/*
 * uloop - event loop implementation
 *
 * Copyright (C) 2010-2016 Felix Fietkau <nbd@openwrt.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/signalfd.h>

/**
 * FIXME: uClibc < 0.9.30.3 does not define EPOLLRDHUP for Linux >= 2.6.17
 */
#ifndef EPOLLRDHUP
#define EPOLLRDHUP 0x2000
#endif

static void
uloop_signal_fd_cb(struct uloop_fd *fd, unsigned int events)
{
	struct signalfd_siginfo fdsi;
	struct sigaction act;
	int ret;

retry:
	ret = read(fd->fd, &fdsi, sizeof(fdsi));
	if (ret < 0 && errno == EINTR)
		goto retry;

	if (ret != sizeof(fdsi))
		return;

	switch (fdsi.ssi_signo) {
	case SIGQUIT:
	case SIGINT:
	case SIGTERM:
		sigaction(fdsi.ssi_signo, NULL, &act);
		if (act.sa_handler != SIG_IGN &&
			act.sa_handler != SIG_DFL) {
			act.sa_handler(fdsi.ssi_signo);
			break;
		}

		/* fall through */
	default:
		uloop_handle_signal(fdsi.ssi_signo);
		break;
	}
}

static bool
uloop_setup_signalfd(bool add)
{
	static struct uloop_fd sfd = {
		.cb = uloop_signal_fd_cb
	};
	static sigset_t prev_mask;
	sigset_t mask;

	if (signal_fd < 0)
		return false;

	sigemptyset(&mask);

	if (!add) {
		uloop_fd_delete(&sfd);
		sigprocmask(SIG_BLOCK, &prev_mask, NULL);
	} else {
		sigaddset(&mask, SIGQUIT);
		sigaddset(&mask, SIGINT);
		sigaddset(&mask, SIGTERM);
		sigaddset(&mask, SIGCHLD);
		sigprocmask(SIG_BLOCK, &mask, &prev_mask);

		sfd.fd = signal_fd;
		uloop_fd_add(&sfd, ULOOP_READ | ULOOP_EDGE_TRIGGER);
	}

	if (signalfd(signal_fd, &mask, SFD_NONBLOCK | SFD_CLOEXEC) < 0) {
		sigprocmask(SIG_BLOCK, &prev_mask, NULL);
		return false;
	}

	return true;
}

int uloop_init(void)
{
	sigset_t mask;

	if (poll_fd >= 0)
		return 0;

	poll_fd = epoll_create(32);
	if (poll_fd < 0)
		return -1;

	fcntl(poll_fd, F_SETFD, fcntl(poll_fd, F_GETFD) | FD_CLOEXEC);

	sigemptyset(&mask);
	signal_fd = signalfd(-1, &mask, SFD_NONBLOCK | SFD_CLOEXEC);

	return 0;
}

static int register_poll(struct uloop_fd *fd, unsigned int flags)
{
	struct epoll_event ev;
	int op = fd->registered ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;

	memset(&ev, 0, sizeof(struct epoll_event));

	if (flags & ULOOP_READ)
		ev.events |= EPOLLIN | EPOLLRDHUP;

	if (flags & ULOOP_WRITE)
		ev.events |= EPOLLOUT;

	if (flags & ULOOP_EDGE_TRIGGER)
		ev.events |= EPOLLET;

	ev.data.fd = fd->fd;
	ev.data.ptr = fd;
	fd->flags = flags;

	return epoll_ctl(poll_fd, op, fd->fd, &ev);
}

static struct epoll_event events[ULOOP_MAX_EVENTS];

static int __uloop_fd_delete(struct uloop_fd *sock)
{
	sock->flags = 0;
	return epoll_ctl(poll_fd, EPOLL_CTL_DEL, sock->fd, 0);
}

static int uloop_fetch_events(int timeout)
{
	int n, nfds;

	nfds = epoll_wait(poll_fd, events, ARRAY_SIZE(events), timeout);
	for (n = 0; n < nfds; ++n) {
		struct uloop_fd_event *cur = &cur_fds[n];
		struct uloop_fd *u = events[n].data.ptr;
		unsigned int ev = 0;

		cur->fd = u;
		if (!u)
			continue;

		if (events[n].events & (EPOLLERR|EPOLLHUP)) {
			u->error = true;
			if (!(u->flags & ULOOP_ERROR_CB))
				uloop_fd_delete(u);
		}

		if(!(events[n].events & (EPOLLRDHUP|EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP))) {
			cur->fd = NULL;
			continue;
		}

		if(events[n].events & EPOLLRDHUP)
			u->eof = true;

		if(events[n].events & EPOLLIN)
			ev |= ULOOP_READ;

		if(events[n].events & EPOLLOUT)
			ev |= ULOOP_WRITE;

		cur->events = ev;
	}

	return nfds;
}