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https://github.com/SerenityOS/serenity
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96e1391c23
This change has many improvements: - We don't use `LockRefPtr` to hold instances of many base devices as with the DeviceManagement class. Instead, we have a saner pattern of holding them in a `NonnullRefPtr<T> const`, in a small-text footprint class definition in the `Device.cpp` file. - The awkwardness of using `::the()` each time we need to get references to mostly-static objects (like the Event queue) in runtime is now gone in the migration to using the `Device` class. - Acquiring a device feel more obvious because we use now the Device class for this method. The method name is improved as well.
46 lines
1.1 KiB
C++
46 lines
1.1 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Singleton.h>
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#include <Kernel/API/MajorNumberAllocation.h>
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#include <Kernel/Devices/Device.h>
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#include <Kernel/Devices/Generic/NullDevice.h>
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#include <Kernel/Sections.h>
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namespace Kernel {
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UNMAP_AFTER_INIT NonnullLockRefPtr<NullDevice> NullDevice::must_initialize()
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{
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auto null_device_or_error = Device::try_create_device<NullDevice>();
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// FIXME: Find a way to propagate errors
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VERIFY(!null_device_or_error.is_error());
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return null_device_or_error.release_value();
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}
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UNMAP_AFTER_INIT NullDevice::NullDevice()
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: CharacterDevice(MajorAllocation::CharacterDeviceFamily::Generic, 3)
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{
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}
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UNMAP_AFTER_INIT NullDevice::~NullDevice() = default;
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bool NullDevice::can_read(OpenFileDescription const&, u64) const
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{
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return true;
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}
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ErrorOr<size_t> NullDevice::read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t)
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{
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return 0;
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}
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ErrorOr<size_t> NullDevice::write(OpenFileDescription&, u64, UserOrKernelBuffer const&, size_t buffer_size)
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{
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return buffer_size;
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}
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}
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