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