Re: [Qemu-devel] [PATCH] ui: sdl2: Fix crash with -nodefaults -sdl

[Gerd Hoffmann]

On Di, 2016-05-31 at 16:56 -0400, Cole Robinson wrote:
> $ ./x86_64-softmmu/qemu-system-x86_64 -nodefaults -sdl
> Segmentation fault (core dumped)
> 
> 0  0x00005555559631af in sdl_display_init (ds=<optimized out>, full_screen=0, 
> no_frame=<optimized out>) at ui/sdl2.c:822
> 1  0x00005555556c8a9a in main (argc=<optimized out>, argv=<optimized out>, 
> envp=<optimized out>) at vl.c:4527
> 
> Setting the window icon assumes there's always an SDL output window
> available, which isn't the case with when there's no video device,
> like via -nodefaults. So don't try to set a window icon when we don't
> have any outputs.

Hmm, I guess we can skip pretty much all of the init in case there are
no outputs:

@@ -794,6 +794,9 @@ void sdl_display_init(DisplayState *ds, int
full_screen, int no_frame)
         }
     }
     sdl2_num_outputs = i;
+    if (sdl2_num_outputs == 0) {
+        return;
+    }
     sdl2_console = g_new0(struct sdl2_console, sdl2_num_outputs);
     for (i = 0; i < sdl2_num_outputs; i++) {
         QemuConsole *con = qemu_console_lookup_by_index(i);


Maybe even move up the loop counting the outputs, so we can skip the
SDL_Init() call too.  We don't get a empty window then.

cheers,
  Gerd