261 lines
8.8 KiB
C++
261 lines
8.8 KiB
C++
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#ifndef _NFFMSTM_HXX_
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#define _NFFMSTM_HXX_
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#include <propstm.hxx>
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class CNtfsStream;
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class CNtfsUpdateStreamForPropStg;
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//+----------------------------------------------------------------------------
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//
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// Class: CNFFMappedStream
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//
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// This class is used by CNtfsStream, and implements the IMappedStream
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// interface for use on NFF (NTFS Flat-File) files. The mapping
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// exposed by this implementation is robust, in that updates to the
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// underlying stream are atomic (though not durable until flushed).
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//
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// This atomicity is accomplished by using stream renaming (which is only
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// supported in NTFS5). When this mapping is written to the underlying
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// NTFS files, it is written to a second stream (the "update" stream),
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// rather than the original stream. When Flush is called,
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// the update stream is renamed over the original stream. In order to
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// make NTFS stream renaming atomic, the overwritten stream must be
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// truncated first to have zero length. The the overall flush operation
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// is: truncate the original stream, rename the update stream over
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// the original stream, and optionally create a new update stream to be
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// ready for the next write.
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//
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// When the original stream is truncated, the update stream is then
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// considered master. So if there is a crash before the truncate, then
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// the original stream, with the original data, is master. If there is
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// a crash after the truncate but before the rename, then the update stream
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// is considered master. In this case, on the next open, the update stream
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// is either renamed over the zero-length original (if opening for write),
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// or the update stream is simply used as is (if opening for read).
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//
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// If the file isn't on an NTFS5 volume, so stream renaming isn't supported,
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// we just use the original stream unconditionally and there is no robustness.
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//
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// To accomplish all of this, this class works with two stream handles,
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// the original and the update. The original is the stream handle held
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// by the parent CNtfsStream. The update stream handle must behave like all other
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// stream handles, wrt USN, oplock, timestamps, etc (see CNtfsStream).
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// So the update stream is wrapped in a CNtfsStream too, but a special
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// one - the CNtfsUpdateStreamForPropStg derivation. An instance of this
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// CNtfsUpdateStreamForPropStg class is maintained by here (by CNFFMappedStream).
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//
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//
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//
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// +-------------+ +------------------+
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// | |------->| |
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// | CNtfsStream | | CNFFMappedStream |
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// | |<-------| |
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// +-------------+ +------------------+
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// | | +------------------------------+
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// | | | |
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// | +----->| CNtfsUpdateStreamForPropStg |
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// V | : public CNtfsStream |
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// Original | |
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// NTFS +------------------------------+
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// Stream |
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// |
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// V
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// Updated
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// NTFS
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// Stream
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//
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//+----------------------------------------------------------------------------
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class CNFFMappedStream : public IMappedStream
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#if DBG
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, public IStorageTest // For testing only
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#endif
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{
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// Constructors
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public:
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CNFFMappedStream( CNtfsStream *pnffstm );
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~CNFFMappedStream();
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// -------------
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// IMappedStream
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// -------------
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public:
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STDMETHODIMP QueryInterface(REFIID riid, void **ppvObject);
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STDMETHODIMP_(ULONG) AddRef(void);
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STDMETHODIMP_(ULONG) Release(void);
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STDMETHODIMP_(VOID) Open(IN NTPROP np, OUT LONG *phr);
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STDMETHODIMP_(VOID) Close(OUT LONG *phr);
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STDMETHODIMP_(VOID) ReOpen(IN OUT VOID **ppv, OUT LONG *phr);
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STDMETHODIMP_(VOID) Quiesce(VOID);
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STDMETHODIMP_(VOID) Map(IN BOOLEAN fCreate, OUT VOID **ppv);
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STDMETHODIMP_(VOID) Unmap(IN BOOLEAN fFlush, IN OUT VOID **ppv);
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STDMETHODIMP_(VOID) Flush(OUT LONG *phr);
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STDMETHODIMP_(ULONG) GetSize(OUT LONG *phr);
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STDMETHODIMP_(VOID) SetSize(IN ULONG cb, IN BOOLEAN fPersistent, IN OUT VOID **ppv, OUT LONG *phr);
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STDMETHODIMP_(NTSTATUS) Lock(IN BOOLEAN fExclusive);
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STDMETHODIMP_(NTSTATUS) Unlock(VOID);
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STDMETHODIMP_(VOID) QueryTimeStamps(OUT STATPROPSETSTG *pspss, BOOLEAN fNonSimple) const;
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STDMETHODIMP_(BOOLEAN) QueryModifyTime(OUT LONGLONG *pll) const;
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STDMETHODIMP_(BOOLEAN) QuerySecurity(OUT ULONG *pul) const;
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STDMETHODIMP_(BOOLEAN) IsWriteable(VOID) const;
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STDMETHODIMP_(BOOLEAN) IsModified(VOID) const;
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STDMETHODIMP_(VOID) SetModified(OUT LONG *phr);
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STDMETHODIMP_(HANDLE) GetHandle(VOID) const;
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#if DBG
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STDMETHODIMP_(BOOLEAN) SetChangePending(BOOLEAN fChangePending);
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STDMETHODIMP_(BOOLEAN) IsNtMappedStream(VOID) const;
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#endif
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// ------------
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// IStorageTest
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// ------------
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public:
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#if DBG
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STDMETHOD(UseNTFS4Streams)( BOOL fUseNTFS4Streams );
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STDMETHOD(GetFormatVersion)(WORD *pw);
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STDMETHOD(SimulateLowMemory)( BOOL fSimulate );
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STDMETHOD_(LONG, GetLockCount)();
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STDMETHOD(IsDirty)();
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#endif
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// -----------------------------
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// Public, non-interface methods
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// -----------------------------
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public:
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inline BOOL IsMapped();
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inline ULONG SizeOfMapping();
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void Read( void *pv, ULONG ulOffset, ULONG *pcbCopy );
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void Write( const void *pv, ULONG ulOffset, ULONG *pcbCopy );
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HRESULT Init( HANDLE hStream );
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HRESULT ShutDown();
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// ----------------
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// Internal Methods
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// ----------------
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private:
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void InitMappedStreamMembers();
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void BeginUsingUpdateStream();
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void EndUsingUpdateStream();
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void BeginUsingLatestStream();
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void EndUsingLatestStream();
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HRESULT WriteMappedStream();
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enum enumCREATE_NEW_UPDATE_STREAM
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{
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CREATE_NEW_UPDATE_STREAM = 1,
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DONT_CREATE_NEW_UPDATE_STREAM = 2
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};
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inline HRESULT CreateUpdateStreamIfNecessary();
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HRESULT ReplaceOriginalWithUpdate( enumCREATE_NEW_UPDATE_STREAM CreateNewUpdateStream );
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HRESULT OpenUpdateStream( BOOL fCreate );
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HRESULT RollForwardIfNecessary();
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// --------------
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// Internal state
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// --------------
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private:
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// Containing stream (i.e., we're an embedded object in this CNtfsStream)
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CNtfsStream *_pnffstm;
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// Are we using global reserved memory?
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BOOL _fLowMem:1;
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// Does the mapped stream have unflushed changes?
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BOOL _fMappedStreamDirty:1;
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#if DBG
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// Should we pretent that CoTaskMemAlloc fails?
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BOOL _fSimulateLowMem:1;
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#endif
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// Is the latest data in _pstmUpdate?
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BOOL _fUpdateStreamHasLatest:1;
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// Have we already called the RollForwardIfNecessary method?
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BOOL _fCheckedForRollForward:1;
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// Is this an NTFS5 volume?
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BOOL _fStreamRenameSupported:1;
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// The current mapping
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BYTE *_pbMappedStream;
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// The size of the buffer referred to by _pbMappedStream
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ULONG _cbMappedStream;
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// The size of the underlying stream that _pbMappedStream represents
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ULONG _cbMappedStreamActual;
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// Cookie used in PrOnMappedStreamEvent
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VOID *_pMappedStreamOwner;
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// Count of calls to BeginUsingUpdateStream unmatched by a call to
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// EndUsingUpdateStream
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USHORT _cUpdateStreamInUse;
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// Count of calls to BeginUsingLatestStream unmatched by a call to
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// EndUsingLatestStream
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USHORT _cLatestStreamInUse;
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// The Update stream.
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CNtfsUpdateStreamForPropStg
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*_pstmUpdate;
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}; // class CNFFMappedStream
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inline CNFFMappedStream::CNFFMappedStream( CNtfsStream *pnffstm )
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{
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_pnffstm = pnffstm;
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_pstmUpdate = NULL;
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_fUpdateStreamHasLatest = FALSE;
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IFDBG( _fSimulateLowMem = FALSE );
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InitMappedStreamMembers();
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}
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inline BOOL
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CNFFMappedStream::IsMapped()
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{
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return( NULL != _pbMappedStream );
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}
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inline ULONG
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CNFFMappedStream::SizeOfMapping()
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{
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return( _cbMappedStream );
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}
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#endif // #ifndef _NFFMSTM_HXX_
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