[webkit-changes] [WebKit/WebKit] b2788c: [macOS] Occasional crash when invoking the complet...

[Wenson Hsieh]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: b2788c65e9c925f0484298df163aa2b7fee81ede
      https://github.com/WebKit/WebKit/commit/b2788c65e9c925f0484298df163aa2b7fee81ede
  Author: Wenson Hsieh <wenson_hsieh at apple.com>
  Date:   2023-12-07 (Thu, 07 Dec 2023)

  Changed paths:
    M Source/WebKit/Platform/cocoa/ImageAnalysisUtilities.mm

  Log Message:
  -----------
  [macOS] Occasional crash when invoking the completion handler in WebKit::requestPayloadForQRCode
https://bugs.webkit.org/show_bug.cgi?id=266000
rdar://117083360

Reviewed by Aditya Keerthi.

This is a speculative fix for rdar://117083360, where (on certain version of macOS), Safari crashes
underneath this QR code detection codepath, due to the completion handler being invoked more than
once. While I wasn't able to reproduce the crash locally, forcing the completion handler to be
called twice was sufficient to replicate a crash under the same stack.

It's possible that Vision has a bug wherein `-[VNImageRequestHandler performRequests:error:]` yields
a non-null `NSError` for the error outparam, yet the `VNDetectBarcodesRequest`'s completion handler
is still invoked (presumably, also with an `NSError`). rdar://119319173 tracks further investigation
here.

* Source/WebKit/Platform/cocoa/ImageAnalysisUtilities.mm:
(WebKit::requestPayloadForQRCode):

Canonical link: https://commits.webkit.org/271695@main