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Disable SA_RESTART for some signals on macOS

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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.
This commit is contained in:
Matthew Bauer 2022-09-03 00:27:16 -05:00
parent 0c7f213c87
commit 102434e4cb
1 changed files with 10 additions and 3 deletions
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13
src/libmain/shared.cc
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@ -194,9 +194,16 @@ void initNix()
/* HACK: on darwin, we need can’t use sigprocmask with SIGWINCH. /* HACK: on darwin, we need can’t use sigprocmask with SIGWINCH.
* Instead, add a dummy sigaction handler, and signalHandlerThread * Instead, add a dummy sigaction handler, and signalHandlerThread
* can handle the rest. */ * can handle the rest. */
struct sigaction sa; act.sa_handler = sigHandler;
sa.sa_handler = sigHandler; if (sigaction(SIGWINCH, &act, 0)) throw SysError("handling SIGWINCH");
if (sigaction(SIGWINCH, &sa, 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 #endif
/* Register a SIGSEGV handler to detect stack overflows. */ /* Register a SIGSEGV handler to detect stack overflows. */