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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.
51 lines
1.2 KiB
C++
51 lines
1.2 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 <Kernel/Devices/DeviceManagement.h>
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#include <Kernel/Devices/RandomDevice.h>
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#include <Kernel/Random.h>
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#include <Kernel/Sections.h>
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namespace Kernel {
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UNMAP_AFTER_INIT NonnullRefPtr<RandomDevice> RandomDevice::must_create()
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{
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auto random_device_or_error = DeviceManagement::try_create_device<RandomDevice>();
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// FIXME: Find a way to propagate errors
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VERIFY(!random_device_or_error.is_error());
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return random_device_or_error.release_value();
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}
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UNMAP_AFTER_INIT RandomDevice::RandomDevice()
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: CharacterDevice(1, 8)
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{
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}
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UNMAP_AFTER_INIT RandomDevice::~RandomDevice()
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{
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}
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bool RandomDevice::can_read(const OpenFileDescription&, size_t) const
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{
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return true;
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}
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KResultOr<size_t> RandomDevice::read(OpenFileDescription&, u64, UserOrKernelBuffer& buffer, size_t size)
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{
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return buffer.write_buffered<256>(size, [&](Bytes bytes) {
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get_good_random_bytes(bytes);
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return bytes.size();
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});
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}
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KResultOr<size_t> RandomDevice::write(OpenFileDescription&, u64, const UserOrKernelBuffer&, size_t size)
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{
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// FIXME: Use input for entropy? I guess that could be a neat feature?
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return size;
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}
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}
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