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file_sys: Implement function to apply IPS patches

This commit is contained in:
Zach Hilman 2018-09-29 22:13:15 -04:00
parent 3c9e70fefa
commit 21b2411c44
2 changed files with 103 additions and 0 deletions

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// Copyright 2018 yuzu emulator team
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include "common/assert.h"
#include "common/swap.h"
#include "core/file_sys/ips_layer.h"
#include "core/file_sys/vfs_vector.h"
namespace FileSys {
enum class IPSFileType {
IPS,
IPS32,
Error,
};
static IPSFileType IdentifyMagic(const std::vector<u8>& magic) {
if (magic.size() != 5)
return IPSFileType::Error;
if (magic == std::vector<u8>{'P', 'A', 'T', 'C', 'H'})
return IPSFileType::IPS;
if (magic == std::vector<u8>{'I', 'P', 'S', '3', '2'})
return IPSFileType::IPS32;
return IPSFileType::Error;
}
VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips) {
if (in == nullptr || ips == nullptr)
return nullptr;
const auto type = IdentifyMagic(ips->ReadBytes(0x5));
if (type == IPSFileType::Error)
return nullptr;
auto in_data = in->ReadAllBytes();
std::vector<u8> temp(type == IPSFileType::IPS ? 3 : 4);
u64 offset = 5; // After header
while (ips->Read(temp.data(), temp.size(), offset) == temp.size()) {
offset += temp.size();
if (type == IPSFileType::IPS32 && temp == std::vector<u8>{'E', 'E', 'O', 'F'} ||
type == IPSFileType::IPS && temp == std::vector<u8>{'E', 'O', 'F'}) {
break;
}
u32 real_offset{};
if (type == IPSFileType::IPS32)
real_offset = (temp[0] << 24) | (temp[1] << 16) | (temp[2] << 8) | temp[3];
else
real_offset = (temp[0] << 16) | (temp[1] << 8) | temp[2];
u16 data_size{};
if (ips->ReadObject(&data_size, offset) != sizeof(u16))
return nullptr;
data_size = Common::swap16(data_size);
offset += sizeof(u16);
if (data_size == 0) { // RLE
u16 rle_size{};
if (ips->ReadObject(&rle_size, offset) != sizeof(u16))
return nullptr;
rle_size = Common::swap16(data_size);
offset += sizeof(u16);
const auto data = ips->ReadByte(offset++);
if (data == boost::none)
return nullptr;
if (real_offset + rle_size > in_data.size())
rle_size = in_data.size() - real_offset;
std::memset(in_data.data() + real_offset, data.get(), rle_size);
} else { // Standard Patch
auto read = data_size;
if (real_offset + read > in_data.size())
read = in_data.size() - real_offset;
if (ips->Read(in_data.data() + real_offset, read, offset) != data_size)
return nullptr;
offset += data_size;
}
}
if (temp != std::vector<u8>{'E', 'E', 'O', 'F'} && temp != std::vector<u8>{'E', 'O', 'F'})
return nullptr;
return std::make_shared<VectorVfsFile>(in_data, in->GetName(), in->GetContainingDirectory());
}
} // namespace FileSys

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// Copyright 2018 yuzu emulator team
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <memory>
#include "core/file_sys/vfs.h"
namespace FileSys {
VirtualFile PatchIPS(const VirtualFile& in, const VirtualFile& ips);
} // namespace FileSys