Initial commit: syslite lightweight init system (cd0d6853) · Commits · tuxist / syslite

.gitignore

0 → 100644

+3 −0

Changes for .gitignore: 3 added lines, 0 removed lines.
Original line number	Diff line number	Diff line
		build/
		*.o
		*.d

CMakeLists.txt

0 → 100644

+30 −0

Changes for CMakeLists.txt: 30 added lines, 0 removed lines.
Original line number	Diff line number	Diff line
		cmake_minimum_required(VERSION 3.18)

		project(syslite VERSION 0.1.0 LANGUAGES CXX)

		set(CMAKE_CXX_STANDARD 17)
		set(CMAKE_CXX_STANDARD_REQUIRED ON)

		find_package(libconfplus REQUIRED)
		find_package(libcmdplus REQUIRED)

		add_executable(syslite
		src/main.cpp
		src/unitfile.cpp
		src/service.cpp
		src/tty.cpp
		src/syslite.cpp
		)

		target_include_directories(syslite PRIVATE
		${CMAKE_CURRENT_SOURCE_DIR}/src
		)

		target_link_libraries(syslite PRIVATE
		confplus::confplus
		cmdplus::cmdplus
		dl
		)

		install(TARGETS syslite DESTINATION sbin)
		install(FILES data/syslite.yaml DESTINATION etc/syslite)

data/syslite.yaml

0 → 100644

+8 −0

Changes for data/syslite.yaml: 8 added lines, 0 removed lines.
Original line number	Diff line number	Diff line
		SYSLITE:
		HOSTNAME: ""
		UNIT_DIR: "/etc/syslite/services"
		DEFAULT_TARGET: "multi-user.target"

		TTY:
		COUNT: 3
		COMMAND: ""

src/main.cpp

0 → 100644

+78 −0

Changes for src/main.cpp: 78 added lines, 0 removed lines.
Original line number	Diff line number	Diff line
		#include "syslite.h"

		#include <cmdplus/cmdplus.h>

		#include <iostream>
		#include <csignal>

		static syslite::Init *g_init = nullptr;

		static void sigTermHandler(int) {
		if (g_init) g_init->shutdown();
		}

		static void sigIntHandler(int) {
		if (g_init) g_init->shutdown();
		}

		// Ctrl+Alt+Del sends SIGINT to PID 1 on Linux
		static void sigRebootHandler(int) {
		if (g_init) g_init->reboot();
		}

		int main(int argc, char **argv) {
		cmdplus::CmdController &cmd = cmdplus::CmdController::getInstance();
		cmd.registerCmd("help", 'h', false, "", "Show help");
		cmd.registerCmd("config", 'c', true, "", "Config file path (e.g. yaml:/etc/syslite/syslite.yaml)");

		cmd.parseCmd(argc, argv);

		if (cmd.getCmdbyKey("help") && cmd.getCmdbyKey("help")->getFound()) {
		std::cout << "syslite — lightweight Linux init system" << std::endl;
		std::cout << std::endl;
		cmd.printHelp();
		return 0;
		}

		if (!cmd.checkRequired()) {
		// If running as PID 1, use default config path
		if (getpid() != 1) {
		std::cerr << "Usage: syslite -c yaml:/etc/syslite/syslite.yaml" << std::endl;
		return 1;
		}
		}

		syslite::Init init;
		g_init = &init;

		// Set up signal handlers
		struct sigaction sa{};
		sa.sa_handler = sigTermHandler;
		sigemptyset(&sa.sa_mask);
		sa.sa_flags = SA_RESTART;
		sigaction(SIGTERM, &sa, nullptr);

		sa.sa_handler = sigIntHandler;
		sigaction(SIGINT, &sa, nullptr);

		// SIGUSR1 for reboot (alternative to Ctrl+Alt+Del)
		sa.sa_handler = sigRebootHandler;
		sigaction(SIGUSR1, &sa, nullptr);

		// Ignore SIGPIPE
		signal(SIGPIPE, SIG_IGN);

		// Load config
		std::string configPath;
		auto *configCmd = cmd.getCmdbyKey("config");
		if (configCmd && configCmd->getFound()) {
		configPath = configCmd->getValue();
		} else {
		configPath = "yaml:/etc/syslite/syslite.yaml";
		}

		init.loadConfig(configPath);

		// Run the init main loop
		return init.run();
		}

src/service.cpp

0 → 100644

+492 −0

Changes for src/service.cpp: 492 added lines, 0 removed lines.
Original line number	Diff line number	Diff line
		#include "service.h"

		#include <iostream>
		#include <fstream>
		#include <filesystem>
		#include <algorithm>
		#include <cstring>
		#include <csignal>

		#include <unistd.h>
		#include <sys/wait.h>
		#include <sys/stat.h>
		#include <pwd.h>
		#include <grp.h>
		#include <fcntl.h>

		namespace syslite {

		ServiceManager::ServiceManager() {}
		ServiceManager::~ServiceManager() {}

		int ServiceManager::loadDirectory(const std::string &path) {
		int count = 0;
		if (!std::filesystem::exists(path))
		return 0;

		for (auto &entry : std::filesystem::directory_iterator(path)) {
		if (entry.is_regular_file() \|\| entry.is_symlink()) {
		std::string fname = entry.path().filename().string();
		if (fname.size() > 8 && fname.substr(fname.size() - 8) == ".service") {
		if (loadUnit(entry.path().string()))
		++count;
		}
		}
		}

		std::cout << "[syslite] Loaded " << count << " service(s) from " << path << std::endl;
		return count;
		}

		bool ServiceManager::loadUnit(const std::string &path) {
		UnitFile unit;
		if (!parseUnitFile(path, unit)) {
		std::cerr << "[syslite] Failed to parse: " << path << std::endl;
		return false;
		}

		ServiceEntry entry;
		entry.unit = std::move(unit);
		_services[entry.unit.name] = std::move(entry);
		return true;
		}

		// Resolve dependencies and determine start order for a target
		void ServiceManager::startTarget(const std::string &target) {
		// Collect services that are WantedBy this target
		std::vector<std::string> toStart;
		for (auto &[name, entry] : _services) {
		for (auto &wb : entry.unit.wantedBy) {
		if (wb == target) {
		toStart.push_back(name);
		break;
		}
		}
		}

		// Simple dependency-based ordering: start services whose After
		// dependencies have already been started first
		std::vector<std::string> started;
		std::vector<std::string> pending = toStart;
		int maxPasses = static_cast<int>(pending.size()) + 1;

		while (!pending.empty() && maxPasses-- > 0) {
		std::vector<std::string> nextPending;
		for (auto &name : pending) {
		auto *entry = findService(name);
		if (!entry) continue;

		// Check if all After deps are either started or not in our set
		bool depsReady = true;
		for (auto &dep : entry->unit.after) {
		// Strip .service suffix if present
		std::string depName = dep;
		if (depName.size() > 8 && depName.substr(depName.size() - 8) == ".service")
		depName = depName.substr(0, depName.size() - 8);

		// If this dep is in our start set and not yet started, wait
		if (std::find(toStart.begin(), toStart.end(), depName) != toStart.end()) {
		if (std::find(started.begin(), started.end(), depName) == started.end()) {
		depsReady = false;
		break;
		}
		}
		}

		if (depsReady) {
		startService(name);
		started.push_back(name);
		} else {
		nextPending.push_back(name);
		}
		}
		pending = nextPending;
		}

		// Start any remaining that couldn't resolve deps
		for (auto &name : pending) {
		std::cerr << "[syslite] Starting " << name << " (unresolved deps)" << std::endl;
		startService(name);
		}

		_startOrder = started;
		for (auto &name : pending)
		_startOrder.push_back(name);
		}

		std::vector<std::string> ServiceManager::buildArgv(const std::string &cmdline) {
		std::vector<std::string> args;
		std::string current;
		bool inQuote = false;
		char quoteChar = 0;

		for (size_t i = 0; i < cmdline.size(); ++i) {
		char c = cmdline[i];

		if (inQuote) {
		if (c == quoteChar) {
		inQuote = false;
		} else {
		current += c;
		}
		} else if (c == '"' \|\| c == '\'') {
		inQuote = true;
		quoteChar = c;
		} else if (c == ' ' \|\| c == '\t') {
		if (!current.empty()) {
		args.push_back(current);
		current.clear();
		}
		} else {
		current += c;
		}
		}
		if (!current.empty())
		args.push_back(current);

		return args;
		}

		void ServiceManager::resolveEnvironment(std::string &cmd, const ServiceEntry &entry) {
		// Replace $MAINPID with actual PID
		std::string pidStr = std::to_string(entry.pid);
		size_t pos;
		while ((pos = cmd.find("$MAINPID")) != std::string::npos)
		cmd.replace(pos, 8, pidStr);
		}

		void ServiceManager::createRuntimeDirectory(const ServiceEntry &entry) {
		if (entry.unit.runtimeDirectory.empty())
		return;

		std::string dir = "/run/" + entry.unit.runtimeDirectory;
		std::filesystem::create_directories(dir);

		if (!entry.unit.user.empty()) {
		struct passwd *pw = getpwnam(entry.unit.user.c_str());
		struct group *gr = entry.unit.group.empty()
		? nullptr : getgrnam(entry.unit.group.c_str());
		if (pw) {
		chown(dir.c_str(), pw->pw_uid, gr ? gr->gr_gid : pw->pw_gid);
		}
		}
		}

		void ServiceManager::setupChildProcess(const ServiceEntry &entry) {
		// Set working directory
		if (!entry.unit.workingDirectory.empty()) {
		if (chdir(entry.unit.workingDirectory.c_str()) != 0) {
		std::cerr << "[syslite] chdir failed: " << entry.unit.workingDirectory << std::endl;
		}
		}

		// Load environment file
		if (!entry.unit.environmentFile.empty()) {
		std::string envPath = entry.unit.environmentFile;
		// Strip leading '-' (optional file)
		if (!envPath.empty() && envPath[0] == '-')
		envPath = envPath.substr(1);

		std::ifstream envFile(envPath);
		if (envFile.is_open()) {
		std::string line;
		while (std::getline(envFile, line)) {
		if (line.empty() \|\| line[0] == '#') continue;
		putenv(strdup(line.c_str()));
		}
		}
		}

		// Set individual environment variables
		for (auto &[key, val] : entry.unit.environment) {
		setenv(key.c_str(), val.c_str(), 1);
		}

		// Drop privileges
		if (!entry.unit.group.empty()) {
		struct group *gr = getgrnam(entry.unit.group.c_str());
		if (gr) setgid(gr->gr_gid);
		}
		if (!entry.unit.user.empty()) {
		struct passwd *pw = getpwnam(entry.unit.user.c_str());
		if (pw) {
		initgroups(entry.unit.user.c_str(), pw->pw_gid);
		setuid(pw->pw_uid);
		}
		}

		// Reset signals
		signal(SIGCHLD, SIG_DFL);
		signal(SIGTERM, SIG_DFL);
		signal(SIGINT, SIG_DFL);

		// New session for the service
		setsid();
		}

		bool ServiceManager::execService(ServiceEntry &entry) {
		if (entry.unit.execStart.empty()) {
		std::cerr << "[syslite] No ExecStart for " << entry.unit.name << std::endl;
		entry.state = ServiceState::Failed;
		return false;
		}

		createRuntimeDirectory(entry);

		// Run ExecStartPre if set
		if (!entry.unit.execStartPre.empty()) {
		std::string preCmd = entry.unit.execStartPre;
		// Strip leading '-' (ignore failures)
		bool ignoreFailure = false;
		if (!preCmd.empty() && preCmd[0] == '-') {
		ignoreFailure = true;
		preCmd = preCmd.substr(1);
		}

		pid_t prePid = fork();
		if (prePid == 0) {
		setupChildProcess(entry);
		auto args = buildArgv(preCmd);
		std::vector<char*> argv;
		for (auto &a : args)
		argv.push_back(const_cast<char*>(a.c_str()));
		argv.push_back(nullptr);
		execvp(argv[0], argv.data());
		_exit(127);
		} else if (prePid > 0) {
		int preStatus;
		waitpid(prePid, &preStatus, 0);
		if (WIFEXITED(preStatus) && WEXITSTATUS(preStatus) != 0 && !ignoreFailure) {
		std::cerr << "[syslite] ExecStartPre failed for " << entry.unit.name << std::endl;
		entry.state = ServiceState::Failed;
		return false;
		}
		}
		}

		entry.state = ServiceState::Starting;

		pid_t pid = fork();
		if (pid == 0) {
		// Child
		setupChildProcess(entry);

		auto args = buildArgv(entry.unit.execStart);
		std::vector<char*> argv;
		for (auto &a : args)
		argv.push_back(const_cast<char*>(a.c_str()));
		argv.push_back(nullptr);

		execvp(argv[0], argv.data());
		std::cerr << "[syslite] exec failed: " << entry.unit.execStart
		<< ": " << strerror(errno) << std::endl;
		_exit(127);
		}

		if (pid < 0) {
		std::cerr << "[syslite] fork failed for " << entry.unit.name << std::endl;
		entry.state = ServiceState::Failed;
		return false;
		}

		entry.pid = pid;

		if (entry.unit.type == ServiceType::Forking) {
		// Wait for the forking parent to exit, then read PID file
		int status;
		waitpid(pid, &status, 0);

		if (!entry.unit.pidFile.empty()) {
		std::ifstream pf(entry.unit.pidFile);
		if (pf.is_open()) {
		pid_t realPid;
		pf >> realPid;
		if (realPid > 0)
		entry.pid = realPid;
		}
		} else {
		// No PID file — we can't reliably track the daemon
		entry.pid = -1;
		}
		entry.state = ServiceState::Running;
		}
		else if (entry.unit.type == ServiceType::Oneshot) {
		// Wait for completion
		int status;
		waitpid(pid, &status, 0);
		entry.exitCode = WIFEXITED(status) ? WEXITSTATUS(status) : -1;
		entry.pid = -1;
		entry.state = (entry.exitCode == 0) ? ServiceState::Stopped : ServiceState::Failed;
		}
		else {
		// Simple — process stays running
		entry.state = ServiceState::Running;
		}

		std::cout << "[syslite] Started " << entry.unit.name
		<< " (pid=" << entry.pid << ")" << std::endl;
		return true;
		}

		bool ServiceManager::startService(const std::string &name) {
		auto it = _services.find(name);
		if (it == _services.end()) {
		std::cerr << "[syslite] Unknown service: " << name << std::endl;
		return false;
		}

		auto &entry = it->second;
		if (entry.state == ServiceState::Running) {
		return true;
		}

		// Start required dependencies first
		for (auto &req : entry.unit.requires) {
		std::string depName = req;
		if (depName.size() > 8 && depName.substr(depName.size() - 8) == ".service")
		depName = depName.substr(0, depName.size() - 8);
		startService(depName);
		}

		std::cout << "[syslite] Starting " << name << "..." << std::endl;
		return execService(entry);
		}

		bool ServiceManager::stopService(const std::string &name) {
		auto it = _services.find(name);
		if (it == _services.end())
		return false;

		auto &entry = it->second;
		if (entry.state != ServiceState::Running)
		return true;

		entry.state = ServiceState::Stopping;
		std::cout << "[syslite] Stopping " << name << "..." << std::endl;

		// ExecStop if defined
		if (!entry.unit.execStop.empty() && entry.pid > 0) {
		std::string stopCmd = entry.unit.execStop;
		resolveEnvironment(stopCmd, entry);

		pid_t stopPid = fork();
		if (stopPid == 0) {
		auto args = buildArgv(stopCmd);
		std::vector<char*> argv;
		for (auto &a : args)
		argv.push_back(const_cast<char*>(a.c_str()));
		argv.push_back(nullptr);
		execvp(argv[0], argv.data());
		_exit(127);
		} else if (stopPid > 0) {
		int status;
		waitpid(stopPid, &status, 0);
		}
		} else if (entry.pid > 0) {
		// Default: send SIGTERM
		kill(entry.pid, SIGTERM);
		}

		// Wait for process to exit with timeout
		if (entry.pid > 0) {
		int timeoutMs = entry.unit.timeoutStopSec * 1000;
		int waited = 0;
		int step = 100; // 100ms

		while (waited < timeoutMs) {
		int status;
		pid_t ret = waitpid(entry.pid, &status, WNOHANG);
		if (ret > 0) {
		entry.pid = -1;
		entry.state = ServiceState::Stopped;
		std::cout << "[syslite] Stopped " << name << std::endl;
		return true;
		}
		if (ret < 0) break; // already gone
		usleep(step * 1000);
		waited += step;
		}

		// Timeout: SIGKILL
		if (entry.pid > 0) {
		std::cerr << "[syslite] " << name << " did not stop, sending SIGKILL" << std::endl;
		kill(entry.pid, SIGKILL);
		waitpid(entry.pid, nullptr, 0);
		}
		}

		entry.pid = -1;
		entry.state = ServiceState::Stopped;
		return true;
		}

		void ServiceManager::stopAll() {
		// Stop in reverse start order
		std::vector<std::string> order = _startOrder;
		std::reverse(order.begin(), order.end());

		// Also stop anything not in the start order
		for (auto &[name, entry] : _services) {
		if (entry.state == ServiceState::Running) {
		if (std::find(order.begin(), order.end(), name) == order.end())
		order.push_back(name);
		}
		}

		for (auto &name : order) {
		stopService(name);
		}
		}

		void ServiceManager::handleChild(pid_t pid, int status) {
		for (auto &[name, entry] : _services) {
		if (entry.pid == pid) {
		entry.exitCode = WIFEXITED(status) ? WEXITSTATUS(status) : -1;
		entry.pid = -1;

		if (entry.state == ServiceState::Stopping) {
		entry.state = ServiceState::Stopped;
		} else if (entry.state == ServiceState::Running) {
		if (entry.exitCode == 0) {
		entry.state = ServiceState::Stopped;
		std::cout << "[syslite] " << name << " exited normally" << std::endl;
		} else {
		entry.state = ServiceState::Failed;
		std::cerr << "[syslite] " << name << " exited with code "
		<< entry.exitCode << std::endl;
		}
		}
		return;
		}
		}
		}

		void ServiceManager::checkRestarts() {
		for (auto &[name, entry] : _services) {
		bool shouldRestart = false;

		if (entry.unit.restart == RestartPolicy::Always &&
		(entry.state == ServiceState::Stopped \|\| entry.state == ServiceState::Failed)) {
		shouldRestart = true;
		}
		else if (entry.unit.restart == RestartPolicy::OnFailure &&
		entry.state == ServiceState::Failed) {
		shouldRestart = true;
		}

		if (shouldRestart && entry.pid <= 0) {
		++entry.restartCount;
		std::cout << "[syslite] Restarting " << name
		<< " (attempt " << entry.restartCount << ")" << std::endl;
		execService(entry);
		}
		}
		}

		ServiceEntry *ServiceManager::findService(const std::string &name) {
		auto it = _services.find(name);
		if (it == _services.end()) return nullptr;
		return &it->second;
		}

		}