citra/src/core/hle/romfs.cpp

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// Copyright 2017 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <cstring>
#include "common/swap.h"
#include "core/hle/romfs.h"
namespace RomFS {
struct Header {
u32_le header_length;
u32_le dir_hash_table_offset;
u32_le dir_hash_table_length;
u32_le dir_table_offset;
u32_le dir_table_length;
u32_le file_hash_table_offset;
u32_le file_hash_table_length;
u32_le file_table_offset;
u32_le file_table_length;
u32_le data_offset;
};
static_assert(sizeof(Header) == 0x28, "Header has incorrect size");
struct DirectoryMetadata {
u32_le parent_dir_offset;
u32_le next_dir_offset;
u32_le first_child_dir_offset;
u32_le first_file_offset;
u32_le same_hash_next_dir_offset;
u32_le name_length; // in bytes
// followed by directory name
};
static_assert(sizeof(DirectoryMetadata) == 0x18, "DirectoryMetadata has incorrect size");
struct FileMetadata {
u32_le parent_dir_offset;
u32_le next_file_offset;
u64_le data_offset;
u64_le data_length;
u32_le same_hash_next_file_offset;
u32_le name_length; // in bytes
// followed by file name
};
static_assert(sizeof(FileMetadata) == 0x20, "FileMetadata has incorrect size");
static bool MatchName(const u8* buffer, u32 name_length, const std::u16string& name) {
std::vector<char16_t> name_buffer(name_length / sizeof(char16_t));
std::memcpy(name_buffer.data(), buffer, name_length);
return name == std::u16string(name_buffer.begin(), name_buffer.end());
}
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RomFSFile::RomFSFile(const u8* data, u64 length) : data(data), length(length) {}
const u8* RomFSFile::Data() const {
return data;
}
u64 RomFSFile::Length() const {
return length;
}
const RomFSFile GetFile(const u8* romfs, const std::vector<std::u16string>& path) {
constexpr u32 INVALID_FIELD = 0xFFFFFFFF;
// Split path into directory names and file name
std::vector<std::u16string> dir_names = path;
dir_names.pop_back();
const std::u16string& file_name = path.back();
Header header;
std::memcpy(&header, romfs, sizeof(header));
// Find directories of each level
DirectoryMetadata dir;
const u8* current_dir = romfs + header.dir_table_offset;
std::memcpy(&dir, current_dir, sizeof(dir));
for (const std::u16string& dir_name : dir_names) {
u32 child_dir_offset;
child_dir_offset = dir.first_child_dir_offset;
while (true) {
if (child_dir_offset == INVALID_FIELD) {
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return RomFSFile();
}
const u8* current_child_dir = romfs + header.dir_table_offset + child_dir_offset;
std::memcpy(&dir, current_child_dir, sizeof(dir));
if (MatchName(current_child_dir + sizeof(dir), dir.name_length, dir_name)) {
current_dir = current_child_dir;
break;
}
child_dir_offset = dir.next_dir_offset;
}
}
// Find the file
FileMetadata file;
u32 file_offset = dir.first_file_offset;
while (file_offset != INVALID_FIELD) {
const u8* current_file = romfs + header.file_table_offset + file_offset;
std::memcpy(&file, current_file, sizeof(file));
if (MatchName(current_file + sizeof(file), file.name_length, file_name)) {
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return RomFSFile(romfs + header.data_offset + file.data_offset, file.data_length);
}
file_offset = file.next_file_offset;
}
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return RomFSFile();
}
} // namespace RomFS