1 files changed, 58 insertions, 0 deletions
diff --git a/osdep/semaphore.h b/osdep/semaphore.h
new file mode 100644
index 0000000000..832f059df4
--- /dev/null
+++ b/osdep/semaphore.h
@@ -0,0 +1,58 @@
+#ifndef MP_SEMAPHORE_H_
+#define MP_SEMAPHORE_H_
+
+#include <semaphore.h>
+
+// OSX provides non-working empty stubs, so we emulate them.
+// This should be AS-safe, but cancellation issues were ignored.
+// sem_getvalue() is not provided.
+// sem_post() won't always correctly return an error on overflow.
+// Process-shared semantics are not provided.
+
+#ifdef __APPLE__
+
+#define MP_SEMAPHORE_EMULATION
+
+#include <pthread.h>
+
+#define MP_SEM_VALUE_MAX 4096
+
+typedef struct {
+    int wakeup_pipe[2];
+    pthread_mutex_t lock;
+    // protected by lock
+    unsigned int count;
+} mp_sem_t;
+
+int mp_sem_init(mp_sem_t *sem, int pshared, unsigned int value);
+int mp_sem_wait(mp_sem_t *sem);
+int mp_sem_trywait(mp_sem_t *sem);
+int mp_sem_timedwait(mp_sem_t *sem, const struct timespec *abs_timeout);
+int mp_sem_post(mp_sem_t *sem);
+int mp_sem_destroy(mp_sem_t *sem);
+
+#undef sem_init
+#undef sem_wait
+#undef sem_trywait
+#undef sem_timedwait
+#undef sem_post
+#undef sem_getvalue
+#undef sem_destroy
+#undef sem_getvalue
+#undef sem_t
+#undef SEM_VALUE_MAX
+
+#define sem_init        mp_sem_init
+#define sem_wait        mp_sem_wait
+#define sem_trywait     mp_sem_trywait
+#define sem_timedwait   mp_sem_timedwait
+#define sem_post        mp_sem_post
+#define sem_destroy     mp_sem_destroy
+#define sem_t           mp_sem_t
+#define SEM_VALUE_MAX   MP_SEM_VALUE_MAX
+
+#define sem_getvalue    (void)
+
+#endif
+
+#endif