ciderpress/diskimg/Win32BlockIO.h

/*
 * CiderPress
 * Copyright (C) 2007 by faddenSoft, LLC.  All Rights Reserved.
 * See the file LICENSE for distribution terms.
 */
#ifdef _WIN32
/*
 * Structures and functions for performing block-level I/O on Win32 logical
 * and physical volumes.
 *
 * Under Win2K/XP this is pretty straightforward: open the volume and
 * issue seek and read calls.  It's not quite that simple -- reads need to
 * be in 512-byte sectors for floppy and hard drives, seeks need to be on
 * sector boundaries, and you can't seek from the end, which makes it hard
 * to figure out how big the volume is -- but it's palatable.
 *
 * Under Win95/Win98/WinME, life is more difficult.  You need to use the
 * Int21h/7305h services to access logical volumes.  Of course, those weren't
 * available until Win95 OSR2, before which you used Int25h/6000h, but those
 * don't work with FAT32 volumes.  Access to physical devices requires Int13h,
 * which is fine for floppies but requires 16-bit flat thunks for hard drives
 * (see Q137176: "DeviceIoControl Int 13h Does Not Support Hard Disks").
 *
 * If Win98 can't recognize the volume on a floppy, it tries to reacquire
 * the volume information every time you ask it to read a sector.  This makes
 * things *VERY* slow.  The solution is to use the physical drive Int13h
 * services.  These come in two variants, one of which will work on just
 * about any machine but only works with floppies.  The other will work on
 * anything built since about 1996.
 *
 * Figuring out whether something is or isn't a floppy requires yet
 * another call.  All things considered it's quite an ordeal.  The block I/O
 * functions are wrapped up in classes so nobody else has to worry about all
 * this mess.
 *
 * Implementation note: this class is broken down by how the devices are
 * opened, e.g. logical, physical, or ASPI address.  Breaking it down by device
 * type seems more appropriate, but Win98 vs Win2K can require completely
 * different approaches (e.g. physical vs. logical for floppy disk, logical
 * vs. ASPI for CD-ROM).  There is no perfect decomposition.
 *
 * Summary:
 *	Win9x/ME physical drive: Int13h (doesn't work for hard drives)
 *	Win9x/ME logical drive: Int21h/7305h
 *	Win9x/ME SCSI drive or CD-ROM drive: ASPI
 *	Win2K/XP physical drive: CreateFile("\\.\PhysicalDriveN")
 *	Win2K/XP logical drive: CreateFile("\\.\X")
 *	Win2K/XP SCSI drive or CD-ROM drive: SPTI
 */
#ifndef __WIN32BLOCKIO__
#define __WIN32BLOCKIO__


namespace DiskImgLib {

extern bool IsWin9x(void);


/*
 * Cache a contiguous set of blocks.  This was originally motivated by poor
 * write performance, but that problem was largely solved in other ways.
 * It's still handy to write an entire track at once under Win98 though.
 *
 * Only storing continuous runs of blocks makes the cache less useful, but
 * much easier to write, and hence less likely to break in unpleasant ways.
 *
 * This class just manages the blocks.  The FlushCache() function in
 * Win32LogicalVolume is responsible for actually pushing the writes through.
 *
 * (I'm not entirely happy with this, especially since it doesn't take into
 * account the underlying device block size.  This could've been a good place
 * to handle the 2048-byte CD-ROM block size, rather than caching it again in
 * the CD-ROM handler.)
 */
class CBCache {
public:
	CBCache(void) : fFirstBlock(kEmpty), fNumBlocks(0)
	{
		for (int i = 0; i < kMaxCachedBlocks; i++)
			fDirty[i] = false;
	}
	virtual ~CBCache(void) { Purge(); }

	enum { kEmpty = -1 };

	// is the block we want in the cache?
	bool IsBlockInCache(long blockNum) const;
	// read block out of cache (after verifying that it's present)
	DIError GetFromCache(long blockNum, void* buf);
	// can the cache store this block?
	bool IsRoomInCache(long blockNum) const;
	// write block to cache (after verifying that it will fit)
	DIError PutInCache(long blockNum, const void* buf, bool isDirty);

	// are there any dirty blocks in the cache?
	bool IsDirty(void) const;
	// get start, count, and buffer so we can write the cached data
	void GetCachePointer(long* pFirstBlock, int* pNumBlocks, void** pBuf) const;
	// clear all the dirty flags
	void Scrub(void);
	// purge all cache entries (ideally after writing w/help from GetCachePtr)
	void Purge(void);

private:
	enum {
		kMaxCachedBlocks = 18,		// one track on 1.4MB floppy
		kBlockSize = 512,			// must match with Win32LogicalVolume::
	};

	long		fFirstBlock;		// set to kEmpty when cache is empty
	int			fNumBlocks;
	bool		fDirty[kMaxCachedBlocks];
	unsigned char	fCache[kMaxCachedBlocks * kBlockSize];
};


/*
 * This class encapsulates block access to a logical or physical volume.
 */
class Win32VolumeAccess {
public:
	Win32VolumeAccess(void) : fpBlockAccess(NULL)
	{}
	virtual ~Win32VolumeAccess(void) {
		if (fpBlockAccess != NULL) {
			FlushCache(true);
			fpBlockAccess->Close();
		}
	}

	// "deviceName" has the form "X:\" (logical), "81:\" (physical), or
	//  "ASPI:x:y:z\" (ASPI)
	DIError Open(const char* deviceName, bool readOnly);
	// close the device
	void Close(void);
	// is the device open and working?
	bool Ready(void) const { return fpBlockAccess != NULL; }

	// return the volume's EOF
	long GetTotalBlocks(void) const { return fTotalBlocks; }
	// return the block size for this volume (always a power of 2)
	int GetBlockSize(void) const { return BlockAccess::kBlockSize; }

	// read one or more consecutive blocks
	DIError ReadBlocks(long startBlock, short blockCount, void* buf);
	// write one or more consecutive blocks
	DIError WriteBlocks(long startBlock, short blockCount, const void* buf);
	// flush our internal cache
	DIError FlushCache(bool purge);

private:
	/*
	 * Abstract base class with some handy functions.
	 */
	class BlockAccess {
	public:
		BlockAccess(void) { fIsWin9x = DiskImgLib::IsWin9x(); }
		virtual ~BlockAccess(void) {}

		typedef struct {
			int		numCyls;
			int		numHeads;
			int		numSectors;
			long	blockCount;		// total #of blocks on this kind of disk
		} DiskGeometry;

		// generic interfaces
		virtual DIError Open(const char* deviceName, bool readOnly) = 0;
		virtual DIError DetectCapacity(long* pNumBlocks) = 0;
		virtual DIError ReadBlocks(long startBlock, short blockCount,
			void* buf) = 0;
		virtual DIError WriteBlocks(long startBlock, short blockCount,
			const void* buf) = 0;
		virtual DIError Close(void) = 0;

		static bool BlockToCylinderHeadSector(long blockNum,
			const DiskGeometry* pGeometry, int* pCylinder, int* pHead,
			int* pSector, long* pLastBlockOnTrack);

		enum {
			kNumLogicalVolumes = 26,	// A-Z
			kBlockSize = 512,
			kCDROMSectorSize = 2048,
			kMaxFloppyRetries = 3,		// retry floppy reads/writes
		};

		// BIOS floppy disk drive type; doubles here as media type
		typedef enum {
			kFloppyUnknown = 0,
			kFloppy525_360 = 1,
			kFloppy525_1200 = 2,
			kFloppy35_720 = 3,
			kFloppy35_1440 = 4,
			kFloppy35_2880 = 5,

			kFloppyMax
		} FloppyKind;

	protected:
		static DIError GetFloppyDriveKind(HANDLE handle, int unitNum,
			FloppyKind* pKind);
		// detect the #of blocks on the volume
		static DIError ScanCapacity(BlockAccess* pThis, long* pNumBlocks);
		// determine whether a block is readable
		static bool CanReadBlock(BlockAccess* pThis, long blockNum);
		// try to detect device capacity using SPTI
		DIError DetectCapacitySPTI(HANDLE handle,
			bool isCDROM, long* pNumBlocks);

		static int ReadBlocksInt13h(HANDLE handle, int unitNum,
			int cylinder, int head, int sector, short blockCount, void* buf);
		static DIError ReadBlocksInt13h(HANDLE handle, int unitNum,
			const DiskGeometry* pGeometry, long startBlock, short blockCount,
			void* buf);
		static int WriteBlocksInt13h(HANDLE handle, int unitNum,
			int cylinder, int head, int sector, short blockCount,
			const void* buf);
		static DIError WriteBlocksInt13h(HANDLE handle, int unitNum,
			const DiskGeometry* pGeometry, long startBlock, short blockCount,
			const void* buf);

		static DIError ReadBlocksInt21h(HANDLE handle, int driveNum,
			long startBlock, short blockCount, void* buf);
		static DIError WriteBlocksInt21h(HANDLE handle, int driveNum,
			long startBlock, short blockCount, const void* buf);

		static DIError ReadBlocksWin2K(HANDLE handle,
			long startBlock, short blockCount, void* buf);
		static DIError WriteBlocksWin2K(HANDLE handle,
			long startBlock, short blockCount, const void* buf);

		bool	fIsWin9x;			// Win9x/ME=true, Win2K/XP=false
	};

	/*
	 * Access to a logical volume (e.g. "C:\") under Win9x and Win2K/XP.
	 */
	class LogicalBlockAccess : public BlockAccess {
	public:
		LogicalBlockAccess(void) : fHandle(NULL), fIsCDROM(false),
			fDriveNum(-1), fLastSectorCache(nil), fLastSectorNum(-1)
			{}
		virtual ~LogicalBlockAccess(void) {
			if (fHandle != NULL) {
				//WMSG0("HEY: LogicalBlockAccess: forcing close\n");
				Close();
			}
			delete[] fLastSectorCache;
		}

		virtual DIError Open(const char* deviceName, bool readOnly);
		virtual DIError DetectCapacity(long* pNumBlocks) {
			/* use SCSI length value if at all possible */
			DIError dierr;
			dierr = DetectCapacitySPTI(fHandle, fIsCDROM, pNumBlocks);
			if (fIsCDROM)
				return dierr;		// SPTI should always work for CD-ROM
			if (dierr != kDIErrNone)
				return ScanCapacity(this, pNumBlocks);	// fall back on scan
			else
				return dierr;
		}
		virtual DIError ReadBlocks(long startBlock, short blockCount,
			void* buf)
		{
			if (fIsCDROM)
				return ReadBlocksCDROM(fHandle, startBlock, blockCount, buf);
			if (fIsWin9x)
				return ReadBlocksInt21h(fHandle, fDriveNum, startBlock,
							blockCount, buf);
			else
				return ReadBlocksWin2K(fHandle, startBlock, blockCount, buf);
		}
		virtual DIError WriteBlocks(long startBlock, short blockCount,
			const void* buf)
		{
			if (fIsCDROM)
				return kDIErrWriteProtected;
			if (fIsWin9x)
				return WriteBlocksInt21h(fHandle, fDriveNum, startBlock,
							blockCount, buf);
			else
				return WriteBlocksWin2K(fHandle, startBlock, blockCount, buf);
		}
		virtual DIError Close(void);

	private:
		//DIError DetectCapacitySPTI(long* pNumBlocks);
		DIError ReadBlocksCDROM(HANDLE handle,
			long startBlock, short numBlocks, void* buf);

		// Win2K/XP and Win9x/ME
		HANDLE			fHandle;
		bool			fIsCDROM;		// set for CD-ROM devices
		// Win9x/ME
		int				fDriveNum;		// 1=A, 3=C, etc
		// CD-ROM goodies
		unsigned char*	fLastSectorCache;
		long			fLastSectorNum;
	};

	/*
	 * Access to a physical volume (e.g. 00h or 80h) under Win9x and
	 * Win2K/XP.
	 */
	class PhysicalBlockAccess : public BlockAccess {
	public:
		PhysicalBlockAccess(void) : fHandle(NULL), fInt13Unit(-1) {}
		virtual ~PhysicalBlockAccess(void) {}

		virtual DIError Open(const char* deviceName, bool readOnly);
		virtual DIError DetectCapacity(long* pNumBlocks) {
			/* try SPTI in case it happens to work */
			DIError dierr;
			dierr = DetectCapacitySPTI(fHandle, false, pNumBlocks);
			if (dierr != kDIErrNone)
				return ScanCapacity(this, pNumBlocks);
			else
				return dierr;
		}
		virtual DIError ReadBlocks(long startBlock, short blockCount,
			void* buf)
		{
			if (fIsWin9x)
				return ReadBlocksInt13h(fHandle, fInt13Unit,
							&fGeometry, startBlock, blockCount, buf);
			else
				return ReadBlocksWin2K(fHandle,
							startBlock, blockCount, buf);
		}
		virtual DIError WriteBlocks(long startBlock, short blockCount,
			const void* buf)
		{
			if (fIsWin9x)
				return WriteBlocksInt13h(fHandle, fInt13Unit,
							&fGeometry, startBlock, blockCount, buf);
			else
				return WriteBlocksWin2K(fHandle,
							startBlock, blockCount, buf);
		}
		virtual DIError Close(void);

	private:
		DIError DetectFloppyGeometry(void);

		// Win2K/XP
		HANDLE			fHandle;
		// Win9x/ME
		int				fInt13Unit;		// 00h=floppy #1, 80h=HD#1
		FloppyKind		fFloppyKind;
		DiskGeometry	fGeometry;
	};

	/*
	 * Access to a SCSI volume via the ASPI interface.
	 */
	class ASPIBlockAccess : public BlockAccess {
	public:
		ASPIBlockAccess(void) : fpASPI(nil),
			fAdapter(0xff), fTarget(0xff), fLun(0xff), fReadOnly(false),
			fLastChunkCache(nil), fLastChunkNum(-1), fChunkSize(-1)
			{}
		virtual ~ASPIBlockAccess(void) { delete[] fLastChunkCache; }

		virtual DIError Open(const char* deviceName, bool readOnly);
		virtual DIError DetectCapacity(long* pNumBlocks);
		virtual DIError ReadBlocks(long startBlock, short blockCount,
			void* buf);
		virtual DIError WriteBlocks(long startBlock, short blockCount,
			const void* buf);
		virtual DIError Close(void);

	private:
		int ExtractInt(const char** pStr, int* pResult);

		ASPI*			fpASPI;
		unsigned char	fAdapter;
		unsigned char	fTarget;
		unsigned char	fLun;

		bool			fReadOnly;

		// block cache
		unsigned char*	fLastChunkCache;
		long			fLastChunkNum;
		long			fChunkSize;		// set by DetectCapacity
	};


	// write a series of blocks to the volume
	DIError DoWriteBlocks(long startBlock, short blockCount, const void* buf)
	{
		return fpBlockAccess->WriteBlocks(startBlock, blockCount, buf);
	}

	long			fTotalBlocks;
	BlockAccess*	fpBlockAccess;	// really LogicalBA or PhysicalBA
	CBCache			fBlockCache;
};

}; // namespace DiskImgLib

#endif /*WIN32BLOCKIO*/

#endif /*_WIN32*/