1 /**

     2  * ShaderShark

     3  * Copyright © 2023 František Kučera (Frantovo.cz, GlobalCode.info)

     4  *

     5  * This program is free software: you can redistribute it and/or modify

     6  * it under the terms of the GNU General Public License as published by

     7  * the Free Software Foundation, version 3 of the License.

     8  *

     9  * This program is distributed in the hope that it will be useful,

    10  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

    12  * GNU General Public License for more details.

    13  *

    14  * You should have received a copy of the GNU General Public License

    15  * along with this program. If not, see <http://www.gnu.org/licenses/>.

    16  */

    17 

    18 #pragma once

    19 

    20 #include <stdexcept>

    21 #include <string>

    22 

    23 #include <signal.h>

    24 #include <sys/signalfd.h>

    25 #include <sys/epoll.h>

    26 #include <unistd.h>

    27 #include <sys/fcntl.h>

    28 #include <sys/socket.h>

    29 #include <sys/un.h>

    30 

    31 #include <stdexcept>

    32 #include <string>

    33 

    34 class EPoll {

    35 private:

    36 	int epollEventCount;

    37 	epoll_event* epollEvents;

    38 	int epollFD;

    39 

    40 	void static log(const std::string& message) {

    41 		std::cout << message << std::endl;

    42 	}

    43 public:

    44 

    45 	class Exception : public std::logic_error {

    46 	public:

    47 

    48 		Exception(const std::string& msg) : logic_error(msg) {

    49 		}

    50 

    51 		Exception(const std::string& msg, int errNo) :

    52 				logic_error(msg + strerror(errNo)) {

    53 		}

    54 

    55 	};

    56 

    57 	EPoll(int eventCount = 5) : epollEventCount(eventCount) {

    58 		epollEvents = (epoll_event*) malloc(sizeof (*epollEvents) * eventCount);

    59 		epollFD = epoll_create1(0);

    60 		log("EPoll(): epoll_create() = " + std::to_string(epollFD));

    61 	}

    62 

    63 	virtual ~EPoll() {

    64 		::close(epollFD);

    65 		free(epollEvents);

    66 	}

    67 

    68 	EPoll(const EPoll&) = delete;

    69 	EPoll& operator=(const EPoll&) = delete;

    70 

    71 	static void processSignal(int signal) {

    72 		log("got signal: " + std::to_string(signal));

    73 	}

    74 

    75 	int addSignals() {

    76 		::signal(SIGTERM, EPoll::processSignal);

    77 		::signal(SIGINT, EPoll::processSignal);

    78 

    79 		sigset_t mask;

    80 		::sigemptyset(&mask);

    81 		::sigaddset(&mask, SIGTERM);

    82 		::sigaddset(&mask, SIGINT);

    83 		int signalFD = ::signalfd(-1, &mask, 0);

    84 		add(signalFD, EPOLLIN | EPOLLET | EPOLLHUP);

    85 		log("signalFD=" + std::to_string(signalFD));

    86 		return signalFD;

    87 	}

    88 

    89 	void add(int fd, uint32_t events = EPOLL_EVENTS::EPOLLIN) {

    90 		struct epoll_event ev;

    91 		ev.data.fd = fd;

    92 		ev.events = events;

    93 		int err = epoll_ctl(epollFD, EPOLL_CTL_ADD, ev.data.fd, &ev);

    94 		if (err) throw Exception("EPoll::add() failed (a file?):", errno);

    95 		// Regular files can not be monitored this way, thus:

    96 		//   cat Makefile | opengl-pdf      # works

    97 		//   opengl-pdf < Makefile          # does not work

    98 	}

    99 

   100 	void del(int fd) {

   101 		int err = epoll_ctl(epollFD, EPOLL_CTL_DEL, fd, nullptr);

   102 		if (err) throw Exception("EPoll::del() failed: ", errno);

   103 	}

   104 

   105 	int wait(int timeout = 1000) {

   106 		int count = epoll_wait(epollFD, epollEvents, epollEventCount, timeout);

   107 		if (count >= 0) return count;

   108 		else throw Exception("EPoll::wait() failed: ", errno);

   109 	}

   110 

   111 	const epoll_event& operator[](std::size_t index) const {

   112 		if (index < epollEventCount) return epollEvents[index];

   113 		else throw std::out_of_range("invalid index of epollEvents");

   114 	}

   115 

   116 };