Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 492490a51a6c23ab76a9556c49c56ea445903b43
https://github.com/WebKit/WebKit/commit/492490a51a6c23ab76a9556c49c56ea445903b43
Author: Wenson Hsieh <[email protected]>
Date: 2022-12-14 (Wed, 14 Dec 2022)
Changed paths:
M Source/WebKit/UIProcess/mac/WebViewImpl.mm
M Tools/TestWebKitAPI/Tests/WebKitCocoa/PrepareForMoveToWindow.mm
Log Message:
-----------
Mitigate crashes when removing KVO from NSWindow in
-[WKWindowVisibilityObserver stopObserving:]
https://bugs.webkit.org/show_bug.cgi?id=249103
rdar://102360839
Reviewed by Patrick Angle.
After the fix in 256334@main, Music sometimes crashes when destroying
`NSWindow`, when
`WKWindowVisibilityObserver` attempts to remove key-value observers for
"contentLayoutRect" and
"titlebarAppearsTransparent" from the window that were not added in the first
place.
While I haven't been able to reproduce the crash locally or come up with a test
case that (exactly)
replicates the crashing stack during `NSWindow` destruction, it should be
possible to avoid it
altogether by guarding KVO registration and unregistration by using an
associated object on the
`NSWindow` to indicate when `WKWindowVisibilityObserver` has key-value
observers to the window. If
this flag is not set, then we avoid attempting to unregister KVO; similarly, if
this flag is set,
then we avoid attempting to re-register KVO.
Test: WKWebView.PrepareForMoveToWindowShouldNotCrashWhenRemovingWindowObservers
* Source/WebKit/UIProcess/mac/WebViewImpl.mm:
(-[WKWindowVisibilityObserver startObserving:]):
(-[WKWindowVisibilityObserver stopObserving:]):
Use the `_impl` pointer as the context key.
(WebKit::WebViewImpl::viewWillMoveToWindowImpl):
(WebKit::WebViewImpl::viewWillMoveToWindow):
Move a debug assertion from `viewWillMoveToWindowImpl` into the call site in
`viewWillMoveToWindow`,
such that the assertion doesn't fire due to the SPI being misused by a client
(which the new test
case exercises).
* Tools/TestWebKitAPI/Tests/WebKitCocoa/PrepareForMoveToWindow.mm:
Add a (somewhat contrived) API test that exercises the mitigation.
Canonical link: https://commits.webkit.org/257860@main
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