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/*
* 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 <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <cutils/atomic.h>
#include <cutils/compiler.h>
#include <cutils/properties.h>
#include <cutils/trace.h>
#define LOG_TAG "cutils-trace"
#include <log/log.h>
volatile int32_t atrace_is_ready = 0;
int atrace_marker_fd = -1;
uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY;
static bool atrace_is_debuggable = false;
static volatile int32_t atrace_is_enabled = 1;
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)
{
android_atomic_release_store(enabled ? 1 : 0, &atrace_is_enabled);
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)
{
char value[PROPERTY_VALUE_MAX];
char* start = value;
property_get("debug.atrace.app_cmdlines", value, "");
while (start != NULL) {
char* end = strchr(start, ',');
if (end != NULL) {
*end = '\0';
end++;
}
if (strcmp(cmdline, start) == 0) {
return true;
}
start = end;
}
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", "r");
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(android_atomic_acquire_load(&atrace_is_ready))) {
if (android_atomic_acquire_load(&atrace_is_enabled)) {
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);
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:
android_atomic_release_store(1, &atrace_is_ready);
}
void atrace_setup()
{
pthread_once(&atrace_once_control, atrace_init_once);
}
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