// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/io_uring.h>
#include <linux/eventpoll.h>

#include <uapi/linux/io_uring.h>

#include "io_uring.h"
#include "epoll.h"

struct io_epoll {
        struct file                     *file;
        int                             epfd;
        int                             op;
        int                             fd;
        struct epoll_event              event;
};

struct io_epoll_wait {
        struct file                     *file;
        int                             maxevents;
        struct epoll_event __user       *events;
};

int io_epoll_ctl_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_epoll *epoll = io_kiocb_to_cmd(req, struct io_epoll);

        if (sqe->buf_index || sqe->splice_fd_in)
                return -EINVAL;

        epoll->epfd = READ_ONCE(sqe->fd);
        epoll->op = READ_ONCE(sqe->len);
        epoll->fd = READ_ONCE(sqe->off);

        if (ep_op_has_event(epoll->op)) {
                struct epoll_event __user *ev;

                ev = u64_to_user_ptr(READ_ONCE(sqe->addr));
                if (copy_from_user(&epoll->event, ev, sizeof(*ev)))
                        return -EFAULT;
        }

        return 0;
}

int io_epoll_ctl(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_epoll *ie = io_kiocb_to_cmd(req, struct io_epoll);
        int ret;
        bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;

        ret = do_epoll_ctl(ie->epfd, ie->op, ie->fd, &ie->event, force_nonblock);
        if (force_nonblock && ret == -EAGAIN)
                return -EAGAIN;

        if (ret < 0)
                req_set_fail(req);
        io_req_set_res(req, ret, 0);
        return IOU_COMPLETE;
}

int io_epoll_wait_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_epoll_wait *iew = io_kiocb_to_cmd(req, struct io_epoll_wait);

        if (sqe->off || sqe->rw_flags || sqe->buf_index || sqe->splice_fd_in)
                return -EINVAL;

        iew->maxevents = READ_ONCE(sqe->len);
        iew->events = u64_to_user_ptr(READ_ONCE(sqe->addr));
        return 0;
}

int io_epoll_wait(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_epoll_wait *iew = io_kiocb_to_cmd(req, struct io_epoll_wait);
        int ret;

        ret = epoll_sendevents(req->file, iew->events, iew->maxevents);
        if (ret == 0)
                return -EAGAIN;
        if (ret < 0)
                req_set_fail(req);

        io_req_set_res(req, ret, 0);
        return IOU_COMPLETE;
}