1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <errno.h>
18#include <fcntl.h>
19#include <limits.h>
20#include <pthread.h>
21#include <stdatomic.h>
22#include <stdbool.h>
23#include <stdlib.h>
24#include <string.h>
25#include <sys/types.h>
26#include <cutils/compiler.h>
27#include <cutils/properties.h>
28#include <cutils/trace.h>
29
30#define LOG_TAG "cutils-trace"
31#include <log/log.h>
32
33/**
34 * Maximum size of a message that can be logged to the trace buffer.
35 * Note this message includes a tag, the pid, and the string given as the name.
36 * Names should be kept short to get the most use of the trace buffer.
37 */
38#define ATRACE_MESSAGE_LENGTH 1024
39
40atomic_bool             atrace_is_ready      = ATOMIC_VAR_INIT(false);
41int                     atrace_marker_fd     = -1;
42uint64_t                atrace_enabled_tags  = ATRACE_TAG_NOT_READY;
43static bool             atrace_is_debuggable = false;
44static atomic_bool      atrace_is_enabled    = ATOMIC_VAR_INIT(true);
45static pthread_once_t   atrace_once_control  = PTHREAD_ONCE_INIT;
46static pthread_mutex_t  atrace_tags_mutex    = PTHREAD_MUTEX_INITIALIZER;
47
48// Set whether this process is debuggable, which determines whether
49// application-level tracing is allowed when the ro.debuggable system property
50// is not set to '1'.
51void atrace_set_debuggable(bool debuggable)
52{
53    atrace_is_debuggable = debuggable;
54    atrace_update_tags();
55}
56
57// Set whether tracing is enabled in this process.  This is used to prevent
58// the Zygote process from tracing.
59void atrace_set_tracing_enabled(bool enabled)
60{
61    atomic_store_explicit(&atrace_is_enabled, enabled, memory_order_release);
62    atrace_update_tags();
63}
64
65// Check whether the given command line matches one of the comma-separated
66// values listed in the app_cmdlines property.
67static bool atrace_is_cmdline_match(const char* cmdline)
68{
69    int count = property_get_int32("debug.atrace.app_number", 0);
70
71    char buf[PROPERTY_KEY_MAX];
72    char value[PROPERTY_VALUE_MAX];
73
74    for (int i = 0; i < count; i++) {
75        snprintf(buf, sizeof(buf), "debug.atrace.app_%d", i);
76        property_get(buf, value, "");
77        if (strcmp(value, cmdline) == 0) {
78            return true;
79        }
80    }
81
82    return false;
83}
84
85// Determine whether application-level tracing is enabled for this process.
86static bool atrace_is_app_tracing_enabled()
87{
88    bool sys_debuggable = false;
89    char value[PROPERTY_VALUE_MAX];
90    bool result = false;
91
92    // Check whether the system is debuggable.
93    property_get("ro.debuggable", value, "0");
94    if (value[0] == '1') {
95        sys_debuggable = true;
96    }
97
98    if (sys_debuggable || atrace_is_debuggable) {
99        // Check whether tracing is enabled for this process.
100        FILE * file = fopen("/proc/self/cmdline", "re");
101        if (file) {
102            char cmdline[4096];
103            if (fgets(cmdline, sizeof(cmdline), file)) {
104                result = atrace_is_cmdline_match(cmdline);
105            } else {
106                ALOGE("Error reading cmdline: %s (%d)", strerror(errno), errno);
107            }
108            fclose(file);
109        } else {
110            ALOGE("Error opening /proc/self/cmdline: %s (%d)", strerror(errno),
111                    errno);
112        }
113    }
114
115    return result;
116}
117
118// Read the sysprop and return the value tags should be set to
119static uint64_t atrace_get_property()
120{
121    char value[PROPERTY_VALUE_MAX];
122    char *endptr;
123    uint64_t tags;
124
125    property_get("debug.atrace.tags.enableflags", value, "0");
126    errno = 0;
127    tags = strtoull(value, &endptr, 0);
128    if (value[0] == '\0' || *endptr != '\0') {
129        ALOGE("Error parsing trace property: Not a number: %s", value);
130        return 0;
131    } else if (errno == ERANGE || tags == ULLONG_MAX) {
132        ALOGE("Error parsing trace property: Number too large: %s", value);
133        return 0;
134    }
135
136    // Only set the "app" tag if this process was selected for app-level debug
137    // tracing.
138    if (atrace_is_app_tracing_enabled()) {
139        tags |= ATRACE_TAG_APP;
140    } else {
141        tags &= ~ATRACE_TAG_APP;
142    }
143
144    return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK;
145}
146
147// Update tags if tracing is ready. Useful as a sysprop change callback.
148void atrace_update_tags()
149{
150    uint64_t tags;
151    if (CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) {
152        if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) {
153            tags = atrace_get_property();
154            pthread_mutex_lock(&atrace_tags_mutex);
155            atrace_enabled_tags = tags;
156            pthread_mutex_unlock(&atrace_tags_mutex);
157        } else {
158            // Tracing is disabled for this process, so we simply don't
159            // initialize the tags.
160            pthread_mutex_lock(&atrace_tags_mutex);
161            atrace_enabled_tags = ATRACE_TAG_NOT_READY;
162            pthread_mutex_unlock(&atrace_tags_mutex);
163        }
164    }
165}
166
167static void atrace_init_once()
168{
169    atrace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY | O_CLOEXEC);
170    if (atrace_marker_fd == -1) {
171        ALOGE("Error opening trace file: %s (%d)", strerror(errno), errno);
172        atrace_enabled_tags = 0;
173        goto done;
174    }
175
176    atrace_enabled_tags = atrace_get_property();
177
178done:
179    atomic_store_explicit(&atrace_is_ready, true, memory_order_release);
180}
181
182void atrace_setup()
183{
184    pthread_once(&atrace_once_control, atrace_init_once);
185}
186
187void atrace_begin_body(const char* name)
188{
189    char buf[ATRACE_MESSAGE_LENGTH];
190
191    int len = snprintf(buf, sizeof(buf), "B|%d|%s", getpid(), name);
192    if (len >= (int) sizeof(buf)) {
193        ALOGW("Truncated name in %s: %s\n", __FUNCTION__, name);
194        len = sizeof(buf) - 1;
195    }
196    write(atrace_marker_fd, buf, len);
197}
198
199#define WRITE_MSG(format_begin, format_end, pid, name, value) { \
200    char buf[ATRACE_MESSAGE_LENGTH]; \
201    int len = snprintf(buf, sizeof(buf), format_begin "%s" format_end, pid, \
202        name, value); \
203    if (len >= (int) sizeof(buf)) { \
204        /* Given the sizeof(buf), and all of the current format buffers, \
205         * it is impossible for name_len to be < 0 if len >= sizeof(buf). */ \
206        int name_len = strlen(name) - (len - sizeof(buf)) - 1; \
207        /* Truncate the name to make the message fit. */ \
208        ALOGW("Truncated name in %s: %s\n", __FUNCTION__, name); \
209        len = snprintf(buf, sizeof(buf), format_begin "%.*s" format_end, pid, \
210            name_len, name, value); \
211    } \
212    write(atrace_marker_fd, buf, len); \
213}
214
215void atrace_async_begin_body(const char* name, int32_t cookie)
216{
217    WRITE_MSG("S|%d|", "|%" PRId32, getpid(), name, cookie);
218}
219
220void atrace_async_end_body(const char* name, int32_t cookie)
221{
222    WRITE_MSG("F|%d|", "|%" PRId32, getpid(), name, cookie);
223}
224
225void atrace_int_body(const char* name, int32_t value)
226{
227    WRITE_MSG("C|%d|", "|%" PRId32, getpid(), name, value);
228}
229
230void atrace_int64_body(const char* name, int64_t value)
231{
232    WRITE_MSG("C|%d|", "|%" PRId64, getpid(), name, value);
233}
234