1 
2 #include "util.h"
3 #include "sysfs.h"
4 
5 static const char * const sysfs_known_mountpoints[] = {
6 	"/sys",
7 	0,
8 };
9 
10 static int sysfs_found;
11 char sysfs_mountpoint[PATH_MAX + 1];
12 
sysfs_valid_mountpoint(const char * sysfs)13 static int sysfs_valid_mountpoint(const char *sysfs)
14 {
15 	struct statfs st_fs;
16 
17 	if (statfs(sysfs, &st_fs) < 0)
18 		return -ENOENT;
19 	else if (st_fs.f_type != (long) SYSFS_MAGIC)
20 		return -ENOENT;
21 
22 	return 0;
23 }
24 
sysfs_find_mountpoint(void)25 const char *sysfs_find_mountpoint(void)
26 {
27 	const char * const *ptr;
28 	char type[100];
29 	FILE *fp;
30 
31 	if (sysfs_found)
32 		return (const char *) sysfs_mountpoint;
33 
34 	ptr = sysfs_known_mountpoints;
35 	while (*ptr) {
36 		if (sysfs_valid_mountpoint(*ptr) == 0) {
37 			sysfs_found = 1;
38 			strcpy(sysfs_mountpoint, *ptr);
39 			return sysfs_mountpoint;
40 		}
41 		ptr++;
42 	}
43 
44 	/* give up and parse /proc/mounts */
45 	fp = fopen("/proc/mounts", "r");
46 	if (fp == NULL)
47 		return NULL;
48 
49 	while (!sysfs_found &&
50 	       fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
51 		      sysfs_mountpoint, type) == 2) {
52 
53 		if (strcmp(type, "sysfs") == 0)
54 			sysfs_found = 1;
55 	}
56 
57 	fclose(fp);
58 
59 	return sysfs_found ? sysfs_mountpoint : NULL;
60 }
61