1#ifndef _GNU_SOURCE
2# define _GNU_SOURCE
3#endif
4
5#include <stdio.h>
6#include <stdlib.h>
7#include <string.h>
8#include <errno.h>
9#include <unistd.h>
10#include "fs.h"
11
12#include "tracing_path.h"
13
14
15char tracing_mnt[PATH_MAX]         = "/sys/kernel/debug";
16char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
17char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
18
19
20static void __tracing_path_set(const char *tracing, const char *mountpoint)
21{
22	snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
23	snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
24		 mountpoint, tracing);
25	snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
26		 mountpoint, tracing, "events");
27}
28
29static const char *tracing_path_tracefs_mount(void)
30{
31	const char *mnt;
32
33	mnt = tracefs__mount();
34	if (!mnt)
35		return NULL;
36
37	__tracing_path_set("", mnt);
38
39	return mnt;
40}
41
42static const char *tracing_path_debugfs_mount(void)
43{
44	const char *mnt;
45
46	mnt = debugfs__mount();
47	if (!mnt)
48		return NULL;
49
50	__tracing_path_set("tracing/", mnt);
51
52	return mnt;
53}
54
55const char *tracing_path_mount(void)
56{
57	const char *mnt;
58
59	mnt = tracing_path_tracefs_mount();
60	if (mnt)
61		return mnt;
62
63	mnt = tracing_path_debugfs_mount();
64
65	return mnt;
66}
67
68void tracing_path_set(const char *mntpt)
69{
70	__tracing_path_set("tracing/", mntpt);
71}
72
73char *get_tracing_file(const char *name)
74{
75	char *file;
76
77	if (asprintf(&file, "%s/%s", tracing_path, name) < 0)
78		return NULL;
79
80	return file;
81}
82
83void put_tracing_file(char *file)
84{
85	free(file);
86}
87
88static int strerror_open(int err, char *buf, size_t size, const char *filename)
89{
90	char sbuf[128];
91
92	switch (err) {
93	case ENOENT:
94		/*
95		 * We will get here if we can't find the tracepoint, but one of
96		 * debugfs or tracefs is configured, which means you probably
97		 * want some tracepoint which wasn't compiled in your kernel.
98		 * - jirka
99		 */
100		if (debugfs__configured() || tracefs__configured()) {
101			snprintf(buf, size,
102				 "Error:\tFile %s/%s not found.\n"
103				 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
104				 tracing_events_path, filename);
105			break;
106		}
107		snprintf(buf, size, "%s",
108			 "Error:\tUnable to find debugfs/tracefs\n"
109			 "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
110			 "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
111			 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
112		break;
113	case EACCES: {
114		snprintf(buf, size,
115			 "Error:\tNo permissions to read %s/%s\n"
116			 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
117			 tracing_events_path, filename, tracing_mnt);
118	}
119		break;
120	default:
121		snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));
122		break;
123	}
124
125	return 0;
126}
127
128int tracing_path__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name)
129{
130	char path[PATH_MAX];
131
132	snprintf(path, PATH_MAX, "%s/%s", sys, name ?: "*");
133
134	return strerror_open(err, buf, size, path);
135}
136