ciderpress/diskimg/OzDOS.cpp

/*
 * CiderPress
 * Copyright (C) 2007 by faddenSoft, LLC.  All Rights Reserved.
 * See the file LICENSE for distribution terms.
 */
/*
 * Implementation of DiskFSOzDOS class.
 *
 * It would make life MUCH EASIER to have the DiskImg recognize this as
 * a file format and just rearrange the blocks into linear order for us,
 * but unfortunately that's not going to happen.
 */
#include "StdAfx.h"
#include "DiskImgPriv.h"


/*
 * ===========================================================================
 *		DiskFSOzDOS
 * ===========================================================================
 */

const int kExpectedNumBlocks = 1600;
const int kExpectedTracks = 50;			// 50 tracks of 32 sectors == 400K
const int kExpectedSectors = 32;
const int kVTOCTrack = 17;
const int kVTOCSector = 0;
const int kSctSize = 256;

const int kCatalogEntrySize = 0x23;		// length in bytes of catalog entries
const int kCatalogEntriesPerSect = 7;	// #of entries per catalog sector
const int kMaxTSPairs = 0x7a;			// 122 entries for 256-byte sectors
const int kTSOffset = 0x0c;				// first T/S entry in a T/S list

const int kMaxTSIterations = 32;
const int kMaxCatalogIterations = 64;


/*
 * Read a track/sector, adjusting for 32-sector disks being treated as
 * if they were 16-sector.
 */
static DIError
ReadTrackSectorAdjusted(DiskImg* pImg, int track, int sector,
	int sectorOffset, unsigned char* buf, DiskImg::SectorOrder imageOrder)
{
	track *= 4;
	sector = sector * 2 + sectorOffset;
	while (sector >= 16) {
		track++;
		sector -= 16;
	}
	return pImg->ReadTrackSectorSwapped(track, sector, buf, imageOrder,
			DiskImg::kSectorOrderDOS);
}

/*
 * Test for presence of 400K OzDOS 3.3 volumes.
 */
static DIError
TestImageHalf(DiskImg* pImg, int sectorOffset, DiskImg::SectorOrder imageOrder)
{
	DIError dierr = kDIErrNone;
	unsigned char sctBuf[kSctSize];
	int numTracks, numSectors;
	int catTrack, catSect;
	int foundGood = 0;
	int iterations = 0;

	assert(sectorOffset == 0 || sectorOffset == 1);

	dierr = ReadTrackSectorAdjusted(pImg, kVTOCTrack, kVTOCSector,
				sectorOffset, sctBuf, imageOrder);
	if (dierr != kDIErrNone)
		goto bail;

	catTrack = sctBuf[0x01];
	catSect = sctBuf[0x02];
	numTracks = sctBuf[0x34];
	numSectors = sctBuf[0x35];

	if (!(sctBuf[0x27] == kMaxTSPairs) ||
		/*!(sctBuf[0x36] == 0 && sctBuf[0x37] == 1) ||*/	// bytes per sect
		!(numTracks == kExpectedTracks) ||
		!(numSectors == 32) ||
		!(catTrack < numTracks && catSect < numSectors) ||
		0)
	{
		WMSG1("  OzDOS header test %d failed\n", sectorOffset);
		dierr = kDIErrFilesystemNotFound;
		goto bail;
	}

	/*
	 * Walk through the catalog track to try to figure out ordering.
	 */
	while (catTrack != 0 && catSect != 0 && iterations < kMaxCatalogIterations)
	{
		dierr = ReadTrackSectorAdjusted(pImg, catTrack, catSect,
					sectorOffset, sctBuf, imageOrder);
		if (dierr != kDIErrNone)
			goto bail_ok;		/* allow it if not fully broken */

		if (sctBuf[1] == catTrack && sctBuf[2] == catSect-1)
			foundGood++;

		catTrack = sctBuf[1];
		catSect = sctBuf[2];
		iterations++;		// watch for infinite loops
	}
	if (iterations >= kMaxCatalogIterations) {
		dierr = kDIErrDirectoryLoop;
		goto bail;
	}

bail_ok:
	WMSG3(" OzDOS foundGood=%d off=%d swap=%d\n", foundGood, sectorOffset,
		imageOrder);
	/* foundGood hits 3 even when swap is wrong */
	if (foundGood > 4)
		dierr = kDIErrNone;
	else
		dierr = kDIErrFilesystemNotFound;

bail:
	return dierr;
}

/*
 * Test both of the DOS partitions.
 */
static DIError
TestImage(DiskImg* pImg, DiskImg::SectorOrder imageOrder)
{
	DIError dierr;

	WMSG1(" OzDOS checking first half (swap=%d)\n", imageOrder);
	dierr = TestImageHalf(pImg, 0, imageOrder);
	if (dierr != kDIErrNone)
		return dierr;

	WMSG1(" OzDOS checking second half (swap=%d)\n", imageOrder);
	dierr = TestImageHalf(pImg, 1, imageOrder);
	if (dierr != kDIErrNone)
		return dierr;

	return kDIErrNone;
}

/*
 * Test to see if the image is a OzDOS volume.
 */
/*static*/ DIError
DiskFSOzDOS::TestFS(DiskImg* pImg, DiskImg::SectorOrder* pOrder,
    DiskImg::FSFormat* pFormat, FSLeniency leniency)
{
	/* only on 800K disks (at the least, insist on numTracks being even) */
	if (pImg->GetNumBlocks() != kExpectedNumBlocks)
		return kDIErrFilesystemNotFound;

	/* if a value is specified, try that first -- useful for OverrideFormat */
	if (*pOrder != DiskImg::kSectorOrderUnknown) {
		if (TestImage(pImg, *pOrder) == kDIErrNone) {
			WMSG0(" OzDOS accepted FirstTry value\n");
			return kDIErrNone;
		}
	}

	DiskImg::SectorOrder ordering[DiskImg::kSectorOrderMax];
	
	DiskImg::GetSectorOrderArray(ordering, *pOrder);

	for (int i = 0; i < DiskImg::kSectorOrderMax; i++) {
		if (ordering[i] == DiskImg::kSectorOrderUnknown)
			continue;
		if (TestImage(pImg, ordering[i]) == kDIErrNone) {
			*pOrder = ordering[i];
			*pFormat = DiskImg::kFormatOzDOS;
			return kDIErrNone;
		}
	}

	WMSG0(" OzDOS didn't find valid FS\n");
	return kDIErrFilesystemNotFound;
}

#if 0
/*
 * Test to see if the image is a 'wide' (32-sector) DOS3.3 volume, i.e.
 * half of a OzDOS volume.
 */
/*static*/ DIError
DiskFS::TestOzWideDOS33(const DiskImg* pImg, DiskImg::SectorOrder* pOrder)
{
	DIError dierr = kDIErrNone;

	/* only on 400K disks (at the least, insist on numTracks being even) */
	if (pImg->GetNumBlocks() != kExpectedNumBlocks/2)
		return kDIErrFilesystemNotFound;

	/* if a value is specified, try that first -- useful for OverrideFormat */
	if (*pOrder != DiskImg::kSectorOrderUnknown) {
		if (TestImageHalf(pImg, 0, *pOrder) == kDIErrNone) {
			WMSG0(" WideDOS accepted FirstTry value\n");
			return kDIErrNone;
		}
	}

	if (TestImageHalf(pImg, 0, DiskImg::kSectorOrderDOS) == kDIErrNone) {
		*pOrder = DiskImg::kSectorOrderDOS;
	} else if (TestImageHalf(pImg, 0, DiskImg::kSectorOrderProDOS) == kDIErrNone) {
		*pOrder = DiskImg::kSectorOrderProDOS;
	} else if (TestImageHalf(pImg, 0, DiskImg::kSectorOrderPhysical) == kDIErrNone) {
		*pOrder = DiskImg::kSectorOrderPhysical;
	} else {
		WMSG0("  FS didn't find valid 'wide' DOS3.3\n");
		return kDIErrFilesystemNotFound;
	}

	return kDIErrNone;
}
#endif

/*
 * Set up our sub-volumes.
 */
DIError
DiskFSOzDOS::Initialize(void)
{
	DIError dierr = kDIErrNone;

	if (fScanForSubVolumes != kScanSubDisabled) {
		dierr = OpenSubVolume(0);
		if (dierr != kDIErrNone)
			return dierr;

		dierr = OpenSubVolume(1);
		if (dierr != kDIErrNone)
			return dierr;
	} else {
		WMSG0(" OzDOS not scanning for sub-volumes\n");
	}

	SetVolumeUsageMap();

	return kDIErrNone;
}

/*
 * Open up one of the DOS 3.3 sub-volumes.
 */
DIError
DiskFSOzDOS::OpenSubVolume(int idx)
{
	DIError dierr = kDIErrNone;
	DiskFS* pNewFS = nil;
	DiskImg* pNewImg = nil;
	
	pNewImg = new DiskImg;
	if (pNewImg == nil) {
		dierr = kDIErrMalloc;
		goto bail;
	}

	// open the full 800K; SetPairedSectors cuts it in half
	dierr = pNewImg->OpenImage(fpImg, 0, 0,
				2 * kExpectedTracks * kExpectedSectors);
	if (dierr != kDIErrNone) {
		WMSG3(" OzSub: OpenImage(%d,0,%d) failed (err=%d)\n",
			0, 2 * kExpectedTracks * kExpectedSectors, dierr);
		goto bail;
	}

	assert(idx == 0 || idx == 1);
	pNewImg->SetPairedSectors(true, 1-idx);

	WMSG1(" OzSub: testing for recognizable volume in idx=%d\n", idx);
	dierr = pNewImg->AnalyzeImage();
	if (dierr != kDIErrNone) {
		WMSG1(" OzSub: analysis failed (err=%d)\n", dierr);
		goto bail;
	}

	if (pNewImg->GetFSFormat() == DiskImg::kFormatUnknown ||
		pNewImg->GetSectorOrder() == DiskImg::kSectorOrderUnknown)
	{
		WMSG0(" OzSub: unable to identify filesystem\n");
		dierr = kDIErrUnsupportedFSFmt;
		goto bail;
	}

	/* open a DiskFS for the sub-image */
	WMSG1(" UNISub %d succeeded!\n", idx);
	pNewFS = pNewImg->OpenAppropriateDiskFS();
	if (pNewFS == nil) {
		WMSG0(" OzSub: OpenAppropriateDiskFS failed\n");
		dierr = kDIErrUnsupportedFSFmt;
		goto bail;
	}

	/* load the files from the sub-image */
	dierr = pNewFS->Initialize(pNewImg, kInitFull);
	if (dierr != kDIErrNone) {
		WMSG1(" OzSub: error %d reading list of files from disk", dierr);
		goto bail;
	}

	/* if this really is DOS 3.3, override the "volume name" */
	if (pNewImg->GetFSFormat() == DiskImg::kFormatDOS33) {
		DiskFSDOS33* pDOS = (DiskFSDOS33*) pNewFS;	/* eek, a downcast */
		pDOS->SetDiskVolumeNum(idx+1);
	}

	/*
	 * Success, add it to the sub-volume list.
	 */
	AddSubVolumeToList(pNewImg, pNewFS);

bail:
	if (dierr != kDIErrNone) {
		delete pNewFS;
		delete pNewImg;
	}
	return dierr;
}