Kernel/Devices/ZeroDevice.cpp


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
36
37
38
39
40

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

#include "ZeroDevice.h"
#include <AK/Memory.h>
#include <AK/StdLibExtras.h>

namespace Kernel {

UNMAP_AFTER_INIT ZeroDevice::ZeroDevice()
    : CharacterDevice(1, 5)
{
}

UNMAP_AFTER_INIT ZeroDevice::~ZeroDevice()
{
}

bool ZeroDevice::can_read(const FileDescription&, size_t) const
{
    return true;
}

KResultOr<size_t> ZeroDevice::read(FileDescription&, u64, UserOrKernelBuffer& buffer, size_t size)
{
    ssize_t count = min(static_cast<size_t>(PAGE_SIZE), size);
    if (!buffer.memset(0, count))
        return EFAULT;
    return count;
}

KResultOr<size_t> ZeroDevice::write(FileDescription&, u64, const UserOrKernelBuffer&, size_t size)
{
    return min(static_cast<size_t>(PAGE_SIZE), size);
}

}