finddev.c revision 31dbecd482405e0d3a67eb58e1a1c8cb9f2ad83e 
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#if EXT2_FLAT_INCLUDES
35#include "ext2_fs.h"
36#else
37#include <linux/ext2_fs.h>
38#endif
39
40#include "ext2fs.h"
41
42struct dir_list {
43	char	*name;
44	struct dir_list *next;
45};
46
47/*
48 * This function adds an entry to the directory list
49 */
50static 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 */
70static 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
82static 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				return ENOMEM;
111			strcpy(cp, path);
112			*ret_path = cp;
113			return 0;
114		}
115	skip_to_next:
116		dp = readdir(dir);
117	}
118	closedir(dir);
119	return 0;
120}
121
122/*
123 * This function finds the pathname to a block device with a given
124 * device number.  It returns a pointer to allocated memory to the
125 * pathname on success, and NULL on failure.
126 */
127char *ext2fs_find_block_device(dev_t device)
128{
129	struct dir_list *list = 0, *new_list = 0;
130	struct dir_list *current;
131	char	*ret_path = 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		}
159	}
160	free_dirlist(&list);
161	free_dirlist(&new_list);
162	return ret_path;
163}
164
165
166#ifdef DEBUG
167int main(int argc, char** argv)
168{
169	char	*devname, *tmp;
170	int	major, minor;
171	dev_t	device;
172	const char *errmsg = "Couldn't parse %s: %s\n";
173
174	if ((argc != 2) && (argc != 3)) {
175		fprintf(stderr, "Usage: %s device_number\n", argv[0]);
176		fprintf(stderr, "\t: %s major minor\n", argv[0]);
177		exit(1);
178	}
179	if (argc == 2) {
180		device = strtoul(argv[1], &tmp, 0);
181		if (*tmp) {
182			fprintf(stderr, errmsg, "device number", argv[1]);
183			exit(1);
184		}
185	} else {
186		major = strtoul(argv[1], &tmp, 0);
187		if (*tmp) {
188			fprintf(stderr, errmsg, "major number", argv[1]);
189			exit(1);
190		}
191		minor = strtoul(argv[2], &tmp, 0);
192		if (*tmp) {
193			fprintf(stderr, errmsg, "minor number", argv[2]);
194			exit(1);
195		}
196		device = makedev(major, minor);
197		printf("Looking for device 0x%04x (%d:%d)\n", device,
198		       major, minor);
199	}
200	devname = ext2fs_find_block_device(device);
201	if (devname) {
202		printf("Found device!  %s\n", devname);
203		free(devname);
204	} else {
205		printf("Couldn't find device.\n");
206	}
207	return 0;
208}
209
210#endif
211