From 64a4713fe6ae51b87554ec8dc921f66b8282b171 Mon Sep 17 00:00:00 2001
From: Christian Helmuth <christian.helmuth@genode-labs.com>
Date: Thu, 8 Oct 2015 17:12:25 +0200
Subject: [PATCH] fb_sdl: check for X11 / prevent invalid-event flood

We check for X11 as required platform now and are more verbose on
errors.
---
 .../drivers/framebuffer/spec/sdl/fb_sdl.cc    | 24 +++++++++--
 .../src/drivers/framebuffer/spec/sdl/input.cc | 43 +++++++++++++++----
 2 files changed, 55 insertions(+), 12 deletions(-)

diff --git a/repos/os/src/drivers/framebuffer/spec/sdl/fb_sdl.cc b/repos/os/src/drivers/framebuffer/spec/sdl/fb_sdl.cc
index 5473c2b62..b058a9435 100644
--- a/repos/os/src/drivers/framebuffer/spec/sdl/fb_sdl.cc
+++ b/repos/os/src/drivers/framebuffer/spec/sdl/fb_sdl.cc
@@ -1,11 +1,12 @@
 /*
  * \brief  SDL-based implementation of the Genode framebuffer
  * \author Norman Feske
+ * \author Christian Helmuth
  * \date   2006-07-10
  */
 
 /*
- * Copyright (C) 2006-2013 Genode Labs GmbH
+ * Copyright (C) 2006-2015 Genode Labs GmbH
  *
  * This file is part of the Genode OS framework, which is distributed
  * under the terms of the GNU General Public License version 2.
@@ -119,7 +120,7 @@ class Framebuffer::Session_component : public Genode::Rpc_object<Session>
 /**
  * Main program
  */
-extern "C" int main(int, char**)
+int main()
 {
 	using namespace Genode;
 	using namespace Framebuffer;
@@ -132,12 +133,27 @@ extern "C" int main(int, char**)
 	 */
 	if (SDL_Init(SDL_INIT_VIDEO) < 0)
 	{
-		PERR("SDL_Init failed\n");
+		PERR("SDL_Init failed (%s)", SDL_GetError());
 		return -1;
 	}
 
+	/*
+	 * We're testing only X11.
+	 */
+	static char driver[16] = { 0 };
+	SDL_VideoDriverName(driver, sizeof(driver));
+	if (::strcmp(driver, "x11") != 0) {
+		PERR("fb_sdl works on X11 only. Your SDL backend is \"%s\".", driver);
+		return -2;
+	}
+
 	Genode::size_t bpp = Framebuffer::Mode::bytes_per_pixel(scr_format);
 	screen = SDL_SetVideoMode(scr_width, scr_height, bpp*8, SDL_SWSURFACE);
+	if (!screen) {
+		PERR("SDL_SetVideoMode failed (%s)", SDL_GetError());
+		return -3;
+	}
+
 	SDL_ShowCursor(0);
 
 	Genode::printf("creating virtual framebuffer for mode %ldx%ld@%zd\n",
@@ -152,7 +168,7 @@ extern "C" int main(int, char**)
 		fb_ds_addr = fb_ds.local_addr<void>();
 	} catch (...) {
 		PERR("Could not allocate dataspace for virtual frame buffer");
-		return -2;
+		return -4;
 	}
 
 	/*
diff --git a/repos/os/src/drivers/framebuffer/spec/sdl/input.cc b/repos/os/src/drivers/framebuffer/spec/sdl/input.cc
index 65e5be90a..d9fa82628 100644
--- a/repos/os/src/drivers/framebuffer/spec/sdl/input.cc
+++ b/repos/os/src/drivers/framebuffer/spec/sdl/input.cc
@@ -1,11 +1,12 @@
 /*
  * \brief  SDL input support
  * \author Norman Feske
+ * \author Christian Helmuth
  * \date   2006-08-16
  */
 
 /*
- * Copyright (C) 2006-2013 Genode Labs GmbH
+ * Copyright (C) 2006-2015 Genode Labs GmbH
  *
  * This file is part of the Genode OS framework, which is distributed
  * under the terms of the GNU General Public License version 2.
@@ -138,7 +139,7 @@ static long convert_keycode(int sdl_keycode)
 };
 
 
-Input::Event wait_for_event()
+static Input::Event wait_for_sdl_event()
 {
 	using namespace Input;
 
@@ -166,18 +167,30 @@ Input::Event wait_for_event()
 	case SDL_MOUSEBUTTONUP:
 
 		switch (event.button.button) {
-		case SDL_BUTTON_LEFT:  keycode = BTN_LEFT;  break;
-		case SDL_BUTTON_RIGHT: keycode = BTN_RIGHT; break;
-		default:               keycode = 0;
+		case SDL_BUTTON_LEFT:   keycode = BTN_LEFT;   break;
+		case SDL_BUTTON_MIDDLE: keycode = BTN_MIDDLE; break;
+		case SDL_BUTTON_RIGHT:  keycode = BTN_RIGHT;  break;
+		default:                keycode = 0;
 		}
 	}
 
 	/* determine event type */
 	Event::Type type;
 	switch (event.type) {
-	case SDL_MOUSEMOTION:     type = Event::MOTION;  break;
+	case SDL_MOUSEMOTION:
+		type = Event::MOTION;
+		break;
+
 	case SDL_KEYUP:
-	case SDL_MOUSEBUTTONUP:   type = Event::RELEASE; break;
+	case SDL_MOUSEBUTTONUP:
+		if (event.button.button == SDL_BUTTON_WHEELUP
+		 || event.button.button == SDL_BUTTON_WHEELDOWN)
+			/* ignore */
+			return Event();
+
+		type = Event::RELEASE;
+		break;
+
 	case SDL_KEYDOWN:
 	case SDL_MOUSEBUTTONDOWN:
 		if (event.button.button == SDL_BUTTON_WHEELUP) {
@@ -189,8 +202,22 @@ Input::Event wait_for_event()
 		}
 		type = Event::PRESS;
 		break;
-	default:                  type = Event::INVALID;
+
+	default:
+		return Event();
 	}
 
 	return Event(type, keycode, mx, my, mx - ox, my - oy);
 }
+
+Input::Event wait_for_event()
+{
+	Input::Event e;
+
+	/* prevent flooding of client with invalid events */
+	do {
+		e = wait_for_sdl_event();
+	} while (e.type() == Input::Event::INVALID);
+
+	return e;
+}