[win32] support win32_select(0,0,0,msec) (winsock doesn't)

p4raw-id: //depot/win32/perl@461

diff --git a/win32/win32sck.c b/win32/win32sck.c
index 8019cc3..14d2e6a 100644 (file)
--- a/win32/win32sck.c
+++ b/win32/win32sck.c
@@ -269,6 +269,14 @@ win32_select(int nfds, Perl_fd_set* rd, Perl_fd_set* wr, Perl_fd_set* ex, const
     int i, fd, bit, offset;
     FD_SET nrd, nwr, nex, *prd, *pwr, *pex;
 
+    /* winsock seems incapable of dealing with all three null fd_sets,
+     * so do the (millisecond) sleep as a special case
+     */
+    if (!(rd || wr || ex)) {
+       Sleep(timeout->tv_sec  * 1000 +
+             timeout->tv_usec / 1000);         /* do the best we can */
+       return 0;
+    }
     StartSockets();
     PERL_FD_ZERO(&dummy);
     if (!rd)