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// Copyright 2018 yuzu emulator team
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <algorithm>
#include <array>
#include <cstddef>
#include <cstring>
#include "common/assert.h"
#include "core/crypto/aes_util.h"
#include "core/file_sys/nca_patch.h"
namespace FileSys {
namespace {
template <bool Subsection, typename BlockType, typename BucketType>
std::pair<std::size_t, std::size_t> SearchBucketEntry(u64 offset, const BlockType& block,
const BucketType& buckets) {
if constexpr (Subsection) {
const auto& last_bucket = buckets[block.number_buckets - 1];
if (offset >= last_bucket.entries[last_bucket.number_entries].address_patch) {
return {block.number_buckets - 1, last_bucket.number_entries};
}
} else {
ASSERT_MSG(offset <= block.size, "Offset is out of bounds in BKTR relocation block.");
}
std::size_t bucket_id = std::count_if(
block.base_offsets.begin() + 1, block.base_offsets.begin() + block.number_buckets,
[&offset](u64 base_offset) { return base_offset <= offset; });
const auto& bucket = buckets[bucket_id];
if (bucket.number_entries == 1) {
return {bucket_id, 0};
}
std::size_t low = 0;
std::size_t mid = 0;
std::size_t high = bucket.number_entries - 1;
while (low <= high) {
mid = (low + high) / 2;
if (bucket.entries[mid].address_patch > offset) {
high = mid - 1;
} else {
if (mid == bucket.number_entries - 1 ||
bucket.entries[mid + 1].address_patch > offset) {
return {bucket_id, mid};
}
low = mid + 1;
}
}
UNREACHABLE_MSG("Offset could not be found in BKTR block.");
return {0, 0};
}
} // Anonymous namespace
BKTR::BKTR(VirtualFile base_romfs_, VirtualFile bktr_romfs_, RelocationBlock relocation_,
std::vector<RelocationBucket> relocation_buckets_, SubsectionBlock subsection_,
std::vector<SubsectionBucket> subsection_buckets_, bool is_encrypted_,
Core::Crypto::Key128 key_, u64 base_offset_, u64 ivfc_offset_,
std::array<u8, 8> section_ctr_)
: relocation(relocation_), relocation_buckets(std::move(relocation_buckets_)),
subsection(subsection_), subsection_buckets(std::move(subsection_buckets_)),
base_romfs(std::move(base_romfs_)), bktr_romfs(std::move(bktr_romfs_)),
encrypted(is_encrypted_), key(key_), base_offset(base_offset_), ivfc_offset(ivfc_offset_),
section_ctr(section_ctr_) {
for (std::size_t i = 0; i < relocation.number_buckets - 1; ++i) {
relocation_buckets[i].entries.push_back({relocation.base_offsets[i + 1], 0, 0});
}
for (std::size_t i = 0; i < subsection.number_buckets - 1; ++i) {
subsection_buckets[i].entries.push_back({subsection_buckets[i + 1].entries[0].address_patch,
{0},
subsection_buckets[i + 1].entries[0].ctr});
}
relocation_buckets.back().entries.push_back({relocation.size, 0, 0});
}
BKTR::~BKTR() = default;
std::size_t BKTR::Read(u8* data, std::size_t length, std::size_t offset) const {
// Read out of bounds.
if (offset >= relocation.size) {
return 0;
}
const auto relocation_entry = GetRelocationEntry(offset);
const auto section_offset =
offset - relocation_entry.address_patch + relocation_entry.address_source;
const auto bktr_read = relocation_entry.from_patch;
const auto next_relocation = GetNextRelocationEntry(offset);
if (offset + length > next_relocation.address_patch) {
const u64 partition = next_relocation.address_patch - offset;
return Read(data, partition, offset) +
Read(data + partition, length - partition, offset + partition);
}
if (!bktr_read) {
ASSERT_MSG(section_offset >= ivfc_offset, "Offset calculation negative.");
return base_romfs->Read(data, length, section_offset - ivfc_offset);
}
if (!encrypted) {
return bktr_romfs->Read(data, length, section_offset);
}
const auto subsection_entry = GetSubsectionEntry(section_offset);
Core::Crypto::AESCipher<Core::Crypto::Key128> cipher(key, Core::Crypto::Mode::CTR);
// Calculate AES IV
std::array<u8, 16> iv{};
auto subsection_ctr = subsection_entry.ctr;
auto offset_iv = section_offset + base_offset;
for (std::size_t i = 0; i < section_ctr.size(); ++i) {
iv[i] = section_ctr[0x8 - i - 1];
}
offset_iv >>= 4;
for (std::size_t i = 0; i < sizeof(u64); ++i) {
iv[0xF - i] = static_cast<u8>(offset_iv & 0xFF);
offset_iv >>= 8;
}
for (std::size_t i = 0; i < sizeof(u32); ++i) {
iv[0x7 - i] = static_cast<u8>(subsection_ctr & 0xFF);
subsection_ctr >>= 8;
}
cipher.SetIV(iv);
const auto next_subsection = GetNextSubsectionEntry(section_offset);
if (section_offset + length > next_subsection.address_patch) {
const u64 partition = next_subsection.address_patch - section_offset;
return Read(data, partition, offset) +
Read(data + partition, length - partition, offset + partition);
}
const auto block_offset = section_offset & 0xF;
if (block_offset != 0) {
auto block = bktr_romfs->ReadBytes(0x10, section_offset & ~0xF);
cipher.Transcode(block.data(), block.size(), block.data(), Core::Crypto::Op::Decrypt);
if (length + block_offset < 0x10) {
std::memcpy(data, block.data() + block_offset, std::min(length, block.size()));
return std::min(length, block.size());
}
const auto read = 0x10 - block_offset;
std::memcpy(data, block.data() + block_offset, read);
return read + Read(data + read, length - read, offset + read);
}
const auto raw_read = bktr_romfs->Read(data, length, section_offset);
cipher.Transcode(data, raw_read, data, Core::Crypto::Op::Decrypt);
return raw_read;
}
RelocationEntry BKTR::GetRelocationEntry(u64 offset) const {
const auto res = SearchBucketEntry<false>(offset, relocation, relocation_buckets);
return relocation_buckets[res.first].entries[res.second];
}
RelocationEntry BKTR::GetNextRelocationEntry(u64 offset) const {
const auto res = SearchBucketEntry<false>(offset, relocation, relocation_buckets);
const auto bucket = relocation_buckets[res.first];
if (res.second + 1 < bucket.entries.size())
return bucket.entries[res.second + 1];
return relocation_buckets[res.first + 1].entries[0];
}
SubsectionEntry BKTR::GetSubsectionEntry(u64 offset) const {
const auto res = SearchBucketEntry<true>(offset, subsection, subsection_buckets);
return subsection_buckets[res.first].entries[res.second];
}
SubsectionEntry BKTR::GetNextSubsectionEntry(u64 offset) const {
const auto res = SearchBucketEntry<true>(offset, subsection, subsection_buckets);
const auto bucket = subsection_buckets[res.first];
if (res.second + 1 < bucket.entries.size())
return bucket.entries[res.second + 1];
return subsection_buckets[res.first + 1].entries[0];
}
std::string BKTR::GetName() const {
return base_romfs->GetName();
}
std::size_t BKTR::GetSize() const {
return relocation.size;
}
bool BKTR::Resize(std::size_t new_size) {
return false;
}
VirtualDir BKTR::GetContainingDirectory() const {
return base_romfs->GetContainingDirectory();
}
bool BKTR::IsWritable() const {
return false;
}
bool BKTR::IsReadable() const {
return true;
}
std::size_t BKTR::Write(const u8* data, std::size_t length, std::size_t offset) {
return 0;
}
bool BKTR::Rename(std::string_view name) {
return base_romfs->Rename(name);
}
} // namespace FileSys
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