struct timeval tv = { 0, 0 };
int val = -1;
-
FD_ZERO (&rdset);
FD_ZERO (&wrset);
FD_ZERO (&exset);
if (val < fd)
val = fd;
- /* I assume the OS has a solution select overflow if it does not have
- * poll(). If it did not, we are screwed anyway. */
+ /* With POSIX, FD_SET & FD_ISSET are not defined if fd is negative or
+ * bigger or equal than FD_SETSIZE. That is one of the reasons why VLC
+ * uses poll() rather than select(). Most POSIX systems implement
+ * fd_set has a bit field with no sanity checks. This is especially bad
+ * on systems (such as BSD) that have no process open files limit by
+ * default, such that it is quite feasible to get fd >= FD_SETSIZE.
+ * The next instructions will result in a buffer overflow if run on
+ * a POSIX system, and the later FD_ISSET will do undefined memory
+ * access.
+ *
+ * With Winsock, fd_set is a table of integers. This is awfully slow.
+ * However, FD_SET and FD_ISSET silently and safely discard
+ * overflows. If it happens we will loose socket events. Note that
+ * most (if not all) Winsock SOCKET handles are actually bigger than
+ * FD_SETSIZE in terms of absolute value - they are not POSIX file
+ * descriptors. From Vista, there is a much nicer WSAPoll(), but Mingw
+ * is yet to support it.
+ *
+ * With BeOS, the situation is unknown (FIXME: document).
+ */
if (fds[i].events & POLLIN)
FD_SET (fd, &rdset);
if (fds[i].events & POLLOUT)