flexnbd read/write: Switch to a non-blocking connect() to allow us to time these out

src/sockutil.h

@@ -2,11 +2,9 @@
 
 #define SOCKUTIL_H
 
-#include <sys/types.h>
+#include <sys/time.h>
 #include <sys/socket.h>
-#include <sys/un.h>
-#include <arpa/inet.h>
-#include <netinet/tcp.h>
+#include <sys/select.h>
 
 /* Returns the size of the sockaddr, or 0 on error */
 size_t sockaddr_size(const struct sockaddr* sa);
@@ -25,8 +23,16 @@ int sock_set_tcp_nodelay(int fd, int optval);
 /* TODO: Set the tcp_cork option */
 // int sock_set_cork(int fd, int optval);
 
+int sock_set_nonblock(int fd, int optval);
+
 /* Attempt to bind the fd to the sockaddr, retrying common transient failures */
 int sock_try_bind(int fd, const struct sockaddr* sa);
 
+/* Try to call select(), retrying EINTR */
+int sock_try_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);
+
+/* Try to call connect(), timing out after wait seconds */
+int sock_try_connect( int fd, struct sockaddr* to, socklen_t addrlen, int wait );
+
 #endif