[Pharo-dev] OSWindow OS X VM bug

Ronie Salgado roniesalg at gmail.com
Wed Nov 1 21:48:16 EDT 2017


Hi,

I finally managed to track the problem with keyboard events with OSWindow.
However, I cannot fix it without introducing a crash in an autorelease, or
a memory leak.

The SDL2 problem can be fixed by applying the following patch:

diff --git a/platforms/iOS/vm/Common/Classes/sqSqueakEventsAPI.m
b/platforms/iOS/vm/Common/Classes/sqSqueakEventsAPI.m
index 94c3c4c82..4b5aec8c5 100644
--- a/platforms/iOS/vm/Common/Classes/sqSqueakEventsAPI.m
+++ b/platforms/iOS/vm/Common/Classes/sqSqueakEventsAPI.m
@@ -100,9 +100,7 @@ sqInt ioProcessEvents(void) {

  // We need to run the vmIOProcessEvents even if we are using SDL2,
  // otherwise we end with some double free errors in an autorelease pool.
- vmIOProcessEvents();
-    if(ioProcessEventsHandler && ioProcessEventsHandler !=
vmIOProcessEvents)
-        ioProcessEventsHandler();
+    ioProcessEventsHandler();

However, this introduces a crash in an Objective-C autorelease pool, in at
leas two locations:

diff --git a/platforms/iOS/vm/OSX/sqSqueakOSXApplication+events.m
b/platforms/iOS/vm/OSX/sqSqueakOSXApplication+events.m
index 4f2ac06ea..c1ec3e1ea 100644
--- a/platforms/iOS/vm/OSX/sqSqueakOSXApplication+events.m
+++ b/platforms/iOS/vm/OSX/sqSqueakOSXApplication+events.m
@@ -152,9 +152,10 @@ - (void) recordCharEvent:(NSString *) unicodeString
fromView: (NSView <sqSqueakO
  }
  }

- NSString *lookupString = AUTORELEASEOBJ([[NSString alloc]
initWithCharacters: &unicode length: 1]);
+ NSString *lookupString = [[NSString alloc] initWithCharacters: &unicode
length: 1];
  [lookupString getBytes: &macRomanCharacter maxLength: 1 usedLength: NULL
encoding: NSMacOSRomanStringEncoding
    options: 0 range: picker remainingRange: NULL];
+        [lookupString release];

  evt.pressCode = EventKeyDown;
  unsigned short keyCodeRemembered = evt.charCode;

diff --git a/platforms/iOS/vm/OSX/sqSqueakOSXOpenGLView.m
b/platforms/iOS/vm/OSX/sqSqueakOSXOpenGLView.m
index c441332a3..72aa8c42d 100644
--- a/platforms/iOS/vm/OSX/sqSqueakOSXOpenGLView.m
+++ b/platforms/iOS/vm/OSX/sqSqueakOSXOpenGLView.m
@@ -747,7 +747,7 @@ - (NSString *) dealWithOpenStepChars: (NSString *)
openStep {


 -(void)keyDown:(NSEvent*)theEvent {
- keyBoardStrokeDetails *aKeyBoardStrokeDetails =
AUTORELEASEOBJ([[keyBoardStrokeDetails alloc] init]);
+ keyBoardStrokeDetails *aKeyBoardStrokeDetails = ([[keyBoardStrokeDetails
alloc] init]);
  aKeyBoardStrokeDetails.keyCode = [theEvent keyCode];
  aKeyBoardStrokeDetails.modifierFlags = [theEvent modifierFlags];

@@ -757,6 +757,8 @@ -(void)keyDown:(NSEvent*)theEvent {
  [self interpretKeyEvents: down];
  self.lastSeenKeyBoardStrokeDetails = NULL;
  }
+
+ //[aKeyBoardStrokeDetails release];
 }

In the last location I had to comment my attempt on doing a manual release
because it introduces a crash.

OSWindow can be tested in a fresh Pharo image by doing the following in a
workspace:

FFIExternalStructure allSubclassesDo: #rebuildFieldAccessors.
> SDL_Event initialize.
> SDL2 findSDL2.
> OSWindowWorldMorph new open.


I have attached the full diff with my bug fix attempt. I hope that someone
that is more familiar with the OS X platform code and Objective-C can
remove these autoreleases without introducing crashes.

When executed in a debugger, the crash is detected in SDL2 Cocoa_PumpEvents:

void
>
> Cocoa_PumpEvents(_THIS)
>
> { @autoreleasepool
>
> {
>
>     /* Update activity every 30 seconds to prevent screensaver */
>
>     SDL_VideoData *data = (SDL_VideoData *)_this->driverdata;
>
>     if (_this->suspend_screensaver && !data->screensaver_use_iopm) {
>
>         Uint32 now = SDL_GetTicks();
>
>         if (!data->screensaver_activity ||
>
>             SDL_TICKS_PASSED(now, data->screensaver_activity + 30000)) {
>
>             UpdateSystemActivity(UsrActivity);
>
>             data->screensaver_activity = now;
>
>         }
>
>     }
>
>
>>     for ( ; ; ) {
>
>         NSEvent *event = [NSApp nextEventMatchingMask:NSAnyEventMask
>> untilDate:[NSDate distantPast] inMode:NSDefaultRunLoopMode dequeue:YES ];
>
>         if ( event == nil ) {
>
>             break;
>
>         }
>
>
>>         if (!s_bShouldHandleEventsInSDLApplication) {
>
>             Cocoa_DispatchEvent(event);
>
>         }
>
>
>>         // Pass events down to SDLApplication to be handled in sendEvent:
>
>         [NSApp sendEvent:event];
>
>     }
>
> }}
>
>
>
For tracking these actual calls to #autorelease, I had to set a breakpoint
on the #autorelease Objective-C selector, and log the stacktrace to find
where it is called in our code.

Best regards,
Ronie
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.pharo.org/pipermail/pharo-dev_lists.pharo.org/attachments/20171101/52116310/attachment-0002.html>


More information about the Pharo-dev mailing list