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904 lines
16 KiB
904 lines
16 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 FirstDiskCluster = 2;
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CONST MaxNumClusForSmallFat = 4085;
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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 USHORT NumberOfEntries,
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IN USHORT NumSectors DEFAULT 0
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);
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NONVIRTUAL
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USHORT
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QueryEntry(
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IN USHORT 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 USHORT ClusterNumber,
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IN USHORT 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 USHORT 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 USHORT 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 USHORT 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 USHORT 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 USHORT 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 USHORT 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 USHORT 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 USHORT 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 USHORT 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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USHORT
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QueryFreeClusters(
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) CONST;
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NONVIRTUAL
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USHORT
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QueryBadClusters(
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) CONST;
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NONVIRTUAL
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USHORT
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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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USHORT
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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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USHORT
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QueryNthCluster(
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IN USHORT StartingCluster,
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IN USHORT Index
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) CONST;
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NONVIRTUAL
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UFAT_EXPORT
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USHORT
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QueryLengthOfChain(
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IN USHORT StartingCluster,
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OUT PUSHORT LastCluster DEFAULT NULL
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) CONST;
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NONVIRTUAL
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USHORT
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QueryLengthOfChain(
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IN USHORT StartingCluster,
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IN USHORT EndingCluster
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) CONST;
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NONVIRTUAL
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USHORT
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QueryPrevious(
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IN USHORT 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 USHORT 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 USHORT 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 PUSHORT 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 USHORT StartingCluster
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) CONST;
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NONVIRTUAL
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UFAT_EXPORT
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USHORT
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AllocChain(
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IN USHORT Length,
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OUT PUSHORT LastCluster DEFAULT NULL
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);
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NONVIRTUAL
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USHORT
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ReAllocChain(
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IN USHORT StartOfChain,
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IN USHORT NewLength,
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OUT PUSHORT 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 USHORT StartOfChain
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);
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NONVIRTUAL
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USHORT
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RemoveChain(
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IN USHORT PreceedingCluster,
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IN USHORT 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 USHORT StartOfChain,
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IN USHORT EndOfChain,
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IN USHORT PreceedingCluster
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);
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NONVIRTUAL
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USHORT
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InsertChain(
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IN USHORT StartOfChain,
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IN USHORT Cluster
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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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USHORT
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Index(
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IN USHORT ClusterNumber
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) CONST;
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NONVIRTUAL
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UFAT_EXPORT
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USHORT
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Index12(
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IN USHORT ClusterNumber
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) CONST;
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NONVIRTUAL
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USHORT
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Index16(
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IN USHORT 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 USHORT ClusterNumber,
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IN USHORT 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 USHORT ClusterNumber,
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IN USHORT 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 USHORT ClusterNumber,
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IN USHORT Value
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);
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PVOID _fat;
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USHORT _num_entries;
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BOOLEAN _is_big;
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USHORT _low_end_of_chain; // 0xFFF8 or 0x0FF8
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USHORT _end_of_chain; // 0xFFFF or 0x0FFF
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USHORT _bad_cluster; // 0xFFF7 or 0x0FF7
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USHORT _low_reserved; // 0xFFF0 or 0x0FF0
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USHORT _high_reserved; // 0xFFF6 or 0x0FF6
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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 USHORT 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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USHORT
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FAT::Index16(
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IN USHORT 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 ((PUSHORT) _fat)[ClusterNumber];
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}
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INLINE
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USHORT
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FAT::Index(
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IN USHORT 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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return _is_big ? Index16(ClusterNumber) : Index12(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 USHORT ClusterNumber,
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IN USHORT 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] = Value;
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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 USHORT ClusterNumber,
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IN USHORT 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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_is_big ? Set16(ClusterNumber, Value) : Set12(ClusterNumber, Value);
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}
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INLINE
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USHORT
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FAT::QueryEntry(
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IN USHORT 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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VOID
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FAT::SetEntry(
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IN USHORT ClusterNumber,
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IN USHORT 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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INLINE
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BOOLEAN
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FAT::IsClusterFree(
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IN USHORT ClusterNumber
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) CONST
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/*++
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Routine Description:
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This routine computes whether of not ClusterNumber is a free cluster.
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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 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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}
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INLINE
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VOID
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FAT::SetClusterFree(
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IN USHORT ClusterNumber
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)
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/*++
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Routine Description:
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This routine marks the cluster ClusterNumber as free on the FAT.
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Arguments:
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ClusterNumber - Supplies the number of the cluster to mark free.
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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, 0);
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}
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INLINE
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BOOLEAN
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FAT::IsEndOfChain(
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IN USHORT 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 the cluster ClusterNumber is the
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end of its cluster chain.
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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 the end of a chain.
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TRUE - The cluster is the end of a chain.
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--*/
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{
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return Index(ClusterNumber) >= _low_end_of_chain;
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}
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INLINE
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VOID
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FAT::SetEndOfChain(
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IN USHORT ClusterNumber
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)
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/*++
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Routine Description:
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This routine sets the cluster ClusterNumber to the end of its cluster
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chain.
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Arguments:
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ClusterNumber - Supplies the cluster to be set to end of chain.
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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, _end_of_chain);
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}
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INLINE
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BOOLEAN
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FAT::IsClusterBad(
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IN USHORT 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 cluster ClusterNumber is bad.
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Arguments:
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ClusterNumber - Supplies the number of the cluster to be checked.
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Return Value:
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FALSE - The cluster is good.
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TRUE - The cluster is bad.
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--*/
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{
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return Index(ClusterNumber) == _bad_cluster;
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}
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INLINE
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VOID
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FAT::SetClusterBad(
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IN USHORT ClusterNumber
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)
|
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/*++
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Routine Description:
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This routine sets the cluster ClusterNumber to bad on the FAT.
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Arguments:
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ClusterNumber - Supplies the cluster number to mark bad.
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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, _bad_cluster);
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}
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INLINE
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BOOLEAN
|
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FAT::IsClusterReserved(
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IN USHORT 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 the cluster ClusterNumber is
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a reserved cluster.
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|
Arguments:
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ClusterNumber - Supplies the cluster to check.
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Return Value:
|
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FALSE - The cluster is not reserved.
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TRUE - The cluster is reserved.
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--*/
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{
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return Index(ClusterNumber) >= _low_reserved &&
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Index(ClusterNumber) <= _high_reserved;
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}
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|
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INLINE
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VOID
|
|
FAT::SetClusterReserved(
|
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IN USHORT ClusterNumber
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)
|
|
/*++
|
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Routine Description:
|
|
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|
This routine marks the cluster ClusterNumber as reserved in the FAT.
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|
Arguments:
|
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ClusterNumber - Supplies the cluster to mark reserved.
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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, _low_reserved);
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}
|
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|
|
|
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INLINE
|
|
UCHAR
|
|
FAT::QueryMediaByte(
|
|
) CONST
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
The media byte for the partition is stored in the first character of the
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FAT. This routine will return its value provided that the two following
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bytes are 0xFF.
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|
|
|
Arguments:
|
|
|
|
None.
|
|
|
|
Return Value:
|
|
|
|
The media byte for the partition.
|
|
|
|
--*/
|
|
{
|
|
PUCHAR p;
|
|
|
|
p = (PUCHAR) _fat;
|
|
|
|
DebugAssert(p);
|
|
|
|
return (p[2] == 0xFF && p[1] == 0xFF &&
|
|
(_is_big ? p[3] == 0xFF : 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 (_is_big) {
|
|
p[3] = 0xFF;
|
|
}
|
|
}
|
|
|
|
|
|
INLINE
|
|
USHORT
|
|
FAT::RemoveChain(
|
|
IN USHORT PreceedingCluster,
|
|
IN USHORT 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.
|
|
|
|
--*/
|
|
{
|
|
USHORT r;
|
|
|
|
r = QueryEntry(PreceedingCluster);
|
|
SetEntry(PreceedingCluster, QueryEntry(LastCluster));
|
|
SetEndOfChain(LastCluster);
|
|
return r;
|
|
}
|
|
|
|
|
|
INLINE
|
|
VOID
|
|
FAT::InsertChain(
|
|
IN USHORT StartOfChain,
|
|
IN USHORT EndOfChain,
|
|
IN USHORT 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
|
|
USHORT
|
|
FAT::InsertChain(
|
|
IN USHORT StartOfChain,
|
|
IN USHORT 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:
|
|
|
|
USHORT - The new head of the chain (i.e. Cluster )
|
|
|
|
--*/
|
|
{
|
|
if ( StartOfChain ) {
|
|
SetEntry( Cluster, StartOfChain );
|
|
} else {
|
|
SetEndOfChain( Cluster );
|
|
}
|
|
|
|
return Cluster;
|
|
}
|
|
|
|
|
|
#endif // FAT_DEFN
|