commit aed4e5d82c7082635a09bcc999760489e573b406
author Raphael Kubo da Costa <kubo@igalia.com> Tue May 13 22:09:30 2025
committer Crashpad LUCI CQ <crashpad-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed May 14 18:35:44 2025
tree 643a19fc20c644eef9b43260992b82a7f557cce9
parent 73eb9005339f63522224b25031e61869c8703a91

client: Add a tvOS version of CrashHandler, add tvOS support to tests

tvOS as a platform is very similar to iOS, but one of significant
difference is that Mach message passing (including mach_msg()) is not
allowed. This means that it is completely impossible to handle Mach
exceptions on tvOS.

Consequently, we need a CrashHandler implementation that is entirely
based on the POSIX signals API. Breakpad has had such an implementation
for years [1], so some of the code was based on Breakpad's.

[1] https://source.chromium.org/chromium/chromium/src/+/main:third_party/breakpad/breakpad/src/client/ios/exception_handler_no_mach.cc

In general terms:
- GN: Most of the code in util/mach/ is not built on tvOS, and the mig
  calls are skipped altogether. The only allowed files at the moment are
  util/mach/mach_extensions.{cc,h}, which contain some constants and
  functions that are useful and allowed outside the Mach exception
  context.
- CrashHandler: the code was split into multiple files for clarity. The
  user-visible API (i.e. the CrashpadClient calls) remains in
  crashpad_client_ios.cc, while the internal CrashHandler class was
  split into multiple files and classes.
  Namely, the common code handling NSExceptions and communication with
  InProcessHandler is part of CrashHandlerBase and the iOS and
  tvOS-specific implementations are in crash_handler_{ios,tvos}.{cc,h}.
  The tvOS CrashHandler code is basically a simplified version of the
  iOS one: we watch a lot of signals in Initialize() and call
  DumpExceptionFromSignal() when we get one (after which we call
  Signals::RestoreHandlerAndReraiseSignalOnReturn() and exit).
- Tests:
  - Tests that checked for specific Mach exceptions needed a new
    tvOS-specific code path. We need to check for specific signal values
    where possible instead.
  - testRecursion() had to be skipped altogether. We cannot monitor Mach
    exceptions, and sigaltstack() is also forbidden on tvOS. This means
    there is no reliable way of monitoring a stack overflow as explained
    in the comment in code.

Bug: 405140658, 351887716
Change-Id: I2f13a5788d8e5ac085b49716c43bb375d017ad35
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/6421038
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Raphael Kubo da Costa <kubo@igalia.com>