Adding support for other events than EPOLLIN and EPOLLOUT for system sockets when using srt_epoll_wait()

[remjey]

Hello,

I was blocked in my progress on my Linux project because srt_epoll_wait() seemingly didn't detect the closure of the write end of a pipe by observing its read end's file descriptor (as system socket). No problem detecting available data on it though.

I had a look at the libsrt code and made tests with standard epoll().

epoll() will detect this closure event and report the file descriptor with the event EPOLLHUP. srt_epoll_wait() only watches EPOLLIN and EPOLLOUT in the events reported for system sockets so it cannot report this occurrence.

You can see this here:

srt/srtcore/epoll.cpp

Lines 641 to 653 in fd56385

	for (int i = 0; i < nfds; ++ i)
	{
	if ((NULL != lrfds) && (ev[i].events & EPOLLIN))
	{
	lrfds->insert(ev[i].data.fd);
	++ total;
	}
	if ((NULL != lwfds) && (ev[i].events & EPOLLOUT))
	{
	lwfds->insert(ev[i].data.fd);
	++ total;
	}
	}

I could work around this limitation in my project. I considered posting a bug report but didn't know if it should be a bug report or a feature resquest. Maybe it's out of scope, although there are other useful events that epoll() can report that srt_epoll_wait() cannot.

Do you think this limitation should be addressed?