--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/EPoll.h	Sun Nov 26 16:27:50 2023 +0100
@@ -0,0 +1,116 @@
+/**
+ * ShaderShark
+ * Copyright © 2023 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdexcept>
+#include <string>
+
+#include <signal.h>
+#include <sys/signalfd.h>
+#include <sys/epoll.h>
+#include <unistd.h>
+#include <sys/fcntl.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+#include <stdexcept>
+#include <string>
+
+class EPoll {
+private:
+	int epollEventCount;
+	epoll_event* epollEvents;
+	int epollFD;
+
+	void static log(const std::string& message) {
+		std::cout << message << std::endl;
+	}
+public:
+
+	class Exception : public std::logic_error {
+	public:
+
+		Exception(const std::string& msg) : logic_error(msg) {
+		}
+
+		Exception(const std::string& msg, int errNo) :
+				logic_error(msg + strerror(errNo)) {
+		}
+
+	};
+
+	EPoll(int eventCount = 5) : epollEventCount(eventCount) {
+		epollEvents = (epoll_event*) malloc(sizeof (*epollEvents) * eventCount);
+		epollFD = epoll_create1(0);
+		log("EPoll(): epoll_create() = " + std::to_string(epollFD));
+	}
+
+	virtual ~EPoll() {
+		::close(epollFD);
+		free(epollEvents);
+	}
+
+	EPoll(const EPoll&) = delete;
+	EPoll& operator=(const EPoll&) = delete;
+
+	static void processSignal(int signal) {
+		log("got signal: " + std::to_string(signal));
+	}
+
+	int addSignals() {
+		::signal(SIGTERM, EPoll::processSignal);
+		::signal(SIGINT, EPoll::processSignal);
+
+		sigset_t mask;
+		::sigemptyset(&mask);
+		::sigaddset(&mask, SIGTERM);
+		::sigaddset(&mask, SIGINT);
+		int signalFD = ::signalfd(-1, &mask, 0);
+		add(signalFD, EPOLLIN | EPOLLET | EPOLLHUP);
+		log("signalFD=" + std::to_string(signalFD));
+		return signalFD;
+	}
+
+	void add(int fd, uint32_t events = EPOLL_EVENTS::EPOLLIN) {
+		struct epoll_event ev;
+		ev.data.fd = fd;
+		ev.events = events;
+		int err = epoll_ctl(epollFD, EPOLL_CTL_ADD, ev.data.fd, &ev);
+		if (err) throw Exception("EPoll::add() failed (a file?):", errno);
+		// Regular files can not be monitored this way, thus:
+		//   cat Makefile | opengl-pdf      # works
+		//   opengl-pdf < Makefile          # does not work
+	}
+
+	void del(int fd) {
+		int err = epoll_ctl(epollFD, EPOLL_CTL_DEL, fd, nullptr);
+		if (err) throw Exception("EPoll::del() failed: ", errno);
+	}
+
+	int wait(int timeout = 1000) {
+		int count = epoll_wait(epollFD, epollEvents, epollEventCount, timeout);
+		if (count >= 0) return count;
+		else throw Exception("EPoll::wait() failed: ", errno);
+	}
+
+	const epoll_event& operator[](std::size_t index) const {
+		if (index < epollEventCount) return epollEvents[index];
+		else throw std::out_of_range("invalid index of epollEvents");
+	}
+
+};