+/* Wrapper for select. This function is not yet exported from this
+ file because it is not sufficiently general. For example,
+ ser-base.c uses select to check for socket activity, and this
+ function does not support sockets under Windows, so we do not want
+ to use gdb_select in ser-base.c. */
+
+static int
+gdb_select (int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
+ struct timeval *timeout)
+{
+#ifdef USE_WIN32API
+ HANDLE handles[MAXIMUM_WAIT_OBJECTS];
+ HANDLE h;
+ DWORD event;
+ DWORD num_handles;
+ int fd;
+ int num_ready;
+
+ num_handles = 0;
+ for (fd = 0; fd < n; ++fd)
+ {
+ /* EXCEPTFDS is silently ignored. GDB always sets GDB_EXCEPTION
+ when calling add_file_handler, but there is no natural analog
+ under Windows. */
+ /* 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 (!FD_ISSET (fd, writefds));
+ if (FD_ISSET (fd, readfds))
+ {
+ gdb_assert (num_handles < MAXIMUM_WAIT_OBJECTS);
+ handles[num_handles++] = (HANDLE) _get_osfhandle (fd);
+ }
+ }
+ event = WaitForMultipleObjects (num_handles,
+ handles,
+ FALSE,
+ timeout
+ ? (timeout->tv_sec * 1000 + timeout->tv_usec)
+ : 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));
+ 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. */
+ num_ready = num_handles;
+ h = handles[event - WAIT_OBJECT_0];
+ for (fd = 0; fd < n; ++fd)
+ {
+ HANDLE fd_h;
+ if (!FD_ISSET (fd, readfds))
+ continue;
+ fd_h = (HANDLE) _get_osfhandle (fd);
+ /* 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);
+ --num_ready;
+ }
+ }
+ /* We never report any descriptors available for writing or with
+ exceptional conditions. */
+ FD_ZERO (writefds);
+ FD_ZERO (exceptfds);
+
+ return num_ready;
+#else
+ return select (n, readfds, writefds, exceptfds, timeout);
+#endif
+}
+