// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/io_uring.h>
#include <linux/splice.h>

#include <uapi/linux/io_uring.h>

#include "filetable.h"
#include "io_uring.h"
#include "splice.h"

struct io_splice {
        struct file                     *file_out;
        loff_t                          off_out;
        loff_t                          off_in;
        u64                             len;
        int                             splice_fd_in;
        unsigned int                    flags;
        struct io_rsrc_node             *rsrc_node;
};

static int __io_splice_prep(struct io_kiocb *req,
                            const struct io_uring_sqe *sqe)
{
        struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);
        unsigned int valid_flags = SPLICE_F_FD_IN_FIXED | SPLICE_F_ALL;

        sp->len = READ_ONCE(sqe->len);
        sp->flags = READ_ONCE(sqe->splice_flags);
        if (unlikely(sp->flags & ~valid_flags))
                return -EINVAL;
        sp->splice_fd_in = READ_ONCE(sqe->splice_fd_in);
        sp->rsrc_node = NULL;
        req->flags |= REQ_F_FORCE_ASYNC;
        return 0;
}

int io_tee_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        if (READ_ONCE(sqe->splice_off_in) || READ_ONCE(sqe->off))
                return -EINVAL;
        return __io_splice_prep(req, sqe);
}

void io_splice_cleanup(struct io_kiocb *req)
{
        struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);

        if (sp->rsrc_node)
                io_put_rsrc_node(req->ctx, sp->rsrc_node);
}

static struct file *io_splice_get_file(struct io_kiocb *req,
                                       unsigned int issue_flags)
{
        struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);
        struct io_ring_ctx *ctx = req->ctx;
        struct io_rsrc_node *node;
        struct file *file = NULL;

        if (!(sp->flags & SPLICE_F_FD_IN_FIXED))
                return io_file_get_normal(req, sp->splice_fd_in);

        io_ring_submit_lock(ctx, issue_flags);
        node = io_rsrc_node_lookup(&ctx->file_table.data, sp->splice_fd_in);
        if (node) {
                node->refs++;
                sp->rsrc_node = node;
                file = io_slot_file(node);
                req->flags |= REQ_F_NEED_CLEANUP;
        }
        io_ring_submit_unlock(ctx, issue_flags);
        return file;
}

int io_tee(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);
        struct file *out = sp->file_out;
        unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED;
        struct file *in;
        ssize_t ret = 0;

        WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK);

        in = io_splice_get_file(req, issue_flags);
        if (!in) {
                ret = -EBADF;
                goto done;
        }

        if (sp->len)
                ret = do_tee(in, out, sp->len, flags);

        if (!(sp->flags & SPLICE_F_FD_IN_FIXED))
                fput(in);
done:
        if (ret != sp->len)
                req_set_fail(req);
        io_req_set_res(req, ret, 0);
        return IOU_COMPLETE;
}

int io_splice_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);

        sp->off_in = READ_ONCE(sqe->splice_off_in);
        sp->off_out = READ_ONCE(sqe->off);
        return __io_splice_prep(req, sqe);
}

int io_splice(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);
        struct file *out = sp->file_out;
        unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED;
        loff_t *poff_in, *poff_out;
        struct file *in;
        ssize_t ret = 0;

        WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK);

        in = io_splice_get_file(req, issue_flags);
        if (!in) {
                ret = -EBADF;
                goto done;
        }

        poff_in = (sp->off_in == -1) ? NULL : &sp->off_in;
        poff_out = (sp->off_out == -1) ? NULL : &sp->off_out;

        if (sp->len)
                ret = do_splice(in, poff_in, out, poff_out, sp->len, flags);

        if (!(sp->flags & SPLICE_F_FD_IN_FIXED))
                fput(in);
done:
        if (ret != sp->len)
                req_set_fail(req);
        io_req_set_res(req, ret, 0);
        return IOU_COMPLETE;
}