1/* TODO merge/factor in debugfs.c here */
2
3#include <ctype.h>
4#include <errno.h>
5#include <stdbool.h>
6#include <stdio.h>
7#include <stdlib.h>
8#include <string.h>
9#include <sys/vfs.h>
10#include <sys/types.h>
11#include <sys/stat.h>
12#include <fcntl.h>
13#include <unistd.h>
14
15#include "debugfs.h"
16#include "fs.h"
17
18static const char * const sysfs__fs_known_mountpoints[] = {
19	"/sys",
20	0,
21};
22
23static const char * const procfs__known_mountpoints[] = {
24	"/proc",
25	0,
26};
27
28struct fs {
29	const char		*name;
30	const char * const	*mounts;
31	char			 path[PATH_MAX + 1];
32	bool			 found;
33	long			 magic;
34};
35
36enum {
37	FS__SYSFS  = 0,
38	FS__PROCFS = 1,
39};
40
41static struct fs fs__entries[] = {
42	[FS__SYSFS] = {
43		.name	= "sysfs",
44		.mounts	= sysfs__fs_known_mountpoints,
45		.magic	= SYSFS_MAGIC,
46	},
47	[FS__PROCFS] = {
48		.name	= "proc",
49		.mounts	= procfs__known_mountpoints,
50		.magic	= PROC_SUPER_MAGIC,
51	},
52};
53
54static bool fs__read_mounts(struct fs *fs)
55{
56	bool found = false;
57	char type[100];
58	FILE *fp;
59
60	fp = fopen("/proc/mounts", "r");
61	if (fp == NULL)
62		return NULL;
63
64	while (!found &&
65	       fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
66		      fs->path, type) == 2) {
67
68		if (strcmp(type, fs->name) == 0)
69			found = true;
70	}
71
72	fclose(fp);
73	return fs->found = found;
74}
75
76static int fs__valid_mount(const char *fs, long magic)
77{
78	struct statfs st_fs;
79
80	if (statfs(fs, &st_fs) < 0)
81		return -ENOENT;
82	else if ((long)st_fs.f_type != magic)
83		return -ENOENT;
84
85	return 0;
86}
87
88static bool fs__check_mounts(struct fs *fs)
89{
90	const char * const *ptr;
91
92	ptr = fs->mounts;
93	while (*ptr) {
94		if (fs__valid_mount(*ptr, fs->magic) == 0) {
95			fs->found = true;
96			strcpy(fs->path, *ptr);
97			return true;
98		}
99		ptr++;
100	}
101
102	return false;
103}
104
105static void mem_toupper(char *f, size_t len)
106{
107	while (len) {
108		*f = toupper(*f);
109		f++;
110		len--;
111	}
112}
113
114/*
115 * Check for "NAME_PATH" environment variable to override fs location (for
116 * testing). This matches the recommendation in Documentation/sysfs-rules.txt
117 * for SYSFS_PATH.
118 */
119static bool fs__env_override(struct fs *fs)
120{
121	char *override_path;
122	size_t name_len = strlen(fs->name);
123	/* name + "_PATH" + '\0' */
124	char upper_name[name_len + 5 + 1];
125	memcpy(upper_name, fs->name, name_len);
126	mem_toupper(upper_name, name_len);
127	strcpy(&upper_name[name_len], "_PATH");
128
129	override_path = getenv(upper_name);
130	if (!override_path)
131		return false;
132
133	fs->found = true;
134	strncpy(fs->path, override_path, sizeof(fs->path));
135	return true;
136}
137
138static const char *fs__get_mountpoint(struct fs *fs)
139{
140	if (fs__env_override(fs))
141		return fs->path;
142
143	if (fs__check_mounts(fs))
144		return fs->path;
145
146	if (fs__read_mounts(fs))
147		return fs->path;
148
149	return NULL;
150}
151
152static const char *fs__mountpoint(int idx)
153{
154	struct fs *fs = &fs__entries[idx];
155
156	if (fs->found)
157		return (const char *)fs->path;
158
159	return fs__get_mountpoint(fs);
160}
161
162#define FS__MOUNTPOINT(name, idx)	\
163const char *name##__mountpoint(void)	\
164{					\
165	return fs__mountpoint(idx);	\
166}
167
168FS__MOUNTPOINT(sysfs,  FS__SYSFS);
169FS__MOUNTPOINT(procfs, FS__PROCFS);
170
171int filename__read_int(const char *filename, int *value)
172{
173	char line[64];
174	int fd = open(filename, O_RDONLY), err = -1;
175
176	if (fd < 0)
177		return -1;
178
179	if (read(fd, line, sizeof(line)) > 0) {
180		*value = atoi(line);
181		err = 0;
182	}
183
184	close(fd);
185	return err;
186}
187
188int sysctl__read_int(const char *sysctl, int *value)
189{
190	char path[PATH_MAX];
191	const char *procfs = procfs__mountpoint();
192
193	if (!procfs)
194		return -1;
195
196	snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
197
198	return filename__read_int(path, value);
199}
200