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#include "BlockReader.h"
#include <cstring>
#include <stdexcept>
#include <string>
#if __has_include(<zlib.h>)
#include <zlib.h>
#define GCZ_HAS_ZLIB
#endif
namespace GC {
static constexpr uint32_t CISO_HEADER_SIZE = 0x8000;
static constexpr uint32_t CISO_MAP_SIZE = CISO_HEADER_SIZE - 8;
static constexpr uint32_t GCZ_MAGIC = 0xB10BC001;
static constexpr uint32_t GCZ_HEADER_SIZE = 32;
uint32_t ReadBE32(const uint8_t* p) {
return (uint32_t(p[0]) << 24) | (uint32_t(p[1]) << 16) | (uint32_t(p[2]) << 8) | uint32_t(p[3]);
}
uint16_t ReadBE16(const uint8_t* p) {
return (uint16_t)((p[0] << 8) | p[1]);
}
void WriteBE32(uint8_t* p, uint32_t v) {
p[0] = v >> 24;
p[1] = v >> 16;
p[2] = v >> 8;
p[3] = v;
}
void WriteBE16(uint8_t* p, uint16_t v) {
p[0] = v >> 8;
p[1] = v;
}
static uint32_t ReadLE32(const uint8_t* p) {
return uint32_t(p[0]) | (uint32_t(p[1]) << 8) | (uint32_t(p[2]) << 16) | (uint32_t(p[3]) << 24);
}
static uint64_t ReadLE64(const uint8_t* p) {
return uint64_t(ReadLE32(p)) | (uint64_t(ReadLE32(p + 4)) << 32);
}
RawImageReader::RawImageReader(const std::filesystem::path& path) : mFile(path, std::ios::binary) {
if (!mFile.is_open()) {
throw std::runtime_error("Failed to open disc image " + path.string());
}
mFile.seekg(0, std::ios::end);
mSize = static_cast<uint64_t>(mFile.tellg());
}
void RawImageReader::Read(uint64_t offset, void* dst, size_t size) {
if (offset + size > mSize) {
throw std::runtime_error("Disc read out of range at 0x" + std::to_string(offset));
}
std::lock_guard<std::mutex> lock(mMutex);
mFile.clear();
mFile.seekg(static_cast<std::streamoff>(offset));
mFile.read(static_cast<char*>(dst), static_cast<std::streamsize>(size));
if (!mFile) {
throw std::runtime_error("Disc read failed at 0x" + std::to_string(offset));
}
}
void MemoryBlockReader::Read(uint64_t offset, void* dst, size_t size) {
if (offset + size > mData.size()) {
throw std::runtime_error("Disc read out of range at 0x" + std::to_string(offset));
}
std::memcpy(dst, mData.data() + offset, size);
}
bool CisoReader::Probe(IBlockReader& base) {
if (base.Size() < CISO_HEADER_SIZE) {
return false;
}
uint8_t magic[4];
base.Read(0, magic, 4);
return std::memcmp(magic, "CISO", 4) == 0;
}
CisoReader::CisoReader(std::shared_ptr<IBlockReader> base) : mBase(std::move(base)) {
auto header = mBase->Read(0, CISO_HEADER_SIZE);
mBlockSize = ReadLE32(header.data() + 4);
if (mBlockSize == 0) {
throw std::runtime_error("CISO: invalid block size");
}
mBlockOffsets.resize(CISO_MAP_SIZE, -1);
uint64_t next = CISO_HEADER_SIZE;
uint32_t last = 0;
for (uint32_t i = 0; i < CISO_MAP_SIZE; i++) {
if (header[8 + i] == 1) {
mBlockOffsets[i] = static_cast<int64_t>(next);
next += mBlockSize;
last = i + 1;
}
}
mSize = static_cast<uint64_t>(last) * mBlockSize;
}
void CisoReader::Read(uint64_t offset, void* dst, size_t size) {
auto* out = static_cast<uint8_t*>(dst);
while (size > 0) {
const uint64_t block = offset / mBlockSize;
const uint64_t inner = offset % mBlockSize;
const size_t chunk = static_cast<size_t>(std::min<uint64_t>(size, mBlockSize - inner));
if (block < mBlockOffsets.size() && mBlockOffsets[block] >= 0) {
mBase->Read(static_cast<uint64_t>(mBlockOffsets[block]) + inner, out, chunk);
} else {
std::memset(out, 0, chunk);
}
out += chunk;
offset += chunk;
size -= chunk;
}
}
bool GczReader::Probe(IBlockReader& base) {
if (base.Size() < GCZ_HEADER_SIZE) {
return false;
}
uint8_t magic[4];
base.Read(0, magic, 4);
return ReadLE32(magic) == GCZ_MAGIC;
}
GczReader::GczReader(std::shared_ptr<IBlockReader> base) : mBase(std::move(base)) {
auto header = mBase->Read(0, GCZ_HEADER_SIZE);
mCompressedSize = ReadLE64(header.data() + 8);
mDataSize = ReadLE64(header.data() + 16);
mBlockSize = ReadLE32(header.data() + 24);
const uint32_t numBlocks = ReadLE32(header.data() + 28);
if (mBlockSize == 0) {
throw std::runtime_error("GCZ: invalid block size");
}
auto pointers = mBase->Read(GCZ_HEADER_SIZE, static_cast<size_t>(numBlocks) * 8);
mBlockPointers.resize(numBlocks);
for (uint32_t i = 0; i < numBlocks; i++) {
mBlockPointers[i] = ReadLE64(pointers.data() + i * 8);
}
mDataStart = GCZ_HEADER_SIZE + static_cast<uint64_t>(numBlocks) * 12;
}
void GczReader::LoadBlock(uint32_t index) {
if (mCachedBlock == index) {
return;
}
constexpr uint64_t uncompressedFlag = 1ULL << 63;
const uint64_t start = mBlockPointers[index] & ~uncompressedFlag;
const uint64_t end = index + 1 < mBlockPointers.size() ? (mBlockPointers[index + 1] & ~uncompressedFlag)
: mCompressedSize;
auto raw = mBase->Read(mDataStart + start, static_cast<size_t>(end - start));
mCache.assign(mBlockSize, 0);
if (mBlockPointers[index] & uncompressedFlag) {
std::memcpy(mCache.data(), raw.data(), std::min<size_t>(raw.size(), mBlockSize));
} else {
#ifdef GCZ_HAS_ZLIB
uLongf destLen = mBlockSize;
if (uncompress(mCache.data(), &destLen, raw.data(), static_cast<uLong>(raw.size())) != Z_OK) {
throw std::runtime_error("GCZ: failed to inflate block " + std::to_string(index));
}
#else
throw std::runtime_error("GCZ: built without zlib");
#endif
}
mCachedBlock = index;
}
void GczReader::Read(uint64_t offset, void* dst, size_t size) {
if (offset + size > mDataSize) {
throw std::runtime_error("GCZ read out of range at 0x" + std::to_string(offset));
}
std::lock_guard<std::mutex> lock(mMutex);
auto* out = static_cast<uint8_t*>(dst);
while (size > 0) {
const uint32_t block = static_cast<uint32_t>(offset / mBlockSize);
const uint64_t inner = offset % mBlockSize;
const size_t chunk = static_cast<size_t>(std::min<uint64_t>(size, mBlockSize - inner));
LoadBlock(block);
std::memcpy(out, mCache.data() + inner, chunk);
out += chunk;
offset += chunk;
size -= chunk;
}
}
std::shared_ptr<IBlockReader> WrapDiscImage(std::shared_ptr<IBlockReader> base) {
if (CisoReader::Probe(*base)) {
return std::make_shared<CisoReader>(base);
}
if (GczReader::Probe(*base)) {
return std::make_shared<GczReader>(base);
}
return base;
}
std::shared_ptr<IBlockReader> OpenDiscImage(const std::filesystem::path& path) {
return WrapDiscImage(std::make_shared<RawImageReader>(path));
}
} // namespace GC
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