+#include <poll.h>
+
+/* A setting for actions to always run (eg. zero-length reads). */
+#define POLLALWAYS (((POLLIN|POLLOUT) + 1) & ~((POLLIN|POLLOUT)))
+
+struct io_alloc {
+ void *(*alloc)(size_t size);
+ void *(*realloc)(void *ptr, size_t size);
+ void (*free)(void *ptr);
+};
+extern struct io_alloc io_alloc;