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Cygwin: select: Fix FD_CLOSE handling 

An FD_CLOSE event sets a socket descriptor ready for writing.
This is incorrect if the FD_CLOSE is a result of shutdown(SHUT_RD).
Only set the socket descriptor ready for writing if the FD_CLOSE
is indicating an connection abort or reset error condition.

This requires to tweak fhandler_socket_wsock::evaluate_events.
FD_CLOSE in conjunction with FD_ACCEPT/FD_CONNECT special cases
a shutdown condition by setting an error code.  This is correct
for accept/connect, but not for select.  In this case, make sure
to return with an error code only if FD_CLOSE indicates a
connection error.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2021-04-06 21:35:43 +02:00
parent caa78917b6
commit ef95c03522
2 changed files with 23 additions and 10 deletions
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16
winsup/cygwin/fhandler_socket_inet.cc
View File

@ -361,10 +361,19 @@ fhandler_socket_wsock::evaluate_events (const long event_mask, long &events,
wsock_events->events |= FD_WRITE; wsock_events->events |= FD_WRITE;
wsock_events->connect_errorcode = 0; wsock_events->connect_errorcode = 0;
} }
/* This test makes accept/connect behave as on Linux when accept/connect
is called on a socket for which shutdown has been called. The second
half of this code is in the shutdown method. */
if (events & FD_CLOSE) if (events & FD_CLOSE)
{
if (evts.iErrorCode[FD_CLOSE_BIT])
{
WSASetLastError (evts.iErrorCode[FD_CLOSE_BIT]);
ret = SOCKET_ERROR;
}
/* This test makes accept/connect behave as on Linux when accept/
connect is called on a socket for which shutdown has been called.
The second half of this code is in the shutdown method. Note that
we only do this when called from accept/connect, not from select.
In this case erase == false, just as with read (MSG_PEEK). */
if (erase)
{ {
if ((event_mask & FD_ACCEPT) && saw_shutdown_read ()) if ((event_mask & FD_ACCEPT) && saw_shutdown_read ())
{ {
@ -377,6 +386,7 @@ fhandler_socket_wsock::evaluate_events (const long event_mask, long &events,
ret = SOCKET_ERROR; ret = SOCKET_ERROR;
} }
} }
}
if (erase) if (erase)
wsock_events->events &= ~(events & ~(FD_WRITE | FD_CLOSE)); wsock_events->events &= ~(events & ~(FD_WRITE | FD_CLOSE));
} }

7
winsup/cygwin/select.cc
View File

@ -1709,7 +1709,8 @@ peek_socket (select_record *me, bool)
fhandler_socket_wsock *fh = (fhandler_socket_wsock *) me->fh; fhandler_socket_wsock *fh = (fhandler_socket_wsock *) me->fh;
long events; long events;
/* Don't play with the settings again, unless having taken a deep look into /* Don't play with the settings again, unless having taken a deep look into
Richard W. Stevens Network Programming book. Thank you. */ Richard W. Stevens Network Programming book and how these flags are
defined in Winsock. Thank you. */
long evt_mask = (me->read_selected ? (FD_READ | FD_ACCEPT | FD_CLOSE) : 0) long evt_mask = (me->read_selected ? (FD_READ | FD_ACCEPT | FD_CLOSE) : 0)
| (me->write_selected ? (FD_WRITE | FD_CONNECT | FD_CLOSE) : 0) | (me->write_selected ? (FD_WRITE | FD_CONNECT | FD_CLOSE) : 0)
| (me->except_selected ? FD_OOB : 0); | (me->except_selected ? FD_OOB : 0);
@ -1717,7 +1718,9 @@ peek_socket (select_record *me, bool)
if (me->read_selected) if (me->read_selected)
me->read_ready |= ret || !!(events & (FD_READ | FD_ACCEPT | FD_CLOSE)); me->read_ready |= ret || !!(events & (FD_READ | FD_ACCEPT | FD_CLOSE));
if (me->write_selected) if (me->write_selected)
me->write_ready |= ret || !!(events & (FD_WRITE | FD_CONNECT | FD_CLOSE)); /* Don't check for FD_CLOSE here. Only an error case (ret == -1)
will set ready for writing. */
me->write_ready |= ret || !!(events & (FD_WRITE | FD_CONNECT));
if (me->except_selected) if (me->except_selected)
me->except_ready |= !!(events & FD_OOB); me->except_ready |= !!(events & FD_OOB);