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/*
* Copyright (C) 2017 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.
*/
#ifndef __TRACE_DEV_INC
#define __TRACE_DEV_INC
#define LOG_TAG "cutils-trace"
#include <errno.h>
#include <fcntl.h>
#include <fnmatch.h>
#include <limits.h>
#include <pthread.h>
#include <stdatomic.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <cutils/compiler.h>
#include <cutils/properties.h>
#include <cutils/trace.h>
#include <log/log.h>
#include <log/log_properties.h>
#if defined(__BIONIC__)
#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include <sys/_system_properties.h>
#endif
/**
* 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
constexpr uint32_t kSeqNoNotInit = static_cast<uint32_t>(-1);
atomic_bool atrace_is_ready = ATOMIC_VAR_INIT(false);
int atrace_marker_fd = -1;
uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY;
static atomic_bool atrace_is_enabled = ATOMIC_VAR_INIT(true);
static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER;
/**
* Sequence number of debug.atrace.tags.enableflags the last time the enabled
* tags were reloaded.
**/
static _Atomic(uint32_t) last_sequence_number = ATOMIC_VAR_INIT(kSeqNoNotInit);
#if defined(__BIONIC__)
// All zero prop_info that has a sequence number of 0. This is easier than
// depending on implementation details of the property implementation.
//
// prop_info is static_assert-ed to be 96 bytes, which cannot change due to
// ABI compatibility.
alignas(uint64_t) static char empty_pi[96];
static const prop_info* atrace_property_info = reinterpret_cast<const prop_info*>(empty_pi);
#endif
/**
* This is called when the sequence number of debug.atrace.tags.enableflags
* changes and we need to reload the enabled tags.
**/
static void atrace_seq_number_changed(uint32_t prev_seq_no, uint32_t seq_no);
void atrace_init() {
#if defined(__BIONIC__)
uint32_t seq_no = __system_property_serial(atrace_property_info); // Acquire semantics.
#else
uint32_t seq_no = 0;
#endif
uint32_t prev_seq_no = atomic_load_explicit(&last_sequence_number, memory_order_relaxed);
if (CC_UNLIKELY(seq_no != prev_seq_no)) {
atrace_seq_number_changed(prev_seq_no, seq_no);
}
}
uint64_t atrace_get_enabled_tags()
{
atrace_init();
return atrace_enabled_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 (fnmatch(value, cmdline, FNM_NOESCAPE) == 0) {
return true;
}
}
return false;
}
// Determine whether application-level tracing is enabled for this process.
static bool atrace_is_app_tracing_enabled()
{
bool result = false;
// 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 (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);
}
}
#define WRITE_MSG(format_begin, format_end, track_name, name, value) { \
char buf[ATRACE_MESSAGE_LENGTH] __attribute__((uninitialized)); \
const char* track_name_sep = track_name[0] != '\0' ? "|" : ""; \
int pid = getpid(); \
int len = snprintf(buf, sizeof(buf), format_begin "%s%s%s" format_end, pid, \
track_name, track_name_sep, name, value); \
if (len >= (int) sizeof(buf)) { \
int name_len = strlen(name) - (len - sizeof(buf)) - 1; \
/* Truncate the name to make the message fit. */ \
if (name_len > 0) { \
len = snprintf(buf, sizeof(buf), format_begin "%s%s%.*s" format_end, pid, \
track_name, track_name_sep, name_len, name, value); \
} else { \
int track_name_len = 0; \
if (track_name[0] != '\0') { \
track_name_len = strlen(track_name) - (len - strlen(name) - sizeof(buf)) - 2; \
} \
if (track_name_len <= 0) { \
/* Data is still too long. Drop it. */ \
len = 0; \
} else { \
/* Truncate the trackName and name to make the message fit */ \
len = snprintf(buf, sizeof(buf), format_begin "%.*s|%.1s" format_end, pid, \
track_name_len, track_name, name, value); \
} \
} \
} \
if (len > 0) { \
write(atrace_marker_fd, buf, len); \
} \
}
#endif // __TRACE_DEV_INC
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