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Cygwin: serial: use per call OVERLAPPED structs

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Sharing the OVERLAPPED struct and event object in there between
read and select calls in the fhandler might have been a nice
optimization way back when, but it is a dangerous, not thread-safe
approach.  Fix this by creating per-fhandler, per-call OVERLAPPED
structs and event objects on demand.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen
2020-03-23 21:06:00 +01:00
parent a1f0585454
commit 2a4b1de773
4 changed files with 56 additions and 81 deletions
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38
winsup/cygwin/select.cc
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@@ -1481,15 +1481,16 @@ serial_read_cleanup (select_record *s, select_stuff *stuff)
{
if (s->h)
{
fhandler_serial *fh = (fhandler_serial *) s->fh;
HANDLE h = fh->get_handle_cyg ();
HANDLE h = ((fhandler_serial *) s->fh)->get_handle_cyg ();
DWORD undefined;
if (h)
{
CancelIo (h);
GetOverlappedResult (h, &fh->io_status, &undefined, TRUE);
GetOverlappedResult (h, &s->fh_data_serial->ov, &undefined, TRUE);
}
CloseHandle (s->fh_data_serial->ov.hEvent);
delete s->fh_data_serial;
}
}
@@ -1513,27 +1514,30 @@ fhandler_serial::select_read (select_stuff *ss)
s->peek = peek_serial;
s->read_selected = true;
s->read_ready = false;
s->fh_data_serial = new (fh_select_data_serial);
s->fh_data_serial->ov.hEvent = CreateEvent (&sec_none_nih, TRUE, FALSE, NULL);
/* This is apparently necessary for the com0com driver.
See: http://cygwin.com/ml/cygwin/2009-01/msg00667.html */
ResetEvent (io_status.hEvent);
SetCommMask (get_handle_cyg (), 0);
SetCommMask (get_handle_cyg (), EV_RXCHAR);
if (ClearCommError (get_handle_cyg (), &io_err, &st) && st.cbInQue)
s->read_ready = true;
else if (WaitCommEvent (get_handle_cyg (), &s->fh_data_serial->event,
&s->fh_data_serial->ov))
s->read_ready = true;
else if (GetLastError () == ERROR_IO_PENDING)
s->h = s->fh_data_serial->ov.hEvent;
else
select_printf ("WaitCommEvent %E");
/* No overlapped operation? Destroy the helper struct */
if (!s->h)
{
s->read_ready = true;
return s;
CloseHandle (s->fh_data_serial->ov.hEvent);
delete s->fh_data_serial;
}
if (WaitCommEvent (get_handle_cyg (), &event, &io_status))
{
s->read_ready = true;
return s;
}
if (GetLastError () == ERROR_IO_PENDING)
{
s->h = io_status.hEvent;
return s;
}
select_printf ("WaitCommEvent %E");
return s;
}