🤖 Gemini Suggested Commit Message

starboard: Use SIGUSR2 in KillSendsSignalToSelf

The KillSendsSignalToSelf test currently fails on Android because
SIGUSR1 is intercepted by the Android runtime and never reaches the
handler installed by the test.

Switch to SIGUSR2 to ensure the signal is correctly delivered and
processed during the test.

Bug: 532068409

💡 Pro Tips for a Better Commit Message:

1. Influence the Result: Want to change the output? You can write custom prompts or instructions directly in the Pull Request description. The model uses that text to generate the message.
2. Re-run the Generator: Post a comment with: /generate-commit-message

Is the behavior of SIGUSR1 documented anywhere by AOSP? I was able to find https://android.googlesource.com/platform/bionic/+/master/tests/signal_test.cpp#398 which leads me to believe it just blocks SIGKILL and SIGSTOP, in which case can we try unblocking them instead of switching to SIGUSR2? Ex:

@sacuff sorry, my change was poorly documented

I did the change based on ART's SignalCatcher that sets up handlers for SIGUSR1: https://android.googlesource.com/platform/art/+/refs/heads/main/runtime/signal_catcher.cc#207

and the runtime errors that show that it's being intercepted by it:

07-27 15:43:10.074 30939 30973 I starboard: [ RUN      ] PosixSignalTest.KillSendsSignalToSelf
07-27 15:43:10.074 30939 30950 I dev.cobalt.coa: Thread[5,tid=30950,WaitingInMainSignalCatcherLoop,Thread*=0xf1052800,peer=0x13780110,"Signal Catcher"]: reacting to signal 10

posix_signal_test already tries to unblock SIGUSR1, so I tried adding SIGKILL and SIGSTOP, but the signal is still being intercepted by the ART's signal catcher.

I think one possible solution is to do something similat to the fix of #11340 and make the signal thread-directed in a posix_emu kill() wrapper, so it ART won't have the chance to intercept it, wdty? AFAIU it's a very similar issue

@jellefoks I see SIGUSR1 (and 2) are used for lifecycle stuff. Do you have an opinion on how AOSP should handle the interception here?

I created this as a proposal: #11562