Add Win32 service to run Sunshine as LocalSystem on login

tools/sunshinesvc.cpp

@@ -0,0 +1,160 @@
+#define WIN32_LEAN_AND_MEAN
+#include <Windows.h>
+#include <wtsapi32.h>
+#include <psapi.h>
+
+SERVICE_STATUS_HANDLE service_status_handle;
+SERVICE_STATUS service_status;
+HANDLE stop_event;
+
+#define SERVICE_NAME "SunshineSvc"
+
+DWORD WINAPI HandlerEx(DWORD dwControl, DWORD dwEventType, LPVOID lpEventData, LPVOID lpContext) {
+  switch(dwControl) {
+  case SERVICE_CONTROL_INTERROGATE:
+    return NO_ERROR;
+
+  case SERVICE_CONTROL_STOP:
+    // Let SCM know we're stopping in up to 30 seconds
+    service_status.dwCurrentState     = SERVICE_STOP_PENDING;
+    service_status.dwControlsAccepted = 0;
+    service_status.dwWaitHint         = 30 * 1000;
+    SetServiceStatus(service_status_handle, &service_status);
+
+    // Trigger ServiceMain() to start cleanup
+    SetEvent(stop_event);
+    return NO_ERROR;
+
+  default:
+    return NO_ERROR;
+  }
+}
+
+HANDLE DuplicateTokenForConsoleSession() {
+  auto console_session_id = WTSGetActiveConsoleSessionId();
+  if(console_session_id == 0xFFFFFFFF) {
+    // No console session yet
+    return NULL;
+  }
+
+  HANDLE current_token;
+  if(!OpenProcessToken(GetCurrentProcess(), TOKEN_DUPLICATE, &current_token)) {
+    return NULL;
+  }
+
+  // Duplicate our own LocalSystem token
+  HANDLE new_token;
+  if(!DuplicateTokenEx(current_token, TOKEN_ALL_ACCESS, NULL, SecurityImpersonation, TokenPrimary, &new_token)) {
+    CloseHandle(current_token);
+    return NULL;
+  }
+
+  CloseHandle(current_token);
+
+  // Change the duplicated token to the console session ID
+  if(!SetTokenInformation(new_token, TokenSessionId, &console_session_id, sizeof(console_session_id))) {
+    CloseHandle(new_token);
+    return NULL;
+  }
+
+  return new_token;
+}
+
+VOID WINAPI ServiceMain(DWORD dwArgc, LPTSTR *lpszArgv) {
+  stop_event = CreateEventA(NULL, TRUE, FALSE, NULL);
+  if(stop_event == NULL) {
+    return;
+  }
+
+  service_status_handle = RegisterServiceCtrlHandlerEx(SERVICE_NAME, HandlerEx, NULL);
+  if(service_status_handle == NULL) {
+    return;
+  }
+
+  // Tell SCM we're running
+  service_status.dwServiceType             = SERVICE_WIN32_OWN_PROCESS;
+  service_status.dwServiceSpecificExitCode = 0;
+  service_status.dwWin32ExitCode           = NO_ERROR;
+  service_status.dwWaitHint                = 0;
+  service_status.dwControlsAccepted        = SERVICE_ACCEPT_STOP;
+  service_status.dwCheckPoint              = 0;
+  service_status.dwCurrentState            = SERVICE_RUNNING;
+  SetServiceStatus(service_status_handle, &service_status);
+
+  // Loop every 3 seconds until the stop event is set or Sunshine.exe is running
+  while(WaitForSingleObject(stop_event, 3000) != WAIT_OBJECT_0) {
+    auto console_token = DuplicateTokenForConsoleSession();
+    if(console_token == NULL) {
+      continue;
+    }
+
+    STARTUPINFOW startup_info = {};
+    startup_info.cb = sizeof(startup_info);
+    startup_info.lpDesktop = (LPWSTR)L"winsta0\\default";
+
+    // TODO: Redirect stdout to file and set CREATE_NO_WINDOW
+    PROCESS_INFORMATION process_info;
+    if(!CreateProcessAsUserW(console_token,
+                             L"Sunshine.exe",
+                             NULL,
+                             NULL,
+                             NULL,
+                             FALSE,
+                             ABOVE_NORMAL_PRIORITY_CLASS | CREATE_UNICODE_ENVIRONMENT /*| CREATE_NO_WINDOW */,
+                             NULL,
+                             NULL,
+                             &startup_info,
+                             &process_info)) {
+      CloseHandle(console_token);
+      continue;
+    }
+
+    // Close handles that are no longer needed
+    CloseHandle(console_token);
+    CloseHandle(process_info.hThread);
+
+    // Wait for either the stop event to be set or Sunshine.exe to terminate
+    const HANDLE wait_objects[] = { stop_event, process_info.hProcess };
+    switch(WaitForMultipleObjects(_countof(wait_objects), wait_objects, FALSE, INFINITE)) {
+    case WAIT_OBJECT_0:
+      // The service is shutting down, so terminate Sunshine.exe.
+      // TODO: Send a graceful exit request and only terminate forcefully as a last resort.
+      TerminateProcess(process_info.hProcess, ERROR_PROCESS_ABORTED);
+      break;
+
+    case WAIT_OBJECT_0 + 1:
+      // Sunshine terminated itself.
+      break;
+    }
+
+    CloseHandle(process_info.hProcess);
+  }
+
+  // Let SCM know we've stopped
+  service_status.dwCurrentState = SERVICE_STOPPED;
+  SetServiceStatus(service_status_handle, &service_status);
+}
+
+int main(int argc, char* argv[])
+{
+  static const SERVICE_TABLE_ENTRY service_table[] = {
+    { (LPSTR)SERVICE_NAME, ServiceMain },
+    { NULL, NULL }
+  };
+
+  // By default, services have their current directory set to %SYSTEMROOT%\System32.
+  // We want to use the directory where Sunshine.exe is located instead of system32.
+  // This requires stripping off 2 path components: the file name and the last folder
+  WCHAR module_path[MAX_PATH];
+  GetModuleFileNameW(NULL, module_path, _countof(module_path));
+  for(auto i = 0; i < 2; i++) {
+    auto last_sep = wcsrchr(module_path, '\\');
+    if(last_sep) {
+      *last_sep = 0;
+    }
+  }
+  SetCurrentDirectoryW(module_path);
+
+  // Trigger our ServiceMain()
+  return StartServiceCtrlDispatcher(service_table);
+}