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Corrects buffer overwrites resulting from failure to treat a number of records of 0x80 as a special case.

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This commit is contained in:
Thomas Harte 2017-10-17 20:49:12 -04:00
parent 19c03a08a6
commit b4583e976e
1 changed files with 4 additions and 3 deletions
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7
Storage/Disk/Parsers/CPM.cpp
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@ -88,7 +88,7 @@ std::unique_ptr<Storage::Disk::CPM::Catalogue> Storage::Disk::CPM::GetCatalogue(
std::unique_ptr<Catalogue> result(new Catalogue);
bool has_long_allocation_units = (parameters.tracks * parameters.sectors_per_track * (int)sector_size / parameters.block_size) >= 256;
size_t bytes_per_catalogue_entry = (has_long_allocation_units ? 16 : 8) * (size_t)parameters.block_size;
size_t bytes_per_catalogue_entry = (has_long_allocation_units ? 8 : 16) * (size_t)parameters.block_size;
int sectors_per_block = parameters.block_size / (int)sector_size;
int records_per_sector = (int)sector_size / 128;
@ -117,7 +117,8 @@ std::unique_ptr<Storage::Disk::CPM::Catalogue> Storage::Disk::CPM::GetCatalogue(
// Accumulate all data.
while(entry <= final_entry) {
int record = 0;
for(size_t block = 0; block < (has_long_allocation_units ? 8 : 16) && record < entry->number_of_records; block++) {
int number_of_records = (entry->number_of_records != 0x80) ? entry->number_of_records : (has_long_allocation_units ? 8 : 16);
for(size_t block = 0; block < (has_long_allocation_units ? 8 : 16) && record < number_of_records; block++) {
int block_number;
if(has_long_allocation_units) {
block_number = catalogue[entry->catalogue_index + 16 + (block << 1)] + (catalogue[entry->catalogue_index + 16 + (block << 1) + 1] << 8);
@ -133,7 +134,7 @@ std::unique_ptr<Storage::Disk::CPM::Catalogue> Storage::Disk::CPM::GetCatalogue(
sector = first_sector % parameters.sectors_per_track;
track = first_sector / parameters.sectors_per_track;
for(int s = 0; s < sectors_per_block && record < entry->number_of_records; s++) {
for(int s = 0; s < sectors_per_block && record < number_of_records; s++) {
Storage::Encodings::MFM::Sector *sector_contents = parser.get_sector(0, static_cast<uint8_t>(track), static_cast<uint8_t>(parameters.first_sector + sector));
if(!sector_contents) break;
sector++;