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Add sector_chain_validator for T/S chain cycle protection #7

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Merged
vschwaberow merged 1 commit into from
Aug 15, 2026
Merged

Add sector_chain_validator for T/S chain cycle protection #7

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30 changes: 28 additions & 2 deletions d64.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -225,7 +225,9 @@ std::optional<directoryEntryPtr> d64::findEmptyDirectorySlot()
auto dir_track = DIRECTORY_TRACK;
auto dir_sector = DIRECTORY_SECTOR;

sector_chain_validator validator(*this);
while (dir_track != 0) {
if (!validator.visit(dir_track, dir_sector)) return std::nullopt;
directorySectorPtr dirSectorPtr = getDirectory_SectorPtr(dir_track, dir_sector);
for (auto& fileEntry : dirSectorPtr->fileEntry) {
if (!fileEntry.file_type.closed) {
Expand Down Expand Up @@ -572,7 +574,9 @@ bool d64::verifyBAMIntegrity(bool fix, const std::string& logFile)
auto dir_sector = DIRECTORY_SECTOR;
directorySectorPtr dirSectorPtr;

sector_chain_validator dir_validator(*this);
while (dir_track != 0) {
if (!dir_validator.visit(dir_track, dir_sector)) break;
dirSectorPtr = getDirectory_SectorPtr(dir_track, dir_sector);

// Mark directory sector as used
Expand Down Expand Up @@ -608,7 +612,9 @@ bool d64::verifyBAMIntegrity(bool fix, const std::string& logFile)
}
}
else {
sector_chain_validator file_validator(*this);
while (track != 0) {
if (!file_validator.visit(track, sector)) break;
sectorUsage[track - 1][sector] = true;
auto next = getTrackSectorPtr(track, sector);

Expand Down Expand Up @@ -732,7 +738,9 @@ bool d64::compactDirectory()
directorySectorPtr dirSectorPtr;

// **Step 1: Collect all valid directory entries**
sector_chain_validator validator1(*this);
while (dir_track != 0) {
if (!validator1.visit(dir_track, dir_sector)) break;
dirSectorPtr = getDirectory_SectorPtr(dir_track, dir_sector);

for (auto &entry : dirSectorPtr->fileEntry) {
Expand All @@ -756,7 +764,9 @@ bool d64::compactDirectory()
size_t index = 0;
bool freedSector = false;

sector_chain_validator validator2(*this);
while (dir_track != 0) {
if (!validator2.visit(dir_track, dir_sector)) break;
std::fill_n(reinterpret_cast<uint8_t*>(dirSectorPtr), SECTOR_SIZE, 0); // Clear sector

for (auto i = 0; i < FILES_PER_SECTOR && index < files.size(); ++i, ++index) {
Expand All @@ -766,7 +776,9 @@ bool d64::compactDirectory()
// **Step 3: If no more files, free remaining sectors**
if (index >= files.size()) {
// Mark remaining directory sectors as free in BAM
sector_chain_validator validator3(*this);
while (dir_track != 0) {
if (!validator3.visit(dir_track, dir_sector)) break;
int next_track = dirSectorPtr->next.track;
int next_sector = dirSectorPtr->next.sector;

Expand Down Expand Up @@ -810,7 +822,9 @@ std::optional<directoryEntryPtr> d64::findFile(std::string_view filename)
auto dir_track = DIRECTORY_TRACK;
auto dir_sector = DIRECTORY_SECTOR;

sector_chain_validator validator(*this);
while (dir_track != 0) {
if (!validator.visit(dir_track, dir_sector)) break;
auto dirSectorPtr = getDirectory_SectorPtr(dir_track, dir_sector);
for (auto& fileEntry : dirSectorPtr->fileEntry) {
if (fileEntry.file_type.closed == 0) {
Expand Down Expand Up @@ -853,7 +867,9 @@ bool d64::removeFile(std::string_view filename)
int track = fileEntry.value()->start.track;
int sector = fileEntry.value()->start.sector;

sector_chain_validator validator(*this);
while (track != 0) {
if (!validator.visit(track, sector)) break;
auto sectorPtr = getTrackSectorPtr(track, sector);
auto next_track = sectorPtr->track;
auto next_sector = sectorPtr->sector;
Expand Down Expand Up @@ -966,9 +982,9 @@ std::optional<std::vector<uint8_t>> d64::readFile(std::string filename)
int sector = fileEntry.value()->start.sector;

// track 0 signifies end
sector_chain_validator validator(*this);
while (track != 0) {

// get the next track and sector of file
if (!validator.visit(track, sector)) break;
auto sectorPtr = getSectorPtr(track, sector);

// if the track is not zero then write the whole block
Expand Down Expand Up @@ -1331,7 +1347,9 @@ bool d64::reorderDirectory(std::vector<directoryEntry>& files)
auto dirSectorPtr = getDirectory_SectorPtr(dir_track, dir_sector);
size_t index = 0;

sector_chain_validator validator(*this);
while (dir_track != 0 && index < files.size()) {
if (!validator.visit(dir_track, dir_sector)) break;
std::fill_n(reinterpret_cast<uint8_t*>(dirSectorPtr), SECTOR_SIZE, 0); // Clear sector

auto len = std::min(FILES_PER_SECTOR, static_cast<int>(files.size() - index));
Expand Down Expand Up @@ -1379,7 +1397,9 @@ std::vector<directoryEntry> d64::directory()
int dir_sector = DIRECTORY_SECTOR;

// Read all directory entries
sector_chain_validator validator(*this);
while (dir_track != 0) {
if (!validator.visit(dir_track, dir_sector)) break;
auto dirSectorPtr = getDirectory_SectorPtr(dir_track, dir_sector);

std::copy_if(dirSectorPtr->fileEntry,
Expand Down Expand Up @@ -1431,7 +1451,9 @@ std::vector<trackSector> d64::parseSideSectors(int sideTrack, int sideSector)
{
std::vector<trackSector> recordMap;

sector_chain_validator validator(*this);
while (sideTrack != 0) {
if (!validator.visit(sideTrack, sideSector)) break;
auto sideSectorPtr = getSideSectorPtr(sideTrack, sideSector);

uint8_t nextTrack = sideSectorPtr->next.track;
Expand Down Expand Up @@ -1479,7 +1501,9 @@ int d64::getRecordCount(std::string_view filename) {
int totalPayloadBytes = 0;
trackSector sidePosition = fileEntry.value()->side;

sector_chain_validator validator(*this);
while (sidePosition.track != 0) {
if (!validator.visit(sidePosition.track, sidePosition.sector)) break;
auto side = getSideSectorPtr(sidePosition.track, sidePosition.sector);
for (int i = 0; i < SIDE_SECTOR_CHAIN_SZ; ++i) {
if (side->chain[i].track == 0) break;
Expand Down Expand Up @@ -1653,7 +1677,9 @@ bool d64::expandRelFile(std::string_view filename, int requiredBytes) {
if (sideSectorsCount > SIDE_SECTOR_ENTRY_SIZE) return false;

trackSector iterSidePos = fileEntry.value()->side;
sector_chain_validator validator(*this);
while (iterSidePos.track != 0) {
if (!validator.visit(iterSidePos.track, iterSidePos.sector)) break;
auto iterSide = getSideSectorPtr(iterSidePos.track, iterSidePos.sector);
iterSide->sideSectors[newSide->block] = {static_cast<uint8_t>(newSideTrack), static_cast<uint8_t>(newSideSector)};
iterSidePos = iterSide->next;
Expand Down
16 changes: 16 additions & 0 deletions d64.h
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,22 @@ class d64 {
}

private:
struct sector_chain_validator {
const d64& disk;
std::bitset<TRACKS_40 * 21> visited;

explicit sector_chain_validator(const d64& d) : disk(d) {}

bool visit(int track, int sector) {
if (track == 0) return true;
if (!disk.isValidTrackSector(track, sector)) return false;
size_t idx = static_cast<size_t>(disk.calcOffset(track, sector) / SECTOR_SIZE);
if (visited.test(idx)) return false;
visited.set(idx);
return true;
}
};

static constexpr int INTERLEAVE = 10;
std::array<int, TRACKS_40> lastSectorUsed = { -1 };
bamPtr diskBamPtr;
Expand Down
21 changes: 21 additions & 0 deletions unittests/d64unittests.cpp
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Expand Up @@ -773,6 +773,27 @@ namespace d64lib_unit_test
d64lib_unit_test_method_cleanup(disk);
}

TEST(d64lib_unit_test, cycle_protection_test)
{
d64lib_unit_test_method_initialize();
d64 disk;
std::vector<uint8_t> data(500, 0xAA);
disk.addFile("CYCLIC", d64FileTypes::PRG, data);

auto entry = disk.findFile("CYCLIC");
EXPECT_TRUE(entry.has_value());

int track = entry.value()->start.track;
int sector = entry.value()->start.sector;

disk.writeByte(track, sector, 0, track);
disk.writeByte(track, sector, 1, sector);

auto readData = disk.readFile("CYCLIC");
EXPECT_TRUE(readData.has_value());

d64lib_unit_test_method_cleanup(disk);
}

}

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