// Copyright 2022 The ChromiumOS Authors

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file.

use std::cmp::max;

use std::cmp::min;

use anyhow::Context;

use base::unix::iov_max;

use cros_async::Executor;

use disk::DiskFile;

use crate::virtio::block::DiskOption;

use crate::virtio::BlockAsync;

pub fn get_seg_max(queue_size: u16) -> u32 {

    let seg_max = min(max(iov_max(), 1), u32::MAX as usize) as u32;

    // Since we do not currently support indirect descriptors, the maximum

    // number of segments must be smaller than the queue size.

    // In addition, the request header and status each consume a descriptor.

    min(seg_max, u32::from(queue_size) - 2)

}

impl DiskOption {

    /// Open the specified disk file.

    pub fn open(&self) -> anyhow::Result<Box<dyn DiskFile>> {

        disk::open_disk_file(disk::DiskFileParams {

            path: self.path.clone(),

            is_read_only: self.read_only,

            is_sparse_file: self.sparse,

            is_overlapped: false,

            is_direct: self.direct,

            lock: self.lock,

            depth: 0,

        })

        .context("open_disk_file failed")

    }

}

impl BlockAsync {

    pub fn create_executor(&self) -> Executor {

        Executor::with_executor_kind(self.executor_kind).expect("Failed to create an executor")

    }

}