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Kernel/FileSystem/FATFS: Support FAT16 file system clusters

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Taj Morton 2023-07-29 20:35:00 -07:00 • committed by Andrew Kaster
parent 67f567348f
commit 1f70a728f0
2 changed files with 92 additions and 8 deletions
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16
Kernel/FileSystem/FATFS/Inode.h
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@ -30,8 +30,16 @@ public:
private:
FATInode(FATFS&, FATEntry, NonnullOwnPtr<KString> filename);
static constexpr u32 no_more_clusters = 0x0FFFFFF8;
static constexpr u32 cluster_number_mask = 0x0FFFFFFF;
// Number of bytes used to store a cluster within the table.
size_t cluster_size() const;
// Returns cluster number value that indicates the end of the chain
// has been reached. Any cluster value >= this value indicates this
// is the last cluster.
u32 end_of_chain_marker() const;
// Reads the cluster number located at the offset within the table.
u32 cluster_number(KBuffer const& fat_sector, u32 entry_offset) const;
static constexpr u8 end_entry_byte = 0x00;
static constexpr u8 unused_entry_byte = 0xE5;
@ -49,6 +57,10 @@ private:
ErrorOr<NonnullOwnPtr<KBuffer>> read_block_list();
ErrorOr<RefPtr<FATInode>> traverse(Function<ErrorOr<bool>(RefPtr<FATInode>)> callback);
u32 first_cluster() const;
// This overload of `first_cluster` does not rely on the base Inode
// already being created to determine the FAT version. It is used
// during FATInode creation (create()).
u32 first_cluster(FATVersion const version) const;
// ^Inode
virtual ErrorOr<size_t> write_bytes_locked(off_t, size_t, UserOrKernelBuffer const& data, OpenFileDescription*) override;