Segmentation fault unmarshalling exception class data member

[pepone]

This crash happens after I add a call to rb_gc for debug builds, the call is to ensure that the unmarshalling of class values isn't broken by a GC call.

* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
  * frame #0: 0x00000001002a9430 libruby.2.7.dylib`iv_index_tbl_make + 18
    frame #1: 0x00000001002a8e96 libruby.2.7.dylib`ivar_set + 233
    frame #2: 0x00000001002a77df libruby.2.7.dylib`rb_ivar_set + 52
    frame #3: 0x0000000106919d61 IceRuby.bundle`IceRuby::RF_3<unsigned long (*)(unsigned long, unsigned long, unsigned long), unsigned long, unsigned long, unsigned long>::operator(this=0x00007ffeefbfe640)() at Util.h:269:40
    frame #4: 0x0000000106919cf5 IceRuby.bundle`IceRuby::RF_3<unsigned long (*)(unsigned long, unsigned long, unsigned long), unsigned long, unsigned long, unsigned long>::call(f=140732920751680) at Util.h:272:16
    frame #5: 0x00000001001908eb libruby.2.7.dylib`rb_protect + 345
    frame #6: 0x00000001069ad388 IceRuby.bundle`IceRuby::callProtected(func=(IceRuby.bundle`IceRuby::RF_3<unsigned long (*)(unsigned long, unsigned long, unsigned long), unsigned long, unsigned long, unsigned long>::call(unsigned long) at Util.h:271), arg=140732920751680)(unsigned long), unsigned long) at Util.cpp:576:29
    frame #7: 0x000000010690f041 IceRuby.bundle`unsigned long IceRuby::callRuby<unsigned long (*)(unsigned long, unsigned long, unsigned long), unsigned long, unsigned long, unsigned long>(fun=(libruby.2.7.dylib`rb_ivar_set), t1=4311900960, t2=67411, t3=4311901600)(unsigned long, unsigned long, unsigned long), unsigned long, unsigned long, unsigned long) at Util.h:288:12
    frame #8: 0x000000010696de6c IceRuby.bundle`IceRuby::DataMember::unmarshaled(this=0x00000001006fd030, val=4311901600, target=4311900960, (null)=0x0000000000000000) at Types.cpp:874:5
    frame #9: 0x000000010697b475 IceRuby.bundle`IceRuby::ReadObjectCallback::invoke(this=0x0000000103923420, p=0x00007ffeefbfe940) at Types.cpp:2763:14
    frame #10: 0x0000000106976482 IceRuby.bundle`(anonymous namespace)::patchObject(addr=0x0000000103923420, v=0x00007ffeefbfe940) at Types.cpp:2126:9
    frame #11: 0x0000000103bf924a libIce.37.dylib`Ice::InputStream::EncapsDecoder::unmarshal(int, IceInternal::Handle<Ice::Object> const&) + 618
    frame #12: 0x0000000103bfa326 libIce.37.dylib`Ice::InputStream::EncapsDecoder10::readInstance() + 614
    frame #13: 0x0000000103bf9fc8 libIce.37.dylib`Ice::InputStream::EncapsDecoder10::readPendingValues() + 72
    frame #14: 0x0000000103bf9aef libIce.37.dylib`Ice::InputStream::EncapsDecoder10::throwException(IceUtil::Handle<Ice::UserExceptionFactory> const&) + 367
    frame #15: 0x0000000106933ccc IceRuby.bundle`IceRuby::OperationI::unmarshalException(this=0x0000000105e44a50, bytes=size=167, communicator=0x00007ffeefbfeda8) at Operation.cpp:576:12
    frame #16: 0x0000000106932ae8 IceRuby.bundle`IceRuby::OperationI::invoke(this=0x0000000105e44a50, proxy=0x00007ffeefbfef60, args=4311861640, hctx=8) at Operation.cpp:332:33
    frame #17: 0x000000010692fed1 IceRuby.bundle`::IceRuby_Operation_invoke(self=4362777960, proxy=4303569600, opArgs=4311861640, ctx=8) at Operation.cpp:126:20
    frame #18: 0x00000001002c19b7 libruby.2.7.dylib`vm_call_cfunc + 345
    frame #19: 0x00000001002af461 libruby.2.7.dylib`vm_exec_core + 8443
    frame #20: 0x00000001002be50d libruby.2.7.dylib`rb_vm_exec + 1872
    frame #21: 0x000000010018fe39 libruby.2.7.dylib`rb_ec_exec_node + 187
    frame #22: 0x000000010018fd38 libruby.2.7.dylib`ruby_run_node + 85
    frame #23: 0x0000000100003f18 ruby`main + 100
    frame #24: 0x00007fff2035c621 libdyld.dylib`start + 1
    frame #25: 0x00007fff2035c621 libdyld.dylib`start + 1

Here the crash happens when trying to set a class data member on the exception object, the problem is that the exception is not longer in the stack and so it is eligible for GC, the ExceptionReader should mark it to avoid this.