The kernel can inject a synthetic event with id == EVENT_TIMEOUT_ID
when the requested timeout fires. The previous loop iterated the raw
event buffer with events.add(i) (in epoll_event strides) and then
interpreted the result as a syscall::Event, which produced out-of-bounds
reads when the kernel interleaved timeout events with real events.
Two changes:
1. Cast events to Event* first, then add i in Event strides so the
pointer arithmetic matches the buffer the kernel filled.
2. Filter out entries with id == EVENT_TIMEOUT_ID before copying them
into the user-visible epoll_event array.
Adds a regression test that builds a synthetic Event buffer with a
timeout entry interleaved and verifies that the timeout entry is
dropped while siblings are preserved.
Red Bear OS
dd2cd44368