Desktop: Handle another instance is already running (#2938)

Handle another instance is already running

desktop/src/cef/context.rs

@@ -1,4 +1,4 @@
-use cef::sys::CEF_API_VERSION_LAST;
+use cef::sys::{CEF_API_VERSION_LAST, cef_resultcode_t};
 use cef::{App, BrowserSettings, Client, DictionaryValue, ImplBrowser, ImplBrowserHost, ImplCommandLine, RenderHandler, RequestContext, WindowInfo, browser_host_create_browser_sync, initialize};
 use cef::{Browser, CefString, Settings, api_hash, args::Args, execute_process};
 use thiserror::Error;
@@ -74,7 +74,11 @@ impl Context<Setup> {
 
 		let result = initialize(Some(self.args.as_main_args()), Some(&settings), Some(&mut cef_app), std::ptr::null_mut());
 		if result != 1 {
-			return Err(InitError::InitializationFailed);
+			let cef_exit_code = cef::get_exit_code() as u32;
+			if cef_exit_code == cef_resultcode_t::CEF_RESULT_CODE_NORMAL_EXIT_PROCESS_NOTIFIED as u32 {
+				return Err(InitError::AlreadyRunning);
+			}
+			return Err(InitError::InitializationFailed(cef_exit_code));
 		}
 
 		let render_handler = RenderHandlerImpl::new(event_handler.clone());
@@ -146,5 +150,7 @@ pub(crate) enum SetupError {
 #[derive(Error, Debug)]
 pub(crate) enum InitError {
 	#[error("initialization failed")]
-	InitializationFailed,
+	InitializationFailed(u32),
+	#[error("Another instance is already running")]
+	AlreadyRunning,
 }

desktop/src/cef/internal/browser_process_handler.rs

@@ -29,6 +29,10 @@ impl<H: CefEventHandler + Clone> ImplBrowserProcessHandler for BrowserProcessHan
 		self.event_handler.schedule_cef_message_loop_work(Instant::now() + Duration::from_millis(delay_ms as u64));
 	}
 
+	fn on_already_running_app_relaunch(&self, _command_line: Option<&mut cef::CommandLine>, _current_directory: Option<&CefString>) -> ::std::os::raw::c_int {
+		1 // Return 1 to prevent default behavior of opening a empty browser window
+	}
+
 	fn get_raw(&self) -> *mut _cef_browser_process_handler_t {
 		self.object.cast()
 	}