mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2024-12-29 06:02:07 +03:00
aee4786d8e
This singleton simplifies many aspects that we struggled with before: 1. There's no need to make derived classes of Device expose the constructor as public anymore. The singleton is a friend of them, so he can call the constructor. This solves the issue with try_create_device helper neatly, hopefully for good. 2. Getting a reference of the NullDevice is now being done from this singleton, which means that NullDevice no longer needs to use its own singleton, and we can apply the try_create_device helper on it too :) 3. We can now defer registration completely after the Device constructor which means the Device constructor is merely assigning the major and minor numbers of the Device, and the try_create_device helper ensures it calls the after_inserting method immediately after construction. This creates a great opportunity to make registration more OOM-safe.
47 lines
1.0 KiB
C++
47 lines
1.0 KiB
C++
/*
|
|
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
|
|
*
|
|
* SPDX-License-Identifier: BSD-2-Clause
|
|
*/
|
|
|
|
#include <AK/Singleton.h>
|
|
#include <Kernel/Devices/DeviceManagement.h>
|
|
#include <Kernel/Devices/NullDevice.h>
|
|
#include <Kernel/Sections.h>
|
|
|
|
namespace Kernel {
|
|
|
|
UNMAP_AFTER_INIT NonnullRefPtr<NullDevice> NullDevice::must_initialize()
|
|
{
|
|
auto null_device_or_error = DeviceManagement::try_create_device<NullDevice>();
|
|
// FIXME: Find a way to propagate errors
|
|
VERIFY(!null_device_or_error.is_error());
|
|
return null_device_or_error.release_value();
|
|
}
|
|
|
|
UNMAP_AFTER_INIT NullDevice::NullDevice()
|
|
: CharacterDevice(1, 3)
|
|
{
|
|
}
|
|
|
|
UNMAP_AFTER_INIT NullDevice::~NullDevice()
|
|
{
|
|
}
|
|
|
|
bool NullDevice::can_read(const OpenFileDescription&, size_t) const
|
|
{
|
|
return true;
|
|
}
|
|
|
|
KResultOr<size_t> NullDevice::read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
KResultOr<size_t> NullDevice::write(OpenFileDescription&, u64, const UserOrKernelBuffer&, size_t buffer_size)
|
|
{
|
|
return buffer_size;
|
|
}
|
|
|
|
}
|