+ static HANDLE never_handle;
+ HANDLE handles[MAXIMUM_WAIT_OBJECTS];
+ HANDLE h;
+ DWORD event;
+ DWORD num_handles;
+ /* SCBS contains serial control objects corresponding to file
+ descriptors in READFDS and WRITEFDS. */
+ struct serial *scbs[MAXIMUM_WAIT_OBJECTS];
+ /* The number of valid entries in SCBS. */
+ size_t num_scbs;
+ int fd;
+ int num_ready;
+ size_t indx;
+
+ if (n == 0)
+ {
+ /* The MS API says that the first argument to
+ WaitForMultipleObjects cannot be zero. That's why we just
+ use a regular Sleep here. */
+ if (timeout != NULL)
+ Sleep (timeout->tv_sec * 1000 + timeout->tv_usec / 1000);
+
+ return 0;
+ }
+
+ num_ready = 0;
+ num_handles = 0;
+ num_scbs = 0;
+ for (fd = 0; fd < n; ++fd)
+ {
+ HANDLE read = NULL, except = NULL;
+ struct serial *scb;
+
+ /* There is no support yet for WRITEFDS. At present, this isn't
+ used by GDB -- but we do not want to silently ignore WRITEFDS
+ if something starts using it. */
+ gdb_assert (!writefds || !FD_ISSET (fd, writefds));
+
+ if ((!readfds || !FD_ISSET (fd, readfds))
+ && (!exceptfds || !FD_ISSET (fd, exceptfds)))
+ continue;
+
+ scb = serial_for_fd (fd);
+ if (scb)
+ {
+ serial_wait_handle (scb, &read, &except);
+ scbs[num_scbs++] = scb;
+ }
+
+ if (read == NULL)
+ read = (HANDLE) _get_osfhandle (fd);
+ if (except == NULL)
+ {
+ if (!never_handle)
+ never_handle = CreateEvent (0, FALSE, FALSE, 0);
+
+ except = never_handle;
+ }
+
+ if (readfds && FD_ISSET (fd, readfds))
+ {
+ gdb_assert (num_handles < MAXIMUM_WAIT_OBJECTS);
+ handles[num_handles++] = read;
+ }
+
+ if (exceptfds && FD_ISSET (fd, exceptfds))
+ {
+ gdb_assert (num_handles < MAXIMUM_WAIT_OBJECTS);
+ handles[num_handles++] = except;
+ }
+ }
+
+ gdb_assert (num_handles <= MAXIMUM_WAIT_OBJECTS);
+
+ event = WaitForMultipleObjects (num_handles,
+ handles,
+ FALSE,
+ timeout
+ ? (timeout->tv_sec * 1000
+ + timeout->tv_usec / 1000)
+ : INFINITE);
+ /* EVENT can only be a value in the WAIT_ABANDONED_0 range if the
+ HANDLES included an abandoned mutex. Since GDB doesn't use
+ mutexes, that should never occur. */
+ gdb_assert (!(WAIT_ABANDONED_0 <= event
+ && event < WAIT_ABANDONED_0 + num_handles));
+ /* We no longer need the helper threads to check for activity. */
+ for (indx = 0; indx < num_scbs; ++indx)
+ serial_done_wait_handle (scbs[indx]);
+ if (event == WAIT_FAILED)
+ return -1;
+ if (event == WAIT_TIMEOUT)
+ return 0;
+ /* Run through the READFDS, clearing bits corresponding to descriptors
+ for which input is unavailable. */
+ h = handles[event - WAIT_OBJECT_0];
+ for (fd = 0, indx = 0; fd < n; ++fd)
+ {
+ HANDLE fd_h;
+
+ if ((!readfds || !FD_ISSET (fd, readfds))
+ && (!exceptfds || !FD_ISSET (fd, exceptfds)))
+ continue;
+
+ if (readfds && FD_ISSET (fd, readfds))
+ {
+ fd_h = handles[indx++];
+ /* This handle might be ready, even though it wasn't the handle
+ returned by WaitForMultipleObjects. */
+ if (fd_h != h && WaitForSingleObject (fd_h, 0) != WAIT_OBJECT_0)
+ FD_CLR (fd, readfds);
+ else
+ num_ready++;
+ }