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

fusl/src/thread/pthread_mutex_trylock.c

Index: fusl/src/thread/pthread_mutex_trylock.c
diff --git a/fusl/src/thread/pthread_mutex_trylock.c b/fusl/src/thread/pthread_mutex_trylock.c
new file mode 100644
index 0000000000000000000000000000000000000000..0df3ce2982ff85d2161ba1e0742e75c73c023a7b
--- /dev/null
+++ b/fusl/src/thread/pthread_mutex_trylock.c
@@ -0,0 +1,58 @@
+#include "pthread_impl.h"
+
+int __pthread_mutex_trylock_owner(pthread_mutex_t *m)
+{
+	int old, own;
+	int type = m->_m_type & 15;
+	pthread_t self = __pthread_self();
+	int tid = self->tid;
+
+	old = m->_m_lock;
+	own = old & 0x7fffffff;
+	if (own == tid && (type&3) == PTHREAD_MUTEX_RECURSIVE) {
+		if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
+		m->_m_count++;
+		return 0;
+	}
+	if (own == 0x40000000) return ENOTRECOVERABLE;
+
+	if (m->_m_type & 128) {
+		if (!self->robust_list.off) {
+			self->robust_list.off = (char*)&m->_m_lock-(char *)&m->_m_next;
+			__syscall(SYS_set_robust_list, &self->robust_list, 3*sizeof(long));
+		}
+		if (m->_m_waiters) tid |= 0x80000000;
+		self->robust_list.pending = &m->_m_next;
+	}
+
+	if ((own && (!(own & 0x40000000) || !(type & 4)))
+	    || a_cas(&m->_m_lock, old, tid) != old) {
+		self->robust_list.pending = 0;
+		return EBUSY;
+	}
+
+	volatile void *next = self->robust_list.head;
+	m->_m_next = next;
+	m->_m_prev = &self->robust_list.head;
+	if (next != &self->robust_list.head) *(volatile void *volatile *)
+		((char *)next - sizeof(void *)) = &m->_m_next;
+	self->robust_list.head = &m->_m_next;
+	self->robust_list.pending = 0;
+
+	if (own) {
+		m->_m_count = 0;
+		m->_m_type |= 8;
+		return EOWNERDEAD;
+	}
+
+	return 0;
+}
+
+int __pthread_mutex_trylock(pthread_mutex_t *m)
+{
+	if ((m->_m_type&15) == PTHREAD_MUTEX_NORMAL)
+		return a_cas(&m->_m_lock, 0, EBUSY) & EBUSY;
+	return __pthread_mutex_trylock_owner(m);
+}
+
+weak_alias(__pthread_mutex_trylock, pthread_mutex_trylock);