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Fix race condition when waiting for a signal

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* cygtls.h (_cygtls::wait_signal_arrived): Renamed from
        set_signal_arrived.
        (_cygtls::set_signal_arrived): New function signalling signal_arrived.
        (_cygtls::reset_signal_arrived): Don't reset will_wait_for_signal.
        (_cygtls::unwait_signal_arrived): New function only resetting
        will_wait_for_signal.
        (class wait_signal_arrived): Rename from set_signal_arrived.
        Accommodate name change throughout Cygwin.
        (wait_signal_arrived::~wait_signal_arrived): Call
        _cygtls::unwait_signal_arrived.  Add comment.
        * cygserver_ipc.h (ipc_set_proc_info): Fetch signal_arrived handle
        via call to _cygtls::get_signal_arrived.
        * exceptions.cc (_cygtls::interrupt_setup): Signal signal_arrived via
        call to _cygtls::set_signal_arrived.
        (_cygtls::handle_SIGCONT): Ditto.
        * fhandler_socket.cc (fhandler_socket::wait_for_events): Generate
        WSAEVENT array prior to entering wait loop.  Add cancel event object
        if available.  Remove calls to pthread_testcancel and just call
        pthread::static_cancel_self if the cancel event object is signalled.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen
2015-11-27 14:39:11 +01:00
parent 9471b0b36d
commit c43e9340f1
12 changed files with 63 additions and 26 deletions
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18
winsup/cygwin/fhandler_socket.cc
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@ -748,6 +748,12 @@ fhandler_socket::wait_for_events (const long event_mask, const DWORD flags)
int ret;
long events = 0;
WSAEVENT ev[3] = { wsock_evt, NULL, NULL };
wait_signal_arrived here (ev[1]);
DWORD ev_cnt = 2;
if ((ev[2] = pthread::get_cancel_event ()) != NULL)
++ev_cnt;
while (!(ret = evaluate_events (event_mask, events, !(flags & MSG_PEEK)))
&& !events)
{
@ -757,14 +763,9 @@ fhandler_socket::wait_for_events (const long event_mask, const DWORD flags)
return SOCKET_ERROR;
}
WSAEVENT ev[2] = { wsock_evt };
set_signal_arrived here (ev[1]);
switch (WSAWaitForMultipleEvents (2, ev, FALSE, 50, FALSE))
switch (WSAWaitForMultipleEvents (ev_cnt, ev, FALSE, 50, FALSE))
{
case WSA_WAIT_TIMEOUT:
pthread_testcancel ();
break;
case WSA_WAIT_EVENT_0:
break;
@ -774,8 +775,11 @@ fhandler_socket::wait_for_events (const long event_mask, const DWORD flags)
WSASetLastError (WSAEINTR);
return SOCKET_ERROR;
case WSA_WAIT_EVENT_0 + 2:
pthread::static_cancel_self ();
break;
default:
pthread_testcancel ();
/* wsock_evt can be NULL. We're generating the same errno values
as for sockets on which shutdown has been called. */
if (WSAGetLastError () != WSA_INVALID_HANDLE)