file_sys: Add support for BPS patches
The BPS format allows distributing patches that are smaller and that do not contain copyrighted content if data is relocated (unlike non-trivial IPS patches). This is essential for games such as MM3D that have three barely different code revisions. Supporting all three versions would demand an unreasonable amount of work; with BPS patches only one version has to be supported.
This commit is contained in:
Léo Lam
parent
3140086c60
commit
756d231ff9
@ -508,22 +508,32 @@ Loader::ResultStatus NCCHContainer::LoadSectionExeFS(const char* name, std::vect
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}
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Loader::ResultStatus NCCHContainer::ApplyCodePatch(std::vector<u8>& code) const {
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const std::string override_ips = filepath + ".exefsdir/code.ips";
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struct PatchLocation {
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std::string path;
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bool (*patch_fn)(const std::vector<u8>& patch, std::vector<u8>& code);
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};
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const std::array<PatchLocation, 2> patch_paths{{
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{filepath + ".exefsdir/code.ips", Patch::ApplyIpsPatch},
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{filepath + ".exefsdir/code.bps", Patch::ApplyBpsPatch},
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}};
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FileUtil::IOFile ips_file{override_ips, "rb"};
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if (!ips_file)
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return Loader::ResultStatus::ErrorNotUsed;
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for (const PatchLocation& info : patch_paths) {
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FileUtil::IOFile file{info.path, "rb"};
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if (!file)
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continue;
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std::vector<u8> ips(ips_file.GetSize());
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if (ips_file.ReadBytes(ips.data(), ips.size()) != ips.size())
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std::vector<u8> patch(file.GetSize());
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if (file.ReadBytes(patch.data(), patch.size()) != patch.size())
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return Loader::ResultStatus::Error;
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LOG_INFO(Service_FS, "File {} patching code.bin", override_ips);
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if (!Patch::ApplyIpsPatch(ips, code))
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LOG_INFO(Service_FS, "File {} patching code.bin", info.path);
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if (!info.patch_fn(patch, code))
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return Loader::ResultStatus::Error;
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return Loader::ResultStatus::Success;
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}
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return Loader::ResultStatus::ErrorNotUsed;
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}
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Loader::ResultStatus NCCHContainer::LoadOverrideExeFSSection(const char* name,
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std::vector<u8>& buffer) {
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@ -2,8 +2,13 @@
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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 <array>
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#include <cstring>
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#include <optional>
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#include <string>
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#include <string_view>
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#include <type_traits>
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#include <boost/crc.hpp>
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#include "common/logging/log.h"
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#include "core/file_sys/patch.h"
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@ -52,4 +57,212 @@ bool ApplyIpsPatch(const std::vector<u8>& ips, std::vector<u8>& buffer) {
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return true;
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}
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namespace Bps {
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// The BPS format uses variable length encoding for all integers.
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// Realistically uint32s are more than enough for code patching.
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using Number = u32;
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constexpr std::size_t FooterSize = 12;
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// The BPS format uses CRC32 checksums.
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static u32 crc32(const u8* data, std::size_t size) {
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boost::crc_32_type result;
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result.process_bytes(data, size);
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return result.checksum();
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}
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// Utility class to make keeping track of offsets and bound checks less error prone.
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template <typename T>
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class Stream {
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public:
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Stream(T* ptr, std::size_t size) : m_ptr{ptr}, m_size{size} {}
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bool Read(void* buffer, std::size_t length) {
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if (m_offset + length > m_size)
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return false;
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std::memcpy(buffer, m_ptr + m_offset, length);
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m_offset += length;
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return true;
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}
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template <typename OtherType>
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bool CopyFrom(Stream<OtherType>& other, std::size_t length) {
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if (m_offset + length > m_size)
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return false;
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if (!other.Read(m_ptr + m_offset, length))
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return false;
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m_offset += length;
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return true;
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}
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template <typename ValueType>
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std::optional<ValueType> Read() {
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static_assert(std::is_pod_v<ValueType>);
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ValueType val{};
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if (!Read(&val, sizeof(val)))
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return std::nullopt;
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return val;
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}
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Number ReadNumber() {
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Number data = 0, shift = 1;
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std::optional<u8> x;
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while ((x = Read<u8>())) {
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data += (*x & 0x7f) * shift;
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if (*x & 0x80)
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break;
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shift <<= 7;
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data += shift;
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}
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return data;
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}
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auto data() const {
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return m_ptr;
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}
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std::size_t size() const {
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return m_size;
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}
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std::size_t Tell() const {
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return m_offset;
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}
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bool Seek(size_t offset) {
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if (offset > m_size)
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return false;
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m_offset = offset;
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return true;
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}
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private:
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T* m_ptr = nullptr;
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std::size_t m_size = 0;
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std::size_t m_offset = 0;
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};
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class PatchApplier {
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public:
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PatchApplier(Stream<const u8> source, Stream<u8> target, Stream<const u8> patch)
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: m_source{source}, m_target{target}, m_patch{patch} {}
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bool Apply() {
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const auto magic = *m_patch.Read<std::array<char, 4>>();
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if (std::string_view(magic.data(), magic.size()) != "BPS1") {
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LOG_ERROR(Service_FS, "Invalid BPS magic");
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return false;
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}
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const Bps::Number source_size = m_patch.ReadNumber();
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const Bps::Number target_size = m_patch.ReadNumber();
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const Bps::Number metadata_size = m_patch.ReadNumber();
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if (source_size > m_source.size() || target_size > m_target.size() || metadata_size != 0) {
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LOG_ERROR(Service_FS, "Invalid sizes");
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return false;
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}
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const std::size_t command_start_offset = m_patch.Tell();
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const std::size_t command_end_offset = m_patch.size() - FooterSize;
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m_patch.Seek(command_end_offset);
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const u32 source_crc32 = *m_patch.Read<u32>();
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const u32 target_crc32 = *m_patch.Read<u32>();
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m_patch.Seek(command_start_offset);
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if (crc32(m_source.data(), source_size) != source_crc32) {
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LOG_ERROR(Service_FS, "Unexpected source hash");
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return false;
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}
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// Process all patch commands.
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std::memset(m_target.data(), 0, m_target.size());
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while (m_patch.Tell() < command_end_offset) {
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if (!HandleCommand())
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return false;
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}
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if (crc32(m_target.data(), target_size) != target_crc32) {
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LOG_ERROR(Service_FS, "Unexpected target hash");
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return false;
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}
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return true;
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}
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private:
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bool HandleCommand() {
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const std::size_t offset = m_patch.Tell();
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const Number data = m_patch.ReadNumber();
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const Number command = data & 3;
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const Number length = (data >> 2) + 1;
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const bool ok = [&] {
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switch (command) {
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case 0:
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return SourceRead(length);
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case 1:
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return TargetRead(length);
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case 2:
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return SourceCopy(length);
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case 3:
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return TargetCopy(length);
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default:
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return false;
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}
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}();
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if (!ok)
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LOG_ERROR(Service_FS, "Failed to process command {} at 0x{:x}", command, offset);
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return ok;
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}
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bool SourceRead(Number length) {
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return m_source.Seek(m_target.Tell()) && m_target.CopyFrom(m_source, length);
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}
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bool TargetRead(Number length) {
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return m_target.CopyFrom(m_patch, length);
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}
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bool SourceCopy(Number length) {
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const Number data = m_patch.ReadNumber();
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m_source_relative_offset += (data & 1 ? -1 : +1) * int(data >> 1);
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if (!m_source.Seek(m_source_relative_offset) || !m_target.CopyFrom(m_source, length))
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return false;
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m_source_relative_offset += length;
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return true;
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}
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bool TargetCopy(Number length) {
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const Number data = m_patch.ReadNumber();
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m_target_relative_offset += (data & 1 ? -1 : +1) * int(data >> 1);
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if (m_target.Tell() + length > m_target.size())
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return false;
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if (m_target_relative_offset + length > m_target.size())
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return false;
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// Byte by byte copy.
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for (size_t i = 0; i < length; ++i)
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m_target.data()[m_target.Tell() + i] = m_target.data()[m_target_relative_offset++];
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m_target.Seek(m_target.Tell() + length);
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return true;
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}
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std::size_t m_source_relative_offset = 0;
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std::size_t m_target_relative_offset = 0;
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Stream<const u8> m_source;
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Stream<u8> m_target;
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Stream<const u8> m_patch;
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};
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} // namespace Bps
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bool ApplyBpsPatch(const std::vector<u8>& patch, std::vector<u8>& buffer) {
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const std::vector<u8> source = buffer;
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Bps::Stream source_stream{source.data(), source.size()};
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Bps::Stream target_stream{buffer.data(), buffer.size()};
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Bps::Stream patch_stream{patch.data(), patch.size()};
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Bps::PatchApplier applier{source_stream, target_stream, patch_stream};
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return applier.Apply();
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}
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} // namespace FileSys::Patch
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@ -12,4 +12,6 @@ namespace FileSys::Patch {
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bool ApplyIpsPatch(const std::vector<u8>& patch, std::vector<u8>& buffer);
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bool ApplyBpsPatch(const std::vector<u8>& patch, std::vector<u8>& buffer);
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} // namespace FileSys::Patch
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