NSPasteboard pasteboardWithName leak when validating toolbar item

Question

R4N OP

Created Apr ’22

Replies 0

Boosts 0

Participants 1

Goal

Use NSPasteboard's canReadObjectForClasses:options: within a custom toolbar item's - (void)validate to determine the toolbar's enabled state.

Issue

When using NSPasteboard pasteboardWithName and then calling canReadObjectForClasses:options: within the toolbar item's - (void)validate method it causes the Leak Profiler to detect leaks.

Stack Trace of detected leak

   0 libsystem_malloc.dylib _malloc_zone_calloc
   1 Foundation -[NSConcreteMapTable initWithKeyOptions:valueOptions:capacity:]
   2 AppKit -[_NSPasteboardTypeCache init]
   3 AppKit -[NSPasteboard _updateTypeCacheIfNeeded]
   4 AppKit -[NSPasteboard _cachedTypeNameUnion]
   5 AppKit -[NSPasteboard(NSTypeConversion) _conformingTypes]
   6 AppKit -[NSPasteboard canReadObjectForClasses:options:]
   7 testingPasteboardLeak -[TestToolbarItem validate] ~/Documents/Code/tests/testingPasteboardLeak/testingPasteboardLeak/TestToolbarItem.m:14
   8 AppKit -[NSToolbarItemViewer configureForLayoutInDisplayMode:andSizeMode:inToolbarView:]
   9 AppKit -[NSToolbarView _layoutDirtyItemViewersAndTileToolbar]
  10 AppKit -[NSToolbarView _syncItemSetAndUpdateItemViewersWithSEL:setNeedsModeConfiguration:sizeToFit:setNeedsDisplay:updateKeyLoop:]
  11 AppKit -[NSToolbarView _noteToolbarLayoutChanged]
  12 AppKit -[NSView _setWindow:]
  13 AppKit -[NSView addSubview:]
  14 AppKit -[NSThemeFrame addTitlebarSubview:]
  15 AppKit -[NSThemeFrame _showHideToolbar:resizeWindow:animate:]
  16 AppKit -[NSWindow _showToolbar:animate:]
  17 AppKit -[NSToolbar _show:animate:]
  18 CoreFoundation -[NSSet makeObjectsPerformSelector:]
  19 AppKit -[NSIBObjectData nibInstantiateWithOwner:options:topLevelObjects:]
  20 AppKit -[NSNib _instantiateNibWithExternalNameTable:options:]
  21 AppKit -[NSNib _instantiateWithOwner:options:topLevelObjects:]
  22 AppKit -[NSStoryboard _instantiateControllerWithIdentifier:creator:storyboardSegueTemplate:sender:]
  23 AppKit NSApplicationMain
  24 libdyld.dylib start

Example Code

Custom Toolbar item's validate method:

- (void)validate {
    NSPasteboard *myPasteboard = [NSPasteboard pasteboardWithName:@"TestPasteboardName"];
    BOOL isValid = [myPasteboard canReadObjectForClasses:@[[NSString class], [NSURL class]] options:nil];
}

WindowController which is a delegate to the toolbar:

- (NSArray *)toolbarDefaultItemIdentifiers:(NSToolbar *)aToolbar {
    return @[@"test"];
}

- (NSArray *)toolbarAllowedItemIdentifiers:(NSToolbar *)aToolbar {
    return @[@"test"];
}

- (nullable NSToolbarItem *)toolbar:(NSToolbar *)toolbar itemForItemIdentifier:(NSToolbarItemIdentifier)itemIdentifier willBeInsertedIntoToolbar:(BOOL)flag {
    TestToolbarItem *item = [[TestToolbarItem alloc] initWithItemIdentifier:itemIdentifier];
    [item setTitle:@"TestToolbar"];
    return item;
}

What I've tried so far

Use NSPasteboard releaseGlobally when closing the window -- leak still present.
Wrap the pasteboard check in @autoreleasepool -- leak still present.
Using releaseGlobally directly after the pasteboard check gets rid of the leak, but obviously also clears out the pasteboard.

So is there a way to use a private pasteboard's canReadObjectForClasses:options: within a custom toolbar item's validate method without causing a leak?

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