usock: add helper waiting for socket to be ready

[project/libubox.git] / usock.c

diff --git a/usock.c b/usock.c
index 64eab9e..db1ddce 100644 (file)
--- 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;
+}