1 #include <ctype.h>
2 #include <errno.h>
3 #include <limits.h>
4 #include <stdbool.h>
5 #include <stdio.h>
6 #include <stdlib.h>
7 #include <string.h>
8 #include <sys/vfs.h>
9 #include <sys/types.h>
10 #include <sys/stat.h>
11 #include <fcntl.h>
12 #include <unistd.h>
13 #include <sys/mount.h>
14
15 #include "fs.h"
16
17 #define _STR(x) #x
18 #define STR(x) _STR(x)
19
20 #ifndef SYSFS_MAGIC
21 #define SYSFS_MAGIC 0x62656572
22 #endif
23
24 #ifndef PROC_SUPER_MAGIC
25 #define PROC_SUPER_MAGIC 0x9fa0
26 #endif
27
28 #ifndef DEBUGFS_MAGIC
29 #define DEBUGFS_MAGIC 0x64626720
30 #endif
31
32 #ifndef TRACEFS_MAGIC
33 #define TRACEFS_MAGIC 0x74726163
34 #endif
35
36 static const char * const sysfs__fs_known_mountpoints[] = {
37 "/sys",
38 0,
39 };
40
41 static const char * const procfs__known_mountpoints[] = {
42 "/proc",
43 0,
44 };
45
46 #ifndef DEBUGFS_DEFAULT_PATH
47 #define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
48 #endif
49
50 static const char * const debugfs__known_mountpoints[] = {
51 DEBUGFS_DEFAULT_PATH,
52 "/debug",
53 0,
54 };
55
56
57 #ifndef TRACEFS_DEFAULT_PATH
58 #define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
59 #endif
60
61 static const char * const tracefs__known_mountpoints[] = {
62 TRACEFS_DEFAULT_PATH,
63 "/sys/kernel/debug/tracing",
64 "/tracing",
65 "/trace",
66 0,
67 };
68
69 struct fs {
70 const char *name;
71 const char * const *mounts;
72 char path[PATH_MAX];
73 bool found;
74 long magic;
75 };
76
77 enum {
78 FS__SYSFS = 0,
79 FS__PROCFS = 1,
80 FS__DEBUGFS = 2,
81 FS__TRACEFS = 3,
82 };
83
84 #ifndef TRACEFS_MAGIC
85 #define TRACEFS_MAGIC 0x74726163
86 #endif
87
88 static struct fs fs__entries[] = {
89 [FS__SYSFS] = {
90 .name = "sysfs",
91 .mounts = sysfs__fs_known_mountpoints,
92 .magic = SYSFS_MAGIC,
93 },
94 [FS__PROCFS] = {
95 .name = "proc",
96 .mounts = procfs__known_mountpoints,
97 .magic = PROC_SUPER_MAGIC,
98 },
99 [FS__DEBUGFS] = {
100 .name = "debugfs",
101 .mounts = debugfs__known_mountpoints,
102 .magic = DEBUGFS_MAGIC,
103 },
104 [FS__TRACEFS] = {
105 .name = "tracefs",
106 .mounts = tracefs__known_mountpoints,
107 .magic = TRACEFS_MAGIC,
108 },
109 };
110
fs__read_mounts(struct fs * fs)111 static bool fs__read_mounts(struct fs *fs)
112 {
113 bool found = false;
114 char type[100];
115 FILE *fp;
116
117 fp = fopen("/proc/mounts", "r");
118 if (fp == NULL)
119 return NULL;
120
121 while (!found &&
122 fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
123 fs->path, type) == 2) {
124
125 if (strcmp(type, fs->name) == 0)
126 found = true;
127 }
128
129 fclose(fp);
130 return fs->found = found;
131 }
132
fs__valid_mount(const char * fs,long magic)133 static int fs__valid_mount(const char *fs, long magic)
134 {
135 struct statfs st_fs;
136
137 if (statfs(fs, &st_fs) < 0)
138 return -ENOENT;
139 else if ((long)st_fs.f_type != magic)
140 return -ENOENT;
141
142 return 0;
143 }
144
fs__check_mounts(struct fs * fs)145 static bool fs__check_mounts(struct fs *fs)
146 {
147 const char * const *ptr;
148
149 ptr = fs->mounts;
150 while (*ptr) {
151 if (fs__valid_mount(*ptr, fs->magic) == 0) {
152 fs->found = true;
153 strcpy(fs->path, *ptr);
154 return true;
155 }
156 ptr++;
157 }
158
159 return false;
160 }
161
mem_toupper(char * f,size_t len)162 static void mem_toupper(char *f, size_t len)
163 {
164 while (len) {
165 *f = toupper(*f);
166 f++;
167 len--;
168 }
169 }
170
171 /*
172 * Check for "NAME_PATH" environment variable to override fs location (for
173 * testing). This matches the recommendation in Documentation/sysfs-rules.txt
174 * for SYSFS_PATH.
175 */
fs__env_override(struct fs * fs)176 static bool fs__env_override(struct fs *fs)
177 {
178 char *override_path;
179 size_t name_len = strlen(fs->name);
180 /* name + "_PATH" + '\0' */
181 char upper_name[name_len + 5 + 1];
182
183 memcpy(upper_name, fs->name, name_len);
184 mem_toupper(upper_name, name_len);
185 strcpy(&upper_name[name_len], "_PATH");
186
187 override_path = getenv(upper_name);
188 if (!override_path)
189 return false;
190
191 fs->found = true;
192 strncpy(fs->path, override_path, sizeof(fs->path) - 1);
193 fs->path[sizeof(fs->path) - 1] = '\0';
194 return true;
195 }
196
fs__get_mountpoint(struct fs * fs)197 static const char *fs__get_mountpoint(struct fs *fs)
198 {
199 if (fs__env_override(fs))
200 return fs->path;
201
202 if (fs__check_mounts(fs))
203 return fs->path;
204
205 if (fs__read_mounts(fs))
206 return fs->path;
207
208 return NULL;
209 }
210
fs__mountpoint(int idx)211 static const char *fs__mountpoint(int idx)
212 {
213 struct fs *fs = &fs__entries[idx];
214
215 if (fs->found)
216 return (const char *)fs->path;
217
218 return fs__get_mountpoint(fs);
219 }
220
mount_overload(struct fs * fs)221 static const char *mount_overload(struct fs *fs)
222 {
223 size_t name_len = strlen(fs->name);
224 /* "PERF_" + name + "_ENVIRONMENT" + '\0' */
225 char upper_name[5 + name_len + 12 + 1];
226
227 snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
228 mem_toupper(upper_name, name_len);
229
230 return getenv(upper_name) ?: *fs->mounts;
231 }
232
fs__mount(int idx)233 static const char *fs__mount(int idx)
234 {
235 struct fs *fs = &fs__entries[idx];
236 const char *mountpoint;
237
238 if (fs__mountpoint(idx))
239 return (const char *)fs->path;
240
241 mountpoint = mount_overload(fs);
242
243 if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
244 return NULL;
245
246 return fs__check_mounts(fs) ? fs->path : NULL;
247 }
248
249 #define FS(name, idx) \
250 const char *name##__mountpoint(void) \
251 { \
252 return fs__mountpoint(idx); \
253 } \
254 \
255 const char *name##__mount(void) \
256 { \
257 return fs__mount(idx); \
258 } \
259 \
260 bool name##__configured(void) \
261 { \
262 return name##__mountpoint() != NULL; \
263 }
264
265 FS(sysfs, FS__SYSFS);
266 FS(procfs, FS__PROCFS);
267 FS(debugfs, FS__DEBUGFS);
268 FS(tracefs, FS__TRACEFS);
269
filename__read_int(const char * filename,int * value)270 int filename__read_int(const char *filename, int *value)
271 {
272 char line[64];
273 int fd = open(filename, O_RDONLY), err = -1;
274
275 if (fd < 0)
276 return -1;
277
278 if (read(fd, line, sizeof(line)) > 0) {
279 *value = atoi(line);
280 err = 0;
281 }
282
283 close(fd);
284 return err;
285 }
286
filename__read_ull(const char * filename,unsigned long long * value)287 int filename__read_ull(const char *filename, unsigned long long *value)
288 {
289 char line[64];
290 int fd = open(filename, O_RDONLY), err = -1;
291
292 if (fd < 0)
293 return -1;
294
295 if (read(fd, line, sizeof(line)) > 0) {
296 *value = strtoull(line, NULL, 10);
297 if (*value != ULLONG_MAX)
298 err = 0;
299 }
300
301 close(fd);
302 return err;
303 }
304
sysfs__read_ull(const char * entry,unsigned long long * value)305 int sysfs__read_ull(const char *entry, unsigned long long *value)
306 {
307 char path[PATH_MAX];
308 const char *sysfs = sysfs__mountpoint();
309
310 if (!sysfs)
311 return -1;
312
313 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
314
315 return filename__read_ull(path, value);
316 }
317
sysfs__read_int(const char * entry,int * value)318 int sysfs__read_int(const char *entry, int *value)
319 {
320 char path[PATH_MAX];
321 const char *sysfs = sysfs__mountpoint();
322
323 if (!sysfs)
324 return -1;
325
326 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
327
328 return filename__read_int(path, value);
329 }
330
sysctl__read_int(const char * sysctl,int * value)331 int sysctl__read_int(const char *sysctl, int *value)
332 {
333 char path[PATH_MAX];
334 const char *procfs = procfs__mountpoint();
335
336 if (!procfs)
337 return -1;
338
339 snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
340
341 return filename__read_int(path, value);
342 }
343