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
37static const char * const sysfs__fs_known_mountpoints[] = {
38 "/sys",
39 0,
40};
41
42static const char * const procfs__known_mountpoints[] = {
43 "/proc",
44 0,
45};
46
47#ifndef DEBUGFS_DEFAULT_PATH
48#define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
49#endif
50
51static const char * const debugfs__known_mountpoints[] = {
52 DEBUGFS_DEFAULT_PATH,
53 "/debug",
54 0,
55};
56
57
58#ifndef TRACEFS_DEFAULT_PATH
59#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
60#endif
61
62static const char * const tracefs__known_mountpoints[] = {
63 TRACEFS_DEFAULT_PATH,
64 "/sys/kernel/debug/tracing",
65 "/tracing",
66 "/trace",
67 0,
68};
69
70struct fs {
71 const char *name;
72 const char * const *mounts;
73 char path[PATH_MAX];
74 bool found;
75 long magic;
76};
77
78enum {
79 FS__SYSFS = 0,
80 FS__PROCFS = 1,
81 FS__DEBUGFS = 2,
82 FS__TRACEFS = 3,
83};
84
85#ifndef TRACEFS_MAGIC
86#define TRACEFS_MAGIC 0x74726163
87#endif
88
89static struct fs fs__entries[] = {
90 [FS__SYSFS] = {
91 .name = "sysfs",
92 .mounts = sysfs__fs_known_mountpoints,
93 .magic = SYSFS_MAGIC,
94 },
95 [FS__PROCFS] = {
96 .name = "proc",
97 .mounts = procfs__known_mountpoints,
98 .magic = PROC_SUPER_MAGIC,
99 },
100 [FS__DEBUGFS] = {
101 .name = "debugfs",
102 .mounts = debugfs__known_mountpoints,
103 .magic = DEBUGFS_MAGIC,
104 },
105 [FS__TRACEFS] = {
106 .name = "tracefs",
107 .mounts = tracefs__known_mountpoints,
108 .magic = TRACEFS_MAGIC,
109 },
110};
111
112static bool fs__read_mounts(struct fs *fs)
113{
114 bool found = false;
115 char type[100];
116 FILE *fp;
117
118 fp = fopen("/proc/mounts", "r");
119 if (fp == NULL)
120 return NULL;
121
122 while (!found &&
123 fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
124 fs->path, type) == 2) {
125
126 if (strcmp(type, fs->name) == 0)
127 found = true;
128 }
129
130 fclose(fp);
131 return fs->found = found;
132}
133
134static int fs__valid_mount(const char *fs, long magic)
135{
136 struct statfs st_fs;
137
138 if (statfs(fs, &st_fs) < 0)
139 return -ENOENT;
140 else if ((long)st_fs.f_type != magic)
141 return -ENOENT;
142
143 return 0;
144}
145
146static bool fs__check_mounts(struct fs *fs)
147{
148 const char * const *ptr;
149
150 ptr = fs->mounts;
151 while (*ptr) {
152 if (fs__valid_mount(*ptr, fs->magic) == 0) {
153 fs->found = true;
154 strcpy(fs->path, *ptr);
155 return true;
156 }
157 ptr++;
158 }
159
160 return false;
161}
162
163static void mem_toupper(char *f, size_t len)
164{
165 while (len) {
166 *f = toupper(*f);
167 f++;
168 len--;
169 }
170}
171
172
173
174
175
176
177static bool fs__env_override(struct fs *fs)
178{
179 char *override_path;
180 size_t name_len = strlen(fs->name);
181
182 char upper_name[name_len + 5 + 1];
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));
193 return true;
194}
195
196static const char *fs__get_mountpoint(struct fs *fs)
197{
198 if (fs__env_override(fs))
199 return fs->path;
200
201 if (fs__check_mounts(fs))
202 return fs->path;
203
204 if (fs__read_mounts(fs))
205 return fs->path;
206
207 return NULL;
208}
209
210static const char *fs__mountpoint(int idx)
211{
212 struct fs *fs = &fs__entries[idx];
213
214 if (fs->found)
215 return (const char *)fs->path;
216
217 return fs__get_mountpoint(fs);
218}
219
220static const char *mount_overload(struct fs *fs)
221{
222 size_t name_len = strlen(fs->name);
223
224 char upper_name[5 + name_len + 12 + 1];
225
226 snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
227 mem_toupper(upper_name, name_len);
228
229 return getenv(upper_name) ?: *fs->mounts;
230}
231
232static const char *fs__mount(int idx)
233{
234 struct fs *fs = &fs__entries[idx];
235 const char *mountpoint;
236
237 if (fs__mountpoint(idx))
238 return (const char *)fs->path;
239
240 mountpoint = mount_overload(fs);
241
242 if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
243 return NULL;
244
245 return fs__check_mounts(fs) ? fs->path : NULL;
246}
247
248#define FS(name, idx) \
249const char *name##__mountpoint(void) \
250{ \
251 return fs__mountpoint(idx); \
252} \
253 \
254const char *name##__mount(void) \
255{ \
256 return fs__mount(idx); \
257} \
258 \
259bool name##__configured(void) \
260{ \
261 return name##__mountpoint() != NULL; \
262}
263
264FS(sysfs, FS__SYSFS);
265FS(procfs, FS__PROCFS);
266FS(debugfs, FS__DEBUGFS);
267FS(tracefs, FS__TRACEFS);
268
269int filename__read_int(const char *filename, int *value)
270{
271 char line[64];
272 int fd = open(filename, O_RDONLY), err = -1;
273
274 if (fd < 0)
275 return -1;
276
277 if (read(fd, line, sizeof(line)) > 0) {
278 *value = atoi(line);
279 err = 0;
280 }
281
282 close(fd);
283 return err;
284}
285
286int filename__read_ull(const char *filename, unsigned long long *value)
287{
288 char line[64];
289 int fd = open(filename, O_RDONLY), err = -1;
290
291 if (fd < 0)
292 return -1;
293
294 if (read(fd, line, sizeof(line)) > 0) {
295 *value = strtoull(line, NULL, 10);
296 if (*value != ULLONG_MAX)
297 err = 0;
298 }
299
300 close(fd);
301 return err;
302}
303
304#define STRERR_BUFSIZE 128
305
306int filename__read_str(const char *filename, char **buf, size_t *sizep)
307{
308 size_t size = 0, alloc_size = 0;
309 void *bf = NULL, *nbf;
310 int fd, n, err = 0;
311 char sbuf[STRERR_BUFSIZE];
312
313 fd = open(filename, O_RDONLY);
314 if (fd < 0)
315 return -errno;
316
317 do {
318 if (size == alloc_size) {
319 alloc_size += BUFSIZ;
320 nbf = realloc(bf, alloc_size);
321 if (!nbf) {
322 err = -ENOMEM;
323 break;
324 }
325
326 bf = nbf;
327 }
328
329 n = read(fd, bf + size, alloc_size - size);
330 if (n < 0) {
331 if (size) {
332 pr_warning("read failed %d: %s\n", errno,
333 strerror_r(errno, sbuf, sizeof(sbuf)));
334 err = 0;
335 } else
336 err = -errno;
337
338 break;
339 }
340
341 size += n;
342 } while (n > 0);
343
344 if (!err) {
345 *sizep = size;
346 *buf = bf;
347 } else
348 free(bf);
349
350 close(fd);
351 return err;
352}
353
354int sysfs__read_ull(const char *entry, unsigned long long *value)
355{
356 char path[PATH_MAX];
357 const char *sysfs = sysfs__mountpoint();
358
359 if (!sysfs)
360 return -1;
361
362 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
363
364 return filename__read_ull(path, value);
365}
366
367int sysfs__read_int(const char *entry, int *value)
368{
369 char path[PATH_MAX];
370 const char *sysfs = sysfs__mountpoint();
371
372 if (!sysfs)
373 return -1;
374
375 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
376
377 return filename__read_int(path, value);
378}
379
380int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
381{
382 char path[PATH_MAX];
383 const char *sysfs = sysfs__mountpoint();
384
385 if (!sysfs)
386 return -1;
387
388 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
389
390 return filename__read_str(path, buf, sizep);
391}
392
393int sysctl__read_int(const char *sysctl, int *value)
394{
395 char path[PATH_MAX];
396 const char *procfs = procfs__mountpoint();
397
398 if (!procfs)
399 return -1;
400
401 snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
402
403 return filename__read_int(path, value);
404}
405
