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/*
* Copyright (C) 2019 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 <pthread.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <libgen.h> // For POSIX basename().
// Use _system_properties.h to use __system_property_wait_any()
#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include <sys/_system_properties.h>
#include "profile-extras.h"
extern "C" {
void __gcov_flush(void);
// storing SIG_ERR helps us detect (unlikely) looping.
static sighandler_t chained_gcov_signal_handler = SIG_ERR;
static void gcov_signal_handler(int signum) {
__gcov_flush();
if (chained_gcov_signal_handler != SIG_ERR &&
chained_gcov_signal_handler != SIG_IGN &&
chained_gcov_signal_handler != SIG_DFL) {
(chained_gcov_signal_handler)(signum);
}
}
static const char kCoveragePropName[] = "debug.coverage.flush";
// In a loop, wait for any change to sysprops and trigger a __gcov_flush when
// <kCoveragePropName> sysprop transistions to "1" after a transistion to "0".
void *property_watch_loop(__unused void *arg) {
uint32_t serial = 0;
// __gcov_flush is called on a state transition from 0 to 1. Initialize state
// to 1 so a process spinning up when the sysprop is already set does not
// immediately dump its coverage.
int previous_state = 1;
while (true) {
// Use deprecated __system_property_wait_any for backward compatibility.
serial = __system_property_wait_any(serial);
const struct prop_info *pi = __system_property_find(kCoveragePropName);
if (!pi)
continue;
char value[PROP_VALUE_MAX];
__system_property_read(pi, nullptr, value);
if (strcmp(value, "0") == 0) {
previous_state = 0;
} else if (strcmp(value, "1") == 0) {
if (previous_state == 0) {
__gcov_flush();
}
previous_state = 1;
}
}
}
#if defined(__ANDROID_API__) && __ANDROID_API__ >= __ANDROID_API_L__
static char prop_watch_disabled_procs[][128] = {
"zygote",
"zygote32",
"app_process",
"app_process32",
"adbd",
"init",
};
static size_t prop_watch_num_disabled_procs = \
sizeof(prop_watch_disabled_procs) / sizeof(prop_watch_disabled_procs[0]);
#endif
__attribute__((weak)) int init_profile_extras_once = 0;
// Initialize libprofile-extras:
// - Install a signal handler that triggers __gcov_flush on <GCOV_FLUSH_SIGNAL>.
// - Create a thread that calls __gcov_flush when <kCoveragePropName> sysprop
// transistions to "1" after a transistion to "0".
//
// We want this initiazlier to run during load time.
//
// Just marking init_profile_extras() with __attribute__((constructor)) isn't
// enough since the linker drops it from its output since no other symbol from
// this static library is referenced.
//
// We force the linker to include init_profile_extras() by passing
// '-uinit_profile_extras' to the linker (in build/soong).
__attribute__((constructor)) int init_profile_extras(void) {
if (init_profile_extras_once)
return 0;
init_profile_extras_once = 1;
// is this instance already registered?
if (chained_gcov_signal_handler != SIG_ERR) {
return -1;
}
sighandler_t ret1 = signal(GCOV_FLUSH_SIGNAL, gcov_signal_handler);
if (ret1 == SIG_ERR) {
return -1;
}
chained_gcov_signal_handler = ret1;
// Do not create thread running property_watch_loop for zygote (it can get
// invoked as zygote or app_process). This check is only needed for the
// platform, but can be done on any version after Android L, when
// getprogname() was added.
#if defined(__ANDROID_API__) && __ANDROID_API__ >= __ANDROID_API_L__
const char *prog_basename = basename(getprogname());
for (size_t i = 0; i < prop_watch_num_disabled_procs; i ++) {
if (strcmp(prog_basename, prop_watch_disabled_procs[i]) == 0) {
return 0;
}
}
#endif
pthread_t thread;
int error = pthread_create(&thread, nullptr, property_watch_loop, nullptr);
if (error != 0) {
return -1;
}
return 0;
}
}
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