ladybird/Kernel/Devices/MemoryDevice.h
Andreas Kling 30861daa93 Kernel: Simplify the File memory-mapping API
Before this change, we had File::mmap() which did all the work of
setting up a VMObject, and then creating a Region in the current
process's address space.

This patch simplifies the interface by removing the region part.
Files now only have to return a suitable VMObject from
vmobject_for_mmap(), and then sys$mmap() itself will take care of
actually mapping it into the address space.

This fixes an issue where we'd try to block on I/O (for inode metadata
lookup) while holding the address space spinlock. It also reduces time
spent holding the address space lock.
2022-08-24 14:57:51 +02:00

38 lines
1.2 KiB
C++

/*
* Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Types.h>
#include <Kernel/Devices/CharacterDevice.h>
#include <Kernel/PhysicalAddress.h>
namespace Kernel {
class MemoryDevice final : public CharacterDevice {
friend class DeviceManagement;
public:
static NonnullLockRefPtr<MemoryDevice> must_create();
~MemoryDevice();
virtual ErrorOr<NonnullLockRefPtr<Memory::VMObject>> vmobject_for_mmap(Process&, Memory::VirtualRange const&, u64& offset, bool shared) override;
private:
MemoryDevice();
virtual StringView class_name() const override { return "MemoryDevice"sv; }
virtual bool can_read(OpenFileDescription const&, u64) const override { return true; }
virtual bool can_write(OpenFileDescription const&, u64) const override { return false; }
virtual bool is_seekable() const override { return true; }
virtual ErrorOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override;
virtual ErrorOr<size_t> write(OpenFileDescription&, u64, UserOrKernelBuffer const&, size_t) override { return EINVAL; }
bool is_allowed_range(PhysicalAddress, Memory::VirtualRange const&) const;
};
}