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https://github.com/fergalmoran/ladybird.git
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33f00a7efb
Caching the cluster list allows us to fill the two fields in the InodeMetadata. While at it, don't cache the metadata as when we have write support having to keep both InodeMetadata and FATEntry correct is going to get very annoying.
111 lines
3.6 KiB
C++
111 lines
3.6 KiB
C++
/*
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* Copyright (c) 2022-2024, Undefine <undefine@undefine.pl>
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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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#include <AK/OwnPtr.h>
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#include <AK/RefPtr.h>
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#include <AK/Types.h>
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#include <Kernel/FileSystem/BlockBasedFileSystem.h>
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#include <Kernel/FileSystem/FATFS/Definitions.h>
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#include <Kernel/FileSystem/Inode.h>
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#include <Kernel/Forward.h>
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#include <Kernel/Library/KBuffer.h>
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namespace Kernel {
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class DOSBIOSParameterBlock final {
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private:
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KBuffer const* const m_boot_record;
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const struct DOS4BIOSParameterBlock* m_dos4_block;
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const struct DOS7BIOSParameterBlock* m_dos7_block;
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const struct DOS3BIOSParameterBlock* m_common_block;
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public:
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DOSBIOSParameterBlock(KBuffer const* const boot_record)
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: m_boot_record(boot_record)
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, m_dos4_block(reinterpret_cast<const struct DOS4BIOSParameterBlock*>(boot_record->bytes().offset_pointer(0x024)))
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, m_dos7_block(reinterpret_cast<const struct DOS7BIOSParameterBlock*>(boot_record->bytes().offset_pointer(0x024)))
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, m_common_block(reinterpret_cast<const struct DOS3BIOSParameterBlock*>(boot_record->bytes().data()))
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{
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}
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DOSBIOSParameterBlockVersion bpb_version() const;
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DOS3BIOSParameterBlock const* common_bpb() const;
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DOS4BIOSParameterBlock const* dos4_bpb() const;
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DOS7BIOSParameterBlock const* dos7_bpb() const;
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u16 sectors_per_fat() const;
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u32 sector_count() const;
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u8 signature() const;
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};
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// Represents a block of contiguous sectors to read. This typically represents a
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// cluster, but is also used to define areas of the root directory region.
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struct FatBlockSpan {
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BlockBasedFileSystem::BlockIndex start_block;
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size_t number_of_sectors;
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};
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class FATFS final : public BlockBasedFileSystem {
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friend FATInode;
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public:
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static ErrorOr<NonnullRefPtr<FileSystem>> try_create(OpenFileDescription&, ReadonlyBytes);
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virtual ~FATFS() override = default;
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virtual StringView class_name() const override { return "FATFS"sv; }
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virtual Inode& root_inode() override;
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virtual u8 internal_file_type_to_directory_entry_type(DirectoryEntryView const& entry) const override;
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private:
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virtual ErrorOr<void> initialize_while_locked() override;
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virtual bool is_initialized_while_locked() override;
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// FIXME: This is not a proper way to clear last mount of a FAT filesystem,
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// but for now we simply have no other way to properly do it.
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virtual ErrorOr<void> prepare_to_clear_last_mount(Inode&) override { return {}; }
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FATFS(OpenFileDescription&);
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static constexpr u8 signature_1 = 0x28;
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static constexpr u8 signature_2 = 0x29;
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static constexpr u32 fs_info_signature_1 = 0x41615252;
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static constexpr u32 fs_info_signature_2 = 0x61417272;
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static constexpr u32 fs_info_signature_3 = 0xAA550000;
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static constexpr u32 first_data_cluster = 2;
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FatBlockSpan first_block_of_cluster(u32 cluster) const;
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size_t fat_offset_for_cluster(u32 cluster) const;
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// Reads the cluster number located at the offset within the table.
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u32 cluster_number(KBuffer const& fat_sector, u32 entry_cluster_number, u32 entry_offset) const;
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// Returns cluster number value that indicates the end of the chain
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// has been reached. Any cluster value >= this value indicates this
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// is the last cluster.
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u32 end_of_chain_marker() const;
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ErrorOr<u32> fat_read(u32 cluster);
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ErrorOr<void> fat_write(u32 cluster, u32 value);
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OwnPtr<KBuffer> m_boot_record;
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FAT32FSInfo m_fs_info;
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OwnPtr<DOSBIOSParameterBlock> m_parameter_block;
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RefPtr<FATInode> m_root_inode;
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u32 m_first_data_sector { 0 };
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FATVersion m_fat_version;
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};
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}
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