ciderpress/diskimg/Win32BlockIO.cpp

/*
 * CiderPress
 * Copyright (C) 2007 by faddenSoft, LLC.  All Rights Reserved.
 * See the file LICENSE for distribution terms.
 */
/*
 * Win32 block I/O routines.
 *
 * See the header file for an explanation of why.
 */
#include "StdAfx.h"
#ifdef _WIN32
#include "DiskImgPriv.h"
#include "SCSIDefs.h"
#include "ASPI.h"
#include "SPTI.h"


/*
 * This is an ugly hack until I can figure out the right way to do this.  To
 * help prevent people from trashing their Windows volumes, we refuse to
 * open "C:\" or physical0 for writing.  On most systems, this is fine.
 *
 * The problem is that, on some systems with a mix of SATA and IDE devices,
 * the boot disk is not physical disk 0.  There should be a way to determine
 * which physical disk is used for booting, or which physical disk
 * corresponds to "C:", but I haven't been able to find it.
 *
 * So, for now, allow a global setting that disables the protection.  I'm
 * doing it this way rather than passing a parameter through because it
 * requires adding an argument to several layers of "open", and I'm hoping
 * to make this go away.
 */
//extern bool DiskImgLib::gAllowWritePhys0;


/*
 * ===========================================================================
 *		Win32VolumeAccess
 * ===========================================================================
 */

/*
 * Open a logical volume.
 */
DIError
Win32VolumeAccess::Open(const char* deviceName, bool readOnly)
{
	DIError dierr = kDIErrNone;

	assert(deviceName != nil);

	if (fpBlockAccess != nil) {
		assert(false);
		return kDIErrAlreadyOpen;
	}

	if (strncmp(deviceName, kASPIDev, strlen(kASPIDev)) == 0) {
		fpBlockAccess = new ASPIBlockAccess;
		if (fpBlockAccess == nil) {
			dierr = kDIErrMalloc;
			goto bail;
		}
		dierr = fpBlockAccess->Open(deviceName, readOnly);
		if (dierr != kDIErrNone)
			goto bail;
	} else if (deviceName[0] >= 'A' && deviceName[0] <= 'Z') {
		fpBlockAccess = new LogicalBlockAccess;
		if (fpBlockAccess == nil) {
			dierr = kDIErrMalloc;
			goto bail;
		}
		dierr = fpBlockAccess->Open(deviceName, readOnly);
		if (dierr != kDIErrNone)
			goto bail;
	} else if (deviceName[0] >= '0' && deviceName[0] <= '9') {
		fpBlockAccess = new PhysicalBlockAccess;
		if (fpBlockAccess == nil) {
			dierr = kDIErrMalloc;
			goto bail;
		}
		dierr = fpBlockAccess->Open(deviceName, readOnly);
		if (dierr != kDIErrNone)
			goto bail;
	} else {
		WMSG1(" Win32VA: '%s' isn't the name of a device\n", deviceName);
		return kDIErrInternal;
	}

	// Need to do this now so we can use floppy geometry.
	dierr = fpBlockAccess->DetectCapacity(&fTotalBlocks);
	if (dierr != kDIErrNone)
		goto bail;
	assert(fTotalBlocks >= 0);

bail:
	if (dierr != kDIErrNone) {
		delete fpBlockAccess;
		fpBlockAccess = nil;
	}
	return dierr;
}

/*
 * Close the device.
 */
void
Win32VolumeAccess::Close(void)
{
	if (fpBlockAccess != nil) {
		DIError dierr;
		WMSG0("  Win32VolumeAccess closing\n");

		dierr = FlushCache(true);
		if (dierr != kDIErrNone) {
			WMSG1("WARNING: Win32VA Close: FlushCache failed (err=%ld)\n",
				dierr);
			// not much we can do
		}
		dierr = fpBlockAccess->Close();
		if (dierr != kDIErrNone) {
			WMSG1("WARNING: Win32VolumeAccess BlockAccess Close failed (err=%ld)\n",
				dierr);
		}
		delete fpBlockAccess;
		fpBlockAccess = nil;
	}
}


/*
 * Read a range of blocks from the device.
 *
 * Because some things like to read partial blocks, we cache the last block
 * we read whenever the caller asks for a single block.  This results in
 * increased data copying, but since we know we're reading from a logical
 * volume it's safe to assume that memory is *many* times faster than
 * reading from this handle.
 *
 * Returns with an error if any of the blocks could not be read.
 */
DIError
Win32VolumeAccess::ReadBlocks(long startBlock, short blockCount,
	void* buf)
{
	DIError dierr = kDIErrNone;

	assert(startBlock >= 0);
	assert(blockCount > 0);
	assert(buf != nil);
	assert(fpBlockAccess != nil);

	if (blockCount == 1) {
		if (fBlockCache.IsBlockInCache(startBlock)) {
			fBlockCache.GetFromCache(startBlock, buf);
			return kDIErrNone;
		}
	} else {
		// If they're reading in large stretches, we don't need to use
		// the cache.  There is some chance that what we're about to
		// read might include dirty blocks currently in the cache, so
		// we flush what we have before the read.
		dierr = FlushCache(true);
		if (dierr != kDIErrNone)
			return dierr;
	}

	/* go read from the volume */
	dierr = fpBlockAccess->ReadBlocks(startBlock, blockCount, buf);
	if (dierr != kDIErrNone)
		goto bail;


	/* if we're doing single-block reads, put it in the cache */
	if (blockCount == 1) {
		if (!fBlockCache.IsRoomInCache(startBlock)) {
			dierr = FlushCache(true);		// make room
			if (dierr != kDIErrNone)
				goto bail;
		}

		// after flushing, this should never fail
		dierr = fBlockCache.PutInCache(startBlock, buf, false);
		if (dierr != kDIErrNone)
			goto bail;
	}

bail:
	return dierr;
}


/*
 * Write a range of blocks to the device.  For the most part this just
 * writes to the cache.
 *
 * Returns with an error if any of the blocks could not be read.
 */
DIError
Win32VolumeAccess::WriteBlocks(long startBlock, short blockCount,
	const void* buf)
{
	DIError dierr = kDIErrNone;

	assert(startBlock >= 0);
	assert(blockCount > 0);
	assert(buf != nil);

	if (blockCount == 1) {
		/* is this block already in the cache? */
		if (!fBlockCache.IsBlockInCache(startBlock)) {
			/* not present, make sure it fits */
			if (!fBlockCache.IsRoomInCache(startBlock)) {
				dierr = FlushCache(true);		// make room
				if (dierr != kDIErrNone)
					goto bail;
			}
		}

		// after flushing, this should never fail
		dierr = fBlockCache.PutInCache(startBlock, buf, true);
		if (dierr != kDIErrNone)
			goto bail;
	} else {
		// If they're writing in large stretches, we don't need to use
		// the cache.  We need to flush the cache in case what we're about
		// to write would overwrite something in the cache -- if we don't,
		// what's in the cache will effectively revert what we're about to
		// write.
		dierr = FlushCache(true);
		if (dierr != kDIErrNone)
			goto bail;
		dierr = DoWriteBlocks(startBlock, blockCount, buf);
		if (dierr != kDIErrNone)
			goto bail;
	}

bail:
	return dierr;
}


/*
 * Write all blocks in the cache to disk if any of them are dirty.  In some
 * ways this is wasteful -- we could be writing stuff that isn't dirty,
 * which isn't a great idea on (say) a CF volume -- but in practice we
 * don't mix a lot of adjacent reads and writes, so this is pretty
 * harmless.
 *
 * The goal was to write whole tracks on floppies.  It's easy enough to
 * disable the cache for CF devices if need be.
 *
 * If "purge" is set, we discard the blocks after writing them.
 */
DIError
Win32VolumeAccess::FlushCache(bool purge)
{
	DIError dierr = kDIErrNone;

	//WMSG1("  Win32VA: FlushCache (%d)\n", purge);

	if (fBlockCache.IsDirty()) {
		long firstBlock;
		int numBlocks;
		void* buf;

		fBlockCache.GetCachePointer(&firstBlock, &numBlocks, &buf);

		WMSG3("FlushCache writing first=%d num=%d (purge=%d)\n",
			firstBlock, numBlocks, purge);
		dierr = DoWriteBlocks(firstBlock, numBlocks, buf);
		if (dierr != kDIErrNone) {
			WMSG1("  Win32VA: FlushCache write blocks failed (err=%d)\n",
				dierr);
			goto bail;
		}

		// all written, clear the dirty flags
		fBlockCache.Scrub();
	}

	if (purge)
		fBlockCache.Purge();

bail:
	return dierr;
}


/*
 * ===========================================================================
 *		BlockAccess
 * ===========================================================================
 */

/*
 * Detect the capacity of a drive using the SCSI READ CAPACITY command.  Only
 * works on CD-ROM drives and SCSI devices.
 *
 * Unfortunately, if you're accessing a hard drive through the BIOS, SPTI
 * doesn't work.  There must be a better way.
 *
 * On success, "*pNumBlocks" gets the number of 512-byte blocks.
 */
DIError
Win32VolumeAccess::BlockAccess::DetectCapacitySPTI(HANDLE handle,
	bool isCDROM, long* pNumBlocks)
{
#ifndef HAVE_WINDOWS_CDROM
	if (isCDROM)
		return kDIErrCDROMNotSupported;
#endif

	DIError dierr = kDIErrNone;
	unsigned long lba, blockLen;

	dierr = SPTI::GetDeviceCapacity(handle, &lba, &blockLen);
	if (dierr != kDIErrNone)
		goto bail;

	WMSG3("READ CAPACITY reports lba=%lu blockLen=%lu (total=%lu)\n",
		lba, blockLen, lba*blockLen);

	if (isCDROM && blockLen != kCDROMSectorSize) {
		WMSG1("Unacceptable CD-ROM blockLen=%ld, bailing\n", blockLen);
		dierr = kDIErrReadFailed;
		goto bail;
	}

	// The LBA is the last valid block on the disk.  To get the disk size,
	// we need to add one.

	*pNumBlocks = (blockLen/512) * (lba+1);
	WMSG1(" SPTI returning 512-byte block count %ld\n", *pNumBlocks);

bail:
	return dierr;
}

/*
 * Figure out how large this disk volume is by probing for readable blocks.
 * We take some guesses for common sizes and then binary-search if necessary.
 *
 * CF cards typically don't have as much space as they're rated for, possibly
 * because of bad-block mapping (either bad blocks or space reserved for when
 * blocks do go bad).
 *
 * This sets "*pNumBlocks" on success.  The largest size this will detect
 * is currently 8GB.
 */
/*static*/ DIError
Win32VolumeAccess::BlockAccess::ScanCapacity(BlockAccess* pThis, long* pNumBlocks)
{
	DIError dierr = kDIErrNone;
	// max out at 8GB (-1 block)
	const long kLargest = DiskImgLib::kVolumeMaxBlocks;
	const long kTypicalSizes[] = {
		// these must be in ascending order
		720*1024 / BlockAccess::kBlockSize,			// 720K floppy
		1440*1024 / BlockAccess::kBlockSize,		// 1.44MB floppy
		32*1024*1024 / BlockAccess::kBlockSize,		// 32MB flash card
		64*1024*1024 / BlockAccess::kBlockSize,		// 64MB flash card
		128*1024*1024 / BlockAccess::kBlockSize,	// 128MB flash card
		256*1024*1024 / BlockAccess::kBlockSize,	// 256MB flash card
		//512*1024*1024 / BlockAccess::kBlockSize,	// 512MB flash card
		2*1024*1024*(1024/BlockAccess::kBlockSize),	// 2GB mark
		kLargest
	};
	long totalBlocks = 0;
	int i;


	// Trivial check to make sure *anything* works, and to establish block 0
	// as valid in case we have to bin-search.
	if (!CanReadBlock(pThis, 0)) {
		WMSG0("  Win32VolumeAccess: can't read block 0\n");
		dierr = kDIErrReadFailed;
		goto bail;
	}

	for (i = 0; i < NELEM(kTypicalSizes); i++) {
		if (!CanReadBlock(pThis, kTypicalSizes[i])) {
			/* failed reading, see if N-1 is readable */
			if (CanReadBlock(pThis, kTypicalSizes[i] - 1)) {
				/* found it */
				totalBlocks = kTypicalSizes[i];
				break;
			} else {
				/* we overshot, binary-search backwards */
				WMSG1("OVERSHOT at %ld\n", kTypicalSizes[i]);
				long good, bad;
				if (i == 0)
					good = 0;
				else
					good = kTypicalSizes[i-1];	// know this one is good
				bad = kTypicalSizes[i]-1;		// know this one is bad

				while (good != bad-1) {
					long check = (good + bad) / 2;
					assert(check > good);
					assert(check < bad);

					if (CanReadBlock(pThis, check))
						good = check;
					else
						bad = check;
				}
				totalBlocks = bad;
				break;
			}
		}
	}
	if (totalBlocks == 0) {
		if (i == NELEM(kTypicalSizes)) {
			/* huge volume, we never found a bad block */
			totalBlocks = kLargest;
		} else {
			/* we never found a good block */
			WMSG0("  Win32VolumeAccess unable to determine size\n");
			dierr = kDIErrReadFailed;
			goto bail;
		}
	}

	if (totalBlocks > (3 * 1024 * 1024) / BlockAccess::kBlockSize) {
		WMSG2("  GFDWinVolume: size is %ld (%.2fMB)\n",
			totalBlocks, (float) totalBlocks / (2048.0));
	} else {
		WMSG2("  GFDWinVolume: size is %ld (%.2fKB)\n",
			totalBlocks, (float) totalBlocks / 2.0);
	}
	*pNumBlocks = totalBlocks;

bail:
	return dierr;
}

/*
 * Figure out if the block at "blockNum" exists.
 */
/*static*/ bool
Win32VolumeAccess::BlockAccess::CanReadBlock(BlockAccess* pThis, long blockNum)
{
	DIError dierr;
	unsigned char buf[BlockAccess::kBlockSize];

	dierr = pThis->ReadBlocks(blockNum, 1, buf);
	if (dierr == kDIErrNone) {
		WMSG1("    +++ Checked %ld (good)\n", blockNum);
		return true;
	} else {
		WMSG1("    +++ Checked %ld (bad)\n", blockNum);
		return false;
	}
}


#ifndef INVALID_SET_FILE_POINTER
# define INVALID_SET_FILE_POINTER 0xFFFFFFFF
#endif


/*
 * Most of these definitions come from MSFT knowledge base article #174569,
 * "BUG: Int 21 Read/Write Track on Logical Drive Fails on OSR2 and Later".
 */
#define VWIN32_DIOC_DOS_IOCTL		1		// Int 21h 4400h through 4411h
#define VWIN32_DIOC_DOS_INT25		2
#define VWIN32_DIOC_DOS_INT26		3
#define VWIN32_DIOC_DOS_INT13		4
#define VWIN32_DIOC_DOS_DRIVEINFO	6		// Int 21h 730x commands

typedef struct _DIOC_REGISTERS {
	DWORD reg_EBX;
	DWORD reg_EDX;
	DWORD reg_ECX;
	DWORD reg_EAX;
	DWORD reg_EDI;
	DWORD reg_ESI;
	DWORD reg_Flags;
} DIOC_REGISTERS, *PDIOC_REGISTERS;

#define CARRY_FLAG 1

#pragma pack(1)
typedef struct _DISKIO {
	DWORD  dwStartSector;   // starting logical sector number
	WORD   wSectors;        // number of sectors
	DWORD  dwBuffer;        // address of read/write buffer
} DISKIO, *PDISKIO;
typedef struct _DRIVEMAPINFO {
    BYTE	dmiAllocationLength;
    BYTE	dmiInfoLength;
    BYTE	dmiFlags;
    BYTE	dmiInt13Unit;
    DWORD	dmiAssociatedDriveMap;
    DWORD	dmiPartitionStartRBA_lo;
	DWORD	dmiPartitionStartRBA_hi;
} DRIVEMAPINFO, *PDRIVEMAPINFO;
#pragma pack()

#define kInt13StatusMissingAddrMark	2		// sector number above media format
#define kInt13StatusWriteProtected	3		// disk is write protected
#define kInt13StatusSectorNotFound	4		// sector number above drive cap
// == 10 for bad blocks??
#define kInt13StatusTimeout			128		// drive not responding

#if 0
/*
 * Determine the mapping between a logical device number (A=1, B=2, etc)
 * and the Int13h unit number (floppy=00h, hard drive=80h, etc).
 *
 * Pass in the vwin32 handle.
 */
/*static*/ DIError
Win32VolumeAccess::BlockAccess::GetInt13Unit(HANDLE handle, int driveNum, int* pInt13Unit)
{
	DIError dierr = kDIErrNone;
	BOOL result;
	DWORD cb;
	DRIVEMAPINFO driveMapInfo = {0};
	DIOC_REGISTERS reg = {0};
	const int kGetDriveMapInfo = 0x6f;
	const int kDeviceCategory1 = 0x08;		// for older stuff
	const int kDeviceCategory2 = 0x48;		// for FAT32

	assert(handle != nil);
	assert(driveNum > 0 && driveNum <= kNumLogicalVolumes);
	assert(pInt13Unit != nil);

	*pInt13Unit = -1;

	driveMapInfo.dmiAllocationLength = sizeof(DRIVEMAPINFO);	// should be 16

	reg.reg_EAX = 0x440d;		// generic IOCTL
	reg.reg_EBX = driveNum;
	reg.reg_ECX = MAKEWORD(kGetDriveMapInfo, kDeviceCategory1);
	reg.reg_EDX = (DWORD) &driveMapInfo;

	result = ::DeviceIoControl(handle, VWIN32_DIOC_DOS_IOCTL,
				&reg, sizeof(reg),
				&reg, sizeof(reg), &cb, 0);
	if (result == 0) {
		WMSG1("  DeviceIoControl(Int21h, 6fh) FAILED (err=%ld)\n",
			GetLastError());
		dierr = LastErrorToDIError();
		goto bail;
	}

	if (reg.reg_Flags & CARRY_FLAG) {
		WMSG1("  --- retrying GDMI with alternate device category (ax=%ld)\n",
			reg.reg_EAX);
		reg.reg_EAX = 0x440d;		// generic IOCTL
		reg.reg_EBX = driveNum;
		reg.reg_ECX = MAKEWORD(kGetDriveMapInfo, kDeviceCategory2);
		reg.reg_EDX = (DWORD) &driveMapInfo;
		result = ::DeviceIoControl(handle, VWIN32_DIOC_DOS_IOCTL,
					&reg, sizeof(reg),
					&reg, sizeof(reg), &cb, 0);
	}
	if (result == 0) {
		WMSG1("  DeviceIoControl(Int21h, 6fh)(retry) FAILED (err=%ld)\n",
			GetLastError());
		dierr = LastErrorToDIError();
		goto bail;
	}
	if (reg.reg_Flags & CARRY_FLAG) {
		WMSG1("  --- GetDriveMapInfo call (retry) failed (ax=%ld)\n",
			reg.reg_EAX);
		dierr = kDIErrReadFailed;	// close enough
		goto bail;
	}

	WMSG3("     +++ DriveMapInfo len=%d flags=%d unit=%d\n",
		driveMapInfo.dmiInfoLength, driveMapInfo.dmiFlags,
		driveMapInfo.dmiInt13Unit);
	WMSG3("     +++   driveMap=0x%08lx RBA=0x%08lx 0x%08lx\n",
		driveMapInfo.dmiAssociatedDriveMap,
		driveMapInfo.dmiPartitionStartRBA_hi,
		driveMapInfo.dmiPartitionStartRBA_lo);

	if (driveMapInfo.dmiInfoLength < 4) {
		/* results not covered in reply? */
		dierr = kDIErrReadFailed;		// not close, but it'll do
		goto bail;
	}

	*pInt13Unit = driveMapInfo.dmiInt13Unit;

bail:
	return dierr;
}
#endif

#if 0
/*
 * Look up the geometry for a floppy disk whose total size is "totalBlocks".
 * There is no BIOS function to detect the media size and geometry, so
 * we have to do it this way.  PC "FAT" disks have a size indication
 * in the boot block, but we can't rely on that.
 *
 * Returns "true" if the geometry is known, "false" otherwise.  When "true"
 * is returned, "*pNumTracks", "*pNumHeads", and "*pNumSectors" will receive
 * values if the pointers are non-nil.
 */
/*static*/ bool
Win32VolumeAccess::BlockAccess::LookupFloppyGeometry(long totalBlocks,
	DiskGeometry* pGeometry)
{
	static const struct {
		FloppyKind	kind;
		long		blockCount;		// total #of blocks on the disk
		int			numCyls;		// #of cylinders
		int			numHeads;		// #of heads per cylinder
		int			numSectors;		// #of sectors/track
	} floppyGeometry[] = {
		{ kFloppyUnknown,	-1,		-1,	-1,	-1 },
		{ kFloppy525_360,	360*2,	40,	2,	9 },
		{ kFloppy525_1200,	1200*2,	80,	2,	15 },
		{ kFloppy35_720,	720*2,	80,	2,	9 },
		{ kFloppy35_1440,	1440*2,	80,	2,	18 },
		{ kFloppy35_2880,	2880*2,	80,	2,	36 }
	};

	/* verify that we can directly index the table with the enum */
	for (int chk = 0; chk < NELEM(floppyGeometry); chk++) {
		assert(floppyGeometry[chk].kind == chk);
	}
	assert(chk == kFloppyMax);

	if (totalBlocks <= 0) {
		// still auto-detecting volume size?
		return false;
	}

	int i;
	for (i = 0; i < NELEM(floppyGeometry); i++)
		if (floppyGeometry[i].blockCount == totalBlocks)
			break;

	if (i == NELEM(floppyGeometry)) {
		WMSG1(  "GetFloppyGeometry: no match for blocks=%ld\n", totalBlocks);
		return false;
	}

	pGeometry->numCyls = floppyGeometry[i].numCyls;
	pGeometry->numHeads = floppyGeometry[i].numHeads;
	pGeometry->numSectors = floppyGeometry[i].numSectors;

	return true;
}
#endif

/*
 * Convert a block number to a cylinder/head/sector offset.  Also figures
 * out what the last block on the current track is.  Sectors are returned
 * in 1-based form.
 *
 * Returns "true" on success, "false" on failure.
 */
/*static*/ bool
Win32VolumeAccess::BlockAccess::BlockToCylinderHeadSector(long blockNum,
	const DiskGeometry* pGeometry, int* pCylinder, int* pHead,
	int* pSector, long* pLastBlockOnTrack)
{
	int cylinder, head, sector;
	long lastBlockOnTrack;
	int leftOver;

	cylinder = blockNum / (pGeometry->numSectors * pGeometry->numHeads);
	leftOver = blockNum - cylinder * (pGeometry->numSectors * pGeometry->numHeads);
	head = leftOver / pGeometry->numSectors;
	sector = leftOver - (head * pGeometry->numSectors);

	assert(cylinder >= 0 && cylinder < pGeometry->numCyls);
	assert(head >= 0 && head < pGeometry->numHeads);
	assert(sector >= 0 && sector < pGeometry->numSectors);

	lastBlockOnTrack = blockNum + (pGeometry->numSectors - sector -1);

	if (pCylinder != nil)
		*pCylinder = cylinder;
	if (pHead != nil)
		*pHead = head;
	if (pSector != nil)
		*pSector = sector+1;
	if (pLastBlockOnTrack != nil)
		*pLastBlockOnTrack = lastBlockOnTrack;

	return true;
}

/*
 * Get the floppy drive kind (*not* the media kind) using Int13h func 8.
 */
/*static*/ DIError
Win32VolumeAccess::BlockAccess::GetFloppyDriveKind(HANDLE handle, int unitNum,
	FloppyKind* pKind)
{
	DIOC_REGISTERS	reg = {0};
	DWORD			cb;
	BOOL			result;

	reg.reg_EAX = MAKEWORD(0, 0x08);	// Read Diskette Drive Parameters
	reg.reg_EDX = MAKEWORD(unitNum, 0);

	result = DeviceIoControl(handle, VWIN32_DIOC_DOS_INT13, &reg,
				sizeof(reg), &reg, sizeof(reg), &cb, 0);

	if (result == 0 || (reg.reg_Flags & CARRY_FLAG)) {
		WMSG3(" GetFloppyKind failed: result=%d flags=0x%04x AH=%d\n",
			result, reg.reg_Flags, HIBYTE(reg.reg_EAX));
		return kDIErrGeneric;
	}

	int bl = LOBYTE(reg.reg_EBX);
	if (bl > 0 && bl < 6)
		*pKind = (FloppyKind) bl;
	else {
		WMSG1(" GetFloppyKind: unrecognized kind %d\n", bl);
		return kDIErrGeneric;
	}

	return kDIErrNone;
}

/*
 * Read one or more blocks using Int13h services.  This only works on
 * floppy drives due to Win9x limitations.
 *
 * The average BIOS will only read one or two tracks reliably, and may
 * not work well when straddling tracks.  It's up to the caller to
 * ensure that the parameters are set properly.
 *
 * "cylinder" and "head" are 0-based, "sector" is 1-based.
 *
 * Returns 0 on success, the status code from AH on failure.  If the call
 * fails but AH is zero, -1 is returned.
 */
/*static*/ int
Win32VolumeAccess::BlockAccess::ReadBlocksInt13h(HANDLE handle, int unitNum,
	int cylinder, int head, int sector, short blockCount, void* buf)
{
	DIOC_REGISTERS	reg = {0};
	DWORD			cb;
	BOOL			result;

	if (unitNum < 0 || unitNum >= 4) {
		assert(false);
		return kDIErrInternal;
	}

	for (int retry = 0; retry < kMaxFloppyRetries; retry++) {
		reg.reg_EAX = MAKEWORD(blockCount, 0x02);	// read N sectors
		reg.reg_EBX = (DWORD) buf;
		reg.reg_ECX = MAKEWORD(sector, cylinder);
		reg.reg_EDX = MAKEWORD(unitNum, head);

		//WMSG4("   DIOC Int13h read c=%d h=%d s=%d rc=%d\n",
		//	cylinder, head, sector, blockCount);
		result = DeviceIoControl(handle, VWIN32_DIOC_DOS_INT13, &reg,
					sizeof(reg), &reg, sizeof(reg), &cb, 0);

		if (result != 0 && !(reg.reg_Flags & CARRY_FLAG))
			break;	// success!

		/* if it's an invalid sector request, bail out immediately */
		if (HIBYTE(reg.reg_EAX) == kInt13StatusSectorNotFound ||
			HIBYTE(reg.reg_EAX) == kInt13StatusMissingAddrMark)
		{
			break;
		}
		WMSG1("   DIOC soft read failure, ax=0x%08lx\n", reg.reg_EAX);
	}
	if (!result || (reg.reg_Flags & CARRY_FLAG)) {
		int ah = HIBYTE(reg.reg_EAX);
		WMSG2("  DIOC read failed, result=%d ah=%ld\n", result, ah);
		if (ah != 0)
			return ah;
		else
			return -1;
	}

	return 0;
}


/*
 * Read one or more blocks using Int13h services.  This only works on
 * floppy drives due to Win9x limitations.
 *
 * It's important to be able to read multiple blocks for performance
 * reasons.  Because this is fairly "raw", we have to retry it 3x before
 * giving up.
 */
/*static*/ DIError
Win32VolumeAccess::BlockAccess::ReadBlocksInt13h(HANDLE handle, int unitNum,
	const DiskGeometry* pGeometry, long startBlock, short blockCount,
	void* buf)
{
	int cylinder, head, sector;
	int status, runCount;
	long lastBlockOnTrack;

	if (unitNum < 0 || unitNum >= 4) {
		assert(false);
		return kDIErrInternal;
	}
	if (startBlock < 0 || blockCount <= 0)
		return kDIErrInvalidArg;
	if (startBlock + blockCount > pGeometry->blockCount) {
		WMSG2(" ReadInt13h: invalid request for start=%ld count=%d\n",
			startBlock, blockCount);
		return kDIErrReadFailed;
	}

	while (blockCount) {
		int result;
		result = BlockToCylinderHeadSector(startBlock, pGeometry,
					&cylinder, &head, &sector, &lastBlockOnTrack);
		assert(result);

		/*
		 * According to "The Undocumented PC", the average BIOS will read
		 * at most one or two tracks reliably.  It's really geared toward
		 * writing a single track or cylinder with one call.  We want to
		 * be sure that our read doesn't straddle tracks, so we break it
		 * down as needed.
		 */
		runCount = lastBlockOnTrack - startBlock +1;
		if (runCount > blockCount)
			runCount = blockCount;
		//WMSG3("R runCount=%d lastBlkOnT=%d start=%d\n",
		//	runCount, lastBlockOnTrack, startBlock);
		assert(runCount > 0);

		status = ReadBlocksInt13h(handle, unitNum, cylinder, head, sector,
					runCount, buf);
		if (status != 0) {
			WMSG1("  DIOC read failed (status=%d)\n", status);
			return kDIErrReadFailed;
		}

		startBlock += runCount;
		blockCount -= runCount;
	}

	return kDIErrNone;
}

/*
 * Write one or more blocks using Int13h services.  This only works on
 * floppy drives due to Win9x limitations.
 *
 * "cylinder" and "head" are 0-based, "sector" is 1-based.
 *
 * It's important to be able to write multiple blocks for performance
 * reasons.  Because this is fairly "raw", we have to retry it 3x before
 * giving up.
 */
/*static*/ int
Win32VolumeAccess::BlockAccess::WriteBlocksInt13h(HANDLE handle, int unitNum,
	int cylinder, int head, int sector, short blockCount,
	const void* buf)
{
	DIOC_REGISTERS	reg = {0};
	DWORD			cb;
	BOOL			result;

	for (int retry = 0; retry < kMaxFloppyRetries; retry++) {
		reg.reg_EAX = MAKEWORD(blockCount, 0x03);	// write N sectors
		reg.reg_EBX = (DWORD) buf;
		reg.reg_ECX = MAKEWORD(sector, cylinder);
		reg.reg_EDX = MAKEWORD(unitNum, head);

		WMSG4("   DIOC Int13h write c=%d h=%d s=%d rc=%d\n",
			cylinder, head, sector, blockCount);
		result = DeviceIoControl(handle, VWIN32_DIOC_DOS_INT13, &reg,
					sizeof(reg), &reg, sizeof(reg), &cb, 0);

		if (result != 0 && !(reg.reg_Flags & CARRY_FLAG))
			break;	// success!

		if (HIBYTE(reg.reg_EAX) == kInt13StatusWriteProtected)
			break;	// no point retrying this
		WMSG1("    DIOC soft write failure, ax=0x%08lx\n", reg.reg_EAX);
	}
	if (!result || (reg.reg_Flags & CARRY_FLAG)) {
		int ah = HIBYTE(reg.reg_EAX);
		WMSG2("  DIOC write failed, result=%d ah=%ld\n", result, ah);
		if (ah != 0)
			return ah;
		else
			return -1;
	}

	return 0;
}

/*
 * Write one or more blocks using Int13h services.  This only works on
 * floppy drives.
 *
 * It's important to be able to write multiple blocks for performance
 * reasons.  Because this is fairly "raw", we have to retry it 3x before
 * giving up.
 *
 * Returns "true" on success, "false" on failure.
 */
/*static*/ DIError
Win32VolumeAccess::BlockAccess::WriteBlocksInt13h(HANDLE handle, int unitNum,
	const DiskGeometry* pGeometry, long startBlock, short blockCount,
	const void* buf)
{
	int cylinder, head, sector;
	int status, runCount;
	long lastBlockOnTrack;

	// make sure this is a floppy drive and we know which unit it is
	if (unitNum < 0 || unitNum >= 4) {
		assert(false);
		return kDIErrInternal;
	}
	if (startBlock < 0 || blockCount <= 0)
		return kDIErrInvalidArg;
	if (startBlock + blockCount > pGeometry->blockCount) {
		WMSG2(" WriteInt13h: invalid request for start=%ld count=%d\n",
			startBlock, blockCount);
		return kDIErrWriteFailed;
	}

	while (blockCount) {
		int result;
		result = BlockToCylinderHeadSector(startBlock, pGeometry,
					&cylinder, &head, &sector, &lastBlockOnTrack);
		assert(result);

		runCount = lastBlockOnTrack - startBlock +1;
		if (runCount > blockCount)
			runCount = blockCount;
		//WMSG3("W runCount=%d lastBlkOnT=%d start=%d\n",
		//	runCount, lastBlockOnTrack, startBlock);
		assert(runCount > 0);

		status = WriteBlocksInt13h(handle, unitNum, cylinder, head, sector,
					runCount, buf);
		if (status != 0) {
			WMSG1("  DIOC write failed (status=%d)\n", status);
			if (status == kInt13StatusWriteProtected)
				return kDIErrWriteProtected;
			else
				return kDIErrWriteFailed;
		}

		startBlock += runCount;
		blockCount -= runCount;
	}

	return kDIErrNone;
}


/*
 * Read blocks from a Win9x logical volume, using Int21h func 7305h.  Pass in
 * a handle to vwin32 and the logical drive number (A=1, B=2, etc).
 *
 * Works on Win95 OSR2 and later.  Earlier versions require Int25 or Int13.
 */
/*static*/ DIError
Win32VolumeAccess::BlockAccess::ReadBlocksInt21h(HANDLE handle, int driveNum,
	long startBlock, short blockCount, void* buf)
{
#if 0
	assert(false);		// discouraged
	BOOL			result;
	DWORD			cb;
	DIOC_REGISTERS	reg = {0};
	DISKIO			dio = {0};

	dio.dwStartSector = startBlock;
	dio.wSectors      = (WORD) blockCount;
	dio.dwBuffer      = (DWORD) buf;

	reg.reg_EAX = fDriveNum - 1;	// Int 25h drive numbers are 0-based.
	reg.reg_EBX = (DWORD)&dio;
	reg.reg_ECX = 0xFFFF;		// use DISKIO struct

	WMSG3("   Int25 read start=%d count=%d\n",
		startBlock, blockCount);
	result = ::DeviceIoControl(handle, VWIN32_DIOC_DOS_INT25,
				&reg, sizeof(reg),
				&reg, sizeof(reg), &cb, 0);

	// Determine if the DeviceIoControl call and the read succeeded.
	result = result && !(reg.reg_Flags & CARRY_FLAG);

	WMSG2("     +++ read from block %ld (result=%d)\n", startBlock, result);
	if (!result)
		return kDIErrReadFailed;
#else
	BOOL			result;
	DWORD			cb;
	DIOC_REGISTERS	reg = {0};
	DISKIO			dio = {0};

	dio.dwStartSector = startBlock;
	dio.wSectors      = (WORD) blockCount;
	dio.dwBuffer      = (DWORD) buf;

	reg.reg_EAX = 0x7305;	// Ext_ABSDiskReadWrite
	reg.reg_EBX = (DWORD)&dio;
	reg.reg_ECX = -1;
	reg.reg_EDX = driveNum;	// Int 21h, fn 7305h drive numbers are 1-based
	assert(reg.reg_ESI == 0);	// read/write flag

	WMSG2("   Int21/7305h read start=%d count=%d\n",
		startBlock, blockCount);
	result = ::DeviceIoControl(handle, VWIN32_DIOC_DOS_DRIVEINFO,
				&reg, sizeof(reg),
				&reg, sizeof(reg), &cb, 0);

	// Determine if the DeviceIoControl call and the read succeeded.
	result = result && !(reg.reg_Flags & CARRY_FLAG);

	WMSG4("     +++ RB21h %ld %d (result=%d lastError=%ld)\n",
		startBlock, blockCount, result, GetLastError());
	if (!result)
		return kDIErrReadFailed;
#endif

	return kDIErrNone;
}

/*
 * Write blocks to a Win9x logical volume.  Pass in a handle to vwin32 and
 * the logical drive number (A=1, B=2, etc).
 *
 * Works on Win95 OSR2 and later.  Earlier versions require Int26 or Int13.
 */
/*static*/ DIError
Win32VolumeAccess::BlockAccess::WriteBlocksInt21h(HANDLE handle, int driveNum,
	long startBlock, short blockCount, const void* buf)
{
	BOOL			result;
	DWORD			cb;
	DIOC_REGISTERS	reg = {0};
	DISKIO			dio = {0};

	dio.dwStartSector = startBlock;
	dio.wSectors      = (WORD) blockCount;
	dio.dwBuffer      = (DWORD) buf;

	reg.reg_EAX = 0x7305;	// Ext_ABSDiskReadWrite
	reg.reg_EBX = (DWORD)&dio;
	reg.reg_ECX = -1;
	reg.reg_EDX = driveNum;	// Int 21h, fn 7305h drive numbers are 1-based
	reg.reg_ESI = 0x6001;		// write normal data (bit flags)

	//WMSG2("   Int21/7305h write start=%d count=%d\n",
	//	startBlock, blockCount);
	result = ::DeviceIoControl(handle, VWIN32_DIOC_DOS_DRIVEINFO,
				&reg, sizeof(reg),
				&reg, sizeof(reg), &cb, 0);

	// Determine if the DeviceIoControl call and the read succeeded.
	result = result && !(reg.reg_Flags & CARRY_FLAG);

	WMSG4("     +++ WB21h %ld %d (result=%d lastError=%ld)\n",
		startBlock, blockCount, result, GetLastError());
	if (!result)
		return kDIErrWriteFailed;

	return kDIErrNone;
}


/*
 * Read blocks from a Win2K logical or physical volume.
 */
/*static*/ DIError
Win32VolumeAccess::BlockAccess::ReadBlocksWin2K(HANDLE handle,
	long startBlock, short blockCount, void* buf)
{
	/*
	 * Try to read the blocks.  Under Win2K the seek and read calls appear
	 * to succeed, but the value in "actual" is set to zero to indicate
	 * that we're trying to read past EOF.
	 */
	DWORD posn, actual;

	/*
	 * Win2K: the 3rd argument holds the high 32 bits of the distance to
	 * move.  This isn't supported in Win9x, which means Win9x is limited
	 * to 2GB files.
	 */
	LARGE_INTEGER li;
	li.QuadPart = (LONGLONG) startBlock * (LONGLONG) kBlockSize;
	posn = ::SetFilePointer(handle, li.LowPart, &li.HighPart,
				FILE_BEGIN);
	if (posn == INVALID_SET_FILE_POINTER) {
		DWORD lerr = GetLastError();
		WMSG1("  GFDWinVolume ReadBlock: SFP failed (err=%ld)\n", lerr);
		return LastErrorToDIError();
	}

	//WMSG2("   ReadFile block start=%d count=%d\n", startBlock, blockCount);

	BOOL result;
	result = ::ReadFile(handle, buf, blockCount * kBlockSize, &actual, nil);
	if (!result) {
		DWORD lerr = GetLastError();
		WMSG3("  ReadBlocksWin2K: ReadFile failed (start=%ld count=%d err=%ld)\n",
			startBlock, blockCount, lerr);
		return LastErrorToDIError();
	}
	if ((long) actual != blockCount * kBlockSize)
		return kDIErrEOF;

	return kDIErrNone;
}


/*
 * Write blocks to a Win2K logical or physical volume.
 */
/*static*/ DIError
Win32VolumeAccess::BlockAccess::WriteBlocksWin2K(HANDLE handle,
	long startBlock, short blockCount, const void* buf)
{
	DWORD posn, actual;

	posn = ::SetFilePointer(handle, startBlock * kBlockSize, nil,
				FILE_BEGIN);
	if (posn == INVALID_SET_FILE_POINTER) {
		DWORD lerr = GetLastError();
		WMSG2("  GFDWinVolume ReadBlocks: SFP %ld failed (err=%ld)\n",
			startBlock * kBlockSize, lerr);
		return LastErrorToDIError();
	}

	BOOL result;
	result = ::WriteFile(handle, buf, blockCount * kBlockSize, &actual, nil);
	if (!result) {
		DWORD lerr = GetLastError();
		WMSG1("  GFDWinVolume WriteBlocks: WriteFile failed (err=%ld)\n",
			lerr);
		return LastErrorToDIError();
	}
	if ((long) actual != blockCount * kBlockSize)
		return kDIErrEOF;		// unexpected on a write call?

	return kDIErrNone;
}


/*
 * ===========================================================================
 *		LogicalBlockAccess
 * ===========================================================================
 */

/*
 * Open a logical device.  The device name should be of the form "A:\".
 */
DIError
Win32VolumeAccess::LogicalBlockAccess::Open(const char* deviceName, bool readOnly)
{
	DIError dierr = kDIErrNone;
	const bool kPreferASPI = true;

	assert(fHandle == nil);
	fIsCDROM = false;
	fDriveNum = -1;

	if (deviceName[0] < 'A' || deviceName[0] > 'Z' ||
		deviceName[1] != ':' || deviceName[2] != '\\' ||
		deviceName[3] != '\0')
	{
		WMSG1("  LogicalBlockAccess: invalid device name '%s'\n", deviceName);
		assert(false);
		dierr = kDIErrInvalidArg;
		goto bail;
	}
	if (deviceName[0] == 'C') {
		if (readOnly == false) {
			WMSG0("  REFUSING WRITE ACCESS TO C:\\ \n");
			return kDIErrVWAccessForbidden;
		}
	}

	DWORD access;
	if (readOnly)
		access = GENERIC_READ;
	else
		access = GENERIC_READ | GENERIC_WRITE;

	UINT driveType;
	driveType = GetDriveType(deviceName);
	if (driveType == DRIVE_CDROM) {
		if (!Global::GetHasSPTI() && !Global::GetHasASPI())
			return kDIErrCDROMNotSupported;

		fIsCDROM = true;
		// SPTI needs this -- maybe to enforce exclusive access?
		access |= GENERIC_WRITE;
	}

	if (fIsWin9x) {
		if (fIsCDROM)
			return kDIErrCDROMNotSupported;

		fHandle = CreateFile("\\\\.\\vwin32", 0, 0, NULL,
					OPEN_EXISTING, FILE_FLAG_DELETE_ON_CLOSE, NULL);
		if (fHandle == INVALID_HANDLE_VALUE) {
			DWORD lastError = GetLastError();
			WMSG1("  Win32LVOpen: CreateFile(vwin32) failed (err=%ld)\n",
				lastError);
			dierr = LastErrorToDIError();
			goto bail;
		}
		fDriveNum = deviceName[0] - 'A' +1;
		assert(fDriveNum > 0 && fDriveNum <= kNumLogicalVolumes);

#if 0
		int int13Unit;
		dierr = GetInt13Unit(fHandle, fDriveNum, &int13Unit);
		if (dierr != kDIErrNone)
			goto bail;
		if (int13Unit < 4) {
			fFloppyUnit = int13Unit;
			WMSG2(" Logical volume #%d looks like floppy unit %d\n",
				fDriveNum, fFloppyUnit);
		}
#endif
	} else {
		char device[7] = "\\\\.\\_:";
		device[4] = deviceName[0];
		WMSG1("Opening '%s'\n", device);

		// If we're reading, allow others to write.  If we're writing, insist
		// upon exclusive access to the volume.
		DWORD shareMode = FILE_SHARE_READ;
		if (access == GENERIC_READ)
			shareMode |= FILE_SHARE_WRITE;

		fHandle = CreateFile(device, access, shareMode,
					NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
		if (fHandle == INVALID_HANDLE_VALUE) {
			DWORD lastError = GetLastError();
			dierr = LastErrorToDIError();
			if (lastError == ERROR_INVALID_PARAMETER && shareMode == FILE_SHARE_READ)
			{
				// Win2K spits this back if the volume is open and we're
				// not specifying FILE_SHARE_WRITE.  Give it a try, just to
				// see if it works, so we can tell the difference between
				// an internal library error and an active filesystem.
				HANDLE tmpHandle;
				tmpHandle = CreateFile(device, access, FILE_SHARE_READ|FILE_SHARE_WRITE,
							NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
				if (tmpHandle != INVALID_HANDLE_VALUE) {
					dierr = kDIErrNoExclusiveAccess;
					::CloseHandle(tmpHandle);
				}
			}
			WMSG2("  LBAccess Open: CreateFile failed (err=%ld dierr=%d)\n",
				lastError, dierr);
			goto bail;
		}
	}

	assert(fHandle != nil && fHandle != INVALID_HANDLE_VALUE);

#if 0
	if (fIsCDROM) {
		assert(Global::GetHasSPTI() || Global::GetHasASPI());
		if (Global::GetHasASPI() && (!Global::GetHasSPTI() || kPreferASPI)) {
			WMSG0("  LBAccess using ASPI\n");
			fCDBaggage.fUseASPI = true;
		} else {
			WMSG0("  LBAccess using SPTI\n");
			fCDBaggage.fUseASPI = false;
		}

		if (fCDBaggage.fUseASPI) {
			dierr = FindASPIDriveMapping(deviceName[0]);
			if (dierr != kDIErrNone) {
				WMSG0("ERROR: couldn't find ASPI drive mapping\n");
				dierr = kDIErrNoASPIMapping;
				goto bail;
			}
		}
	}
#endif

bail:
	if (dierr != kDIErrNone) {
		if (fHandle != nil && fHandle != INVALID_HANDLE_VALUE)
			::CloseHandle(fHandle);
		fHandle = nil;
	}
	return dierr;
}

/*
 * Close the device handle.
 */
DIError
Win32VolumeAccess::LogicalBlockAccess::Close(void)
{
	if (fHandle != nil) {
		::CloseHandle(fHandle);
		fHandle = nil;
	}
	return kDIErrNone;
}


/*
 * Read 512-byte blocks from CD-ROM media using SPTI calls.
 */
DIError
Win32VolumeAccess::LogicalBlockAccess::ReadBlocksCDROM(HANDLE handle,
	long startBlock, short blockCount, void* buf)
{
#ifdef HAVE_WINDOWS_CDROM
	DIError dierr;

	assert(handle != nil);
	assert(startBlock >= 0);
	assert(blockCount > 0);
	assert(buf != nil);

	//WMSG2(" CDROM read block %ld (%ld)\n", startBlock, block);

	/* alloc sector buffer on first use */
	if (fLastSectorCache == nil) {
		fLastSectorCache = new unsigned char[kCDROMSectorSize];
		if (fLastSectorCache == nil)
			return kDIErrMalloc;
		assert(fLastSectorNum == -1);
	}

	/*
	 * Map a range of 512-byte blocks to a range of 2048-byte blocks.
	 */
	assert(kCDROMSectorSize % kBlockSize == 0);
	const int kFactor = kCDROMSectorSize / kBlockSize;
	long sectorIndex = startBlock / kFactor;
	int sectorOffset = (int) (startBlock % kFactor);	// 0-3

	/*
	 * When possible, do multi-block reads directly into "buf".  The first
	 * and last block may require special handling.
	 */
	while (blockCount) {
		assert(blockCount > 0);

		if (sectorOffset != 0 || blockCount < kFactor) {
			assert(sectorOffset >= 0 && sectorOffset < kFactor);

			/* get from single-block cache or from disc */
			if (sectorIndex != fLastSectorNum) {
				fLastSectorNum = -1;		// invalidate, in case of error

				dierr = SPTI::ReadBlocks(handle, sectorIndex, 1,
							kCDROMSectorSize, fLastSectorCache);
				if (dierr != kDIErrNone)
					return dierr;

				fLastSectorNum = sectorIndex;
			}

			int thisNumBlocks;
			thisNumBlocks = kFactor - sectorOffset;
			if (thisNumBlocks > blockCount)
				thisNumBlocks = blockCount;

			//WMSG3("  Small copy (sectIdx=%ld off=%d*512 size=%d*512)\n",
			//	sectorIndex, sectorOffset, thisNumBlocks);
			memcpy(buf, fLastSectorCache + sectorOffset * kBlockSize,
				thisNumBlocks * kBlockSize);

			blockCount -= thisNumBlocks;
			buf = (unsigned char*) buf + (thisNumBlocks * kBlockSize);

			sectorOffset = 0;
			sectorIndex++;
		} else {
			fLastSectorNum = -1;		// invalidate single-block cache

			int numSectors;
			numSectors = blockCount / kFactor;	// rounds down

			//WMSG2("  Big read (sectIdx=%ld numSect=%d)\n",
			//	sectorIndex, numSectors);
			dierr = SPTI::ReadBlocks(handle, sectorIndex, numSectors,
						kCDROMSectorSize, buf);
			if (dierr != kDIErrNone)
				return dierr;

			blockCount -= numSectors * kFactor;
			buf = (unsigned char*) buf + (numSectors * kCDROMSectorSize);

			sectorIndex += numSectors;
		}
	}

	return kDIErrNone;

#else
	return kDIErrCDROMNotSupported;
#endif
}


/*
 * ===========================================================================
 *		PhysicalBlockAccess
 * ===========================================================================
 */

/*
 * Open a physical device.  The device name should be of the form "80:\".
 */
DIError
Win32VolumeAccess::PhysicalBlockAccess::Open(const char* deviceName, bool readOnly)
{
	DIError dierr = kDIErrNone;

	// initialize all local state
	assert(fHandle == nil);
	fInt13Unit = -1;
	fFloppyKind = kFloppyUnknown;
	memset(&fGeometry, 0, sizeof(fGeometry));

	// sanity-check name; not this only works for first 10 devices
	if (deviceName[0] < '0' || deviceName[0] > '9' ||
		deviceName[1] < '0' || deviceName[1] > '9' ||
		deviceName[2] != ':' || deviceName[3] != '\\' ||
		deviceName[4] != '\0')
	{
		WMSG1("  PhysicalBlockAccess: invalid device name '%s'\n", deviceName);
		assert(false);
		dierr = kDIErrInvalidArg;
		goto bail;
	}

	if (deviceName[0] == '8' && deviceName[1] == '0') {
		if (!gAllowWritePhys0 && readOnly == false) {
			WMSG0("  REFUSING WRITE ACCESS TO 80:\\ \n");
			return kDIErrVWAccessForbidden;
		}
	}

	fInt13Unit = (deviceName[0] - '0') * 16 + deviceName[1] - '0';
	if (!fIsWin9x && fInt13Unit < 0x80) {
		WMSG0("GLITCH: can't open floppy as physical unit in Win2K\n");
		dierr = kDIErrInvalidArg;
		goto bail;
	}
	if (fIsWin9x && fInt13Unit >= 0x80) {
		WMSG0("GLITCH: can't access physical HD in Win9x\n");
		dierr = kDIErrInvalidArg;
		goto bail;
	}
	if ((fInt13Unit >= 0x00 && fInt13Unit < 0x04) ||
		(fInt13Unit >= 0x80 && fInt13Unit < 0x88))
	{
		WMSG1("  Win32VA/P: opening unit %02xh\n", fInt13Unit);
	} else {
		WMSG2("GLITCH: converted '%s' to %02xh\n", deviceName, fInt13Unit);
		dierr = kDIErrInternal;
		goto bail;
	}

	DWORD access;
	if (readOnly)
		access = GENERIC_READ;
	else
		access = GENERIC_READ | GENERIC_WRITE;

	if (fIsWin9x) {
		fHandle = CreateFile("\\\\.\\vwin32", 0, 0, NULL,
					OPEN_EXISTING, FILE_FLAG_DELETE_ON_CLOSE, NULL);
		if (fHandle == INVALID_HANDLE_VALUE) {
			DWORD lastError = GetLastError();
			WMSG1("  Win32VA/PBOpen: CreateFile(vwin32) failed (err=%ld)\n",
				lastError);
			dierr = LastErrorToDIError();
			goto bail;
		}

		/* figure out the geometry */
		dierr = DetectFloppyGeometry();
		if (dierr != kDIErrNone)
			goto bail;
	} else {
		char device[19] = "\\\\.\\PhysicalDrive_";
		assert(fInt13Unit >= 0x80 && fInt13Unit <= 0x89);
		device[17] = fInt13Unit - 0x80 + '0';
		WMSG2("Opening '%s' (access=0x%02x)\n", device, access);

		// If we're reading, allow others to write.  If we're writing, insist
		// upon exclusive access to the volume.
		DWORD shareMode = FILE_SHARE_READ;
		if (access == GENERIC_READ)
			shareMode |= FILE_SHARE_WRITE;

		fHandle = CreateFile(device, access, shareMode,
					NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
		if (fHandle == INVALID_HANDLE_VALUE) {
			DWORD lastError = GetLastError();
			dierr = LastErrorToDIError();
			WMSG2("  PBAccess Open: CreateFile failed (err=%ld dierr=%d)\n",
				lastError, dierr);
			goto bail;
		}
	}

	assert(fHandle != nil && fHandle != INVALID_HANDLE_VALUE);

bail:
	if (dierr != kDIErrNone) {
		if (fHandle != nil && fHandle != INVALID_HANDLE_VALUE)
			::CloseHandle(fHandle);
		fHandle = nil;
	}

	return dierr;
}

/*
 * Auto-detect the geometry of a floppy drive.
 *
 * Sets "fFloppyKind" and "fGeometry".
 */
DIError
Win32VolumeAccess::PhysicalBlockAccess::DetectFloppyGeometry(void)
{
	DIError dierr = kDIErrNone;
	static const struct {
		FloppyKind		kind;
		DiskGeometry	geom;
	} floppyGeometry[] = {
		{ kFloppyUnknown,	{ -1,	-1,	-1,	-1		} },
		{ kFloppy525_360,	{ 40,	2,	9,	360*2	} },
		{ kFloppy525_1200,	{ 80,	2,	15,	1200*2	} },
		{ kFloppy35_720,	{ 80,	2,	9,	720*2	} },
		{ kFloppy35_1440,	{ 80,	2,	18,	1440*2	} },
		{ kFloppy35_2880,	{ 80,	2,	36,	2880*2	} }
	};
	unsigned char buf[kBlockSize];
	FloppyKind driveKind;
	int status;

	/* verify that we can directly index the table with the enum */
	for (int chk = 0; chk < NELEM(floppyGeometry); chk++) {
		assert(floppyGeometry[chk].kind == chk);
	}
	assert(chk == kFloppyMax);


	/*
	 * Issue a BIOS call to determine the kind of drive we're looking at.
	 */
	dierr = GetFloppyDriveKind(fHandle, fInt13Unit, &driveKind);
	if (dierr != kDIErrNone)
		goto bail;

	switch (driveKind) {
	case kFloppy35_2880:
		status = ReadBlocksInt13h(fHandle, fInt13Unit, 0, 0, 36, 1, buf);
		if (status == 0) {
			fFloppyKind = kFloppy35_2880;
			break;
		}
		// else, fall through
	case kFloppy35_1440:
		status = ReadBlocksInt13h(fHandle, fInt13Unit, 0, 0, 18, 1, buf);
		if (status == 0) {
			fFloppyKind = kFloppy35_1440;
			break;
		}
		// else, fall through
	case kFloppy35_720:
		status = ReadBlocksInt13h(fHandle, fInt13Unit, 0, 0, 9, 1, buf);
		if (status == 0) {
			fFloppyKind = kFloppy35_720;
			break;
		}
		// else, fail
		dierr = kDIErrReadFailed;
		goto bail;

	case kFloppy525_1200:
		status = ReadBlocksInt13h(fHandle, fInt13Unit, 0, 0, 15, 1, buf);
		if (status == 0) {
			fFloppyKind = kFloppy525_1200;
			break;
		}
		// else, fall through
	case kFloppy525_360:
		status = ReadBlocksInt13h(fHandle, fInt13Unit, 0, 0, 9, 1, buf);
		if (status == 0) {
			fFloppyKind = kFloppy525_360;
			break;
		}
		// else, fail
		dierr = kDIErrReadFailed;
		goto bail;

	default:
		WMSG1(" Unknown driveKind %d\n", driveKind);
		assert(false);
		dierr = kDIErrInternal;
		goto bail;
	}

	WMSG1("PBA: floppy disk appears to be type=%d\n", fFloppyKind);
	fGeometry = floppyGeometry[fFloppyKind].geom;

bail:
	return dierr;
}

#if 0
/*
 * Flush the system disk cache.
 */
DIError
Win32VolumeAccess::PhysicalBlockAccess::FlushBlockDevice(void)
{
	DIError dierr = kDIErrNone;

	if (::FlushFileBuffers(fHandle) == FALSE) {
		DWORD lastError = GetLastError();
		WMSG1("  Win32VA/PBAFlush: FlushFileBuffers failed (err=%ld)\n",
			lastError);
		dierr = LastErrorToDIError();
	}
	return dierr;
}
#endif

/*
 * Close the device handle.
 */
DIError
Win32VolumeAccess::PhysicalBlockAccess::Close(void)
{
	if (fHandle != nil) {
		::CloseHandle(fHandle);
		fHandle = nil;
	}
	return kDIErrNone;
}


/*
 * ===========================================================================
 *		ASPIBlockAccess
 * ===========================================================================
 */

/*
 * Unpack device name and verify that the device is a CD-ROM drive or
 * direct-access storage device.
 */
DIError
Win32VolumeAccess::ASPIBlockAccess::Open(const char* deviceName, bool readOnly)
{
	DIError dierr = kDIErrNone;

	if (fpASPI != nil)
		return kDIErrAlreadyOpen;

	fpASPI = Global::GetASPI();
	if (fpASPI == nil)
		return kDIErrASPIFailure;

	if (strncmp(deviceName, kASPIDev, strlen(kASPIDev)) != 0) {
		assert(false);
		dierr = kDIErrInternal;
		goto bail;
	}

	const char* cp;
	int adapter, target, lun;
	int result;

	cp = deviceName + strlen(kASPIDev);
	result = 0;
	result |= ExtractInt(&cp, &adapter);
	result |= ExtractInt(&cp, &target);
	result |= ExtractInt(&cp, &lun);
	if (result != 0) {
		WMSG1(" Win32VA couldn't parse '%s'\n", deviceName);
		dierr = kDIErrInternal;
		goto bail;
	}

	fAdapter = adapter;
	fTarget = target;
	fLun = lun;

	unsigned char deviceType;
	dierr = fpASPI->GetDeviceType(fAdapter, fTarget, fLun, &deviceType);
	if (dierr != kDIErrNone ||
		(deviceType != kScsiDevTypeCDROM && deviceType != kScsiDevTypeDASD))
	{
		WMSG2(" Win32VA bad GetDeviceType err=%d type=%d\n",
			dierr, deviceType);
		dierr = kDIErrInternal;		// should not be here at all
		goto bail;
	}
	if (deviceType == kScsiDevTypeCDROM)
		fReadOnly = true;
	else
		fReadOnly = readOnly;

	WMSG4(" Win32VA successful 'open' of '%s' on %d:%d:%d\n",
		deviceName, fAdapter, fTarget, fLun);

bail:
	if (dierr != kDIErrNone)
		fpASPI = nil;
	return dierr;
}

/*
 * Extract an integer from a string, advancing to the next integer after
 * doing so.
 *
 * Returns 0 on success, -1 on failure.
 */
int
Win32VolumeAccess::ASPIBlockAccess::ExtractInt(const char** pStr, int* pResult)
{
	char* end = nil;

	if (*pStr == nil) {
		assert(false);
		return -1;
	}

	*pResult = (int) strtol(*pStr, &end, 10);

	if (end == nil)
		*pStr = nil;
	else
		*pStr = end+1;

	return 0;
}

/*
 * Return the device capacity in 512-byte blocks.
 *
 * Sets fChunkSize as a side-effect.
 */
DIError
Win32VolumeAccess::ASPIBlockAccess::DetectCapacity(long* pNumBlocks)
{
	DIError dierr = kDIErrNone;
	unsigned long lba, blockLen;

	dierr = fpASPI->GetDeviceCapacity(fAdapter, fTarget, fLun, &lba,
				&blockLen);
	if (dierr != kDIErrNone)
		goto bail;

	WMSG3("READ CAPACITY reports lba=%lu blockLen=%lu (total=%lu)\n",
		lba, blockLen, lba*blockLen);

	fChunkSize = blockLen;

	if ((blockLen % 512) != 0) {
		WMSG1("Unacceptable CD-ROM blockLen=%ld, bailing\n", blockLen);
		dierr = kDIErrReadFailed;
		goto bail;
	}

	// The LBA is the last valid block on the disk.  To get the disk size,
	// we need to add one.

	*pNumBlocks = (blockLen/512) * (lba+1);
	WMSG1(" ASPI returning 512-byte block count %ld\n", *pNumBlocks);

bail:
	return dierr;
}

/*
 * Read one or more 512-byte blocks from the device.
 *
 * SCSI doesn't promise it'll be in a chunk size we like, but it's pretty
 * safe to assume that it'll be at least 512 bytes, and divisible by 512.
 */
DIError
Win32VolumeAccess::ASPIBlockAccess::ReadBlocks(long startBlock, short blockCount,
	void* buf)
{
	DIError dierr;

	// we're expecting fBlockSize to be 512 or 2048
	assert(fChunkSize >= kBlockSize && fChunkSize <= 65536);
	assert((fChunkSize % kBlockSize) == 0);

	/* alloc chunk buffer on first use */
	if (fLastChunkCache == nil) {
		fLastChunkCache = new unsigned char[fChunkSize];
		if (fLastChunkCache == nil)
			return kDIErrMalloc;
		assert(fLastChunkNum == -1);
	}

	/*
	 * Map a range of N-byte blocks to a range of 2048-byte blocks.
	 */
	const int kFactor = fChunkSize / kBlockSize;
	long chunkIndex = startBlock / kFactor;
	int chunkOffset = (int) (startBlock % kFactor);	// small integer

	/*
	 * When possible, do multi-block reads directly into "buf".  The first
	 * and last block may require special handling.
	 */
	while (blockCount) {
		assert(blockCount > 0);

		if (chunkOffset != 0 || blockCount < kFactor) {
			assert(chunkOffset >= 0 && chunkOffset < kFactor);

			/* get from single-block cache or from disc */
			if (chunkIndex != fLastChunkNum) {
				fLastChunkNum = -1;		// invalidate, in case of error

				dierr = fpASPI->ReadBlocks(fAdapter, fTarget, fLun, chunkIndex,
							1, fChunkSize, fLastChunkCache);
				if (dierr != kDIErrNone)
					return dierr;

				fLastChunkNum = chunkIndex;
			}

			int thisNumBlocks;
			thisNumBlocks = kFactor - chunkOffset;
			if (thisNumBlocks > blockCount)
				thisNumBlocks = blockCount;

			//WMSG3("  Small copy (chIdx=%ld off=%d*512 size=%d*512)\n",
			//	chunkIndex, chunkOffset, thisNumBlocks);
			memcpy(buf, fLastChunkCache + chunkOffset * kBlockSize,
				thisNumBlocks * kBlockSize);

			blockCount -= thisNumBlocks;
			buf = (unsigned char*) buf + (thisNumBlocks * kBlockSize);

			chunkOffset = 0;
			chunkIndex++;
		} else {
			fLastChunkNum = -1;		// invalidate single-block cache

			int numChunks;
			numChunks = blockCount / kFactor;	// rounds down

			//WMSG2("  Big read (chIdx=%ld numCh=%d)\n",
			//	chunkIndex, numChunks);
			dierr = fpASPI->ReadBlocks(fAdapter, fTarget, fLun, chunkIndex,
						numChunks, fChunkSize, buf);
			if (dierr != kDIErrNone)
				return dierr;

			blockCount -= numChunks * kFactor;
			buf = (unsigned char*) buf + (numChunks * fChunkSize);

			chunkIndex += numChunks;
		}
	}

	return kDIErrNone;
}

/*
 * Write one or more 512-byte blocks to the device.
 *
 * SCSI doesn't promise it'll be in a chunk size we like, but it's pretty
 * safe to assume that it'll be at least 512 bytes, and divisible by 512.
 */
DIError
Win32VolumeAccess::ASPIBlockAccess::WriteBlocks(long startBlock, short blockCount,
	const void* buf)
{
	DIError dierr;

	if (fReadOnly)
		return kDIErrAccessDenied;

	// we're expecting fBlockSize to be 512 or 2048
	assert(fChunkSize >= kBlockSize && fChunkSize <= 65536);
	assert((fChunkSize % kBlockSize) == 0);

	/* throw out the cache */
	fLastChunkNum = -1;

	/*
	 * Map a range of N-byte blocks to a range of 2048-byte blocks.
	 */
	const int kFactor = fChunkSize / kBlockSize;
	long chunkIndex = startBlock / kFactor;
	int chunkOffset = (int) (startBlock % kFactor);	// small integer

	/*
	 * When possible, do multi-block writes directly from "buf".  The first
	 * and last block may require special handling.
	 */
	while (blockCount) {
		assert(blockCount > 0);

		if (chunkOffset != 0 || blockCount < kFactor) {
			assert(chunkOffset >= 0 && chunkOffset < kFactor);

			/* read the chunk we're writing a part of */
			dierr = fpASPI->ReadBlocks(fAdapter, fTarget, fLun, chunkIndex,
						1, fChunkSize, fLastChunkCache);
			if (dierr != kDIErrNone)
				return dierr;

			int thisNumBlocks;
			thisNumBlocks = kFactor - chunkOffset;
			if (thisNumBlocks > blockCount)
				thisNumBlocks = blockCount;

			WMSG3("  Small copy out (chIdx=%ld off=%d*512 size=%d*512)\n",
				chunkIndex, chunkOffset, thisNumBlocks);
			memcpy(fLastChunkCache + chunkOffset * kBlockSize, buf,
				thisNumBlocks * kBlockSize);

			blockCount -= thisNumBlocks;
			buf = (const unsigned char*) buf + (thisNumBlocks * kBlockSize);

			chunkOffset = 0;
			chunkIndex++;
		} else {
			int numChunks;
			numChunks = blockCount / kFactor;	// rounds down

			WMSG2("  Big write (chIdx=%ld numCh=%d)\n",
				chunkIndex, numChunks);
			dierr = fpASPI->WriteBlocks(fAdapter, fTarget, fLun, chunkIndex,
						numChunks, fChunkSize, buf);
			if (dierr != kDIErrNone)
				return dierr;

			blockCount -= numChunks * kFactor;
			buf = (const unsigned char*) buf + (numChunks * fChunkSize);

			chunkIndex += numChunks;
		}
	}

	return kDIErrNone;
}

/*
 * Not much to do, really, since we're not holding onto any OS structures.
 */
DIError
Win32VolumeAccess::ASPIBlockAccess::Close(void)
{
	fpASPI = nil;
	return kDIErrNone;
}


/*
 * ===========================================================================
 *		CBCache
 * ===========================================================================
 */

/*
 * Determine whether we're holding a block in the cache.
 */
bool
CBCache::IsBlockInCache(long blockNum) const
{
	if (fFirstBlock == kEmpty)
		return false;
	assert(fNumBlocks > 0);

	if (blockNum >= fFirstBlock && blockNum < fFirstBlock + fNumBlocks)
		return true;
	else
		return false;
}

/*
 * Retrieve a single block from the cache.
 */
DIError
CBCache::GetFromCache(long blockNum, void* buf)
{
	if (!IsBlockInCache(blockNum)) {
		assert(false);
		return kDIErrInternal;
	}

	//WMSG1("   CBCache: getting block %d from cache\n", blockNum);
	int offset = (blockNum - fFirstBlock) * kBlockSize;
	assert(offset >= 0);

	memcpy(buf, fCache + offset, kBlockSize);
	return kDIErrNone;
}

/*
 * Determine whether a block will "fit" in the cache.  There are two
 * criteria: (1) there must actually be room at the end, and (2) the
 * block in question must be the next consecutive block.
 */
bool
CBCache::IsRoomInCache(long blockNum) const
{
	if (fFirstBlock == kEmpty)
		return true;

	// already in cache?
	if (blockNum >= fFirstBlock && blockNum < fFirstBlock + fNumBlocks)
		return true;

	// running off the end?
	if (fNumBlocks == kMaxCachedBlocks)
		return false;

	// is it the exact next one?
	if (fFirstBlock + fNumBlocks != blockNum)
		return false;

	return true;
}

/*
 * Add a block to the cache.
 *
 * We might be adding it after a read or a write.  The "isDirty" flag
 * tells us what the deal is.  If somebody tries to overwrite a dirty
 * block with a new one and doesn't have "isDirty" set, it probably means
 * they're trying to overwrite dirty cached data with the result of a new
 * read, which is a bug.  Trap it here.
 */
DIError
CBCache::PutInCache(long blockNum, const void* buf, bool isDirty)
{
	int blockOffset = -1;
	if (!IsRoomInCache(blockNum)) {
		assert(false);
		return kDIErrInternal;
	}

	if (fFirstBlock == kEmpty) {
		//WMSG1("   CBCache: starting anew with block %ld\n", blockNum);
		fFirstBlock = blockNum;
		fNumBlocks = 1;
		blockOffset = 0;
	} else if (blockNum == fFirstBlock + fNumBlocks) {
		//WMSG1("   CBCache: appending block %ld\n", blockNum);
		blockOffset = fNumBlocks;
		fNumBlocks++;
	} else if (blockNum >= fFirstBlock && blockNum < fFirstBlock + fNumBlocks) {
		blockOffset = blockNum - fFirstBlock;
	} else {
		assert(false);
		return kDIErrInternal;
	}
	assert(blockOffset != -1);
	assert(blockOffset < kMaxCachedBlocks);

	if (fDirty[blockOffset] && !isDirty) {
		WMSG1("BUG: CBCache trying to clear dirty flag for block %ld\n",
			blockNum);
		assert(false);
		return kDIErrInternal;
	}
	fDirty[blockOffset] = isDirty;

	//WMSG2("   CBCache: adding block %d to cache at %d\n", blockNum, blockOffset);
	int offset = blockOffset * kBlockSize;
	assert(offset >= 0);

	memcpy(fCache + offset, buf, kBlockSize);
	return kDIErrNone;
}

/*
 * Determine whether there are any dirty blocks in the cache.
 */
bool
CBCache::IsDirty(void) const
{
	if (fFirstBlock == kEmpty)
		return false;

	assert(fNumBlocks > 0);
	for (int i = 0; i < fNumBlocks; i++) {
		if (fDirty[i]) {
			//WMSG0("   CBCache: dirty blocks found\n");
			return true;
		}
	}

	//WMSG0("   CBCache: no dirty blocks found\n");
	return false;
}

/*
 * Return a pointer to the cache goodies, so that the object sitting
 * on the disk hardware can write our stuff.
 */
void
CBCache::GetCachePointer(long* pFirstBlock, int* pNumBlocks, void** pBuf) const
{
	assert(fFirstBlock != kEmpty);	// not essential, but why call here if not?

	*pFirstBlock = fFirstBlock;
	*pNumBlocks = fNumBlocks;
	*pBuf = (void*) fCache;
}

/*
 * Clear all the dirty flags.
 */
void
CBCache::Scrub(void)
{
	if (fFirstBlock == kEmpty)
		return;

	for (int i = 0; i < fNumBlocks; i++)
		fDirty[i] = false;
}

/*
 * Trash all of our entries.  If any are dirty, scream bloody murder.
 */
void
CBCache::Purge(void)
{
	if (fFirstBlock == kEmpty)
		return;

	if (IsDirty()) {
		// Should only happen after a write failure causes us to clean up.
		WMSG0("HEY: CBCache purging dirty blocks!\n");
		//assert(false);
	}
	Scrub();

	fFirstBlock = kEmpty;
	fNumBlocks = 0;
}


#endif /*_WIN32*/