On Fri, 30 Sep 2022 04:53:51 GMT, David Holmes <dhol...@openjdk.org> wrote:
>> After [JDK-8294314](https://bugs.openjdk.org/browse/JDK-8294314), we would >> have signals_posix.cpp excluded with cast-function-type warning: > > src/hotspot/os/posix/signals_posix.cpp line 1727: > >> 1725: // Set up signal handler for suspend/resume >> 1726: act.sa_flags = SA_RESTART|SA_SIGINFO; >> 1727: act.sa_handler = CAST_FROM_FN_PTR(sa_handler_t, SR_handler); > > The underlying cast in the macro seems a little odd for this situation but if > it appeases the compiler then that is fine. No, don't do this. The code is just wrong, and should be fixed. We have a struct sigaction. We've set the sa_flags member to a value that includes SA_SIGINFO. That means the 3 argument sa_sigaction handler is supposed to be invoked. We're storing the SR_handler (cast to a value matching the type of the sa_handler member of the sigaction). This is "working" purely by accident. Apparently on all POSIX platforms we support, the sa_handler and sa_sigaction occupy the same memory (being in a union, which is permitted by the spec). The signature for SR_handler should be changed from void SR_handler(int, siginfo_t*, ucontext_t*) to void SR_handler(int, siginfo_t*, void*) and adjust the code to deal with the change to the type of the 3rd parameter. Then we can just assign the sa_sigaction member to SR_handler without any casts. ------------- PR: https://git.openjdk.org/jdk/pull/10494
