/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <pthread.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <cutils/compiler.h>
#include <cutils/properties.h>
#include <cutils/trace.h>
#define LOG_TAG "cutils-trace"
#include <log/log.h>
/**
* Maximum size of a message that can be logged to the trace buffer.
* Note this message includes a tag, the pid, and the string given as the name.
* Names should be kept short to get the most use of the trace buffer.
*/
#define ATRACE_MESSAGE_LENGTH 1024
atomic_bool atrace_is_ready = ATOMIC_VAR_INIT(false);
int atrace_marker_fd = -1;
uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY;
static bool atrace_is_debuggable = false;
static atomic_bool atrace_is_enabled = ATOMIC_VAR_INIT(true);
static pthread_once_t atrace_once_control = PTHREAD_ONCE_INIT;
static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER;
// Set whether this process is debuggable, which determines whether
// application-level tracing is allowed when the ro.debuggable system property
// is not set to '1'.
void atrace_set_debuggable(bool debuggable)
{
atrace_is_debuggable = debuggable;
atrace_update_tags();
}
// Set whether tracing is enabled in this process. This is used to prevent
// the Zygote process from tracing.
void atrace_set_tracing_enabled(bool enabled)
{
atomic_store_explicit(&atrace_is_enabled, enabled, memory_order_release);
atrace_update_tags();
}
// Check whether the given command line matches one of the comma-separated
// values listed in the app_cmdlines property.
static bool atrace_is_cmdline_match(const char* cmdline)
{
int count = property_get_int32("debug.atrace.app_number", 0);
char buf[PROPERTY_KEY_MAX];
char value[PROPERTY_VALUE_MAX];
for (int i = 0; i < count; i++) {
snprintf(buf, sizeof(buf), "debug.atrace.app_%d", i);
property_get(buf, value, "");
if (strcmp(value, cmdline) == 0) {
return true;
}
}
return false;
}
// Determine whether application-level tracing is enabled for this process.
static bool atrace_is_app_tracing_enabled()
{
bool sys_debuggable = false;
char value[PROPERTY_VALUE_MAX];
bool result = false;
// Check whether the system is debuggable.
property_get("ro.debuggable", value, "0");
if (value[0] == '1') {
sys_debuggable = true;
}
if (sys_debuggable || atrace_is_debuggable) {
// Check whether tracing is enabled for this process.
FILE * file = fopen("/proc/self/cmdline", "re");
if (file) {
char cmdline[4096];
if (fgets(cmdline, sizeof(cmdline), file)) {
result = atrace_is_cmdline_match(cmdline);
} else {
ALOGE("Error reading cmdline: %s (%d)", strerror(errno), errno);
}
fclose(file);
} else {
ALOGE("Error opening /proc/self/cmdline: %s (%d)", strerror(errno),
errno);
}
}
return result;
}
// Read the sysprop and return the value tags should be set to
static uint64_t atrace_get_property()
{
char value[PROPERTY_VALUE_MAX];
char *endptr;
uint64_t tags;
property_get("debug.atrace.tags.enableflags", value, "0");
errno = 0;
tags = strtoull(value, &endptr, 0);
if (value[0] == '\0' || *endptr != '\0') {
ALOGE("Error parsing trace property: Not a number: %s", value);
return 0;
} else if (errno == ERANGE || tags == ULLONG_MAX) {
ALOGE("Error parsing trace property: Number too large: %s", value);
return 0;
}
// Only set the "app" tag if this process was selected for app-level debug
// tracing.
if (atrace_is_app_tracing_enabled()) {
tags |= ATRACE_TAG_APP;
} else {
tags &= ~ATRACE_TAG_APP;
}
return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK;
}
// Update tags if tracing is ready. Useful as a sysprop change callback.
void atrace_update_tags()
{
uint64_t tags;
if (CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) {
if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) {
tags = atrace_get_property();
pthread_mutex_lock(&atrace_tags_mutex);
atrace_enabled_tags = tags;
pthread_mutex_unlock(&atrace_tags_mutex);
} else {
// Tracing is disabled for this process, so we simply don't
// initialize the tags.
pthread_mutex_lock(&atrace_tags_mutex);
atrace_enabled_tags = ATRACE_TAG_NOT_READY;
pthread_mutex_unlock(&atrace_tags_mutex);
}
}
}
static void atrace_init_once()
{
atrace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY | O_CLOEXEC);
if (atrace_marker_fd == -1) {
ALOGE("Error opening trace file: %s (%d)", strerror(errno), errno);
atrace_enabled_tags = 0;
goto done;
}
atrace_enabled_tags = atrace_get_property();
done:
atomic_store_explicit(&atrace_is_ready, true, memory_order_release);
}
void atrace_setup()
{
pthread_once(&atrace_once_control, atrace_init_once);
}
void atrace_begin_body(const char* name)
{
char buf[ATRACE_MESSAGE_LENGTH];
int len = snprintf(buf, sizeof(buf), "B|%d|%s", getpid(), name);
if (len >= (int) sizeof(buf)) {
ALOGW("Truncated name in %s: %s\n", __FUNCTION__, name);
len = sizeof(buf) - 1;
}
write(atrace_marker_fd, buf, len);
}
#define WRITE_MSG(format_begin, format_end, pid, name, value) { \
char buf[ATRACE_MESSAGE_LENGTH]; \
int len = snprintf(buf, sizeof(buf), format_begin "%s" format_end, pid, \
name, value); \
if (len >= (int) sizeof(buf)) { \
/* Given the sizeof(buf), and all of the current format buffers, \
* it is impossible for name_len to be < 0 if len >= sizeof(buf). */ \
int name_len = strlen(name) - (len - sizeof(buf)) - 1; \
/* Truncate the name to make the message fit. */ \
ALOGW("Truncated name in %s: %s\n", __FUNCTION__, name); \
len = snprintf(buf, sizeof(buf), format_begin "%.*s" format_end, pid, \
name_len, name, value); \
} \
write(atrace_marker_fd, buf, len); \
}
void atrace_async_begin_body(const char* name, int32_t cookie)
{
WRITE_MSG("S|%d|", "|%" PRId32, getpid(), name, cookie);
}
void atrace_async_end_body(const char* name, int32_t cookie)
{
WRITE_MSG("F|%d|", "|%" PRId32, getpid(), name, cookie);
}
void atrace_int_body(const char* name, int32_t value)
{
WRITE_MSG("C|%d|", "|%" PRId32, getpid(), name, value);
}
void atrace_int64_body(const char* name, int64_t value)
{
WRITE_MSG("C|%d|", "|%" PRId64, getpid(), name, value);
}