From ad9b5a387df86c3fa1bdf733b913f5bf4b751f21 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <zajec5@gmail.com>
Date: Thu, 15 Jan 2015 12:59:18 +0100
Subject: [PATCH] usock: add helper waiting for socket to be ready
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Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
---
 usock.c | 27 +++++++++++++++++++++++++++
 usock.h | 11 +++++++++++
 2 files changed, 38 insertions(+)

diff --git a/usock.c b/usock.c
index 64eab9e..db1ddce 100644
--- a/usock.c
+++ b/usock.c
@@ -20,6 +20,7 @@
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <netdb.h>
+#include <poll.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <fcntl.h>
@@ -130,3 +131,29 @@ int usock(int type, const char *host, const char *service) {
 	usock_set_flags(sock, type);
 	return sock;
 }
+
+int usock_wait_ready(int fd, int msecs) {
+	struct pollfd fds[1];
+	int res;
+
+	fds[0].fd = fd;
+	fds[0].events = POLLOUT;
+
+	res = poll(fds, 1, msecs);
+	if (res < 0) {
+		return errno;
+	} else if (res == 0) {
+		return -ETIMEDOUT;
+	} else {
+		int err = 0;
+		socklen_t optlen = sizeof(err);
+
+		res = getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &optlen);
+		if (res)
+			return errno;
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
diff --git a/usock.h b/usock.h
index 8345581..b0b952b 100644
--- a/usock.h
+++ b/usock.h
@@ -33,4 +33,15 @@
 const char *usock_port(int port);
 int usock(int type, const char *host, const char *service);
 
+/**
+ * Wait for a socket to become ready.
+ *
+ * This may be useful for users of USOCK_NONBLOCK to wait (with a timeout)
+ * for a socket.
+ *
+ * @param fd file descriptor of socket
+ * @param msecs timeout in microseconds
+ */
+int usock_wait_ready(int fd, int msecs);
+
 #endif /* USOCK_H_ */