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79fa9765ca
We now use AK::Error and AK::ErrorOr<T> in both kernel and userspace! This was a slightly tedious refactoring that took a long time, so it's not unlikely that some bugs crept in. Nevertheless, it does pass basic functionality testing, and it's just real nice to finally see the same pattern in all contexts. :^)
66 lines
2.3 KiB
C++
66 lines
2.3 KiB
C++
/*
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* Copyright (c) 2018-2021, 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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#pragma once
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// KBuffer: Memory buffer backed by a kernel region.
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//
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// The memory is allocated via the global kernel-only page allocator, rather than via
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// kmalloc() which is what ByteBuffer/Vector/etc will use.
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//
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// This makes KBuffer a little heavier to allocate, but much better for large and/or
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// long-lived allocations, since they don't put all that weight and pressure on the
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// severely limited kmalloc heap.
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#include <AK/Assertions.h>
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#include <AK/Memory.h>
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#include <AK/StringView.h>
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#include <Kernel/Memory/MemoryManager.h>
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namespace Kernel {
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class [[nodiscard]] KBuffer {
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public:
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static ErrorOr<NonnullOwnPtr<KBuffer>> try_create_with_size(size_t size, Memory::Region::Access access = Memory::Region::Access::ReadWrite, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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auto region = TRY(MM.allocate_kernel_region(Memory::page_round_up(size), name, access, strategy));
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return TRY(adopt_nonnull_own_or_enomem(new (nothrow) KBuffer { size, move(region) }));
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}
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static ErrorOr<NonnullOwnPtr<KBuffer>> try_create_with_bytes(ReadonlyBytes bytes, Memory::Region::Access access = Memory::Region::Access::ReadWrite, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
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{
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auto buffer = TRY(try_create_with_size(bytes.size(), access, name, strategy));
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memcpy(buffer->data(), bytes.data(), bytes.size());
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return buffer;
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}
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[[nodiscard]] u8* data() { return m_region->vaddr().as_ptr(); }
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[[nodiscard]] u8 const* data() const { return m_region->vaddr().as_ptr(); }
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[[nodiscard]] size_t size() const { return m_size; }
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[[nodiscard]] size_t capacity() const { return m_region->size(); }
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[[nodiscard]] ReadonlyBytes bytes() const { return { data(), size() }; }
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[[nodiscard]] Bytes bytes() { return { data(), size() }; }
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void set_size(size_t size)
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{
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VERIFY(size <= capacity());
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m_size = size;
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}
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private:
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explicit KBuffer(size_t size, NonnullOwnPtr<Memory::Region> region)
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: m_size(size)
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, m_region(move(region))
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{
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}
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size_t m_size { 0 };
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NonnullOwnPtr<Memory::Region> m_region;
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};
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}
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