under the terms of the
9 * GNU Lesser General Public License.
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 "blkidP.h"
39
blkid_strndup(const char * s,int length)40 char *blkid_strndup(const char *s, int length)
41 {
42 char *ret;
43
44 if (!s)
45 return NULL;
46
47 if (!length)
48 length = strlen(s);
49
50 ret = malloc(length + 1);
51 if (ret) {
52 strncpy(ret, s, length);
53 ret[length] = '\0';
54 }
55 return ret;
56 }
57
blkid_strdup(const char * s)58 char *blkid_strdup(const char *s)
59 {
60 return blkid_strndup(s, 0);
61 }
62
63 /*
64 * This function adds an entry to the directory list
65 */
add_to_dirlist(const char * name,struct dir_list ** list)66 static void add_to_dirlist(const char *name, struct dir_list **list)
67 {
68 struct dir_list *dp;
69
70 dp = malloc(sizeof(struct dir_list));
71 if (!dp)
72 return;
73 dp->name = blkid_strdup(name);
74 if (!dp->name) {
75 free(dp);
76 return;
77 }
78 dp->next = *list;
79 *list = dp;
80 }
81
82 /*
83 * This function frees a directory list
84 */
free_dirlist(struct dir_list ** list)85 static void free_dirlist(struct dir_list **list)
86 {
87 struct dir_list *dp, *next;
88
89 for (dp = *list; dp; dp = next) {
90 next = dp->next;
91 free(dp->name);
92 free(dp);
93 }
94 *list = NULL;
95 }
96
blkid__scan_dir(const char * dirname,dev_t devno,struct dir_list ** list,char ** devname)97 void blkid__scan_dir(const char *dirname, dev_t devno, struct dir_list **list,
98 char **devname)
99 {
100 DIR *dir;
101 struct dirent *dp;
102 char path[1024];
103 int dirlen;
104 struct stat st;
105
106 if ((dir = opendir(dirname)) == NULL)
107 return;
108 dirlen = strlen(dirname) + 2;
109 while ((dp = readdir(dir)) != 0) {
110 if (dirlen + strlen(dp->d_name) >= sizeof(path))
111 continue;
112
113 if (dp->d_name[0] == '.' &&
114 ((dp->d_name[1] == 0) ||
115 ((dp->d_name[1] == '.') && (dp->d_name[2] == 0))))
116 continue;
117
118 sprintf(path, "%s/%s", dirname, dp->d_name);
119 if (stat(path, &st) < 0)
120 continue;
121
122 if (S_ISBLK(st.st_mode) && st.st_rdev == devno) {
123 *devname = blkid_strdup(path);
124 DBG(DEBUG_DEVNO,
125 printf("found 0x%llx at %s (%p)\n", (long long)devno,
126 path, *devname));
127 break;
128 }
129 if (list && S_ISDIR(st.st_mode) && !lstat(path, &st) &&
130 S_ISDIR(st.st_mode))
131 add_to_dirlist(path, list);
132 }
133 closedir(dir);
134 return;
135 }
136
137 /* Directories where we will try to search for device numbers */
138 static const char *devdirs[] = { "/devices", "/devfs", "/dev", NULL };
139
140 /*
141 * This function finds the pathname to a block device with a given
142 * device number. It returns a pointer to allocated memory to the
143 * pathname on success, and NULL on failure.
144 */
blkid_devno_to_devname(dev_t devno)145 char *blkid_devno_to_devname(dev_t devno)
146 {
147 struct dir_list *list = NULL, *new_list = NULL;
148 char *devname = NULL;
149 const char **dir;
150
151 /*
152 * Add the starting directories to search in reverse order of
153 * importance, since we are using a stack...
154 */
155 for (dir = devdirs; *dir; dir++)
156 add_to_dirlist(*dir, &list);
157
158 while (list) {
159 struct dir_list *current = list;
160
161 list = list->next;
162 DBG(DEBUG_DEVNO, printf("directory %s\n", current->name));
163 blkid__scan_dir(current->name, devno, &new_list, &devname);
164 free(current->name);
165 free(current);
166 if (devname)
167 break;
168 /*
169 * If we're done checking at this level, descend to
170 * the next level of subdirectories. (breadth-first)
171 */
172 if (list == NULL) {
173 list = new_list;
174 new_list = NULL;
175 }
176 }
177 free_dirlist(&list);
178 free_dirlist(&new_list);
179
180 if (!devname) {
181 DBG(DEBUG_DEVNO,
182 printf("blkid: couldn't find devno 0x%04lx\n",
183 (unsigned long) devno));
184 } else {
185 DBG(DEBUG_DEVNO,
186 printf("found devno 0x%04llx as %s\n", (long long)devno, devname));
187 }
188
189
190 return devname;
191 }
192
193 #ifdef TEST_PROGRAM
main(int argc,char ** argv)194 int main(int argc, char** argv)
195 {
196 char *devname, *tmp;
197 int major, minor;
198 dev_t devno;
199 const char *errmsg = "Couldn't parse %s: %s\n";
200
201 blkid_debug_mask = DEBUG_ALL;
202 if ((argc != 2) && (argc != 3)) {
203 fprintf(stderr, "Usage:\t%s device_number\n\t%s major minor\n"
204 "Resolve a device number to a device name\n",
205 argv[0], argv[0]);
206 exit(1);
207 }
208 if (argc == 2) {
209 devno = strtoul(argv[1], &tmp, 0);
210 if (*tmp) {
211 fprintf(stderr, errmsg, "device number", argv[1]);
212 exit(1);
213 }
214 } else {
215 major = strtoul(argv[1], &tmp, 0);
216 if (*tmp) {
217 fprintf(stderr, errmsg, "major number", argv[1]);
218 exit(1);
219 }
220 minor = strtoul(argv[2], &tmp, 0);
221 if (*tmp) {
222 fprintf(stderr, errmsg, "minor number", argv[2]);
223 exit(1);
224 }
225 devno = makedev(major, minor);
226 }
227 printf("Looking for device 0x%04llx\n", (long long)devno);
228 devname = blkid_devno_to_devname(devno);
229 free(devname);
230 return 0;
231 }
232 #endif
233