Fix a bug that zmq_poll's select backend spins when timeout=-1, due to

ptimeout not properly recalculated after first pass.
Signed-off-by: Chia-liang Kao <clkao@clkao.org>

AUTHORS

@@ -8,6 +8,7 @@ Bernd Prager <bernd@prager.ws>
 Bernd Melchers <melchers@ZEDAT.FU-Berlin.DE>
 Brian Buchanan <bwb@holo.org>
 Burak Arslan <burak-github@arskom.com.tr>
+Chia-liang Kao <clkao@clkao.org>
 Chris Wong <chris@chriswongstudio.com>
 Christian Gudrian <christian.gudrian@fluidon.com>
 Conrad D. Steenberg <conrad.steenberg@caltech.edu>

src/zmq.cpp

@@ -545,24 +545,24 @@ int zmq_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
     int nevents = 0;
     fd_set inset, outset, errset;
 
-    //  Compute the timeout for the subsequent poll.
-    timeval timeout;
-    timeval *ptimeout;
-    if (first_pass) {
-        timeout.tv_sec = 0;
-        timeout.tv_usec = 0;
-        ptimeout = &timeout;
-    }
-    else if (timeout_ < 0)
-        ptimeout = NULL;
-    else {
-        timeout.tv_sec = (long) ((end - now) / 1000);
-        timeout.tv_usec = (long) ((end - now) % 1000 * 1000);
-        ptimeout = &timeout;
-    }
-
     while (true) {
 
+        //  Compute the timeout for the subsequent poll.
+        timeval timeout;
+        timeval *ptimeout;
+        if (first_pass) {
+            timeout.tv_sec = 0;
+            timeout.tv_usec = 0;
+            ptimeout = &timeout;
+        }
+        else if (timeout_ < 0)
+            ptimeout = NULL;
+        else {
+            timeout.tv_sec = (long) ((end - now) / 1000);
+            timeout.tv_usec = (long) ((end - now) % 1000 * 1000);
+            ptimeout = &timeout;
+        }
+
         //  Wait for events. Ignore interrupts if there's infinite timeout.
         while (true) {
             memcpy (&inset, &pollset_in, sizeof (fd_set));