/*
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* Copyright (C) 2019 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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#include <errno.h>
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#include <pthread.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <string.h>
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#include <libgen.h> // For POSIX basename().
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// Use _system_properties.h to use __system_property_wait_any()
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#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
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#include <sys/_system_properties.h>
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#include "profile-extras.h"
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extern "C" {
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void __gcov_flush(void);
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static void gcov_signal_handler(__unused int signum) {
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__gcov_flush();
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}
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static const char kCoveragePropName[] = "debug.coverage.flush";
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// In a loop, wait for any change to sysprops and trigger a __gcov_flush when
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// <kCoveragePropName> sysprop transistions to "1" after a transistion to "0".
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void *property_watch_loop(__unused void *arg) {
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uint32_t serial = 0;
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// __gcov_flush is called on a state transition from 0 to 1. Initialize state
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// to 1 so a process spinning up when the sysprop is already set does not
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// immediately dump its coverage.
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int previous_state = 1;
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while (true) {
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// Use deprecated __system_property_wait_any for backward compatibility.
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serial = __system_property_wait_any(serial);
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const struct prop_info *pi = __system_property_find(kCoveragePropName);
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if (!pi)
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continue;
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char value[PROP_VALUE_MAX];
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__system_property_read(pi, nullptr, value);
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if (strcmp(value, "0") == 0) {
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previous_state = 0;
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} else if (strcmp(value, "1") == 0) {
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if (previous_state == 0) {
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__gcov_flush();
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}
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previous_state = 1;
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}
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}
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}
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// Initialize libprofile-extras:
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// - Install a signal handler that triggers __gcov_flush on <GCOV_FLUSH_SIGNAL>.
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// - Create a thread that calls __gcov_flush when <kCoveragePropName> sysprop
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// transistions to "1" after a transistion to "0".
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//
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// We want this initiazlier to run during load time.
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//
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// Just marking init_profile_extras() with __attribute__((constructor)) isn't
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// enough since the linker drops it from its output since no other symbol from
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// this static library is referenced.
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//
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// We force the linker to include init_profile_extras() by passing
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// '-uinit_profile_extras' to the linker (in build/soong).
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__attribute__((constructor)) int init_profile_extras(void) {
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sighandler_t ret1 = signal(GCOV_FLUSH_SIGNAL, gcov_signal_handler);
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if (ret1 == SIG_ERR) {
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return -1;
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}
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// Do not create thread running property_watch_loop for zygote (it can get
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// invoked as zygote or app_process). This check is only needed for the
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// platform, but can be done on any version after Android L, when
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// getprogname() was added.
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#if defined(__ANDROID_API__) && __ANDROID_API__ >= __ANDROID_API_L__
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const char *prog_basename = basename(getprogname());
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if (strncmp(prog_basename, "zygote", strlen("zygote")) == 0) {
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return 0;
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}
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if (strncmp(prog_basename, "app_process", strlen("app_process")) == 0) {
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return 0;
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}
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#endif
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pthread_t thread;
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int error = pthread_create(&thread, nullptr, property_watch_loop, nullptr);
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if (error != 0) {
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return -1;
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}
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return 0;
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}
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}
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