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#include "debug-internal.h"
17
18#define _STR(x) #x
19#define STR(x) _STR(x)
20
21#ifndef SYSFS_MAGIC
22#define SYSFS_MAGIC 0x62656572
23#endif
24
25#ifndef PROC_SUPER_MAGIC
26#define PROC_SUPER_MAGIC 0x9fa0
27#endif
28
29#ifndef DEBUGFS_MAGIC
30#define DEBUGFS_MAGIC 0x64626720
31#endif
32
33#ifndef TRACEFS_MAGIC
34#define TRACEFS_MAGIC 0x74726163
35#endif
36
37#ifndef HUGETLBFS_MAGIC
38#define HUGETLBFS_MAGIC 0x958458f6
39#endif
40
41#ifndef BPF_FS_MAGIC
42#define BPF_FS_MAGIC 0xcafe4a11
43#endif
44
45static const char * const sysfs__fs_known_mountpoints[] = {
46 "/sys",
47 0,
48};
49
50static const char * const procfs__known_mountpoints[] = {
51 "/proc",
52 0,
53};
54
55#ifndef DEBUGFS_DEFAULT_PATH
56#define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
57#endif
58
59static const char * const debugfs__known_mountpoints[] = {
60 DEBUGFS_DEFAULT_PATH,
61 "/debug",
62 0,
63};
64
65
66#ifndef TRACEFS_DEFAULT_PATH
67#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
68#endif
69
70static const char * const tracefs__known_mountpoints[] = {
71 TRACEFS_DEFAULT_PATH,
72 "/sys/kernel/debug/tracing",
73 "/tracing",
74 "/trace",
75 0,
76};
77
78static const char * const hugetlbfs__known_mountpoints[] = {
79 0,
80};
81
82static const char * const bpf_fs__known_mountpoints[] = {
83 "/sys/fs/bpf",
84 0,
85};
86
87struct fs {
88 const char *name;
89 const char * const *mounts;
90 char path[PATH_MAX];
91 bool found;
92 long magic;
93};
94
95enum {
96 FS__SYSFS = 0,
97 FS__PROCFS = 1,
98 FS__DEBUGFS = 2,
99 FS__TRACEFS = 3,
100 FS__HUGETLBFS = 4,
101 FS__BPF_FS = 5,
102};
103
104#ifndef TRACEFS_MAGIC
105#define TRACEFS_MAGIC 0x74726163
106#endif
107
108static struct fs fs__entries[] = {
109 [FS__SYSFS] = {
110 .name = "sysfs",
111 .mounts = sysfs__fs_known_mountpoints,
112 .magic = SYSFS_MAGIC,
113 },
114 [FS__PROCFS] = {
115 .name = "proc",
116 .mounts = procfs__known_mountpoints,
117 .magic = PROC_SUPER_MAGIC,
118 },
119 [FS__DEBUGFS] = {
120 .name = "debugfs",
121 .mounts = debugfs__known_mountpoints,
122 .magic = DEBUGFS_MAGIC,
123 },
124 [FS__TRACEFS] = {
125 .name = "tracefs",
126 .mounts = tracefs__known_mountpoints,
127 .magic = TRACEFS_MAGIC,
128 },
129 [FS__HUGETLBFS] = {
130 .name = "hugetlbfs",
131 .mounts = hugetlbfs__known_mountpoints,
132 .magic = HUGETLBFS_MAGIC,
133 },
134 [FS__BPF_FS] = {
135 .name = "bpf",
136 .mounts = bpf_fs__known_mountpoints,
137 .magic = BPF_FS_MAGIC,
138 },
139};
140
141static bool fs__read_mounts(struct fs *fs)
142{
143 bool found = false;
144 char type[100];
145 FILE *fp;
146
147 fp = fopen("/proc/mounts", "r");
148 if (fp == NULL)
149 return NULL;
150
151 while (!found &&
152 fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
153 fs->path, type) == 2) {
154
155 if (strcmp(type, fs->name) == 0)
156 found = true;
157 }
158
159 fclose(fp);
160 return fs->found = found;
161}
162
163static int fs__valid_mount(const char *fs, long magic)
164{
165 struct statfs st_fs;
166
167 if (statfs(fs, &st_fs) < 0)
168 return -ENOENT;
169 else if ((long)st_fs.f_type != magic)
170 return -ENOENT;
171
172 return 0;
173}
174
175static bool fs__check_mounts(struct fs *fs)
176{
177 const char * const *ptr;
178
179 ptr = fs->mounts;
180 while (*ptr) {
181 if (fs__valid_mount(*ptr, fs->magic) == 0) {
182 fs->found = true;
183 strcpy(fs->path, *ptr);
184 return true;
185 }
186 ptr++;
187 }
188
189 return false;
190}
191
192static void mem_toupper(char *f, size_t len)
193{
194 while (len) {
195 *f = toupper(*f);
196 f++;
197 len--;
198 }
199}
200
201
202
203
204
205
206static bool fs__env_override(struct fs *fs)
207{
208 char *override_path;
209 size_t name_len = strlen(fs->name);
210
211 char upper_name[name_len + 5 + 1];
212 memcpy(upper_name, fs->name, name_len);
213 mem_toupper(upper_name, name_len);
214 strcpy(&upper_name[name_len], "_PATH");
215
216 override_path = getenv(upper_name);
217 if (!override_path)
218 return false;
219
220 fs->found = true;
221 strncpy(fs->path, override_path, sizeof(fs->path));
222 return true;
223}
224
225static const char *fs__get_mountpoint(struct fs *fs)
226{
227 if (fs__env_override(fs))
228 return fs->path;
229
230 if (fs__check_mounts(fs))
231 return fs->path;
232
233 if (fs__read_mounts(fs))
234 return fs->path;
235
236 return NULL;
237}
238
239static const char *fs__mountpoint(int idx)
240{
241 struct fs *fs = &fs__entries[idx];
242
243 if (fs->found)
244 return (const char *)fs->path;
245
246 return fs__get_mountpoint(fs);
247}
248
249static const char *mount_overload(struct fs *fs)
250{
251 size_t name_len = strlen(fs->name);
252
253 char upper_name[5 + name_len + 12 + 1];
254
255 snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
256 mem_toupper(upper_name, name_len);
257
258 return getenv(upper_name) ?: *fs->mounts;
259}
260
261static const char *fs__mount(int idx)
262{
263 struct fs *fs = &fs__entries[idx];
264 const char *mountpoint;
265
266 if (fs__mountpoint(idx))
267 return (const char *)fs->path;
268
269 mountpoint = mount_overload(fs);
270
271 if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
272 return NULL;
273
274 return fs__check_mounts(fs) ? fs->path : NULL;
275}
276
277#define FS(name, idx) \
278const char *name##__mountpoint(void) \
279{ \
280 return fs__mountpoint(idx); \
281} \
282 \
283const char *name##__mount(void) \
284{ \
285 return fs__mount(idx); \
286} \
287 \
288bool name##__configured(void) \
289{ \
290 return name##__mountpoint() != NULL; \
291}
292
293FS(sysfs, FS__SYSFS);
294FS(procfs, FS__PROCFS);
295FS(debugfs, FS__DEBUGFS);
296FS(tracefs, FS__TRACEFS);
297FS(hugetlbfs, FS__HUGETLBFS);
298FS(bpf_fs, FS__BPF_FS);
299
300int filename__read_int(const char *filename, int *value)
301{
302 char line[64];
303 int fd = open(filename, O_RDONLY), err = -1;
304
305 if (fd < 0)
306 return -1;
307
308 if (read(fd, line, sizeof(line)) > 0) {
309 *value = atoi(line);
310 err = 0;
311 }
312
313 close(fd);
314 return err;
315}
316
317
318
319
320
321
322int filename__read_ull(const char *filename, unsigned long long *value)
323{
324 char line[64];
325 int fd = open(filename, O_RDONLY), err = -1;
326
327 if (fd < 0)
328 return -1;
329
330 if (read(fd, line, sizeof(line)) > 0) {
331 *value = strtoull(line, NULL, 0);
332 if (*value != ULLONG_MAX)
333 err = 0;
334 }
335
336 close(fd);
337 return err;
338}
339
340#define STRERR_BUFSIZE 128
341
342int filename__read_str(const char *filename, char **buf, size_t *sizep)
343{
344 size_t size = 0, alloc_size = 0;
345 void *bf = NULL, *nbf;
346 int fd, n, err = 0;
347 char sbuf[STRERR_BUFSIZE];
348
349 fd = open(filename, O_RDONLY);
350 if (fd < 0)
351 return -errno;
352
353 do {
354 if (size == alloc_size) {
355 alloc_size += BUFSIZ;
356 nbf = realloc(bf, alloc_size);
357 if (!nbf) {
358 err = -ENOMEM;
359 break;
360 }
361
362 bf = nbf;
363 }
364
365 n = read(fd, bf + size, alloc_size - size);
366 if (n < 0) {
367 if (size) {
368 pr_warning("read failed %d: %s\n", errno,
369 strerror_r(errno, sbuf, sizeof(sbuf)));
370 err = 0;
371 } else
372 err = -errno;
373
374 break;
375 }
376
377 size += n;
378 } while (n > 0);
379
380 if (!err) {
381 *sizep = size;
382 *buf = bf;
383 } else
384 free(bf);
385
386 close(fd);
387 return err;
388}
389
390int filename__write_int(const char *filename, int value)
391{
392 int fd = open(filename, O_WRONLY), err = -1;
393 char buf[64];
394
395 if (fd < 0)
396 return err;
397
398 sprintf(buf, "%d", value);
399 if (write(fd, buf, sizeof(buf)) == sizeof(buf))
400 err = 0;
401
402 close(fd);
403 return err;
404}
405
406int procfs__read_str(const char *entry, char **buf, size_t *sizep)
407{
408 char path[PATH_MAX];
409 const char *procfs = procfs__mountpoint();
410
411 if (!procfs)
412 return -1;
413
414 snprintf(path, sizeof(path), "%s/%s", procfs, entry);
415
416 return filename__read_str(path, buf, sizep);
417}
418
419int sysfs__read_ull(const char *entry, unsigned long long *value)
420{
421 char path[PATH_MAX];
422 const char *sysfs = sysfs__mountpoint();
423
424 if (!sysfs)
425 return -1;
426
427 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
428
429 return filename__read_ull(path, value);
430}
431
432int sysfs__read_int(const char *entry, int *value)
433{
434 char path[PATH_MAX];
435 const char *sysfs = sysfs__mountpoint();
436
437 if (!sysfs)
438 return -1;
439
440 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
441
442 return filename__read_int(path, value);
443}
444
445int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
446{
447 char path[PATH_MAX];
448 const char *sysfs = sysfs__mountpoint();
449
450 if (!sysfs)
451 return -1;
452
453 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
454
455 return filename__read_str(path, buf, sizep);
456}
457
458int sysfs__read_bool(const char *entry, bool *value)
459{
460 char *buf;
461 size_t size;
462 int ret;
463
464 ret = sysfs__read_str(entry, &buf, &size);
465 if (ret < 0)
466 return ret;
467
468 switch (buf[0]) {
469 case '1':
470 case 'y':
471 case 'Y':
472 *value = true;
473 break;
474 case '0':
475 case 'n':
476 case 'N':
477 *value = false;
478 break;
479 default:
480 ret = -1;
481 }
482
483 free(buf);
484
485 return ret;
486}
487int sysctl__read_int(const char *sysctl, int *value)
488{
489 char path[PATH_MAX];
490 const char *procfs = procfs__mountpoint();
491
492 if (!procfs)
493 return -1;
494
495 snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
496
497 return filename__read_int(path, value);
498}
499
500int sysfs__write_int(const char *entry, int value)
501{
502 char path[PATH_MAX];
503 const char *sysfs = sysfs__mountpoint();
504
505 if (!sysfs)
506 return -1;
507
508 if (snprintf(path, sizeof(path), "%s/%s", sysfs, entry) >= PATH_MAX)
509 return -1;
510
511 return filename__write_int(path, value);
512}
513
