/*

 * Copyright (C) 2019 by Sukchan Lee <acetcom@gmail.com>

 *

 * This file is part of Open5GS.

 *

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

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

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * 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 <https://www.gnu.org/licenses/>.

 */

#include "core-config-private.h"

#if HAVE_UNISTD_H

#include <unistd.h>

#endif

#include <sys/epoll.h>

#include "ogs-core.h"

#include "ogs-poll-private.h"

static void epoll_init(ogs_pollset_t *pollset);

static void epoll_cleanup(ogs_pollset_t *pollset);

static int epoll_add(ogs_poll_t *poll);

static int epoll_remove(ogs_poll_t *poll);

static int epoll_process(ogs_pollset_t *pollset, ogs_time_t timeout);

const ogs_pollset_actions_t ogs_epoll_actions = {

    epoll_init,

    epoll_cleanup,

    epoll_add,

    epoll_remove,

    epoll_process,

    ogs_notify_pollset,

};

struct epoll_map_s {

    ogs_poll_t *read;

    ogs_poll_t *write;

};

struct epoll_context_s {

    int epfd;

    ogs_hash_t *map_hash;

    struct epoll_event *event_list;

};

static void epoll_init(ogs_pollset_t *pollset)

{

    struct epoll_context_s *context = NULL;

    ogs_assert(pollset);

    context = ogs_calloc(1, sizeof *context);

    ogs_assert(context);

    pollset->context = context;

    context->event_list = ogs_calloc(

            pollset->capacity, sizeof(struct epoll_event));

    ogs_assert(context->event_list);

    context->map_hash = ogs_hash_make();

    ogs_assert(context->map_hash);

    context->epfd = epoll_create(pollset->capacity);

    ogs_assert(context->epfd >= 0);

    ogs_notify_init(pollset);

}

static void epoll_cleanup(ogs_pollset_t *pollset)

{

    struct epoll_context_s *context = NULL;

    ogs_assert(pollset);

    context = pollset->context;

    ogs_assert(context);

    ogs_notify_final(pollset);

    close(context->epfd);

    ogs_free(context->event_list);

    ogs_hash_destroy(context->map_hash);

    ogs_free(context);

}

static int epoll_add(ogs_poll_t *poll)

{

    int rv, op;

    ogs_pollset_t *pollset = NULL;

    struct epoll_context_s *context = NULL;

    struct epoll_map_s *map = NULL;

    struct epoll_event ee;

    ogs_assert(poll);

    pollset = poll->pollset;

    ogs_assert(pollset);

    context = pollset->context;

    ogs_assert(context);

    map = ogs_hash_get(context->map_hash, &poll->fd, sizeof(poll->fd));

    if (!map) {

        map = ogs_calloc(1, sizeof(*map));

        if (!map) {

            ogs_error("ogs_calloc() failed");

            return OGS_ERROR;

        }

        op = EPOLL_CTL_ADD;

        ogs_hash_set(context->map_hash, &poll->fd, sizeof(poll->fd), map);

    } else {

        op = EPOLL_CTL_MOD;

    }

    if (poll->when & OGS_POLLIN)

        map->read = poll;

    if (poll->when & OGS_POLLOUT)

        map->write = poll;

    memset(&ee, 0, sizeof ee);

    ee.events = 0;

    if (map->read)

        ee.events |= (EPOLLIN|EPOLLRDHUP);

    if (map->write)

        ee.events |= EPOLLOUT;

    ee.data.fd = poll->fd;

    rv = epoll_ctl(context->epfd, op, poll->fd, &ee);

    if (rv < 0) {

        ogs_log_message(OGS_LOG_ERROR, ogs_socket_errno,

                "epoll_ctl[%d] failed", op);

        return OGS_ERROR;

    }

    return OGS_OK;

}

static int epoll_remove(ogs_poll_t *poll)

{

    int rv, op;

    ogs_pollset_t *pollset = NULL;

    struct epoll_context_s *context = NULL;

    struct epoll_map_s *map = NULL;

    struct epoll_event ee;

    ogs_assert(poll);

    pollset = poll->pollset;

    ogs_assert(pollset);

    context = pollset->context;

    ogs_assert(context);

    map = ogs_hash_get(context->map_hash, &poll->fd, sizeof(poll->fd));

    ogs_assert(map);

    if (poll->when & OGS_POLLIN)

        map->read = NULL;

    if (poll->when & OGS_POLLOUT)

        map->write = NULL;

    memset(&ee, 0, sizeof ee);

    ee.events = 0;

    if (map->read)

        ee.events |= (EPOLLIN|EPOLLRDHUP);

    if (map->write)

        ee.events |= EPOLLOUT;

    if (map->read || map->write) {

        op = EPOLL_CTL_MOD;

        ee.data.fd = poll->fd;

    } else {

        op = EPOLL_CTL_DEL;

        ee.data.fd = INVALID_SOCKET;

        ogs_hash_set(context->map_hash, &poll->fd, sizeof(poll->fd), NULL);

        ogs_free(map);

    }

    rv = epoll_ctl(context->epfd, op, poll->fd, &ee);

    if (rv < 0) {

        ogs_log_message(OGS_LOG_ERROR, ogs_socket_errno,

                "epoll_remove[%d] failed", op);

        return OGS_ERROR;

    }

    return OGS_OK;

}

static int epoll_process(ogs_pollset_t *pollset, ogs_time_t timeout)

{

    struct epoll_context_s *context = NULL;

    int num_of_poll;

    int i;

    ogs_assert(pollset);

    context = pollset->context;

    ogs_assert(context);

    num_of_poll = epoll_wait(context->epfd, context->event_list,

            pollset->capacity,

            timeout == OGS_INFINITE_TIME ? OGS_INFINITE_TIME :

                ogs_time_to_msec(timeout));

    if (num_of_poll < 0) {

        ogs_log_message(OGS_LOG_ERROR, ogs_socket_errno, "epoll failed");

        return OGS_ERROR;

    } else if (num_of_poll == 0) {

        return OGS_TIMEUP;

    }

    for (i = 0; i < num_of_poll; i++) {

        struct epoll_map_s *map = NULL;

        uint32_t received;

        short when = 0;

        ogs_socket_t fd;

        received = context->event_list[i].events;

        if (received & EPOLLERR) {

        /*

         * The libevent library has OGS_POLLOUT turned on in EPOLLERR.

         *

         * However, SIGPIPE can occur if write() is called

         * when the peer connection is closed.

         *

         * Therefore, Open5GS turns off OGS_POLLOUT

         * so that write() cannot be called in case of EPOLLERR.

         *

         * See also #2411 and #2312

         */

#if 0

            when = OGS_POLLIN|OGS_POLLOUT;

#else

            when = OGS_POLLIN;

#endif

        } else if ((received & EPOLLHUP) && !(received & EPOLLRDHUP)) {

            when = OGS_POLLIN|OGS_POLLOUT;

        } else {

            if (received & EPOLLIN) {

                when |= OGS_POLLIN;

            }

            if (received & EPOLLOUT) {

                when |= OGS_POLLOUT;

            }

            if (received & EPOLLRDHUP) {

                when |= OGS_POLLIN;

            }

        }

        if (!when)

            continue;

        fd = context->event_list[i].data.fd;

        ogs_assert(fd != INVALID_SOCKET);

        map = ogs_hash_get(context->map_hash, &fd, sizeof(fd));

        if (!map) continue;

        if (map->read && map->write && map->read == map->write) {

            map->read->handler(when, map->read->fd, map->read->data);

        } else {

            if ((when & OGS_POLLIN) && map->read)

                map->read->handler(when, map->read->fd, map->read->data);

            /*

             * map->read->handler() can call ogs_remove_epoll()

             * So, we need to check map instance

             */

            map = ogs_hash_get(context->map_hash, &fd, sizeof(fd));

            if (!map) continue;

            if ((when & OGS_POLLOUT) && map->write)

                map->write->handler(when, map->write->fd, map->write->data);

        }

    }

    return OGS_OK;

}