Thanks to this nice summary of poll() implementations:

http://www.greenend.org.uk/rjk/2001/06/poll.html and further tests by Eugene
Kotlyarov, we now know that cygwin's poll returns only POLLHUP on remote
connection closure so we check for that case (too) and re-enable poll for
cygwin builds.

CHANGES

@@ -8,6 +8,13 @@
 
 
 
+Daniel (13 November 2005)
+- Thanks to this nice summary of poll() implementations:
+  http://www.greenend.org.uk/rjk/2001/06/poll.html and further tests by Eugene
+  Kotlyarov, we now know that cygwin's poll returns only POLLHUP on remote
+  connectin closure so we check for that case (too) and re-enable poll for
+  cygwin builds.
+
 Daniel (12 November 2005)
 - Eugene Kotlyarov found out that cygwin's poll() function isn't doing things
   right: http://curl.haxx.se/mail/archive-2005-11/0045.html so we now disable

RELEASE-NOTES

@@ -18,7 +18,7 @@ This release includes the following changes:
 
 This release includes the following bugfixes:
 
- o don't use poll() on cygwin, it is defective
+ o fixed libcurl's use of poll() on cygwin
  o the GnuTLS code didn't support client certificates
  o TFTP over IPv6 works
  o no reverse lookups on IP addresses when ipv6-enabled

configure.ac

@@ -1591,10 +1591,10 @@ AC_CHECK_DECL(basename, ,
 #endif
 )
 
-AC_MSG_CHECKING([if we are Mac OS X or cygwin to disable poll])
+AC_MSG_CHECKING([if we are Mac OS X (to disable poll)])
 disable_poll=no
 case $host in
-  *-*-darwin* | *-*-cygwin)
+  *-*-darwin*)
     disable_poll="yes";
     ;;
   *)

lib/select.c

@@ -104,7 +104,7 @@ int Curl_select(curl_socket_t readfd, curl_socket_t writefd, int timeout_ms)
   ret = 0;
   num = 0;
   if (readfd != CURL_SOCKET_BAD) {
-    if (pfd[num].revents & POLLIN)
+    if (pfd[num].revents & (POLLIN|POLLHUP))
       ret |= CSELECT_IN;
     if (pfd[num].revents & POLLERR)
       ret |= CSELECT_ERR;