1 files changed, 83 insertions, 0 deletions
diff --git a/discover/waiter.c b/discover/waiter.c
new file mode 100644
index 0000000..21dd4a5
--- /dev/null
+++ b/discover/waiter.c
@@ -0,0 +1,83 @@
+
+#include <poll.h>
+#include <string.h>
+#include <assert.h>
+
+#include <talloc/talloc.h>
+
+#include "waiter.h"
+
+struct waiter {
+	int		fd;
+	int		events;
+	waiter_cb	callback;
+	void		*arg;
+};
+
+static struct waiter *waiters;
+static int n_waiters;
+
+struct waiter *waiter_register(int fd, int events,
+		waiter_cb callback, void *arg)
+{
+	struct waiter *waiter;
+
+	n_waiters++;
+
+	waiters = talloc_realloc(NULL, waiters, struct waiter, n_waiters);
+	waiter = &waiters[n_waiters - 1];
+
+	waiter->fd = fd;
+	waiter->events = events;
+	waiter->callback = callback;
+	waiter->arg = arg;
+
+	return 0;
+}
+
+void waiter_remove(struct waiter *waiter)
+{
+	int i;
+
+	i = waiter - waiters;
+	assert(i >= 0 && i < n_waiters);
+
+	n_waiters--;
+	memmove(&waiters[i], &waiters[i+1], n_waiters - i);
+
+	waiters = talloc_realloc(NULL, waiters, struct waiter, n_waiters);
+}
+
+int waiter_poll(void)
+{
+	static struct pollfd *pollfds;
+	static int n_pollfds;
+	int i, rc;
+
+	if (n_waiters > n_pollfds) {
+		pollfds = talloc_realloc(NULL, pollfds,
+				struct pollfd, n_waiters);
+	}
+
+	for (i = 0; i < n_waiters; i++) {
+		pollfds[i].fd = waiters[i].fd;
+		pollfds[i].events = waiters[i].events;
+		pollfds[i].revents = 0;
+	}
+
+	rc = poll(pollfds, n_waiters, -1);
+
+	if (rc <= 0)
+		return rc;
+
+	for (i = 0; i < n_waiters; i++) {
+		if (pollfds[i].revents) {
+			rc = waiters[i].callback(waiters[i].arg);
+
+			if (rc)
+				waiter_remove(&waiters[i]);
+		}
+	}
+
+	return 0;
+}