implement POSIX semaphores

[musl] / src / thread / sem_trywait.c

diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c
new file mode 100644 (file)
index 0000000..d0e928e
--- /dev/null
+++ b/src/thread/sem_trywait.c
@@ -0,0 +1,11 @@
+#include <semaphore.h>
+#include "pthread_impl.h"
+
+int sem_trywait(sem_t *sem)
+{
+       int val = a_fetch_add(sem->__val, -1);
+       if (val > 0) return 0;
+       a_inc(sem->__val);
+       errno = EAGAIN;
+       return -1;
+}