Fixed bug 2525 - Keyboard focus crash

Todd Seiler

Call Stack:
#0  0x0000000101c29291 in Cocoa_StartTextInput at /Users/Todd/Desktop/codes/sources/SDL/src/video/cocoa/SDL_cocoakeyboard.m:512
#1  0x0000000101c110c5 in SDL_SetKeyboardFocus at /Users/Todd/Desktop/codes/sources/SDL/src/events/SDL_keyboard.c:643
#2  0x0000000101c32be4 in SetupWindowData at /Users/Todd/Desktop/codes/sources/SDL/src/video/cocoa/SDL_cocoawindow.m:981
#3  0x0000000101c32d2a in Cocoa_CreateWindowFrom at /Users/Todd/Desktop/codes/sources/SDL/src/video/cocoa/SDL_cocoawindow.m:1092
#4  0x0000000101c99999 in SDL_CreateWindowFrom_REAL at /Users/Todd/Desktop/codes/sources/SDL/src/video/SDL_video.c:1338
#5  0x0000000101ce1484 in SDL_CreateWindowFrom at /Users/Todd/Desktop/codes/sources/SDL/src/dynapi/SDL_dynapi_procs.h:547
#6  0x0000000100018a5e in SceneRenderer at /Users/Todd/Desktop/codes/sources/tseiler_Todds-MacBook-Pro_3405/AppName/src/SceneRenderer.cpp:138
#7  0x0000000100017ca5 in SceneRenderer at /Users/Todd/Desktop/codes/sources/tseiler_Todds-MacBook-Pro_3405/AppName/src/SceneRenderer.cpp:145
#8  0x000000010000cd96 in App::execute(int, char**) at /Users/Todd/Desktop/codes/sources/tseiler_Todds-MacBook-Pro_3405/AppName/src/App.cpp:28
#9  0x0000000100004402 in main at /Users/Todd/Desktop/codes/sources/tseiler_Todds-MacBook-Pro_3405/AppName/src/main.cpp:8


This issue occurred when using Ogre3D Graphics engine on Mac (cocoa) to create the window. Then handing the window handle off to SDL_CreateWindowFrom().

In Ogre3D application you do the following:
        window_ = root_->initialise(true, "Ogre Window 2");
        loadOgreResources();
        Ogre::WindowEventUtilities::addWindowEventListener(window_, this);

#if OGRE_PLATFORM == OGRE_PLATFORM_APPLE
        NSWindow* Data = 0;
        window_->getCustomAttribute("WINDOW", &Data);
        sdl_window_ = SDL_CreateWindowFrom((void*)Data);
#endif

It results in a crash in this function:
SDL_cocoakeyboard.m

void
Cocoa_StartTextInput(_THIS)
{
    SDL_VideoData *data = (SDL_VideoData *) _this->driverdata;
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    SDL_Window *window = SDL_GetKeyboardFocus();
    NSWindow *nswindow = nil;
    if (window)
        nswindow = ((SDL_WindowData*)window->driverdata)->nswindow;

    // ...
}

The crash occurred because "driverdata" was nil. Before this function call, a call to SetupWindowData is called:

SDL_cocoawindow.m

static int
SetupWindowData(_THIS, SDL_Window * window, NSWindow *nswindow, SDL_bool created)
{
    // ...

    if ([nswindow isKeyWindow]) {
        window->flags |= SDL_WINDOW_INPUT_FOCUS;
        SDL_SetKeyboardFocus(data->window);
    }

    /* Prevents the window's "window device" from being destroyed when it is
     * hidden. See http://www.mikeash.com/pyblog/nsopenglcontext-and-one-shot.html
     */
    [nswindow setOneShot:NO];

    /* All done! */
    [pool release];
    window->driverdata = data;
    return 0;
}

As you can see: "window->driverdata = data" is performed after the "SDL_SetKeyboardFocus()" call, which eventually leads to "Cocoa_StartTextInput()" where the crash occurs.

src/video/cocoa/SDL_cocoawindow.m

@@ -921,7 +921,7 @@ SetupWindowData(_THIS, SDL_Window * window, NSWindow *nswindow, SDL_bool created
     SDL_WindowData *data;
 
     /* Allocate the window data */
-    data = (SDL_WindowData *) SDL_calloc(1, sizeof(*data));
+    window->driverdata = data = (SDL_WindowData *) SDL_calloc(1, sizeof(*data));
     if (!data) {
         return SDL_OutOfMemory();
     }
@@ -995,7 +995,6 @@ SetupWindowData(_THIS, SDL_Window * window, NSWindow *nswindow, SDL_bool created
 
     /* All done! */
     [pool release];
-    window->driverdata = data;
     return 0;
 }