Add a "fork" of musl as //fusl.

fusl/src/time/timer_create.c

Index: fusl/src/time/timer_create.c
diff --git a/fusl/src/time/timer_create.c b/fusl/src/time/timer_create.c
new file mode 100644
index 0000000000000000000000000000000000000000..b54a524ce85bb2e3ec97987bb3b017dc958d96f7
--- /dev/null
+++ b/fusl/src/time/timer_create.c
@@ -0,0 +1,141 @@
+#include <time.h>
+#include <setjmp.h>
+#include "pthread_impl.h"
+
+struct ksigevent {
+	union sigval sigev_value;
+	int sigev_signo;
+	int sigev_notify;
+	int sigev_tid;
+};
+
+struct start_args {
+	pthread_barrier_t b;
+	struct sigevent *sev;
+};
+
+static void dummy_1(pthread_t self)
+{
+}
+weak_alias(dummy_1, __pthread_tsd_run_dtors);
+
+void __reset_tls();
+
+static void cleanup_fromsig(void *p)
+{
+	pthread_t self = __pthread_self();
+	__pthread_tsd_run_dtors(self);
+	self->cancel = 0;
+	self->cancelbuf = 0;
+	self->canceldisable = 0;
+	self->cancelasync = 0;
+	self->unblock_cancel = 0;
+	__reset_tls();
+	longjmp(p, 1);
+}
+
+static void timer_handler(int sig, siginfo_t *si, void *ctx)
+{
+	pthread_t self = __pthread_self();
+	jmp_buf jb;
+	void (*notify)(union sigval) = (void (*)(union sigval))self->start;
+	union sigval val = { .sival_ptr = self->start_arg };
+
+	if (!setjmp(jb) && si->si_code == SI_TIMER) {
+		pthread_cleanup_push(cleanup_fromsig, jb);
+		notify(val);
+		pthread_cleanup_pop(1);
+	}
+}
+
+static void install_handler()
+{
+	struct sigaction sa = {
+		.sa_sigaction = timer_handler,
+		.sa_flags = SA_SIGINFO | SA_RESTART
+	};
+	__libc_sigaction(SIGTIMER, &sa, 0);
+}
+
+static void *start(void *arg)
+{
+	pthread_t self = __pthread_self();
+	struct start_args *args = arg;
+	int id;
+
+	/* Reuse no-longer-needed thread structure fields to avoid
+	 * needing the timer address in the signal handler. */
+	self->start = (void *(*)(void *))args->sev->sigev_notify_function;
+	self->start_arg = args->sev->sigev_value.sival_ptr;
+
+	pthread_barrier_wait(&args->b);
+	if ((id = self->timer_id) >= 0) {
+		__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
+			SIGTIMER_SET, 0, _NSIG/8);
+		__wait(&self->timer_id, 0, id, 1);
+		__syscall(SYS_timer_delete, id);
+	}
+	return 0;
+}
+
+int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict res)
+{
+	static pthread_once_t once = PTHREAD_ONCE_INIT;
+	pthread_t td;
+	pthread_attr_t attr;
+	int r;
+	struct start_args args;
+	struct ksigevent ksev, *ksevp=0;
+	int timerid;
+	sigset_t set;
+
+	switch (evp ? evp->sigev_notify : SIGEV_SIGNAL) {
+	case SIGEV_NONE:
+	case SIGEV_SIGNAL:
+		if (evp) {
+			ksev.sigev_value = evp->sigev_value;
+			ksev.sigev_signo = evp->sigev_signo;
+			ksev.sigev_notify = evp->sigev_notify;
+			ksev.sigev_tid = 0;
+			ksevp = &ksev;
+		}
+		if (syscall(SYS_timer_create, clk, ksevp, &timerid) < 0)
+			return -1;
+		*res = (void *)(intptr_t)timerid;
+		break;
+	case SIGEV_THREAD:
+		pthread_once(&once, install_handler);
+		if (evp->sigev_notify_attributes)
+			attr = *evp->sigev_notify_attributes;
+		else
+			pthread_attr_init(&attr);
+		pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+		pthread_barrier_init(&args.b, 0, 2);
+		args.sev = evp;
+
+		__block_app_sigs(&set);
+		r = pthread_create(&td, &attr, start, &args);
+		__restore_sigs(&set);
+		if (r) {
+			errno = r;
+			return -1;
+		}
+
+		ksev.sigev_value.sival_ptr = 0;
+		ksev.sigev_signo = SIGTIMER;
+		ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
+		ksev.sigev_tid = td->tid;
+		if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
+			timerid = -1;
+		td->timer_id = timerid;
+		pthread_barrier_wait(&args.b);
+		if (timerid < 0) return -1;
+		*res = (void *)(INTPTR_MIN | (uintptr_t)td>>1);
+		break;
+	default:
+		errno = EINVAL;
+		return -1;
+	}
+
+	return 0;
+}