Kernel/Devices/NullDevice.h


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include "CharacterDevice.h"

namespace Kernel {

class NullDevice final : public CharacterDevice {
    AK_MAKE_ETERNAL
public:
    NullDevice();
    virtual ~NullDevice() override;

    static void initialize();
    static NullDevice& the();

    // ^Device
    virtual mode_t required_mode() const override { return 0666; }
    virtual String device_name() const override { return "null"; }

private:
    // ^CharacterDevice
    virtual KResultOr<size_t> read(FileDescription&, u64, UserOrKernelBuffer&, size_t) override;
    virtual KResultOr<size_t> write(FileDescription&, u64, const UserOrKernelBuffer&, size_t) override;
    virtual bool can_write(const FileDescription&, size_t) const override { return true; }
    virtual bool can_read(const FileDescription&, size_t) const override;
    virtual const char* class_name() const override { return "NullDevice"; }
};

}