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Merge pull request #778 from TomHarte/AppleIIDisks

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Resolves a potential crash with NIB files
This commit is contained in:
Thomas Harte 2020-03-25 21:52:26 -04:00 committed by GitHub
commit 272383cac7
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5 changed files with 114 additions and 50 deletions
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10
Analyser/Static/DiskII/StaticAnalyser.cpp
View File

@ -20,7 +20,7 @@ namespace {
Analyser::Static::Target *AppleTarget(const Storage::Encodings::AppleGCR::Sector *sector_zero) {
using Target = Analyser::Static::AppleII::Target;
auto *target = new Target;
auto *const target = new Target;
if(sector_zero && sector_zero->encoding == Storage::Encodings::AppleGCR::Sector::Encoding::FiveAndThree) {
target->disk_controller = Target::DiskController::ThirteenSector;
@ -33,7 +33,7 @@ Analyser::Static::Target *AppleTarget(const Storage::Encodings::AppleGCR::Sector
Analyser::Static::Target *OricTarget(const Storage::Encodings::AppleGCR::Sector *sector_zero) {
using Target = Analyser::Static::Oric::Target;
auto *target = new Target;
auto *const target = new Target;
target->rom = Target::ROM::Pravetz;
target->disk_interface = Target::DiskInterface::Pravetz;
target->loading_command = "CALL 800\n";
@ -47,8 +47,8 @@ Analyser::Static::TargetList Analyser::Static::DiskII::GetTargets(const Media &m
if(media.disks.empty()) return {};
// Grab track 0, sector 0: the boot sector.
auto track_zero = media.disks.front()->get_track_at_position(Storage::Disk::Track::Address(0, Storage::Disk::HeadPosition(0)));
auto sector_map = Storage::Encodings::AppleGCR::sectors_from_segment(
const auto track_zero = media.disks.front()->get_track_at_position(Storage::Disk::Track::Address(0, Storage::Disk::HeadPosition(0)));
const auto sector_map = Storage::Encodings::AppleGCR::sectors_from_segment(
Storage::Disk::track_serialisation(*track_zero, Storage::Time(1, 50000)));
const Storage::Encodings::AppleGCR::Sector *sector_zero = nullptr;
@ -75,7 +75,7 @@ Analyser::Static::TargetList Analyser::Static::DiskII::GetTargets(const Media &m
// If the boot sector looks like it's intended for the Oric, create an Oric.
// Otherwise go with the Apple II.
auto disassembly = Analyser::Static::MOS6502::Disassemble(sector_zero->data, Analyser::Static::Disassembler::OffsetMapper(0xb800), {0xb800});
const auto disassembly = Analyser::Static::MOS6502::Disassemble(sector_zero->data, Analyser::Static::Disassembler::OffsetMapper(0xb800), {0xb800});
bool did_read_shift_register = false;
bool is_oric = false;

2
OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme
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@ -67,7 +67,7 @@
</Testables>
</TestAction>
<LaunchAction
buildConfiguration = "Release"
buildConfiguration = "Debug"
selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
enableASanStackUseAfterReturn = "YES"

39
Storage/Disk/DiskImage/Formats/NIB.cpp
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@ -12,6 +12,9 @@
#include "../../Track/TrackSerialiser.hpp"
#include "../../Encodings/AppleGCR/Encoder.hpp"
#include "../../Encodings/AppleGCR/Encoder.hpp"
#include "../../Encodings/AppleGCR/SegmentParser.hpp"
#include <vector>
using namespace Storage::Disk;
@ -48,7 +51,7 @@ bool NIB::get_is_read_only() {
}
long NIB::file_offset(Track::Address address) {
return static_cast<long>(address.position.as_int()) * track_length;
return long(address.position.as_int()) * track_length;
}
std::shared_ptr<::Storage::Disk::Track> NIB::get_track_at_position(::Storage::Disk::Track::Address address) {
@ -84,7 +87,10 @@ std::shared_ptr<::Storage::Disk::Track> NIB::get_track_at_position(::Storage::Di
++length;
}
// Record a sync position only if there were at least five FFs.
// Record a sync position only if there were at least five FFs, and
// sync only in the final five. One of the many crazy fictions of NIBs
// is the fixed track length in bytes, which is quite long. So the aim
// is to be as conservative as possible with sync placement.
if(length == 5) {
sync_starts.insert((start + 1) % track_data.size());
@ -101,16 +107,21 @@ std::shared_ptr<::Storage::Disk::Track> NIB::get_track_at_position(::Storage::Di
// If the track started in a sync block, write sync first.
if(start_index) {
segment += Encodings::AppleGCR::six_and_two_sync(static_cast<int>(start_index));
segment += Encodings::AppleGCR::six_and_two_sync(int(start_index));
}
std::size_t index = start_index;
for(const auto location: sync_starts) {
// Write data from index to sync_start.
std::vector<uint8_t> data_segment(
track_data.begin() + static_cast<off_t>(index),
track_data.begin() + static_cast<off_t>(location));
segment += PCMSegment(data_segment);
if(location > index) {
// This is the usual case; the only occasion on which it won't be true is
// when the initial sync was detected to carry over the index hole,
// in which case there's nothing to copy.
std::vector<uint8_t> data_segment(
track_data.begin() + off_t(index),
track_data.begin() + off_t(location));
segment += PCMSegment(data_segment);
}
// Add a sync from sync_start to end of 0xffs, if there are
// any before the end of data.
@ -119,13 +130,15 @@ std::shared_ptr<::Storage::Disk::Track> NIB::get_track_at_position(::Storage::Di
++index;
if(index - location)
segment += Encodings::AppleGCR::six_and_two_sync(static_cast<int>(index - location));
segment += Encodings::AppleGCR::six_and_two_sync(int(index - location));
}
// If there's still data remaining on the track, write it out.
// If there's still data remaining on the track, write it out. If a sync ran over
// the notional index hole, the loop above will already have completed the track
// with sync, so no need to deal with that case here.
if(index < track_length) {
std::vector<uint8_t> data_segment(
track_data.begin() + static_cast<off_t>(index),
track_data.begin() + off_t(index),
track_data.end());
segment += PCMSegment(data_segment);
}
@ -149,7 +162,7 @@ void NIB::set_tracks(const std::map<Track::Address, std::shared_ptr<Track>> &tra
int bit_count = 0;
size_t sync_location = 0, location = 0;
for(const auto bit: segment.data) {
shifter = static_cast<uint8_t>((shifter << 1) | (bit ? 1 : 0));
shifter = uint8_t((shifter << 1) | (bit ? 1 : 0));
++bit_count;
++location;
if(shifter & 0x80) {
@ -167,8 +180,8 @@ void NIB::set_tracks(const std::map<Track::Address, std::shared_ptr<Track>> &tra
track.resize(track_length);
} else {
while(track.size() < track_length) {
std::vector<uint8_t> extra_data(static_cast<size_t>(track_length) - track.size(), 0xff);
track.insert(track.begin() + static_cast<off_t>(sync_location), extra_data.begin(), extra_data.end());
std::vector<uint8_t> extra_data(size_t(track_length) - track.size(), 0xff);
track.insert(track.begin() + off_t(sync_location), extra_data.begin(), extra_data.end());
}
}

10
Storage/Disk/Encodings/AppleGCR/Encoder.hpp
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@ -16,12 +16,14 @@ namespace Storage {
namespace Encodings {
namespace AppleGCR {
/// Describes the standard three-byte prologue that begins a header.
const uint8_t header_prologue[3] = {0xd5, 0xaa, 0x96};
/// Describes the standard three-byte prologue that begins a header on both the Macintosh and the Apple II from DOS 3.3.
constexpr uint8_t header_prologue[3] = {0xd5, 0xaa, 0x96};
/// Describes the standard three-byte prologue that begins a data section.
const uint8_t data_prologue[3] = {0xd5, 0xaa, 0xad};
constexpr uint8_t data_prologue[3] = {0xd5, 0xaa, 0xad};
/// Describes the epilogue that ends both data sections and headers.
const uint8_t epilogue[3] = {0xde, 0xaa, 0xeb};
constexpr uint8_t epilogue[3] = {0xde, 0xaa, 0xeb};
/// Describes the standard three-byte prologue used by DOS 3.2 and earlier.
constexpr uint8_t five_and_three_header_prologue[3] = {0xd5, 0xaa, 0xb5};
namespace AppleII {

103
Storage/Disk/Encodings/AppleGCR/SegmentParser.cpp
View File

@ -36,6 +36,25 @@ uint8_t unmap_six_and_two(uint8_t source) {
return six_and_two_unmapping[source - 0x96];
}
const uint8_t five_and_three_unmapping[] = {
/* 0xab */ 0x00, 0xff, 0x01, 0x02, 0x03,
/* 0xb0 */ 0xff, 0xff, 0xff, 0xff, 0xff, 0x04, 0x05, 0x06,
/* 0xb8 */ 0xff, 0xff, 0x07, 0x08, 0xff, 0x09, 0x0a, 0x0b,
/* 0xc0 */ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
/* 0xc8 */ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
/* 0xd0 */ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x0c, 0x0d,
/* 0xd8 */ 0xff, 0xff, 0x0e, 0x0f, 0xff, 0x10, 0x11, 0x12,
/* 0xe0 */ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
/* 0xe8 */ 0xff, 0xff, 0x13, 0x14, 0xff, 0x15, 0x16, 0x17,
/* 0xf0 */ 0xff, 0xff, 0xff, 0xff, 0xff, 0x18, 0x19, 0x1a,
/* 0xf8 */ 0xff, 0xff, 0x1b, 0x1c, 0xff, 0x1d, 0x1e, 0x1f,
};
uint8_t unmap_five_and_three(uint8_t source) {
if(source < 0xab) return 0xff;
return five_and_three_unmapping[source - 0xab];
}
}
using namespace Storage::Encodings::AppleGCR;
@ -56,6 +75,7 @@ std::map<std::size_t, Sector> Storage::Encodings::AppleGCR::sectors_from_segment
// sector is still being parsed.
size_t bit = 0;
int header_delay = 0;
bool is_five_and_three = false;
while(bit < segment.data.size() || pointer != scanning_sentinel || header_delay) {
shift_register = static_cast<uint_fast8_t>((shift_register << 1) | (segment.data[bit % segment.data.size()] ? 1 : 0));
++bit;
@ -77,11 +97,16 @@ std::map<std::size_t, Sector> Storage::Encodings::AppleGCR::sectors_from_segment
scanner[0] == header_prologue[0] &&
scanner[1] == header_prologue[1] &&
(
scanner[2] == five_and_three_header_prologue[2] ||
scanner[2] == header_prologue[2] ||
scanner[2] == data_prologue[2]
)) {
pointer = 0;
if(scanner[2] != data_prologue[2]) {
is_five_and_three = scanner[2] == five_and_three_header_prologue[2];
}
// If this is the start of a data section, and at least
// one header has been witnessed, start a sector.
if(scanner[2] == data_prologue[2]) {
@ -97,7 +122,8 @@ std::map<std::size_t, Sector> Storage::Encodings::AppleGCR::sectors_from_segment
if(new_sector) {
// Check whether the value just read is a legal GCR byte, in six-and-two
// encoding (which is a strict superset of five-and-three).
if(unmap_six_and_two(value) == 0xff) {
const bool is_invalid = is_five_and_three ? (unmap_five_and_three(value) == 0xff) : (unmap_six_and_two(value) == 0xff);
if(is_invalid) {
// The second byte of the standard epilogue is illegal, so this still may
// be a valid sector. If the final byte was the first byte of an epilogue,
// chop it off and see whether the sector is otherwise intelligible.
@ -123,8 +149,7 @@ std::map<std::size_t, Sector> Storage::Encodings::AppleGCR::sectors_from_segment
default: // This is not a decodeable sector.
break;
// TODO: check for five-and-three / 13-sector form sectors.
case 411: // Potentially this is an Apple II five-and-three sector.
case 343: { // Potentially this is an Apple II six-and-two sector.
// Check for apparent four and four encoding.
uint_fast8_t header_mask = 0xff;
@ -137,13 +162,15 @@ std::map<std::size_t, Sector> Storage::Encodings::AppleGCR::sectors_from_segment
sector->address.sector = ((header[4] << 1) | 1) & header[5];
// Check the header checksum.
uint_fast8_t checksum = ((header[6] << 1) | 1) & header[7];
// The 0x11 is reverse engineered from the game 'Alien Rain' and is present even on the boot sector,
// so probably isn't copy protection?
uint_fast8_t checksum = (((header[6] << 1) | 1) & header[7]) ^ (is_five_and_three ? 0x11 : 0x00);
if(checksum != (sector->address.volume^sector->address.track^sector->address.sector)) continue;
// Unmap the sector contents as 6 and 2 data.
// Unmap the sector contents.
bool out_of_bounds = false;
for(auto &c : sector->data) {
c = unmap_six_and_two(c);
c = is_five_and_three ? unmap_five_and_three(c) : unmap_six_and_two(c);
if(c == 0xff) {
out_of_bounds = true;
break;
@ -160,30 +187,52 @@ std::map<std::size_t, Sector> Storage::Encodings::AppleGCR::sectors_from_segment
// Having checked the checksum, remove it.
sector->data.resize(sector->data.size() - 1);
// Undo the 6 and 2 mapping.
const uint8_t bit_reverse[] = {0, 2, 1, 3};
#define unmap(byte, nibble, shift) \
sector->data[86 + byte] = static_cast<uint8_t>(\
(sector->data[86 + byte] << 2) | bit_reverse[(sector->data[nibble] >> shift)&3]);
if(is_five_and_three) {
// TODO: the above is almost certainly incorrect; Beneath Apple DOS partly documents
// the process, enough to give the basic outline below of how five source bytes are
// mapped to eight five-bit quantities, but isn't clear on the order those bytes will
// end up in on disk.
for(std::size_t c = 0; c < 84; ++c) {
unmap(c, c, 0);
unmap(c+86, c, 2);
unmap(c+172, c, 4);
std::vector<uint8_t> buffer(256);
for(size_t c = 0; c < 0x33; ++c) {
const uint8_t *const base = &sector->data[0x032 - c];
buffer[(c * 5) + 0] = uint8_t((base[0x000] << 3) | (base[0x100] >> 2));
buffer[(c * 5) + 1] = uint8_t((base[0x033] << 3) | (base[0x133] >> 2));
buffer[(c * 5) + 2] = uint8_t((base[0x066] << 3) | (base[0x166] >> 2));
buffer[(c * 5) + 3] = uint8_t((base[0x099] << 3) | ((base[0x100] & 2) << 1) | (base[0x133] & 2) | ((base[0x166] & 2) >> 1));
buffer[(c * 5) + 4] = uint8_t((base[0x0cc] << 3) | ((base[0x100] & 1) << 2) | ((base[0x133] & 1) << 1) | (base[0x166] & 1));
}
buffer[255] = uint8_t((sector->data[0x0ff] << 3) | (sector->data[0x199] >> 2));
sector->data = std::move(buffer);
sector->encoding = Sector::Encoding::FiveAndThree;
} else {
// Undo the 6 and 2 mapping.
const uint8_t bit_reverse[] = {0, 2, 1, 3};
#define unmap(byte, nibble, shift) \
sector->data[86 + byte] = static_cast<uint8_t>(\
(sector->data[86 + byte] << 2) | bit_reverse[(sector->data[nibble] >> shift)&3]);
for(std::size_t c = 0; c < 84; ++c) {
unmap(c, c, 0);
unmap(c+86, c, 2);
unmap(c+172, c, 4);
}
unmap(84, 84, 0);
unmap(170, 84, 2);
unmap(85, 85, 0);
unmap(171, 85, 2);
#undef unmap
// Throw away the collection of two-bit chunks from the start of the sector.
sector->data.erase(sector->data.begin(), sector->data.end() - 256);
sector->encoding = Sector::Encoding::SixAndTwo;
}
unmap(84, 84, 0);
unmap(170, 84, 2);
unmap(85, 85, 0);
unmap(171, 85, 2);
#undef unmap
// Throw away the collection of two-bit chunks from the start of the sector.
sector->data.erase(sector->data.begin(), sector->data.end() - 256);
// Add this sector to the map.
sector->encoding = Sector::Encoding::SixAndTwo;
result.insert(std::make_pair(sector_location, std::move(*sector)));
} break;