From 102434e4cbb8ed1b4075f99fb999f092fa068d5b Mon Sep 17 00:00:00 2001 From: Matthew Bauer Date: Sat, 3 Sep 2022 00:27:16 -0500 Subject: [PATCH] Disable SA_RESTART for some signals on macOS MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Disables the SA_RESTART behavior on macOS which causes: > Restarting of pending calls is requested by setting the SA_RESTART bit > in sa_flags. The affected system calls include read(2), write(2), > sendto(2), recvfrom(2), sendmsg(2) and recvmsg(2) on a communications > channel or a slow device (such as a terminal, but not a regular file) > and during a wait(2) or ioctl(2). From: https://man.openbsd.org/sigaction#SA_RESTART This being set on macOS caused a bug where read() calls to the daemon socket were blocking after a SIGINT was received. As a result, checkInterrupt was never reached even though the signal was received by the signal handler thread. On Linux, SA_RESTART is disabled by default. This probably effects other BSDs but I don’t have the ability to test it there right now. --- src/libmain/shared.cc | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc index 31454e49d..0ee3fe772 100644 --- a/src/libmain/shared.cc +++ b/src/libmain/shared.cc @@ -194,9 +194,16 @@ void initNix() /* HACK: on darwin, we need can’t use sigprocmask with SIGWINCH. * Instead, add a dummy sigaction handler, and signalHandlerThread * can handle the rest. */ - struct sigaction sa; - sa.sa_handler = sigHandler; - if (sigaction(SIGWINCH, &sa, 0)) throw SysError("handling SIGWINCH"); + act.sa_handler = sigHandler; + if (sigaction(SIGWINCH, &act, 0)) throw SysError("handling SIGWINCH"); + + // Disable SA_RESTART for interrupts, so that system calls on this thread + // error with EINTR like they do on Linux, and we don’t hang forever. + act.sa_handler = SIG_DFL; + if (sigaction(SIGINT, &act, 0)) throw SysError("handling SIGINT"); + if (sigaction(SIGTERM, &act, 0)) throw SysError("handling SIGTERM"); + if (sigaction(SIGHUP, &act, 0)) throw SysError("handling SIGHUP"); + if (sigaction(SIGPIPE, &act, 0)) throw SysError("handling SIGPIPE"); #endif /* Register a SIGSEGV handler to detect stack overflows. */