66fc037ef2
Previously this function was using ~16KB of stack (16528 bytes), which was caused by the function arguments being taken by value rather than by reference. We can make this significantly lighter on the stack by taking them by reference.
214 lines
7.7 KiB
C++
214 lines
7.7 KiB
C++
// Copyright 2018 yuzu emulator team
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <algorithm>
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#include <array>
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#include <cstddef>
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#include <cstring>
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#include "common/assert.h"
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#include "core/crypto/aes_util.h"
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#include "core/file_sys/nca_patch.h"
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namespace FileSys {
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namespace {
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template <bool Subsection, typename BlockType, typename BucketType>
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std::pair<std::size_t, std::size_t> SearchBucketEntry(u64 offset, const BlockType& block,
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const BucketType& buckets) {
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if constexpr (Subsection) {
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const auto& last_bucket = buckets[block.number_buckets - 1];
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if (offset >= last_bucket.entries[last_bucket.number_entries].address_patch) {
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return {block.number_buckets - 1, last_bucket.number_entries};
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}
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} else {
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ASSERT_MSG(offset <= block.size, "Offset is out of bounds in BKTR relocation block.");
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}
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std::size_t bucket_id = std::count_if(
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block.base_offsets.begin() + 1, block.base_offsets.begin() + block.number_buckets,
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[&offset](u64 base_offset) { return base_offset <= offset; });
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const auto& bucket = buckets[bucket_id];
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if (bucket.number_entries == 1) {
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return {bucket_id, 0};
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}
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std::size_t low = 0;
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std::size_t mid = 0;
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std::size_t high = bucket.number_entries - 1;
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while (low <= high) {
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mid = (low + high) / 2;
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if (bucket.entries[mid].address_patch > offset) {
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high = mid - 1;
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} else {
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if (mid == bucket.number_entries - 1 ||
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bucket.entries[mid + 1].address_patch > offset) {
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return {bucket_id, mid};
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}
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low = mid + 1;
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}
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}
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UNREACHABLE_MSG("Offset could not be found in BKTR block.");
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}
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} // Anonymous namespace
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BKTR::BKTR(VirtualFile base_romfs_, VirtualFile bktr_romfs_, RelocationBlock relocation_,
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std::vector<RelocationBucket> relocation_buckets_, SubsectionBlock subsection_,
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std::vector<SubsectionBucket> subsection_buckets_, bool is_encrypted_,
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Core::Crypto::Key128 key_, u64 base_offset_, u64 ivfc_offset_,
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std::array<u8, 8> section_ctr_)
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: relocation(relocation_), relocation_buckets(std::move(relocation_buckets_)),
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subsection(subsection_), subsection_buckets(std::move(subsection_buckets_)),
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base_romfs(std::move(base_romfs_)), bktr_romfs(std::move(bktr_romfs_)),
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encrypted(is_encrypted_), key(key_), base_offset(base_offset_), ivfc_offset(ivfc_offset_),
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section_ctr(section_ctr_) {
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for (std::size_t i = 0; i < relocation.number_buckets - 1; ++i) {
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relocation_buckets[i].entries.push_back({relocation.base_offsets[i + 1], 0, 0});
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}
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for (std::size_t i = 0; i < subsection.number_buckets - 1; ++i) {
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subsection_buckets[i].entries.push_back({subsection_buckets[i + 1].entries[0].address_patch,
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{0},
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subsection_buckets[i + 1].entries[0].ctr});
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}
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relocation_buckets.back().entries.push_back({relocation.size, 0, 0});
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}
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BKTR::~BKTR() = default;
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std::size_t BKTR::Read(u8* data, std::size_t length, std::size_t offset) const {
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// Read out of bounds.
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if (offset >= relocation.size)
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return 0;
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const auto relocation = GetRelocationEntry(offset);
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const auto section_offset = offset - relocation.address_patch + relocation.address_source;
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const auto bktr_read = relocation.from_patch;
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const auto next_relocation = GetNextRelocationEntry(offset);
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if (offset + length > next_relocation.address_patch) {
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const u64 partition = next_relocation.address_patch - offset;
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return Read(data, partition, offset) +
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Read(data + partition, length - partition, offset + partition);
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}
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if (!bktr_read) {
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ASSERT_MSG(section_offset >= ivfc_offset, "Offset calculation negative.");
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return base_romfs->Read(data, length, section_offset - ivfc_offset);
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}
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if (!encrypted) {
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return bktr_romfs->Read(data, length, section_offset);
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}
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const auto subsection = GetSubsectionEntry(section_offset);
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Core::Crypto::AESCipher<Core::Crypto::Key128> cipher(key, Core::Crypto::Mode::CTR);
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// Calculate AES IV
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std::array<u8, 16> iv{};
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auto subsection_ctr = subsection.ctr;
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auto offset_iv = section_offset + base_offset;
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for (std::size_t i = 0; i < section_ctr.size(); ++i)
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iv[i] = section_ctr[0x8 - i - 1];
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offset_iv >>= 4;
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for (std::size_t i = 0; i < sizeof(u64); ++i) {
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iv[0xF - i] = static_cast<u8>(offset_iv & 0xFF);
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offset_iv >>= 8;
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}
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for (std::size_t i = 0; i < sizeof(u32); ++i) {
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iv[0x7 - i] = static_cast<u8>(subsection_ctr & 0xFF);
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subsection_ctr >>= 8;
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}
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cipher.SetIV(iv);
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const auto next_subsection = GetNextSubsectionEntry(section_offset);
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if (section_offset + length > next_subsection.address_patch) {
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const u64 partition = next_subsection.address_patch - section_offset;
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return Read(data, partition, offset) +
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Read(data + partition, length - partition, offset + partition);
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}
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const auto block_offset = section_offset & 0xF;
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if (block_offset != 0) {
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auto block = bktr_romfs->ReadBytes(0x10, section_offset & ~0xF);
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cipher.Transcode(block.data(), block.size(), block.data(), Core::Crypto::Op::Decrypt);
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if (length + block_offset < 0x10) {
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std::memcpy(data, block.data() + block_offset, std::min(length, block.size()));
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return std::min(length, block.size());
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}
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const auto read = 0x10 - block_offset;
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std::memcpy(data, block.data() + block_offset, read);
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return read + Read(data + read, length - read, offset + read);
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}
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const auto raw_read = bktr_romfs->Read(data, length, section_offset);
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cipher.Transcode(data, raw_read, data, Core::Crypto::Op::Decrypt);
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return raw_read;
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}
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RelocationEntry BKTR::GetRelocationEntry(u64 offset) const {
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const auto res = SearchBucketEntry<false>(offset, relocation, relocation_buckets);
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return relocation_buckets[res.first].entries[res.second];
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}
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RelocationEntry BKTR::GetNextRelocationEntry(u64 offset) const {
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const auto res = SearchBucketEntry<false>(offset, relocation, relocation_buckets);
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const auto bucket = relocation_buckets[res.first];
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if (res.second + 1 < bucket.entries.size())
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return bucket.entries[res.second + 1];
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return relocation_buckets[res.first + 1].entries[0];
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}
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SubsectionEntry BKTR::GetSubsectionEntry(u64 offset) const {
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const auto res = SearchBucketEntry<true>(offset, subsection, subsection_buckets);
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return subsection_buckets[res.first].entries[res.second];
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}
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SubsectionEntry BKTR::GetNextSubsectionEntry(u64 offset) const {
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const auto res = SearchBucketEntry<true>(offset, subsection, subsection_buckets);
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const auto bucket = subsection_buckets[res.first];
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if (res.second + 1 < bucket.entries.size())
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return bucket.entries[res.second + 1];
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return subsection_buckets[res.first + 1].entries[0];
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}
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std::string BKTR::GetName() const {
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return base_romfs->GetName();
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}
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std::size_t BKTR::GetSize() const {
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return relocation.size;
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}
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bool BKTR::Resize(std::size_t new_size) {
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return false;
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}
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std::shared_ptr<VfsDirectory> BKTR::GetContainingDirectory() const {
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return base_romfs->GetContainingDirectory();
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}
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bool BKTR::IsWritable() const {
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return false;
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}
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bool BKTR::IsReadable() const {
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return true;
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}
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std::size_t BKTR::Write(const u8* data, std::size_t length, std::size_t offset) {
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return 0;
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}
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bool BKTR::Rename(std::string_view name) {
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return base_romfs->Rename(name);
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}
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} // namespace FileSys
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