blob: ae326f81a03f752fd57d6a2fb65a6cf111098394
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * devno.c - find a particular device by its device number (major/minor) |
4 | * |
5 | * Copyright (C) 2000, 2001, 2003 Theodore Ts'o |
6 | * Copyright (C) 2001 Andreas Dilger |
7 | * |
8 | * %Begin-Header% |
9 | * This file may be redistributed under the terms of the |
10 | * GNU Lesser General Public License. |
11 | * %End-Header% |
12 | */ |
13 | |
14 | #include <stdio.h> |
15 | #include <string.h> |
16 | #ifdef HAVE_UNISTD_H |
17 | #include <unistd.h> |
18 | #endif |
19 | #include <stdlib.h> |
20 | #include <string.h> |
21 | #ifdef HAVE_SYS_TYPES_H |
22 | #include <sys/types.h> |
23 | #endif |
24 | #include <sys/stat.h> |
25 | #include <dirent.h> |
26 | #ifdef HAVE_ERRNO_H |
27 | #include <errno.h> |
28 | #endif |
29 | #ifdef HAVE_SYS_MKDEV_H |
30 | #include <sys/mkdev.h> |
31 | #endif |
32 | |
33 | #include "blkidP.h" |
34 | |
35 | struct dir_list { |
36 | char *name; |
37 | struct dir_list *next; |
38 | }; |
39 | |
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 = xmalloc(length + 1); |
51 | strncpy(ret, s, length); |
52 | ret[length] = '\0'; |
53 | return ret; |
54 | } |
55 | |
56 | char *blkid_strdup(const char *s) |
57 | { |
58 | return blkid_strndup(s, 0); |
59 | } |
60 | |
61 | /* |
62 | * This function adds an entry to the directory list |
63 | */ |
64 | static void add_to_dirlist(const char *name, struct dir_list **list) |
65 | { |
66 | struct dir_list *dp; |
67 | |
68 | dp = xmalloc(sizeof(struct dir_list)); |
69 | dp->name = blkid_strdup(name); |
70 | dp->next = *list; |
71 | *list = dp; |
72 | } |
73 | |
74 | /* |
75 | * This function frees a directory list |
76 | */ |
77 | static void free_dirlist(struct dir_list **list) |
78 | { |
79 | struct dir_list *dp, *next; |
80 | |
81 | for (dp = *list; dp; dp = next) { |
82 | next = dp->next; |
83 | free(dp->name); |
84 | free(dp); |
85 | } |
86 | *list = NULL; |
87 | } |
88 | |
89 | static void scan_dir(char *dir_name, dev_t devno, struct dir_list **list, |
90 | char **devname) |
91 | { |
92 | DIR *dir; |
93 | struct dirent *dp; |
94 | char path[1024]; |
95 | int dirlen; |
96 | struct stat st; |
97 | |
98 | if ((dir = opendir(dir_name)) == NULL) |
99 | return; |
100 | dirlen = strlen(dir_name) + 2; |
101 | while ((dp = readdir(dir)) != 0) { |
102 | if (dirlen + strlen(dp->d_name) >= sizeof(path)) |
103 | continue; |
104 | |
105 | if (dp->d_name[0] == '.' && |
106 | ((dp->d_name[1] == 0) || |
107 | ((dp->d_name[1] == '.') && (dp->d_name[2] == 0)))) |
108 | continue; |
109 | |
110 | sprintf(path, "%s/%s", dir_name, dp->d_name); |
111 | if (stat(path, &st) < 0) |
112 | continue; |
113 | |
114 | if (S_ISDIR(st.st_mode)) |
115 | add_to_dirlist(path, list); |
116 | else if (S_ISBLK(st.st_mode) && st.st_rdev == devno) { |
117 | *devname = blkid_strdup(path); |
118 | DBG(DEBUG_DEVNO, |
119 | printf("found 0x%llx at %s (%p)\n", devno, |
120 | path, *devname)); |
121 | break; |
122 | } |
123 | } |
124 | closedir(dir); |
125 | } |
126 | |
127 | /* Directories where we will try to search for device numbers */ |
128 | const char *blkid_devdirs[] = { "/devices", "/devfs", "/dev", NULL }; |
129 | |
130 | /* |
131 | * This function finds the pathname to a block device with a given |
132 | * device number. It returns a pointer to allocated memory to the |
133 | * pathname on success, and NULL on failure. |
134 | */ |
135 | char *blkid_devno_to_devname(dev_t devno) |
136 | { |
137 | struct dir_list *list = NULL, *new_list = NULL; |
138 | char *devname = NULL; |
139 | const char **dir; |
140 | |
141 | /* |
142 | * Add the starting directories to search in reverse order of |
143 | * importance, since we are using a stack... |
144 | */ |
145 | for (dir = blkid_devdirs; *dir; dir++) |
146 | add_to_dirlist(*dir, &list); |
147 | |
148 | while (list) { |
149 | struct dir_list *current = list; |
150 | |
151 | list = list->next; |
152 | DBG(DEBUG_DEVNO, printf("directory %s\n", current->name)); |
153 | scan_dir(current->name, devno, &new_list, &devname); |
154 | free(current->name); |
155 | free(current); |
156 | if (devname) |
157 | break; |
158 | /* |
159 | * If we're done checking at this level, descend to |
160 | * the next level of subdirectories. (breadth-first) |
161 | */ |
162 | if (list == NULL) { |
163 | list = new_list; |
164 | new_list = NULL; |
165 | } |
166 | } |
167 | free_dirlist(&list); |
168 | free_dirlist(&new_list); |
169 | |
170 | if (!devname) { |
171 | DBG(DEBUG_DEVNO, |
172 | printf("blkid: cannot find devno 0x%04lx\n", |
173 | (unsigned long) devno)); |
174 | } else { |
175 | DBG(DEBUG_DEVNO, |
176 | printf("found devno 0x%04llx as %s\n", devno, devname)); |
177 | } |
178 | |
179 | |
180 | return devname; |
181 | } |
182 | |
183 | #ifdef TEST_PROGRAM |
184 | int main(int argc, char** argv) |
185 | { |
186 | char *devname, *tmp; |
187 | int major, minor; |
188 | dev_t devno; |
189 | const char *errmsg = "Cannot parse %s: %s\n"; |
190 | |
191 | blkid_debug_mask = DEBUG_ALL; |
192 | if ((argc != 2) && (argc != 3)) { |
193 | fprintf(stderr, "Usage:\t%s device_number\n\t%s major minor\n" |
194 | "Resolve a device number to a device name\n", |
195 | argv[0], argv[0]); |
196 | exit(1); |
197 | } |
198 | if (argc == 2) { |
199 | devno = strtoul(argv[1], &tmp, 0); |
200 | if (*tmp) { |
201 | fprintf(stderr, errmsg, "device number", argv[1]); |
202 | exit(1); |
203 | } |
204 | } else { |
205 | major = strtoul(argv[1], &tmp, 0); |
206 | if (*tmp) { |
207 | fprintf(stderr, errmsg, "major number", argv[1]); |
208 | exit(1); |
209 | } |
210 | minor = strtoul(argv[2], &tmp, 0); |
211 | if (*tmp) { |
212 | fprintf(stderr, errmsg, "minor number", argv[2]); |
213 | exit(1); |
214 | } |
215 | devno = makedev(major, minor); |
216 | } |
217 | printf("Looking for device 0x%04Lx\n", devno); |
218 | devname = blkid_devno_to_devname(devno); |
219 | free(devname); |
220 | return 0; |
221 | } |
222 | #endif |
223 |