/*
 *  ircd-ratbox: A slightly useful ircd.
 *  epoll.c: Linux epoll compatible network routines.
 *
 *  Copyright (C) 1990 Jarkko Oikarinen and University of Oulu, Co Center
 *  Copyright (C) 1996-2002 Hybrid Development Team
 *  Copyright (C) 2001 Adrian Chadd <adrian@creative.net.au>
 *  Copyright (C) 2002-2005 ircd-ratbox development team
 *  Copyright (C) 2002 Aaron Sethman <androsyn@ratbox.org>
 *
 *  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; either version 2 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, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
 *  USA
 *
 */
#define _GNU_SOURCE 1

#include <libratbox_config.h>
#include <ratbox_lib.h>
#include <commio-int.h>
#include <event-int.h>
#if defined(HAVE_EPOLL_CTL) && (HAVE_SYS_EPOLL_H)
#define USING_EPOLL
#include <fcntl.h>
#include <sys/epoll.h>

#if defined(HAVE_SIGNALFD) && (HAVE_SYS_SIGNALFD_H) && (USE_TIMER_CREATE) && (HAVE_SYS_UIO_H)
#include <signal.h>
#include <sys/signalfd.h>
#include <sys/uio.h>
#define EPOLL_SCHED_EVENT 1
#endif

#if defined(USE_TIMERFD_CREATE)
#include <sys/timerfd.h>
#endif

#define RTSIGNAL SIGRTMIN
struct epoll_info {
    int ep;
    struct epoll_event *pfd;
    int pfd_size;
};

static struct epoll_info *ep_info;
static int can_do_event;
static int can_do_timerfd;

/*
 * rb_init_netio
 *
 * This is a needed exported function which will be called to initialise
 * the network loop code.
 */
int
rb_init_netio_epoll(void)
{
    can_do_event = 0;	/* shut up gcc */
    can_do_timerfd = 0;
    ep_info = rb_malloc(sizeof(struct epoll_info));
    ep_info->pfd_size = getdtablesize();
    ep_info->ep = epoll_create(ep_info->pfd_size);
    if(ep_info->ep < 0) {
        return -1;
    }
    rb_open(ep_info->ep, RB_FD_UNKNOWN, "epoll file descriptor");
    ep_info->pfd = rb_malloc(sizeof(struct epoll_event) * ep_info->pfd_size);

    return 0;
}

int
rb_setup_fd_epoll(rb_fde_t *F)
{
    return 0;
}


/*
 * rb_setselect
 *
 * This is a needed exported function which will be called to register
 * and deregister interest in a pending IO state for a given FD.
 */
void
rb_setselect_epoll(rb_fde_t *F, unsigned int type, PF * handler, void *client_data)
{
    struct epoll_event ep_event;
    int old_flags = F->pflags;
    int op = -1;

    lrb_assert(IsFDOpen(F));

    /* Update the list, even though we're not using it .. */
    if(type & RB_SELECT_READ) {
        if(handler != NULL)
            F->pflags |= EPOLLIN;
        else
            F->pflags &= ~EPOLLIN;
        F->read_handler = handler;
        F->read_data = client_data;
    }

    if(type & RB_SELECT_WRITE) {
        if(handler != NULL)
            F->pflags |= EPOLLOUT;
        else
            F->pflags &= ~EPOLLOUT;
        F->write_handler = handler;
        F->write_data = client_data;
    }

    if(old_flags == 0 && F->pflags == 0)
        return;
    else if(F->pflags <= 0)
        op = EPOLL_CTL_DEL;
    else if(old_flags == 0 && F->pflags > 0)
        op = EPOLL_CTL_ADD;
    else if(F->pflags != old_flags)
        op = EPOLL_CTL_MOD;

    if(op == -1)
        return;

    ep_event.events = F->pflags;
    ep_event.data.ptr = F;

    if(op == EPOLL_CTL_ADD || op == EPOLL_CTL_MOD)
        ep_event.events |= EPOLLET;

    if(epoll_ctl(ep_info->ep, op, F->fd, &ep_event) != 0) {
        rb_lib_log("rb_setselect_epoll(): epoll_ctl failed: %s", strerror(errno));
        abort();
    }


}

/*
 * rb_select
 *
 * Called to do the new-style IO, courtesy of squid (like most of this
 * new IO code). This routine handles the stuff we've hidden in
 * rb_setselect and fd_table[] and calls callbacks for IO ready
 * events.
 */

int
rb_select_epoll(long delay)
{
    int num, i, flags, old_flags, op;
    struct epoll_event ep_event;
    int o_errno;
    void *data;

    num = epoll_wait(ep_info->ep, ep_info->pfd, ep_info->pfd_size, delay);

    /* save errno as rb_set_time() will likely clobber it */
    o_errno = errno;
    rb_set_time();
    errno = o_errno;

    if(num < 0 && !rb_ignore_errno(o_errno))
        return RB_ERROR;

    if(num <= 0)
        return RB_OK;

    for(i = 0; i < num; i++) {
        PF *hdl;
        rb_fde_t *F = ep_info->pfd[i].data.ptr;
        old_flags = F->pflags;
        if(ep_info->pfd[i].events & (EPOLLIN | EPOLLHUP | EPOLLERR)) {
            hdl = F->read_handler;
            data = F->read_data;
            F->read_handler = NULL;
            F->read_data = NULL;
            if(hdl) {
                hdl(F, data);
            }
        }

        if(!IsFDOpen(F))
            continue;
        if(ep_info->pfd[i].events & (EPOLLOUT | EPOLLHUP | EPOLLERR)) {
            hdl = F->write_handler;
            data = F->write_data;
            F->write_handler = NULL;
            F->write_data = NULL;

            if(hdl) {
                hdl(F, data);
            }
        }

        if(!IsFDOpen(F))
            continue;

        flags = 0;

        if(F->read_handler != NULL)
            flags |= EPOLLIN;
        if(F->write_handler != NULL)
            flags |= EPOLLOUT;

        if(old_flags != flags) {
            if(flags == 0)
                op = EPOLL_CTL_DEL;
            else
                op = EPOLL_CTL_MOD;
            F->pflags = ep_event.events = flags;
            ep_event.data.ptr = F;
            if(op == EPOLL_CTL_MOD || op == EPOLL_CTL_ADD)
                ep_event.events |= EPOLLET;

            if(epoll_ctl(ep_info->ep, op, F->fd, &ep_event) != 0) {
                rb_lib_log("rb_select_epoll(): epoll_ctl failed: %s",
                           strerror(errno));
            }
        }

    }
    return RB_OK;
}

#ifdef EPOLL_SCHED_EVENT
int
rb_epoll_supports_event(void)
{
    /* try to detect at runtime if everything we need actually works */
    timer_t timer;
    struct sigevent ev;
    struct stat st;
    int fd;
    sigset_t set;

    if(can_do_event == 1)
        return 1;
    if(can_do_event == -1)
        return 0;

    /* Check for openvz..it has a broken timerfd.. */
    if(stat("/proc/user_beancounters", &st) == 0) {
        can_do_event = -1;
        return 0;
    }

#ifdef USE_TIMERFD_CREATE
    if((fd = timerfd_create(CLOCK_REALTIME, 0)) >= 0) {
        close(fd);
        can_do_event = 1;
        can_do_timerfd = 1;
        return 1;
    }
#endif

    ev.sigev_signo = SIGVTALRM;
    ev.sigev_notify = SIGEV_SIGNAL;
    if(timer_create(CLOCK_REALTIME, &ev, &timer) != 0) {
        can_do_event = -1;
        return 0;
    }
    timer_delete(timer);
    sigemptyset(&set);
    fd = signalfd(-1, &set, 0);
    if(fd < 0) {
        can_do_event = -1;
        return 0;
    }
    close(fd);
    can_do_event = 1;
    return 1;
}


/* bleh..work around a glibc header bug on 32bit systems */
struct our_signalfd_siginfo {
    uint32_t signo;
    int32_t err;
    int32_t code;
    uint32_t pid;
    uint32_t uid;
    int32_t fd;
    uint32_t tid;
    uint32_t band;
    uint32_t overrun;
    uint32_t trapno;
    int32_t status;
    int32_t svint;
    uint64_t svptr;
    uint64_t utime;
    uint64_t stime;
    uint64_t addr;
    uint8_t pad[48];
};


#define SIGFDIOV_COUNT 16
static void
signalfd_handler(rb_fde_t *F, void *data)
{
    static struct our_signalfd_siginfo fdsig[SIGFDIOV_COUNT];
    static struct iovec iov[SIGFDIOV_COUNT];
    struct ev_entry *ev;
    int ret, x;

    for(x = 0; x < SIGFDIOV_COUNT; x++) {
        iov[x].iov_base = &fdsig[x];
        iov[x].iov_len = sizeof(struct our_signalfd_siginfo);
    }

    while(1) {
        ret = readv(rb_get_fd(F), iov, SIGFDIOV_COUNT);

        if(ret == 0 || (ret < 0 && !rb_ignore_errno(errno))) {
            rb_close(F);
            rb_epoll_init_event();
            return;
        }

        if(ret < 0) {
            rb_setselect(F, RB_SELECT_READ, signalfd_handler, NULL);
            return;
        }
        for(x = 0; x < ret / (int)sizeof(struct our_signalfd_siginfo); x++) {
#if __WORDSIZE == 32 && defined(__sparc__)
            uint32_t *q = (uint32_t *)&fdsig[x].svptr;
            ev = (struct ev_entry *)q[0];
#else
            ev = (struct ev_entry *)(uintptr_t)(fdsig[x].svptr);

#endif
            if(ev == NULL)
                continue;
            rb_run_event(ev);
        }
    }
}

void
rb_epoll_init_event(void)
{

    sigset_t ss;
    rb_fde_t *F;
    int sfd;
    rb_epoll_supports_event();
    if(!can_do_timerfd) {
        sigemptyset(&ss);
        sigaddset(&ss, RTSIGNAL);
        sigprocmask(SIG_BLOCK, &ss, 0);
        sigemptyset(&ss);
        sigaddset(&ss, RTSIGNAL);
        sfd = signalfd(-1, &ss, 0);
        if(sfd == -1) {
            can_do_event = -1;
            return;
        }
        F = rb_open(sfd, RB_FD_UNKNOWN, "signalfd");
        rb_set_nb(F);
        signalfd_handler(F, NULL);
    }
}

static int
rb_epoll_sched_event_signalfd(struct ev_entry *event, int when)
{
    timer_t *id;
    struct sigevent ev;
    struct itimerspec ts;

    memset(&ev, 0, sizeof(&ev));
    event->comm_ptr = rb_malloc(sizeof(timer_t));
    id = event->comm_ptr;
    ev.sigev_notify = SIGEV_SIGNAL;
    ev.sigev_signo = RTSIGNAL;
    ev.sigev_value.sival_ptr = event;

    if(timer_create(CLOCK_REALTIME, &ev, id) < 0) {
        rb_lib_log("timer_create: %s\n", strerror(errno));
        return 0;
    }
    memset(&ts, 0, sizeof(ts));
    ts.it_value.tv_sec = when;
    ts.it_value.tv_nsec = 0;
    if(event->frequency != 0)
        ts.it_interval = ts.it_value;

    if(timer_settime(*id, 0, &ts, NULL) < 0) {
        rb_lib_log("timer_settime: %s\n", strerror(errno));
        return 0;
    }
    return 1;
}

#ifdef USE_TIMERFD_CREATE
static void
rb_read_timerfd(rb_fde_t *F, void *data)
{
    struct ev_entry *event = (struct ev_entry *)data;
    int retlen;
    uint64_t count;

    if(event == NULL) {
        rb_close(F);
        return;
    }

    retlen = rb_read(F, &count, sizeof(count));

    if(retlen == 0 || (retlen < 0 && !rb_ignore_errno(errno))) {
        rb_close(F);
        rb_lib_log("rb_read_timerfd: timerfd[%s] closed on error: %s", event->name,
                   strerror(errno));
        return;
    }
    rb_setselect(F, RB_SELECT_READ, rb_read_timerfd, event);
    rb_run_event(event);
}


static int
rb_epoll_sched_event_timerfd(struct ev_entry *event, int when)
{
    struct itimerspec ts;
    static char buf[FD_DESC_SZ + 8];
    int fd;
    rb_fde_t *F;

    if((fd = timerfd_create(CLOCK_REALTIME, 0)) < 0) {
        rb_lib_log("timerfd_create: %s\n", strerror(errno));
        return 0;
    }

    memset(&ts, 0, sizeof(ts));
    ts.it_value.tv_sec = when;
    ts.it_value.tv_nsec = 0;
    if(event->frequency != 0)
        ts.it_interval = ts.it_value;

    if(timerfd_settime(fd, 0, &ts, NULL) < 0) {
        rb_lib_log("timerfd_settime: %s\n", strerror(errno));
        close(fd);
        return 0;
    }
    snprintf(buf, sizeof(buf), "timerfd: %s", event->name);
    F = rb_open(fd, RB_FD_UNKNOWN, buf);
    rb_set_nb(F);
    event->comm_ptr = F;
    rb_setselect(F, RB_SELECT_READ, rb_read_timerfd, event);
    return 1;
}
#endif



int
rb_epoll_sched_event(struct ev_entry *event, int when)
{
#ifdef USE_TIMERFD_CREATE
    if(can_do_timerfd) {
        return rb_epoll_sched_event_timerfd(event, when);
    }
#endif
    return rb_epoll_sched_event_signalfd(event, when);
}

void
rb_epoll_unsched_event(struct ev_entry *event)
{
#ifdef USE_TIMERFD_CREATE
    if(can_do_timerfd) {
        rb_close((rb_fde_t *)event->comm_ptr);
        event->comm_ptr = NULL;
        return;
    }
#endif
    timer_delete(*((timer_t *) event->comm_ptr));
    rb_free(event->comm_ptr);
    event->comm_ptr = NULL;
}
#endif /* EPOLL_SCHED_EVENT */

#else /* epoll not supported here */
int
rb_init_netio_epoll(void)
{
    return ENOSYS;
}

void
rb_setselect_epoll(rb_fde_t *F, unsigned int type, PF * handler, void *client_data)
{
    errno = ENOSYS;
    return;
}

int
rb_select_epoll(long delay)
{
    errno = ENOSYS;
    return -1;
}

int
rb_setup_fd_epoll(rb_fde_t *F)
{
    errno = ENOSYS;
    return -1;
}


#endif

#if !defined(USING_EPOLL) || !defined(EPOLL_SCHED_EVENT)
void
rb_epoll_init_event(void)
{
    return;
}

int
rb_epoll_sched_event(struct ev_entry *event, int when)
{
    errno = ENOSYS;
    return -1;
}

void
rb_epoll_unsched_event(struct ev_entry *event)
{
    return;
}

int
rb_epoll_supports_event(void)
{
    errno = ENOSYS;
    return 0;
}
#endif /* !USING_EPOLL || !EPOLL_SCHED_EVENT */