1 files changed, 117 insertions, 0 deletions
diff --git a/osdep/semaphore-mac.c b/osdep/semaphore-mac.c
new file mode 100644
index 0000000000..bfb4d571f0
--- /dev/null
+++ b/osdep/semaphore-mac.c
@@ -0,0 +1,117 @@
+/* Copyright (C) 2017 the mpv developers
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "osdep/semaphore.h"
+
+#ifdef MP_SEMAPHORE_EMULATION
+
+#include <unistd.h>
+#include <poll.h>
+#include <limits.h>
+#include <sys/time.h>
+#include <errno.h>
+
+#include <common/common.h>
+#include "io.h"
+#include "timer.h"
+
+int mp_sem_init(mp_sem_t *sem, int pshared, unsigned int value)
+{
+    if (pshared) {
+        errno = ENOSYS;
+        return -1;
+    }
+    if (value > INT_MAX) {
+        errno = EINVAL;
+        return -1;
+    }
+    if (mp_make_wakeup_pipe(sem->wakeup_pipe) < 0)
+        return -1;
+    sem->count = 0;
+    mp_mutex_init(&sem->lock);
+    return 0;
+}
+
+int mp_sem_wait(mp_sem_t *sem)
+{
+    return mp_sem_timedwait(sem, -1);
+}
+
+int mp_sem_trywait(mp_sem_t *sem)
+{
+    int r = -1;
+    mp_mutex_lock(&sem->lock);
+    if (sem->count == 0) {
+        char buf[1024];
+        ssize_t s = read(sem->wakeup_pipe[0], buf, sizeof(buf));
+        if (s > 0 && s <= INT_MAX - sem->count) // can't handle overflows correctly
+            sem->count += s;
+    }
+    if (sem->count > 0) {
+        sem->count -= 1;
+        r = 0;
+    }
+    mp_mutex_unlock(&sem->lock);
+    if (r < 0)
+        errno = EAGAIN;
+    return r;
+}
+
+int mp_sem_timedwait(mp_sem_t *sem, int64_t until)
+{
+    while (1) {
+        if (!mp_sem_trywait(sem))
+            return 0;
+
+        int timeout = 0;
+        if (until == -1) {
+            timeout = -1;
+        } else if (until >= 0) {
+            timeout = (until - mp_time_ns()) / MP_TIME_MS_TO_NS(1);
+            timeout = MPCLAMP(timeout, 0, INT_MAX);
+        } else {
+            assert(false && "Invalid mp_time value!");
+        }
+
+        struct pollfd fd = {.fd = sem->wakeup_pipe[0], .events = POLLIN};
+        int r = poll(&fd, 1, timeout);
+        if (r < 0)
+            return -1;
+        if (r == 0) {
+            errno = ETIMEDOUT;
+            return -1;
+        }
+    }
+}
+
+int mp_sem_post(mp_sem_t *sem)
+{
+    if (write(sem->wakeup_pipe[1], &(char){0}, 1) == 1)
+        return 0;
+    // Actually we can't handle overflow fully correctly, because we can't
+    // check sem->count atomically, while still being AS-safe.
+    errno = EOVERFLOW;
+    return -1;
+}
+
+int mp_sem_destroy(mp_sem_t *sem)
+{
+    close(sem->wakeup_pipe[0]);
+    close(sem->wakeup_pipe[1]);
+    mp_mutex_destroy(&sem->lock);
+    return 0;
+}
+
+#endif