Curl_poll() which is called whenever not a single valid file descriptor is
passed to these functions.
Improve readibility using a poll() macro to replace WSApoll().
(http://curl.haxx.se/bug/view.cgi?id=1603712) (known bug #36) --limit-rate
(CURLOPT_MAX_SEND_SPEED_LARGE and CURLOPT_MAX_RECV_SPEED_LARGE) are broken
on Windows (since 7.16.0, but that's when they were introduced as previous
to that the limiting logic was made in the application only and not in the
library). It was actually also broken on select()-based systems (as apposed
to poll()) but we haven't had any such reports. We now use select(), Sleep()
or delay() properly to sleep a while without waiting for anything input or
output when the rate limiting is activated with the easy interface.
HTTP upload was disconnected:
"What appears to be happening is that my system (Linux 2.6.17 and 2.6.13) is
setting *only* POLLHUP on poll() when the conditions in my previous mail
occur. As you can see, select.c:Curl_select() does not check for POLLHUP. So
basically what was happening, is poll() was returning immediately (with
POLLHUP set), but when Curl_select() looked at the bits, neither POLLERR or
POLLOUT was set. This still caused Curl_readwrite() to be called, which
quickly returned. Then the transfer() loop kept continuing at full speed
forever."
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.
