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+#include <openssl/pem.h>
+#include <openssl/evp.h>
+#include <openssl/bio.h>
+#include <openssl/err.h>
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <cstring>
+#include <algorithm>
+
+
+using namespace std;
+
+
+int generate_key()
+{
+	ofstream fout;
+	BIO* bio;
+
+	// generate key pair
+	EVP_PKEY* key = NULL;
+	EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_ED25519, NULL);
+	if(EVP_PKEY_keygen_init(pctx) != 1)
+	{
+		cout << "Error: EVP_PKEY_keygen_init" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	if(EVP_PKEY_keygen(pctx, &key) != 1)
+	{
+		cout << "Error: EVP_PKEY_keygen" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	EVP_PKEY_CTX_free(pctx);
+	
+	// save private key
+	bio = BIO_new( BIO_s_mem() );
+	if(PEM_write_bio_PrivateKey(bio, key, NULL, NULL, 0, NULL, NULL) != 1)
+	{
+		cout << "Error: PEM_write_bio_PrivateKey" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	unsigned char private_key[120] = { 0 };
+	BIO_read(bio, private_key, 120);
+	BIO_free(bio);
+	cout << private_key << endl;
+	fout.open("private_key");
+	fout << private_key;
+	fout.close();	
+
+	// save public key
+	bio = BIO_new( BIO_s_mem() );
+	if(PEM_write_bio_PUBKEY(bio, key) != 1)
+	{
+		cout << "Error: PEM_write_bio_PUBKEY" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	EVP_PKEY_free(key);
+	unsigned char public_key[120] = { 0 };
+	BIO_read(bio, public_key, 120);
+	BIO_free(bio);
+	cout << public_key << endl;
+	fout.open("public_key");
+	fout << public_key;
+	fout.close();
+
+	return 1;
+}
+
+
+
+int sign(char* signee_file, char* key_file)
+{
+	ifstream fin;
+	ofstream fout;	
+	BIO* bio;
+	EVP_PKEY* pkey = NULL;
+	int signee_size = 0, key_size = 0;
+	
+	// open signee_file
+	fin.open(signee_file);
+	if (fin.fail()) {
+		cout << "Error: Can't open signee file." << endl;
+		return 0;
+	}
+	fin.seekg(0, ios::end);
+	signee_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* signee = new unsigned char[signee_size];
+	fin.read((char*)signee, signee_size);
+	fin.close();
+
+	// open private key
+	fin.open(key_file);
+	if (fin.fail()) {
+		cout << "Error: Can't open key file." << endl;
+		return 0;
+	}
+	fin.seekg(0, ios::end);
+	key_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* key = new unsigned char[key_size];
+	fin.read((char*)key, key_size);
+	fin.close();
+	cout << key << endl;
+	bio = BIO_new( BIO_s_mem() );
+	BIO_write(bio, key, key_size);
+	if(PEM_read_bio_PrivateKey(bio, &pkey, NULL, NULL) == NULL)
+	{	
+		cout << "Error: PEM_read_bio_PrivateKey" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	BIO_free(bio);
+
+	// File Signing, Make Signature
+	unsigned char sig[65] = { 0 };
+	size_t sig_size = 64;
+	EVP_MD_CTX* ctx = EVP_MD_CTX_new();
+	if(EVP_DigestSignInit(ctx, NULL, NULL, NULL, pkey) != 1)
+	{
+		cout << "Error: EVP_DigestSignInit" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	if(EVP_DigestSign(ctx, sig, &sig_size, signee, signee_size) != 1)
+	{
+		cout << "Error: EVP_DigestSign" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	EVP_MD_CTX_free(ctx);
+	EVP_PKEY_free(pkey);
+
+	fout.open("./signature");
+	cout << hex << setfill('0');
+	fout << hex << setfill('0');
+	for(int i = 0; i < sig_size; i++)
+	{
+		cout << setw(2) << (int)sig[i];
+		fout << setw(2) << (int)sig[i];
+	}
+	cout << endl;
+	fout.close();
+
+	return 1;
+}
+
+
+/*
+int verify(char* signee_file, char* sig_file, char* key_file)
+{
+	ifstream fin;
+	BIO* bio;
+	EVP_PKEY* pkey = NULL;
+	int signee_size = 0, key_size = 0, sig_size = 0;
+	
+	// open signee_file
+	fin.open(signee_file);
+	fin.seekg(0, ios::end);
+	signee_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* signee = new unsigned char[signee_size];
+	fin.read((char*)signee, signee_size);
+	fin.close();
+
+	// open public key
+	fin.open(key_file);
+	fin.seekg(0, ios::end);
+	key_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* key = new unsigned char[key_size];
+	fin.read((char*)key, key_size);
+	fin.close();
+	cout << key << endl;
+	bio = BIO_new( BIO_s_mem() );
+	BIO_write(bio, key, key_size);
+	if(PEM_read_bio_PUBKEY(bio, &pkey, NULL, NULL) == NULL)
+	{	
+		cout << "Error: " << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	BIO_free(bio);
+
+	fin.open(sig_file);
+	fin.seekg(0, ios::end);
+	sig_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* sig_char = new unsigned char[sig_size];
+	fin.read((char*)sig_char, sig_size);
+	fin.close();
+	unsigned char sig[65] = { 0 };
+	char temp[3] = { 0 };
+	for(int i = 0; i < sig_size; i+=2)
+	{
+		temp[0] = sig_char[i];
+		temp[1] = sig_char[i+1];
+		sig[i/2] = (unsigned char) strtol(temp, NULL, 16);
+	}
+	sig_size /= 2;
+
+	EVP_MD_CTX* ctx = EVP_MD_CTX_new();
+	if(EVP_DigestVerifyInit(ctx, NULL, NULL, NULL, pkey) != 1)
+	{
+		cout << "Error: " << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	if(EVP_DigestVerify(ctx, sig, sig_size, signee, signee_size) != 1)
+	{
+		cout << "Error: " << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	EVP_PKEY_free(pkey);
+	
+	cout << "Success" << endl;
+	return 1;
+}
+*/
+
+
+bool cmdOptionExists(char** begin, char** end, const string& option)
+{
+	return find(begin, end, option) != end;
+}
+
+
+
+char* getCmdOption(char** begin, char** end, const string& option)
+{
+	char** itr = find(begin, end, option);
+	if (itr != end && ++itr != end)
+		return *itr;
+	return 0;
+}
+
+
+
+int main(int argc, char* argv[])
+{
+	if (cmdOptionExists(argv, argv+argc, "-h")\
+		|| cmdOptionExists(argv, argv+argc, "--help"))
+	{
+		cout << "Usage" << endl;
+		cout << "Generate key: " << argv[0] << " --genkey" << endl;
+		cout << "Signing file: " << argv[0] << " -f signee_path -k key_path" << endl;
+		return 0;
+	}
+
+	if (cmdOptionExists(argv, argv+argc, "--genkey"))
+	{
+		generate_key();
+		return 0;
+	}
+
+	if (cmdOptionExists(argv, argv+argc, "-f")\
+		&& cmdOptionExists(argv, argv+argc, "-k"))
+	{
+		char* signee_path = getCmdOption(argv, argv+argc, "-f");
+		char* key_path = getCmdOption(argv, argv+argc, "-k");
+		if (sign(signee_path, key_path) != 1)
+			cout << "Error occured" << endl;
+		return 0;
+	}
+	else
+	{
+		cout << "Usage" << endl;
+		cout << "Generate key: " << argv[0] << " --genkey" << endl;
+		cout << "Signing file: " << argv[0] << " -f signee_path -k key_path" << endl;
+	}
+//	generate_key();
+//	sign(argv[1], argv[2]);
+//	verify(argv[1], argv[2], argv[3]);
+	return 0;
+}

+/****************************************************************************
+ *
+ *   Copyright (c) 2015 Mark Charlebois. All rights reserved.
+ *   Copyright (c) 2016-2019 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file simulator.cpp
+ *
+ * This module interfaces via MAVLink to a software in the loop simulator (SITL)
+ * such as jMAVSim or Gazebo.
+ */
+
+#include <px4_platform_common/log.h>
+#include <px4_platform_common/tasks.h>
+#include <px4_platform_common/time.h>
+#include <systemlib/err.h>
+#include <drivers/drv_board_led.h>
+#include <openssl/evp.h>
+#include <openssl/pem.h>
+#include <openssl/bio.h>
+#include <openssl/err.h>
+#include <fstream>
+#include <cstring>
+
+#include "simulator.h"
+
+static px4_task_t g_sim_task = -1;
+
+Simulator *Simulator::_instance = nullptr;
+
+void Simulator::parameters_update(bool force)
+{
+	// check for parameter updates
+	if (_parameter_update_sub.updated() || force) {
+		// clear update
+		parameter_update_s pupdate;
+		_parameter_update_sub.copy(&pupdate);
+
+		// update parameters from storage
+		updateParams();
+	}
+}
+
+int Simulator::verify()
+{
+/*
+	char path[256];
+	if(getcwd(path, 256) == NULL)
+		PX4_INFO("Test path: %s", strerror(errno));
+	else
+		PX4_INFO("Test path: %s", path);
+*/
+
+	std::ifstream fin;
+	BIO* bio;
+	EVP_PKEY* pkey = NULL;
+
+	const char* file_path = "../../bin/px4";	
+//	const char* file_path = "../../../../Tools/test.txt";
+	const char* sig_path = "../../../../Tools/signature";	
+	const char* key_path = "../../../../Tools/public_key";
+
+	int file_size = 0, sig_size = 0, key_size = 0;
+
+	// open exe file
+	fin.open(file_path);
+	if (fin.fail()) {
+		PX4_WARN("Error: Can't open exe file during signature verifying.");
+		return 0;
+	}
+	fin.seekg(0, std::ios::end);
+	file_size = fin.tellg();
+	fin.seekg(0, std::ios::beg);
+	unsigned char* file = new unsigned char[file_size];
+	fin.read((char*)file, file_size);
+	fin.close();
+
+	// open signature file
+	fin.open(sig_path);
+	if (fin.fail()) {
+		PX4_WARN("Error: Can't open signature file during signature verifying.");
+		return 0;
+	}
+	fin.seekg(0, std::ios::end);
+	sig_size = fin.tellg();
+	fin.seekg(0, std::ios::beg);
+	unsigned char* sig_char = new unsigned char[sig_size];
+	fin.read((char*)sig_char, sig_size);
+	fin.close();
+	unsigned char sig[65] = { 0 };
+	char temp[3] = { 0 };
+	for (int i = 0; i < sig_size; i+=2)
+	{
+		temp[0] = sig_char[i];
+		temp[1] = sig_char[i+1];
+		sig[i/2] = (unsigned char)strtol(temp, NULL, 16);
+	}
+	delete[] sig_char;
+	sig_size /= 2;
+
+	// open public key file
+	fin.open(key_path);
+	if (fin.fail()) {
+		PX4_WARN("Error: Can't open public key file during signature verifying.");
+		return 0;
+	}
+	fin.seekg(0, std::ios::end);
+	key_size = fin.tellg();
+	fin.seekg(0, std::ios::beg);
+	unsigned char* key = new unsigned char[key_size];
+	fin.read((char*)key, key_size);
+	fin.close();
+
+	// make key file to pkey
+	bio = BIO_new( BIO_s_mem() );
+	BIO_write(bio, key, key_size);
+	if (PEM_read_bio_PUBKEY(bio, &pkey, NULL, NULL) == NULL) {
+		PX4_WARN("Error: PEM_read_bio_PUBKEY");	//ERR_error_string(ERR_get_error(), NULL)
+		return 0;
+	}
+	delete[] key;
+	BIO_free(bio);
+
+	// verifying signature
+	EVP_MD_CTX* ctx = EVP_MD_CTX_new();
+	if (EVP_DigestVerifyInit(ctx, NULL, NULL, NULL, pkey) != 1) {
+		PX4_WARN("Error: EVP_DigestVerifyInit");	//ERR_error_string(ERR_get_error(), NULL)
+		return 0;
+	}
+	if (EVP_DigestVerify(ctx, sig, sig_size, file, file_size) != 1) {
+		return 0;
+	}
+	EVP_PKEY_free(pkey);	
+	EVP_MD_CTX_free(ctx);
+	delete[] file;
+
+	PX4_INFO("Success: Verifying Signature");
+
+	return 1;
+}
+
+int Simulator::start(int argc, char *argv[])
+{
+
+	_instance = new Simulator();
+
+	if (_instance->verify() != 1) {
+		PX4_ERR("Signature Verifying failed");
+		return 1;
+	}
+
+	if (_instance) {
+
+		if (argc == 5 && strcmp(argv[3], "-u") == 0) {
+			_instance->set_ip(InternetProtocol::UDP);
+			_instance->set_port(atoi(argv[4]));
+		}
+
+		if (argc == 5 && strcmp(argv[3], "-c") == 0) {
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_port(atoi(argv[4]));
+		}
+
+		if (argc == 6 && strcmp(argv[3], "-t") == 0) {
+			PX4_INFO("Simulator using TCP on remote host %s port %s", argv[4], argv[5]);
+			PX4_WARN("Please ensure port %s is not blocked by a firewall.", argv[5]);
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_tcp_remote_ipaddr(argv[4]);
+			_instance->set_port(atoi(argv[5]));
+		}
+
+		if (argc == 6 && strcmp(argv[3], "-h") == 0) {
+			PX4_INFO("Simulator using TCP on remote host %s port %s", argv[4], argv[5]);
+			PX4_WARN("Please ensure port %s is not blocked by a firewall.", argv[5]);
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_hostname(argv[4]);
+			_instance->set_port(atoi(argv[5]));
+		}
+
+		_instance->run();
+
+		return 0;
+
+	} else {
+		PX4_WARN("Simulator creation failed");
+		return 1;
+	}
+}
+
+static void usage()
+{
+	PX4_INFO("Usage: simulator {start -[spt] [-u udp_port / -c tcp_port] |stop|status}");
+	PX4_INFO("Start simulator:     simulator start");
+	PX4_INFO("Connect using UDP: simulator start -u udp_port");
+	PX4_INFO("Connect using TCP: simulator start -c tcp_port");
+	PX4_INFO("Connect to a remote server using TCP: simulator start -t ip_addr tcp_port");
+	PX4_INFO("Connect to a remote server via hostname using TCP: simulator start -h hostname tcp_port");
+}
+
+__BEGIN_DECLS
+extern int simulator_main(int argc, char *argv[]);
+__END_DECLS
+
+
+int simulator_main(int argc, char *argv[])
+{
+	if (argc > 1 && strcmp(argv[1], "start") == 0) {
+
+		if (g_sim_task >= 0) {
+			PX4_WARN("Simulator already started");
+			return 0;
+		}
+
+		g_sim_task = px4_task_spawn_cmd("simulator",
+						SCHED_DEFAULT,
+						SCHED_PRIORITY_MAX,
+						1500,
+						Simulator::start,
+						argv);
+
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
+
+		// We want to prevent the rest of the startup script from running until time
+		// is initialized by the HIL_SENSOR messages from the simulator.
+		while (true) {
+			if (Simulator::getInstance() && Simulator::getInstance()->has_initialized()) {
+				break;
+			}
+
+			system_usleep(100);
+		}
+
+#endif
+
+	} else if (argc == 2 && strcmp(argv[1], "stop") == 0) {
+		if (g_sim_task < 0) {
+			PX4_WARN("Simulator not running");
+			return 1;
+
+		} else {
+			px4_task_delete(g_sim_task);
+			g_sim_task = -1;
+		}
+
+	} else if (argc == 2 && strcmp(argv[1], "status") == 0) {
+		if (g_sim_task < 0) {
+			PX4_WARN("Simulator not running");
+			return 1;
+
+		} else {
+			PX4_INFO("running");
+		}
+
+	} else {
+		usage();
+		return 1;
+	}
+
+	return 0;
+}

+/****************************************************************************
+ *
+ *   Copyright (c) 2015 Mark Charlebois. All rights reserved.
+ *   Copyright (c) 2016-2019 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file simulator.cpp
+ *
+ * This module interfaces via MAVLink to a software in the loop simulator (SITL)
+ * such as jMAVSim or Gazebo.
+ */
+
+#include <px4_platform_common/log.h>
+#include <px4_platform_common/tasks.h>
+#include <px4_platform_common/time.h>
+#include <systemlib/err.h>
+#include <drivers/drv_board_led.h>
+
+#include "simulator.h"
+
+static px4_task_t g_sim_task = -1;
+
+Simulator *Simulator::_instance = nullptr;
+
+void Simulator::parameters_update(bool force)
+{
+	// check for parameter updates
+	if (_parameter_update_sub.updated() || force) {
+		// clear update
+		parameter_update_s pupdate;
+		_parameter_update_sub.copy(&pupdate);
+
+		// update parameters from storage
+		updateParams();
+	}
+}
+
+int Simulator::start(int argc, char *argv[])
+{
+	_instance = new Simulator();
+
+	if (_instance) {
+		if (argc == 5 && strcmp(argv[3], "-u") == 0) {
+			_instance->set_ip(InternetProtocol::UDP);
+			_instance->set_port(atoi(argv[4]));
+		}
+
+		if (argc == 5 && strcmp(argv[3], "-c") == 0) {
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_port(atoi(argv[4]));
+		}
+
+		if (argc == 6 && strcmp(argv[3], "-t") == 0) {
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_tcp_remote_ipaddr(argv[4]);
+			_instance->set_port(atoi(argv[5]));
+		}
+
+		_instance->run();
+
+		return 0;
+
+	} else {
+		PX4_WARN("Simulator creation failed");
+		return 1;
+	}
+}
+
+static void usage()
+{
+	PX4_INFO("Usage: simulator {start -[spt] [-u udp_port / -c tcp_port] |stop|status}");
+	PX4_INFO("Start simulator:     simulator start");
+	PX4_INFO("Connect using UDP: simulator start -u udp_port");
+	PX4_INFO("Connect using TCP: simulator start -c tcp_port");
+	PX4_INFO("Connect to a remote server using TCP: simulator start -t ip_addr tcp_port");
+}
+
+__BEGIN_DECLS
+extern int simulator_main(int argc, char *argv[]);
+__END_DECLS
+
+
+int simulator_main(int argc, char *argv[])
+{
+	if (argc > 1 && strcmp(argv[1], "start") == 0) {
+
+		if (g_sim_task >= 0) {
+			PX4_WARN("Simulator already started");
+			return 0;
+		}
+
+		g_sim_task = px4_task_spawn_cmd("simulator",
+						SCHED_DEFAULT,
+						SCHED_PRIORITY_MAX,
+						1500,
+						Simulator::start,
+						argv);
+
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
+
+		// We want to prevent the rest of the startup script from running until time
+		// is initialized by the HIL_SENSOR messages from the simulator.
+		while (true) {
+			if (Simulator::getInstance() && Simulator::getInstance()->has_initialized()) {
+				break;
+			}
+
+			system_usleep(100);
+		}
+
+#endif
+
+	} else if (argc == 2 && strcmp(argv[1], "stop") == 0) {
+		if (g_sim_task < 0) {
+			PX4_WARN("Simulator not running");
+			return 1;
+
+		} else {
+			px4_task_delete(g_sim_task);
+			g_sim_task = -1;
+		}
+
+	} else if (argc == 2 && strcmp(argv[1], "status") == 0) {
+		if (g_sim_task < 0) {
+			PX4_WARN("Simulator not running");
+			return 1;
+
+		} else {
+			PX4_INFO("running");
+		}
+
+	} else {
+		usage();
+		return 1;
+	}
+
+	return 0;
+}