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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
// KBuffer: Statically sized kernel-only memory buffer.
//
// A KBuffer is a value-type convenience class that wraps a NonnullRefPtr<KBufferImpl>.
// The memory is allocated via the global kernel-only page allocator, rather than via
// kmalloc() which is what ByteBuffer/Vector/etc will use.
//
// This makes KBuffer a little heavier to allocate, but much better for large and/or
// long-lived allocations, since they don't put all that weight and pressure on the
// severely limited kmalloc heap.
#include <AK/Assertions.h>
#include <AK/ByteBuffer.h>
#include <AK/Memory.h>
#include <AK/StringView.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/Region.h>
namespace Kernel {
class KBufferImpl : public RefCounted<KBufferImpl> {
public:
static RefPtr<KBufferImpl> try_create_with_size(size_t size, Region::Access access, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
{
auto region = MM.allocate_kernel_region(page_round_up(size), name, access, strategy);
if (!region)
return nullptr;
return adopt_ref_if_nonnull(new (nothrow) KBufferImpl(region.release_nonnull(), size, strategy));
}
static RefPtr<KBufferImpl> try_create_with_bytes(ReadonlyBytes bytes, Region::Access access, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
{
auto region = MM.allocate_kernel_region(page_round_up(bytes.size()), name, access, strategy);
if (!region)
return nullptr;
memcpy(region->vaddr().as_ptr(), bytes.data(), bytes.size());
return adopt_ref_if_nonnull(new (nothrow) KBufferImpl(region.release_nonnull(), bytes.size(), strategy));
}
static RefPtr<KBufferImpl> create_with_size(size_t size, Region::Access access, StringView name, AllocationStrategy strategy = AllocationStrategy::Reserve)
{
return try_create_with_size(size, access, name, strategy);
}
static RefPtr<KBufferImpl> copy(const void* data, size_t size, Region::Access access, StringView name)
{
auto buffer = create_with_size(size, access, name, AllocationStrategy::AllocateNow);
if (!buffer)
return {};
memcpy(buffer->data(), data, size);
return buffer;
}
[[nodiscard]] bool expand(size_t new_capacity)
{
auto new_region = MM.allocate_kernel_region(page_round_up(new_capacity), m_region->name(), m_region->access(), m_allocation_strategy);
if (!new_region)
return false;
if (m_size > 0)
memcpy(new_region->vaddr().as_ptr(), data(), min(m_region->size(), m_size));
m_region = new_region.release_nonnull();
return true;
}
[[nodiscard]] u8* data() { return m_region->vaddr().as_ptr(); }
[[nodiscard]] const u8* data() const { return m_region->vaddr().as_ptr(); }
[[nodiscard]] size_t size() const { return m_size; }
[[nodiscard]] size_t capacity() const { return m_region->size(); }
void set_size(size_t size)
{
VERIFY(size <= capacity());
m_size = size;
}
[[nodiscard]] const Region& region() const { return *m_region; }
[[nodiscard]] Region& region() { return *m_region; }
private:
explicit KBufferImpl(NonnullOwnPtr<Region>&& region, size_t size, AllocationStrategy strategy)
: m_size(size)
, m_allocation_strategy(strategy)
, m_region(move(region))
{
}
size_t m_size { 0 };
AllocationStrategy m_allocation_strategy { AllocationStrategy::Reserve };
NonnullOwnPtr<Region> m_region;
};
class [[nodiscard]] KBuffer {
public:
explicit KBuffer(RefPtr<KBufferImpl>&& impl)
: m_impl(move(impl))
{
}
[[nodiscard]] static OwnPtr<KBuffer> try_create_with_size(size_t size, Region::Access access = Region::Access::Read | Region::Access::Write, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
{
auto impl = KBufferImpl::try_create_with_size(size, access, name, strategy);
if (!impl)
return {};
return adopt_own_if_nonnull(new (nothrow) KBuffer(impl.release_nonnull()));
}
[[nodiscard]] static OwnPtr<KBuffer> try_create_with_bytes(ReadonlyBytes bytes, Region::Access access = Region::Access::Read | Region::Access::Write, StringView name = "KBuffer", AllocationStrategy strategy = AllocationStrategy::Reserve)
{
auto impl = KBufferImpl::try_create_with_bytes(bytes, access, name, strategy);
if (!impl)
return {};
return adopt_own_if_nonnull(new (nothrow) KBuffer(impl.release_nonnull()));
}
[[nodiscard]] static KBuffer copy(const void* data, size_t size, Region::Access access = Region::Access::Read | Region::Access::Write, StringView name = "KBuffer")
{
return KBuffer(KBufferImpl::copy(data, size, access, name));
}
[[nodiscard]] bool is_null() const { return !m_impl; }
[[nodiscard]] u8* data() { return m_impl ? m_impl->data() : nullptr; }
[[nodiscard]] const u8* data() const { return m_impl ? m_impl->data() : nullptr; }
[[nodiscard]] size_t size() const { return m_impl ? m_impl->size() : 0; }
[[nodiscard]] size_t capacity() const { return m_impl ? m_impl->capacity() : 0; }
[[nodiscard]] void* end_pointer() { return data() + size(); }
[[nodiscard]] const void* end_pointer() const { return data() + size(); }
void set_size(size_t size) { m_impl->set_size(size); }
[[nodiscard]] KBufferImpl& impl() { return *m_impl; }
[[nodiscard]] const KBufferImpl& impl() const { return *m_impl; }
[[nodiscard]] RefPtr<KBufferImpl> take_impl() { return move(m_impl); }
KBuffer(const ByteBuffer& buffer, Region::Access access = Region::Access::Read | Region::Access::Write, StringView name = "KBuffer")
: m_impl(KBufferImpl::copy(buffer.data(), buffer.size(), access, name))
{
}
private:
RefPtr<KBufferImpl> m_impl;
};
}
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