#include <time.h>
#include <unistd.h>

extern void IntoGoAndBack();

int CheckBlocked() {
	sigset_t mask;
	sigprocmask(SIG_BLOCK, NULL, &mask);
	return sigismember(&mask, SIGIO);
}

static void* sigthreadfunc(void* unused) {
	sigset_t mask;
	sigemptyset(&mask);
	sigaddset(&mask, SIGIO);
	sigprocmask(SIG_BLOCK, &mask, NULL);
	IntoGoAndBack();
	return NULL;
}

int RunSigThread() {
	int tries;

Austin Clements <******@****.***> 1683224724 -0400

	// Finally, create the thread. It starts at mstart_stub, which does some low-level
	// setup and then calls mstart.
	var oset sigset
	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
	err := retryOnEAGAIN(func() int32 {
		return pthread_create(&attr, abi.FuncPCABI0(mstart_stub), unsafe.Pointer(mp))
	})
	sigprocmask(_SIG_SETMASK, &oset, nil)
	if err != 0 {
		writeErrStr(failthreadcreate)
		exit(1)
	}

	pthread_attr_destroy(&attr)

	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
	var ret int32
	for tries := 0; tries < 20; tries++ {
		// pthread_create can fail with EAGAIN for no reasons
		// but it will be ok if it retries.
		ret = pthread_create(&tid, &attr, fn, nil)
		if ret != _EAGAIN {
			break
		}
		usleep(uint32(tries+1) * 1000) // Milliseconds.
	}
	sigprocmask(_SIG_SETMASK, &oset, nil)
	if ret != 0 {

		tf_stack: uintptr(stk) - goarch.PtrSize,
	}

	var oset sigset
	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
	ret := retryOnEAGAIN(func() int32 {
		errno := tfork(&param, unsafe.Sizeof(param), mp, mp.g0, abi.FuncPCABI0(mstart))
		// tfork returns negative errno
		return -errno
	})
	sigprocmask(_SIG_SETMASK, &oset, nil)

	if ret != 0 {

//go:noescape
func lwp_create(param *lwpparams) int32

//go:noescape
func sigaltstack(new, old *stackt)

//go:noescape
func sigaction(sig uint32, new, old *sigactiont)

//go:noescape
func sigprocmask(how int32, new, old *sigset)

//go:noescape
func setitimer(mode int32, new, old *itimerval)

//go:noescape
func sysctl(mib *uint32, miblen uint32, out *byte, size *uintptr, dst *byte, ndst uintptr) int32

	callWithVarargs("dummy arg", 3.1415);

	if (sigemptyset(&mask) < 0) {
		die("sigemptyset");
	}
	if (sigaddset(&mask, SIGSEGV) < 0) {
		die("sigaddset");
	}
	i = sigprocmask(SIG_UNBLOCK, &mask, NULL);
	if (i != 0) {
		fprintf(stderr, "sigprocmask: %s\n", strerror(i));
		exit(EXIT_FAILURE);
	}

	// Don't try this at home.
	longjmp(jmp, signo);

	// We should never get here.
	abort();
}

	sigset_t mask;
	int i;

	if (sigemptyset(&mask) < 0) {
		die("sigemptyset");
	}
	if (sigaddset(&mask, SIGSEGV) < 0) {
		die("sigaddset");
	}
	i = sigprocmask(SIG_UNBLOCK, &mask, NULL);
	if (i != 0) {
		fprintf(stderr, "sigprocmask: %s\n", strerror(i));
		exit(EXIT_FAILURE);
	}

	// Don't try this at home.
	longjmp(jmp, signo);

	// We should never get here.
	abort();
}

var Closeonexec = closeonexec

func sigismember(mask *sigset, i int) bool {
	clear := *mask
	sigdelset(&clear, i)
	return clear != *mask
}

func Sigisblocked(i int) bool {
	var sigmask sigset
	sigprocmask(_SIG_SETMASK, nil, &sigmask)
	return sigismember(&sigmask, i)
}

type M = m

var waitForSigusr1 struct {
	rdpipe int32
	wrpipe int32
	mID    int64
}

// the stack is safe to reclaim.
//
//go:noescape
func exitThread(wait *atomic.Uint32)

//go:noescape
func obsdsigprocmask(how int32, new sigset) sigset

//go:nosplit
//go:nowritebarrierrec
func sigprocmask(how int32, new, old *sigset) {
	n := sigset(0)
	if new != nil {
		n = *new
	}
	r := obsdsigprocmask(how, n)
	if old != nil {
		*old = r
	}
}

func pipe2(flags int32) (r, w int32, errno int32)