From 1bc12ba2b3bc2c4fbe8fad4797cf33266eb13f4b Mon Sep 17 00:00:00 2001
From: Tiger Wang <ziwei.tiger@outlook.com>
Date: Thu, 23 Jul 2020 00:34:43 +0100
Subject: Streamline startup sequence

* Clean up cRoot & main
* Move some OS-specifics into OSSupport
---
 src/OSSupport/StartAsService.h | 173 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 173 insertions(+)
 create mode 100644 src/OSSupport/StartAsService.h

(limited to 'src/OSSupport/StartAsService.h')

diff --git a/src/OSSupport/StartAsService.h b/src/OSSupport/StartAsService.h
new file mode 100644
index 000000000..472184367
--- /dev/null
+++ b/src/OSSupport/StartAsService.h
@@ -0,0 +1,173 @@
+
+#pragma once
+
+
+
+
+
+#ifdef _WIN32
+
+#include <csignal>
+
+
+
+
+
+class cStartAsService
+{
+public:
+
+	/** Make a Windows service. */
+	template <auto UniversalMain>
+	static bool MakeIntoService()
+	{
+		SERVICE_TABLE_ENTRY ServiceTable[] =
+		{
+			{ g_ServiceName, (LPSERVICE_MAIN_FUNCTION)serviceMain<UniversalMain> },
+			{ nullptr, nullptr }
+		};
+
+		if (StartServiceCtrlDispatcher(ServiceTable) == FALSE)
+		{
+			throw std::system_error(GetLastError(), std::system_category());
+		}
+
+		return true;
+	}
+
+private:
+
+	/** Set the internal status of the service */
+	static void serviceSetState(DWORD acceptedControls, DWORD newState, DWORD exitCode)
+	{
+		SERVICE_STATUS serviceStatus = {};
+		serviceStatus.dwCheckPoint = 0;
+		serviceStatus.dwControlsAccepted = acceptedControls;
+		serviceStatus.dwCurrentState = newState;
+		serviceStatus.dwServiceSpecificExitCode = 0;
+		serviceStatus.dwServiceType = SERVICE_WIN32;
+		serviceStatus.dwWaitHint = 0;
+		serviceStatus.dwWin32ExitCode = exitCode;
+
+		if (SetServiceStatus(g_StatusHandle, &serviceStatus) == FALSE)
+		{
+			LOGERROR("SetServiceStatus() failed\n");
+		}
+	}
+
+	/** Handle stop events from the Service Control Manager */
+	static void WINAPI serviceCtrlHandler(DWORD CtrlCode)
+	{
+		if (CtrlCode == SERVICE_CONTROL_STOP)
+		{
+			std::raise(SIGINT);
+			serviceSetState(0, SERVICE_STOP_PENDING, 0);
+		}
+	}
+
+	/* Startup logic for running as a service */
+	template <auto MainFunction>
+	static void WINAPI serviceMain(DWORD argc, TCHAR *argv[])
+	{
+		wchar_t applicationFilename[MAX_PATH];
+		wchar_t applicationDirectory[MAX_PATH];
+
+		// Get this binary's file path:
+		if (GetModuleFileName(nullptr, applicationFilename, std::size(applicationFilename)) == 0)
+		{
+			serviceSetState(0, SERVICE_STOPPED, GetLastError());
+			return;
+		}
+
+		const auto LastComponent = wcsrchr(applicationFilename, L'\\');
+		if (LastComponent == nullptr)
+		{
+			serviceSetState(0, SERVICE_STOPPED, E_UNEXPECTED);
+			return;
+		}
+
+		const auto LengthToLastComponent = LastComponent - applicationFilename;
+
+		// Strip off the filename, keep only the path:
+		wcsncpy(applicationDirectory, applicationFilename, LengthToLastComponent);
+		applicationDirectory[LengthToLastComponent] = L'\0';  // Make sure new path is null terminated
+
+		// Services are run by the SCM, and inherit its working directory - usually System32.
+		// Set the working directory to the same location as the binary.
+		if (SetCurrentDirectory(applicationDirectory) == FALSE)
+		{
+			serviceSetState(0, SERVICE_STOPPED, GetLastError());
+			return;
+		}
+
+
+		g_StatusHandle = RegisterServiceCtrlHandler(g_ServiceName, serviceCtrlHandler);
+		if (g_StatusHandle == nullptr)
+		{
+			OutputDebugStringA("RegisterServiceCtrlHandler() failed\n");
+			serviceSetState(0, SERVICE_STOPPED, GetLastError());
+			return;
+		}
+
+		serviceSetState(SERVICE_ACCEPT_STOP, SERVICE_RUNNING, 0);
+
+		char MultibyteArgV0[MAX_PATH];
+		char * MultibyteArgV[] = { MultibyteArgV0 };
+
+		const auto OutputSize = std::size(MultibyteArgV0);
+		const auto TranslateResult = wcstombs(MultibyteArgV0, argv[0], OutputSize);
+
+		if (TranslateResult == static_cast<size_t>(-1))
+		{
+			// Translation failed entirely (!):
+			MultibyteArgV0[0] = '\0';
+		}
+		else if (TranslateResult == OutputSize)
+		{
+			// Output too small:
+			MultibyteArgV0[OutputSize - 1] = '\0';
+		}
+
+		const auto Result = MainFunction(1, MultibyteArgV, true);
+		const auto Return = (Result == EXIT_SUCCESS) ? S_OK : E_FAIL;
+
+		serviceSetState(0, SERVICE_STOPPED, Return);
+	}
+
+	static inline SERVICE_STATUS_HANDLE g_StatusHandle  = nullptr;
+	static inline HANDLE                g_ServiceThread = INVALID_HANDLE_VALUE;
+	static inline wchar_t               g_ServiceName[] = L"Cuberite";
+};
+
+#else
+
+struct cStartAsService
+{
+	/** Make a UNIX daemon. */
+	template <auto>
+	static bool MakeIntoService()
+	{
+		pid_t pid = fork();
+
+		// fork() returns a negative value on error.
+		if (pid < 0)
+		{
+			throw std::system_error(errno, std::system_category());
+		}
+
+		// Check if we are the parent or child process. Parent stops here.
+		if (pid > 0)
+		{
+			return true;
+		}
+
+		//  Child process now goes quiet, running in the background.
+		close(STDIN_FILENO);
+		close(STDOUT_FILENO);
+		close(STDERR_FILENO);
+
+		return false;
+	}
+};
+
+#endif
-- 
cgit v1.2.3