gh-128627: Fix iPad detection in wasm-gc #135388

ryanking13 · 2025-06-11T13:24:59Z

As of iOS / iPadOS 18.3.1, enabling wasm-gc is making the interpreter fail to load.

This issue was handled by @ambv in #130418, but that fix had an issue with not detecting the iPad correctly.
In iPad + Safari, iPad behaves like a Mac and checking iPad string in navigator.platform fails to detect iPad.

Confirmed on device + downstream PR (pyodide/pyodide#5695)

cc: @hoodmane @WebReflection

Issue: Emscripten: Use wasm-gc for call trampolines instead of JS type reflection #128627

bedevere-app · 2025-06-11T13:25:04Z

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hoodmane · 2025-06-11T16:07:55Z

While we're at it maybe let's add links to the relevant webkit issue and the fix:
https://bugs.webkit.org/show_bug.cgi?id=293113
WebKit/WebKit#46379

hoodmane · 2025-06-11T16:08:37Z

Otherwise looks good to me. Thanks @ryanking13!

hoodmane · 2025-06-11T16:10:50Z

Maybe we should also add a comment saying this code is only needed to make jspi work and since jspi is not yet supported on Safari it would be okay to turn it off for desktop Safari as well if we need to.

hoodmane

Thanks!

WebReflection · 2025-06-11T20:05:10Z

Python/emscripten_trampoline.c

+        // Starting with iPadOS 13, iPads might send a platform string that looks like a desktop Mac.
+        // To differentiate, we check if the platform is 'MacIntel' (common for Macs and newer iPads)
+        // AND if the device has multi-touch capabilities (navigator.maxTouchPoints > 1)
+        (navigator.platform === 'MacIntel' && typeof navigator.maxTouchPoints !== 'undefined' && navigator.maxTouchPoints > 1)


duplicated same-comment here: pyodide/pyodide#5695 (review)

freakboy3742

Added in a reference to the radar and CPython issues, but otherwise, LGTM.

Python/emscripten_trampoline.c

miss-islington-app · 2025-06-12T04:04:16Z

Thanks @ryanking13 for the PR, and @freakboy3742 for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

On some iPad versions, Safari reports as "macOS". Modifies the GC trampoline detection to add a feature-based check to detect this case. (cherry picked from commit d447129) Co-authored-by: Gyeongjae Choi <def6488@gmail.com>

bedevere-app · 2025-06-12T04:04:26Z

GH-135419 is a backport of this pull request to the 3.14 branch.

On some iPad versions, Safari reports as "macOS". Modifies the GC trampoline detection to add a feature-based check to detect this case. (cherry picked from commit d447129) Co-authored-by: Gyeongjae Choi <def6488@gmail.com>

bedevere-bot · 2025-06-12T05:55:35Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 RHEL8 Refleaks 3.14 (tier-1) has failed when building commit e76dbc8.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1795/builds/170) and take a look at the build logs.
Check if the failure is related to this commit (e76dbc8) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1795/builds/170

Failed tests:

test.test_multiprocessing_fork.test_processes

Failed subtests:

test_interrupt - test.test_multiprocessing_fork.test_processes.WithProcessesTestProcess.test_interrupt

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 588, in test_interrupt
    exitcode = self._kill_process(multiprocessing.Process.interrupt)
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 570, in _kill_process
    self.assertEqual(join(), None)
                     ~~~~^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 250, in __call__
    return self.func(*args, **kwds)
           ~~~~~~~~~^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/process.py", line 156, in join
    res = self._popen.wait(timeout)
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
           ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)
               ~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 566, in handler
    raise RuntimeError('join took too long: %s' % p)
RuntimeError: join took too long: <Process name='Process-931' pid=3787289 parent=3781804 started daemon>


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 588, in test_interrupt
    exitcode = self._kill_process(multiprocessing.Process.interrupt)
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 570, in _kill_process
    self.assertEqual(join(), None)
                     ~~~~^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 250, in __call__
    return self.func(*args, **kwds)
           ~~~~~~~~~^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/process.py", line 156, in join
    res = self._popen.wait(timeout)
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
           ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)
               ~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 566, in handler
    raise RuntimeError('join took too long: %s' % p)
RuntimeError: join took too long: <Process name='Process-3' pid=3894134 parent=3894130 started daemon>


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/process.py", line 320, in _bootstrap
    self.run()
    ~~~~~~~~^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 518, in _sleep_some_event
    time.sleep(100)
    ~~~~~~~~~~^^^^^
KeyboardInterrupt
k

freakboy3742 · 2025-06-12T07:27:59Z

Buildbot failure is a false positive.

Fix iPad detection in wasm-gc

486bd2b

bedevere-app bot added the awaiting review label Jun 11, 2025

bedevere-app bot mentioned this pull request Jun 11, 2025

Emscripten: Use wasm-gc for call trampolines instead of JS type reflection #128627

Closed

ryanking13 mentioned this pull request Jun 11, 2025

Fix iPad detection in wasm-gc pyodide/pyodide#5695

Merged

1 task

hoodmane added the skip news label Jun 11, 2025

hoodmane requested a review from freakboy3742 June 11, 2025 16:08

hoodmane approved these changes Jun 11, 2025

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bedevere-app bot added awaiting core review and removed awaiting review labels Jun 11, 2025

WebReflection reviewed Jun 11, 2025

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freakboy3742 added the needs backport to 3.14 bugs and security fixes label Jun 12, 2025

freakboy3742 approved these changes Jun 12, 2025

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bedevere-app bot added awaiting merge and removed awaiting core review labels Jun 12, 2025

Add a comment about why this special case is needed.

35b6c64

freakboy3742 enabled auto-merge (squash) June 12, 2025 03:38

freakboy3742 merged commit d447129 into python:main Jun 12, 2025
38 checks passed

bedevere-app bot removed the awaiting merge label Jun 12, 2025

bedevere-app bot removed the needs backport to 3.14 bugs and security fixes label Jun 12, 2025

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gh-128627: Fix iPad detection in wasm-gc #135388

gh-128627: Fix iPad detection in wasm-gc #135388

ryanking13 commented Jun 11, 2025 •

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gh-128627: Fix iPad detection in wasm-gc #135388

gh-128627: Fix iPad detection in wasm-gc #135388

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