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1089 lines
19 KiB
1089 lines
19 KiB
/*++
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Copyright (c) 1990 Microsoft Corporation
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Module Name:
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fat.hxx
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Abstract:
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This class models a file allocation table. The composition is of
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virtual functions because there are two different kinds of file
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allocation tables. A user of this class will be able to manipulate
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the FAT regardless of the implementation.
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Author:
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Norbert P. Kusters (norbertk) 6-Dec-90
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--*/
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#if !defined(FAT_DEFN)
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#define FAT_DEFN
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#include "secrun.hxx"
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#if defined ( _AUTOCHECK_ )
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#define UFAT_EXPORT
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#elif defined ( _UFAT_MEMBER_ )
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#define UFAT_EXPORT __declspec(dllexport)
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#else
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#define UFAT_EXPORT __declspec(dllimport)
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#endif
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//
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// Forward references
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//
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DECLARE_CLASS( FAT );
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DECLARE_CLASS( BITVECTOR );
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CONST ULONG FirstDiskCluster = 2;
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CONST ULONG MaxNumClusForSmallFat = 4086;
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// - flags to denote three state FAT type
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CONST ULONG MinNumClusForFat32 = 65526; // Min # Fat32 clusters is 65525
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// The largest FAT16 entry goes
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// up to 65527
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CONST fFat12 = 12;
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CONST fFat16 = 16;
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CONST fFat32 = 32;
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class FAT : public SECRUN {
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public:
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DECLARE_CONSTRUCTOR(FAT);
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VIRTUAL
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~FAT(
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);
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NONVIRTUAL
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BOOLEAN
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Initialize(
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IN OUT PMEM Mem,
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IN OUT PLOG_IO_DP_DRIVE Drive,
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IN LBN StartSector,
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IN ULONG NumOfEntries,
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IN ULONG NumSectors DEFAULT 0
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);
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NONVIRTUAL
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BOOLEAN
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Initialize(
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IN OUT PSECRUN Srun,
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IN OUT PMEM Mem,
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IN OUT PLOG_IO_DP_DRIVE Drive,
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IN LBN StartSector,
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IN ULONG NumOfEntries,
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IN ULONG NumSectors DEFAULT 0
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);
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NONVIRTUAL
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ULONG
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QueryEntry(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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VOID
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SetEntry(
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IN ULONG ClusterNumber,
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IN ULONG Value
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);
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NONVIRTUAL
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BOOLEAN
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IsInRange(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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BOOLEAN
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IsClusterFree(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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VOID
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SetClusterFree(
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IN ULONG ClusterNumber
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);
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NONVIRTUAL
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BOOLEAN
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IsEndOfChain(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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VOID
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SetEndOfChain(
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IN ULONG ClusterNumber
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);
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NONVIRTUAL
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BOOLEAN
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IsClusterBad(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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VOID
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SetClusterBad(
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IN ULONG ClusterNumber
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);
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NONVIRTUAL
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BOOLEAN
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IsClusterReserved(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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VOID
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SetClusterReserved(
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IN ULONG ClusterNumber
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);
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NONVIRTUAL
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VOID
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SetEarlyEntries(
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IN UCHAR MediaByte
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);
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NONVIRTUAL
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UCHAR
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QueryMediaByte(
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) CONST;
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NONVIRTUAL
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ULONG
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QueryFreeClusters(
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) CONST;
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NONVIRTUAL
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ULONG
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QueryBadClusters(
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) CONST;
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NONVIRTUAL
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ULONG
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QueryReservedClusters(
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) CONST;
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NONVIRTUAL
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UFAT_EXPORT
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ULONG
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QueryAllocatedClusters(
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) CONST;
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NONVIRTUAL
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UFAT_EXPORT
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ULONG
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QueryNthCluster(
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IN ULONG StartingCluster,
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IN ULONG Index
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) CONST;
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NONVIRTUAL
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UFAT_EXPORT
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ULONG
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QueryLengthOfChain(
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IN ULONG StartingCluster,
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OUT PULONG LastCluster DEFAULT NULL
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) CONST;
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NONVIRTUAL
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ULONG
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QueryLengthOfChain(
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IN ULONG StartingCluster,
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IN ULONG EndingCluster
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) CONST;
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NONVIRTUAL
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ULONG
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QueryPrevious(
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IN ULONG Cluster
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) CONST;
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NONVIRTUAL
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VOID
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Scrub(
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OUT PBOOLEAN ChangesMade DEFAULT NULL
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);
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NONVIRTUAL
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VOID
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ScrubChain(
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IN ULONG StartingCluster,
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OUT PBOOLEAN ChangesMade
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);
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NONVIRTUAL
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VOID
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ScrubChain(
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IN ULONG StartingCluster,
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OUT PBITVECTOR UsedClusters,
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OUT PBOOLEAN ChangesMade,
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OUT PBOOLEAN CrossLinkDetected,
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OUT PULONG CrossLinkPreviousCluster
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);
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NONVIRTUAL
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BOOLEAN
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IsValidChain(
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IN ULONG StartingCluster
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) CONST;
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NONVIRTUAL
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UFAT_EXPORT
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ULONG
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AllocChain(
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IN ULONG Length,
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OUT PULONG LastCluster DEFAULT NULL
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);
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NONVIRTUAL
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ULONG
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ReAllocChain(
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IN ULONG StartOfChain,
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IN ULONG NewLength,
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OUT PULONG LastCluster DEFAULT NULL
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);
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NONVIRTUAL
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UFAT_EXPORT
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VOID
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FreeChain(
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IN ULONG StartOfChain
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);
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NONVIRTUAL
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ULONG
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RemoveChain(
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IN ULONG PreceedingCluster,
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IN ULONG LastCluster
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);
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NONVIRTUAL
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VOID
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InsertChain(
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IN ULONG StartOfChain,
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IN ULONG EndOfChain,
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IN ULONG PreceedingCluster
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);
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NONVIRTUAL
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ULONG
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InsertChain(
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IN ULONG StartOfChain,
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IN ULONG Cluster
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);
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NONVIRTUAL
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ULONG
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QueryAllocatedClusterCount(
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VOID
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) ;
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NONVIRTUAL
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VOID
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InvalidateAllocatedClusterCount(
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VOID
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) ;
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private:
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NONVIRTUAL
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VOID
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Construct(
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);
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NONVIRTUAL
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VOID
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Destroy(
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);
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NONVIRTUAL
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ULONG
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Index(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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UFAT_EXPORT
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ULONG
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Index12(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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ULONG
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Index16(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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ULONG
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Index32(
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IN ULONG ClusterNumber
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) CONST;
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NONVIRTUAL
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VOID
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Set(
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IN ULONG ClusterNumber,
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IN ULONG Value
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);
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NONVIRTUAL
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UFAT_EXPORT
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VOID
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Set12(
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IN ULONG ClusterNumber,
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IN ULONG Value
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);
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NONVIRTUAL
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VOID
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Set16(
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IN ULONG ClusterNumber,
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IN ULONG Value
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);
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NONVIRTUAL
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VOID
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Set32(
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IN ULONG ClusterNumber,
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IN ULONG Value
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);
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PVOID _fat;
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ULONG _num_entries;
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ULONG _low_end_of_chain; // 0xFFF8 or 0x0FF8
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ULONG _end_of_chain; // 0xFFFF or 0x0FFF
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ULONG _bad_cluster; // 0xFFF7 or 0x0FF7
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ULONG _low_reserved; // 0xFFF0 or 0x0FF0
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ULONG _high_reserved; // 0xFFF6 or 0x0FF6
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UCHAR _fat_bits; // Replacing _is_big with count of bits in FAT entry
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// BOOLEAN _is_big; // Boolean TRUE for FAT16, FALSE for FAT12
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ULONG _AllocatedClusters; // Count of allocated clusters
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};
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INLINE
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BOOLEAN
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FAT::IsInRange(
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IN ULONG ClusterNumber
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) CONST
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/*++
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Routine Description:
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This routine computes whether or not ClusterNumber is a cluster on
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the disk.
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Arguments:
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ClusterNumber - Supplies the cluster to be checked.
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Return Value:
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FALSE - The cluster is not on the disk.
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TRUE - The cluster is on the disk.
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--*/
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{
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return (FirstDiskCluster <= ClusterNumber && ClusterNumber < _num_entries);
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}
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INLINE
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ULONG
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FAT::Index16(
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IN ULONG ClusterNumber
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) CONST
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/*++
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Routine Description:
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This routine indexes the FAT as 16 bit little endian entries.
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Arguments:
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ClusterNumber - Supplies the FAT entry desired.
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Return Value:
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The value of the FAT entry at ClusterNumber.
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--*/
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{
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//DebugAssert(IsInRange(ClusterNumber));
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return (ULONG )(((PUSHORT) _fat)[ClusterNumber]);
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}
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INLINE
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ULONG
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FAT::Index32(
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IN ULONG ClusterNumber
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) CONST
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/*++
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Routine Description:
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This routine indexes the FAT as 32 bit little endian entries.
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Arguments:
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ClusterNumber - Supplies the FAT entry desired.
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Return Value:
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The value of the 32 (actually 28) bit FAT entry at ClusterNumber.
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--*/
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{
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//DebugAssert(IsInRange(ClusterNumber));
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return (((PULONG) _fat)[ClusterNumber]) & 0x0FFFFFFF;
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}
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INLINE
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ULONG
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FAT::Index(
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IN ULONG ClusterNumber
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) CONST
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/*++
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Routine Description:
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This routine indexes the FAT as 16 bit or 12 bit little endian entries.
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Arguments:
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ClusterNumber - Supplies the FAT entry desired.
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Return Value:
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The value of the FAT entry at ClusterNumber.
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--*/
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{
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if (fFat12 == _fat_bits)
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return Index12(ClusterNumber);
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else if (fFat16 == _fat_bits)
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return Index16(ClusterNumber);
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else
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return Index32(ClusterNumber);
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}
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INLINE
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VOID
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FAT::Set16(
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IN ULONG ClusterNumber,
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IN ULONG Value
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)
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/*++
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Routine Description:
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This routine sets the ClusterNumber'th 16 bit FAT entry to Value.
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Arguments:
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ClusterNumber - Supplies the FAT entry to set.
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Value - Supplies the value to set the FAT entry to.
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Return Value:
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None.
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--*/
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{
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//DebugAssert(IsInRange(ClusterNumber));
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((PUSHORT) _fat)[ClusterNumber] = (USHORT)Value;
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_AllocatedClusters = 0xFFFFFFFF;
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}
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INLINE
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VOID
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FAT::Set32(
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IN ULONG ClusterNumber,
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IN ULONG Value
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)
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/*++
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Routine Description:
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This routine sets the ClusterNumber'th 32 (actually 28) bit FAT entry to Value.
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Arguments:
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ClusterNumber - Supplies the FAT entry to set.
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Value - Supplies the value to set the FAT entry to.
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Return Value:
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None.
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--*/
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{
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//DebugAssert(IsInRange(ClusterNumber));
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((PULONG) _fat)[ClusterNumber] &= 0xF0000000;
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((PULONG) _fat)[ClusterNumber] |= (Value & 0x0FFFFFFF);
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_AllocatedClusters = 0xFFFFFFFF;
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}
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INLINE
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VOID
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FAT::Set(
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IN ULONG ClusterNumber,
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IN ULONG Value
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)
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/*++
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Routine Description:
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This routine sets the ClusterNumber'th 12 bit or 16 bit FAT entry to Value.
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Arguments:
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ClusterNumber - Supplies the FAT entry to set.
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Value - Supplies the value to set the FAT entry to.
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Return Value:
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None.
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--*/
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{
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if (fFat12 == _fat_bits)
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Set12(ClusterNumber, Value);
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else if (fFat16 == _fat_bits)
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Set16(ClusterNumber, Value);
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else
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Set32(ClusterNumber, Value);
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}
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INLINE
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ULONG
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FAT::QueryEntry(
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IN ULONG ClusterNumber
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) CONST
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/*++
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Routine Description:
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This routine returns the FAT value for ClusterNumber.
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Arguments:
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ClusterNumber - Supplies an index into the FAT.
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Return Value:
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The FAT table entry at offset ClusterNumber.
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--*/
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{
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return Index(ClusterNumber);
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}
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INLINE
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ULONG
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FAT::QueryAllocatedClusterCount(
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)
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/*++
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Routine Description:
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This routine computes the total number of clusters for the volume.
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which are allocated.
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Arguments:
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None.
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Return Value:
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The total number of allocated clusters for the volume.
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--*/
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{
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if(_AllocatedClusters == 0xFFFFFFFF)
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{
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if(_fat == NULL) {
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return(0);
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}
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_AllocatedClusters = FAT::QueryAllocatedClusters();
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}
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return _AllocatedClusters;
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}
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|
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INLINE
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VOID
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FAT::InvalidateAllocatedClusterCount(
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)
|
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/*++
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Routine Description:
|
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|
This routine invalidates trhe cached allocated clusters count so that the next
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call to QueryAllocatedClusterCount will re-compute it.
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Arguments:
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None.
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Return Value:
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None.
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--*/
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{
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_AllocatedClusters = 0xFFFFFFFF;
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return;
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}
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|
|
INLINE
|
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VOID
|
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FAT::SetEntry(
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IN ULONG ClusterNumber,
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IN ULONG Value
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)
|
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/*++
|
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Routine Description:
|
|
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|
This routine sets the FAT entry at ClusterNumber to Value.
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|
Arguments:
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ClusterNumber - Supplies the position in the FAT to update.
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Value - Supplies the new value for that position.
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Return Value:
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None.
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--*/
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{
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Set(ClusterNumber, Value);
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}
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|
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INLINE
|
|
BOOLEAN
|
|
FAT::IsClusterFree(
|
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IN ULONG ClusterNumber
|
|
) CONST
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine computes whether of not ClusterNumber is a free cluster.
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|
|
|
Arguments:
|
|
|
|
ClusterNumber - Supplies the cluster to be checked.
|
|
|
|
Return Value:
|
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|
|
FALSE - The cluster is not free.
|
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TRUE - The cluster is free.
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|
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--*/
|
|
{
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return Index(ClusterNumber) == 0;
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}
|
|
|
|
|
|
INLINE
|
|
VOID
|
|
FAT::SetClusterFree(
|
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IN ULONG ClusterNumber
|
|
)
|
|
/*++
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|
|
|
Routine Description:
|
|
|
|
This routine marks the cluster ClusterNumber as free on the FAT.
|
|
|
|
Arguments:
|
|
|
|
ClusterNumber - Supplies the number of the cluster to mark free.
|
|
|
|
Return Value:
|
|
|
|
None.
|
|
|
|
--*/
|
|
{
|
|
Set(ClusterNumber, 0);
|
|
}
|
|
|
|
|
|
INLINE
|
|
BOOLEAN
|
|
FAT::IsEndOfChain(
|
|
IN ULONG ClusterNumber
|
|
) CONST
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine computes whether or not the cluster ClusterNumber is the
|
|
end of its cluster chain.
|
|
|
|
Arguments:
|
|
|
|
ClusterNumber - Supplies the cluster to be checked.
|
|
|
|
Return Value:
|
|
|
|
FALSE - The cluster is not the end of a chain.
|
|
TRUE - The cluster is the end of a chain.
|
|
|
|
--*/
|
|
{
|
|
return Index(ClusterNumber) >= _low_end_of_chain;
|
|
}
|
|
|
|
|
|
INLINE
|
|
VOID
|
|
FAT::SetEndOfChain(
|
|
IN ULONG ClusterNumber
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine sets the cluster ClusterNumber to the end of its cluster
|
|
chain.
|
|
|
|
Arguments:
|
|
|
|
ClusterNumber - Supplies the cluster to be set to end of chain.
|
|
|
|
Return Value:
|
|
|
|
None.
|
|
|
|
--*/
|
|
{
|
|
Set(ClusterNumber, _end_of_chain);
|
|
}
|
|
|
|
|
|
INLINE
|
|
BOOLEAN
|
|
FAT::IsClusterBad(
|
|
IN ULONG ClusterNumber
|
|
) CONST
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine computes whether or not cluster ClusterNumber is bad.
|
|
|
|
Arguments:
|
|
|
|
ClusterNumber - Supplies the number of the cluster to be checked.
|
|
|
|
Return Value:
|
|
|
|
FALSE - The cluster is good.
|
|
TRUE - The cluster is bad.
|
|
|
|
--*/
|
|
{
|
|
return Index(ClusterNumber) == _bad_cluster;
|
|
}
|
|
|
|
|
|
INLINE
|
|
VOID
|
|
FAT::SetClusterBad(
|
|
IN ULONG ClusterNumber
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine sets the cluster ClusterNumber to bad on the FAT.
|
|
|
|
Arguments:
|
|
|
|
ClusterNumber - Supplies the cluster number to mark bad.
|
|
|
|
Return Value:
|
|
|
|
None.
|
|
|
|
--*/
|
|
{
|
|
Set(ClusterNumber, _bad_cluster);
|
|
}
|
|
|
|
|
|
INLINE
|
|
BOOLEAN
|
|
FAT::IsClusterReserved(
|
|
IN ULONG ClusterNumber
|
|
) CONST
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine computes whether or not the cluster ClusterNumber is
|
|
a reserved cluster.
|
|
|
|
Arguments:
|
|
|
|
ClusterNumber - Supplies the cluster to check.
|
|
|
|
Return Value:
|
|
|
|
FALSE - The cluster is not reserved.
|
|
TRUE - The cluster is reserved.
|
|
|
|
--*/
|
|
{
|
|
return Index(ClusterNumber) >= _low_reserved &&
|
|
Index(ClusterNumber) <= _high_reserved;
|
|
}
|
|
|
|
|
|
INLINE
|
|
VOID
|
|
FAT::SetClusterReserved(
|
|
IN ULONG ClusterNumber
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine marks the cluster ClusterNumber as reserved in the FAT.
|
|
|
|
Arguments:
|
|
|
|
ClusterNumber - Supplies the cluster to mark reserved.
|
|
|
|
Return Value:
|
|
|
|
None.
|
|
|
|
--*/
|
|
{
|
|
Set(ClusterNumber, _low_reserved);
|
|
}
|
|
|
|
|
|
INLINE
|
|
UCHAR
|
|
FAT::QueryMediaByte(
|
|
) CONST
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
The media byte for the partition is stored in the first character of the
|
|
FAT. This routine will return its value provided that the two following
|
|
bytes are 0xFF.
|
|
|
|
Arguments:
|
|
|
|
None.
|
|
|
|
Return Value:
|
|
|
|
The media byte for the partition.
|
|
|
|
--*/
|
|
{
|
|
PUCHAR p;
|
|
|
|
p = (PUCHAR) _fat;
|
|
|
|
DebugAssert(p);
|
|
|
|
return (p[2] == 0xFF && p[1] == 0xFF && ((fFat12 != _fat_bits) ? (0x0F == (p[3] & 0x0F)) : TRUE)) ? p[0] : 0;
|
|
}
|
|
|
|
|
|
INLINE
|
|
VOID
|
|
FAT::SetEarlyEntries(
|
|
IN UCHAR MediaByte
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine sets the first two FAT entries as required by the
|
|
FAT file system. The first byte gets set to the media descriptor.
|
|
The remaining bytes gets set to FF.
|
|
|
|
Arguments:
|
|
|
|
MediaByte - Supplies the media byte for the volume.
|
|
|
|
Return Value:
|
|
|
|
None.
|
|
|
|
--*/
|
|
{
|
|
PUCHAR p;
|
|
|
|
p = (PUCHAR) _fat;
|
|
|
|
DebugAssert(p);
|
|
|
|
p[0] = MediaByte;
|
|
p[1] = p[2] = 0xFF;
|
|
|
|
if (fFat32 == _fat_bits) {
|
|
|
|
p[3] = 0x0F;
|
|
p[4] = 0xFF;
|
|
p[5] = 0xFF;
|
|
p[6] = 0xFF;
|
|
p[7] = 0x0F;
|
|
|
|
#if 0
|
|
// allocate cluster 2 for the root (set 2=end of chain)
|
|
p[8] = 0xFF;
|
|
p[9] = 0xFF;
|
|
p[10] = 0xFF;
|
|
p[11] = 0x0F;
|
|
#endif
|
|
} else if (fFat16 == _fat_bits) {
|
|
p[3] = 0xFF;
|
|
}
|
|
_AllocatedClusters = 0xFFFFFFFF;
|
|
}
|
|
|
|
|
|
INLINE
|
|
ULONG
|
|
FAT::RemoveChain(
|
|
IN ULONG PreceedingCluster,
|
|
IN ULONG LastCluster
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine removes a subchain of length 'Length' from a containing
|
|
chain. This routine cannot remove subchains beginning at the head
|
|
of the containing chain. To do this use the routine named
|
|
'SplitChain'.
|
|
|
|
This routine returns the number of the first cluster of the
|
|
removed subchain. The FAT is edited so that the removed subchain
|
|
is promoted to a full chain.
|
|
|
|
Arguments:
|
|
|
|
PreceedingCluster - Supplies the cluster which preceeds the one to be
|
|
removed in the chain.
|
|
LastCluster - Supplies the last cluster of the chain to remove.
|
|
|
|
Return Value:
|
|
|
|
The cluster number for the head of the chain removed.
|
|
|
|
--*/
|
|
{
|
|
ULONG r;
|
|
|
|
r = QueryEntry(PreceedingCluster);
|
|
SetEntry(PreceedingCluster, QueryEntry(LastCluster));
|
|
SetEndOfChain(LastCluster);
|
|
return r;
|
|
}
|
|
|
|
|
|
INLINE
|
|
VOID
|
|
FAT::InsertChain(
|
|
IN ULONG StartOfChain,
|
|
IN ULONG EndOfChain,
|
|
IN ULONG PreceedingCluster
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine inserts one chain into another chain. This routine
|
|
cannot insert a chain at the head of another chain. To do this
|
|
use the routine named 'JoinChains'.
|
|
|
|
Arguments:
|
|
|
|
StartOfChain - Supplies the first cluster of the chain to insert.
|
|
EndOfChain - Supplies the last cluster of the chain to insert.
|
|
PreceedingCluster - Supplies the cluster immediately preceeding the
|
|
position where the chain is to be inserted.
|
|
|
|
Return Value:
|
|
|
|
None.
|
|
|
|
--*/
|
|
{
|
|
SetEntry(EndOfChain, QueryEntry(PreceedingCluster));
|
|
SetEntry(PreceedingCluster, StartOfChain);
|
|
}
|
|
|
|
|
|
INLINE
|
|
ULONG
|
|
FAT::InsertChain(
|
|
IN ULONG StartOfChain,
|
|
IN ULONG Cluster
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
This routine inserts one cluster at the head of a chain.
|
|
|
|
Arguments:
|
|
|
|
StartOfChain - Supplies the first cluster of the chain to insert.
|
|
Cluster - Supplies the cluster to be inserted
|
|
|
|
Return Value:
|
|
|
|
ULONG - The new head of the chain (i.e. Cluster )
|
|
|
|
--*/
|
|
{
|
|
if ( StartOfChain ) {
|
|
SetEntry( Cluster, StartOfChain );
|
|
} else {
|
|
SetEndOfChain( Cluster );
|
|
}
|
|
|
|
return Cluster;
|
|
}
|
|
|
|
|
|
#endif // FAT_DEFN
|