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 2019-11-25 20:49:48 +01:00
parent 3140086c60
commit 756d231ff9
3 changed files with 236 additions and 11 deletions

View File

@ -508,21 +508,31 @@ Loader::ResultStatus NCCHContainer::LoadSectionExeFS(const char* name, std::vect
}
Loader::ResultStatus NCCHContainer::ApplyCodePatch(std::vector<u8>& code) const {
const std::string override_ips = filepath + ".exefsdir/code.ips";
struct PatchLocation {
std::string path;
bool (*patch_fn)(const std::vector<u8>& patch, std::vector<u8>& code);
};
const std::array<PatchLocation, 2> patch_paths{{
{filepath + ".exefsdir/code.ips", Patch::ApplyIpsPatch},
{filepath + ".exefsdir/code.bps", Patch::ApplyBpsPatch},
}};
FileUtil::IOFile ips_file{override_ips, "rb"};
if (!ips_file)
return Loader::ResultStatus::ErrorNotUsed;
for (const PatchLocation& info : patch_paths) {
FileUtil::IOFile file{info.path, "rb"};
if (!file)
continue;
std::vector<u8> ips(ips_file.GetSize());
if (ips_file.ReadBytes(ips.data(), ips.size()) != ips.size())
return Loader::ResultStatus::Error;
std::vector<u8> patch(file.GetSize());
if (file.ReadBytes(patch.data(), patch.size()) != patch.size())
return Loader::ResultStatus::Error;
LOG_INFO(Service_FS, "File {} patching code.bin", override_ips);
if (!Patch::ApplyIpsPatch(ips, code))
return Loader::ResultStatus::Error;
LOG_INFO(Service_FS, "File {} patching code.bin", info.path);
if (!info.patch_fn(patch, code))
return Loader::ResultStatus::Error;
return Loader::ResultStatus::Success;
return Loader::ResultStatus::Success;
}
return Loader::ResultStatus::ErrorNotUsed;
}
Loader::ResultStatus NCCHContainer::LoadOverrideExeFSSection(const char* name,

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@ -2,8 +2,13 @@
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <array>
#include <cstring>
#include <optional>
#include <string>
#include <string_view>
#include <type_traits>
#include <boost/crc.hpp>
#include "common/logging/log.h"
#include "core/file_sys/patch.h"
@ -52,4 +57,212 @@ bool ApplyIpsPatch(const std::vector<u8>& ips, std::vector<u8>& buffer) {
return true;
}
namespace Bps {
// The BPS format uses variable length encoding for all integers.
// Realistically uint32s are more than enough for code patching.
using Number = u32;
constexpr std::size_t FooterSize = 12;
// The BPS format uses CRC32 checksums.
static u32 crc32(const u8* data, std::size_t size) {
boost::crc_32_type result;
result.process_bytes(data, size);
return result.checksum();
}
// Utility class to make keeping track of offsets and bound checks less error prone.
template <typename T>
class Stream {
public:
Stream(T* ptr, std::size_t size) : m_ptr{ptr}, m_size{size} {}
bool Read(void* buffer, std::size_t length) {
if (m_offset + length > m_size)
return false;
std::memcpy(buffer, m_ptr + m_offset, length);
m_offset += length;
return true;
}
template <typename OtherType>
bool CopyFrom(Stream<OtherType>& other, std::size_t length) {
if (m_offset + length > m_size)
return false;
if (!other.Read(m_ptr + m_offset, length))
return false;
m_offset += length;
return true;
}
template <typename ValueType>
std::optional<ValueType> Read() {
static_assert(std::is_pod_v<ValueType>);
ValueType val{};
if (!Read(&val, sizeof(val)))
return std::nullopt;
return val;
}
Number ReadNumber() {
Number data = 0, shift = 1;
std::optional<u8> x;
while ((x = Read<u8>())) {
data += (*x & 0x7f) * shift;
if (*x & 0x80)
break;
shift <<= 7;
data += shift;
}
return data;
}
auto data() const {
return m_ptr;
}
std::size_t size() const {
return m_size;
}
std::size_t Tell() const {
return m_offset;
}
bool Seek(size_t offset) {
if (offset > m_size)
return false;
m_offset = offset;
return true;
}
private:
T* m_ptr = nullptr;
std::size_t m_size = 0;
std::size_t m_offset = 0;
};
class PatchApplier {
public:
PatchApplier(Stream<const u8> source, Stream<u8> target, Stream<const u8> patch)
: m_source{source}, m_target{target}, m_patch{patch} {}
bool Apply() {
const auto magic = *m_patch.Read<std::array<char, 4>>();
if (std::string_view(magic.data(), magic.size()) != "BPS1") {
LOG_ERROR(Service_FS, "Invalid BPS magic");
return false;
}
const Bps::Number source_size = m_patch.ReadNumber();
const Bps::Number target_size = m_patch.ReadNumber();
const Bps::Number metadata_size = m_patch.ReadNumber();
if (source_size > m_source.size() || target_size > m_target.size() || metadata_size != 0) {
LOG_ERROR(Service_FS, "Invalid sizes");
return false;
}
const std::size_t command_start_offset = m_patch.Tell();
const std::size_t command_end_offset = m_patch.size() - FooterSize;
m_patch.Seek(command_end_offset);
const u32 source_crc32 = *m_patch.Read<u32>();
const u32 target_crc32 = *m_patch.Read<u32>();
m_patch.Seek(command_start_offset);
if (crc32(m_source.data(), source_size) != source_crc32) {
LOG_ERROR(Service_FS, "Unexpected source hash");
return false;
}
// Process all patch commands.
std::memset(m_target.data(), 0, m_target.size());
while (m_patch.Tell() < command_end_offset) {
if (!HandleCommand())
return false;
}
if (crc32(m_target.data(), target_size) != target_crc32) {
LOG_ERROR(Service_FS, "Unexpected target hash");
return false;
}
return true;
}
private:
bool HandleCommand() {
const std::size_t offset = m_patch.Tell();
const Number data = m_patch.ReadNumber();
const Number command = data & 3;
const Number length = (data >> 2) + 1;
const bool ok = [&] {
switch (command) {
case 0:
return SourceRead(length);
case 1:
return TargetRead(length);
case 2:
return SourceCopy(length);
case 3:
return TargetCopy(length);
default:
return false;
}
}();
if (!ok)
LOG_ERROR(Service_FS, "Failed to process command {} at 0x{:x}", command, offset);
return ok;
}
bool SourceRead(Number length) {
return m_source.Seek(m_target.Tell()) && m_target.CopyFrom(m_source, length);
}
bool TargetRead(Number length) {
return m_target.CopyFrom(m_patch, length);
}
bool SourceCopy(Number length) {
const Number data = m_patch.ReadNumber();
m_source_relative_offset += (data & 1 ? -1 : +1) * int(data >> 1);
if (!m_source.Seek(m_source_relative_offset) || !m_target.CopyFrom(m_source, length))
return false;
m_source_relative_offset += length;
return true;
}
bool TargetCopy(Number length) {
const Number data = m_patch.ReadNumber();
m_target_relative_offset += (data & 1 ? -1 : +1) * int(data >> 1);
if (m_target.Tell() + length > m_target.size())
return false;
if (m_target_relative_offset + length > m_target.size())
return false;
// Byte by byte copy.
for (size_t i = 0; i < length; ++i)
m_target.data()[m_target.Tell() + i] = m_target.data()[m_target_relative_offset++];
m_target.Seek(m_target.Tell() + length);
return true;
}
std::size_t m_source_relative_offset = 0;
std::size_t m_target_relative_offset = 0;
Stream<const u8> m_source;
Stream<u8> m_target;
Stream<const u8> m_patch;
};
} // namespace Bps
bool ApplyBpsPatch(const std::vector<u8>& patch, std::vector<u8>& buffer) {
const std::vector<u8> source = buffer;
Bps::Stream source_stream{source.data(), source.size()};
Bps::Stream target_stream{buffer.data(), buffer.size()};
Bps::Stream patch_stream{patch.data(), patch.size()};
Bps::PatchApplier applier{source_stream, target_stream, patch_stream};
return applier.Apply();
}
} // namespace FileSys::Patch

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@ -12,4 +12,6 @@ namespace FileSys::Patch {
bool ApplyIpsPatch(const std::vector<u8>& patch, std::vector<u8>& buffer);
bool ApplyBpsPatch(const std::vector<u8>& patch, std::vector<u8>& buffer);
} // namespace FileSys::Patch