poll_win: restore fd_sets before each select() retry

select() strips not-ready descriptors from the fd_sets, so a timed-out
pass leaves them empty and the next pass calls select() with three empty
sets, which Windows rejects with WSAEINVAL. Keep a pristine copy and
restore it before each retry so an idle socket waits out the timeout.

1 files changed, 16 insertions, 0 deletions

diff --git a/apps/openssl/compat/poll_win.c b/apps/openssl/compat/poll_win.c
index c518962..0d15522 100644
--- a/apps/openssl/compat/poll_win.c
+++ b/apps/openssl/compat/poll_win.c
@@ -166,6 +166,7 @@ poll(struct pollfd *pfds, nfds_t nfds, int timeout_ms)
          * select machinery
          */
         fd_set rfds, wfds, efds;
+        fd_set rfds_in, wfds_in, efds_in;
         int rc;
         int num_sockets;
 
@@ -250,12 +251,27 @@ poll(struct pollfd *pfds, nfds_t nfds, int timeout_ms)
 
         looptime_ms = (timeout_ms > 100 || timeout_ms == -1) ? 100 : timeout_ms;
 
+        /*
+         * select() clears every descriptor that is not ready from the
+         * fd_sets, so a pass that times out leaves them empty. Keep a
+         * pristine copy and restore it before each select(), otherwise the
+         * next pass hands select() three empty sets and Windows fails it with
+         * WSAEINVAL instead of waiting out the remaining timeout.
+         */
+        rfds_in = rfds;
+        wfds_in = wfds;
+        efds_in = efds;
+
         do {
                 TIMEVAL tv;
                 tv.tv_sec = 0;
                 tv.tv_usec = looptime_ms * 1000;
                 int handle_signaled = 0;
 
+                rfds = rfds_in;
+                wfds = wfds_in;
+                efds = efds_in;
+
                 /*
                  * Check if any file handles have signaled
                  */