PCK.cpp

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#include <vpkpp/format/PCK.h>
 
#include <filesystem>
#include <format>
#include <ranges>
 
#include <FileStream.h>
#include <sourcepp/crypto/MD5.h>
 
using namespace sourcepp;
using namespace vpkpp;
 
constexpr int PCK_DIRECTORY_STRING_PADDING = 4;
constexpr int PCK_FILE_DATA_PADDING = 16;
 
std::unique_ptr<PackFile> PCK::create(const std::string& path, uint32_t version, uint32_t godotMajorVersion, uint32_t godotMinorVersion, uint32_t godotPatchVersion) {
    if (version != 1 && version != 2) {
        return nullptr;
    }
 
    {
        FileStream stream{path, FileStream::OPT_TRUNCATE | FileStream::OPT_CREATE_IF_NONEXISTENT};
 
        stream
            .write(PCK_SIGNATURE)
            .write(version)
            .write(godotMajorVersion)
            .write(godotMinorVersion)
            .write(godotPatchVersion);
 
        if (version > 1) {
            stream
                .write(FLAG_DIR_NONE)
                .write<uint64_t>(0);
        }
 
        stream
            .write(std::array<int32_t, 16>{})
            .write<uint32_t>(0);
    }
    return PCK::open(path);
}
 
std::unique_ptr<PackFile> PCK::open(const std::string& path, const EntryCallback& callback) {
    if (!std::filesystem::exists(path)) {
        // File does not exist
        return nullptr;
    }
 
    auto* pck = new PCK{path};
    auto packFile = std::unique_ptr<PackFile>(pck);
 
    FileStream reader{pck->fullFilePath};
    reader.seek_in(0);
 
    if (auto signature = reader.read<uint32_t>(); signature != PCK_SIGNATURE) {
        // PCK might be embedded
        reader.seek_in(sizeof(uint32_t), std::ios::end);
        if (auto endSignature = reader.read<uint32_t>(); endSignature != PCK_SIGNATURE) {
            return nullptr;
        }
 
        reader.seek_in(-static_cast<int64_t>(sizeof(uint32_t) + sizeof(uint64_t)), std::ios::cur);
        auto distanceIntoFile = reader.read<uint64_t>();
 
        reader.seek_in(-static_cast<int64_t>(distanceIntoFile + sizeof(uint64_t)), std::ios::cur);
        if (auto startSignature = reader.read<uint32_t>(); startSignature != PCK_SIGNATURE) {
            return nullptr;
        }
 
        pck->startOffset = reader.tell_in() - sizeof(uint32_t);
    }
 
    reader.read(pck->header.packVersion);
    if (pck->header.packVersion < 1 || pck->header.packVersion > 2) {
        // We don't support v3 yet
        return nullptr;
    }
 
    reader.read(pck->header.godotVersionMajor);
    reader.read(pck->header.godotVersionMinor);
    reader.read(pck->header.godotVersionPatch);
 
    pck->header.flags = FLAG_DIR_NONE;
    std::size_t extraEntryContentsOffset = 0;
    if (pck->header.packVersion > 1) {
        pck->header.flags = reader.read<FlagsDirV2>();
        extraEntryContentsOffset = reader.read<uint64_t>();
    }
 
    if (pck->header.flags & FLAG_DIR_ENCRYPTED) {
        // File directory is encrypted
        return nullptr;
    }
    if (pck->header.flags & FLAG_DIR_RELATIVE_FILE_DATA) {
        extraEntryContentsOffset += pck->startOffset;
        pck->header.flags = static_cast<FlagsDirV2>(pck->header.flags & ~FLAG_DIR_RELATIVE_FILE_DATA);
    }
 
    // Reserved
    reader.skip_in<int32_t>(16);
 
    // Directory
    auto fileCount = reader.read<uint32_t>();
    for (uint32_t i = 0; i < fileCount; i++) {
        Entry entry = createNewEntry();
 
        auto entryPath = pck->cleanEntryPath(reader.read_string(reader.read<uint32_t>()));
        if (entryPath.starts_with(PCK_PATH_PREFIX)) {
            entryPath = entryPath.substr(PCK_PATH_PREFIX.length());
        }
 
        entry.offset = reader.read<uint64_t>() + extraEntryContentsOffset;
        entry.length = reader.read<uint64_t>();
        entry.extraData = reader.read_bytes(16);
 
        if (pck->header.packVersion > 1) {
            entry.flags = reader.read<uint32_t>();
            if (entry.flags & FLAG_FILE_REMOVED) {
                continue;
            }
        }
 
        pck->entries.emplace(entryPath, entry);
 
        if (callback) {
            callback(entryPath, entry);
        }
    }
 
    // File data
    pck->dataOffset = reader.tell_in();
 
    return packFile;
}
 
std::optional<std::vector<std::byte>> PCK::readEntry(const std::string& path_) const {
    auto path = this->cleanEntryPath(path_);
    auto entry = this->findEntry(path);
    if (!entry) {
        return std::nullopt;
    }
    if (entry->unbaked) {
        return readUnbakedEntry(*entry);
    }
 
    // It's baked into the file on disk
    if (entry->flags & FLAG_FILE_ENCRYPTED) {
        // File is encrypted
        return std::nullopt;
    }
 
    FileStream stream{this->fullFilePath};
    if (!stream) {
        return std::nullopt;
    }
    stream.seek_in_u(entry->offset);
    return stream.read_bytes(entry->length);
}
 
void PCK::addEntryInternal(Entry& entry, const std::string& path, std::vector<std::byte>& buffer, EntryOptions options) {
    entry.length = buffer.size();
 
    const auto md5 = crypto::computeMD5(buffer);
    entry.extraData = {md5.begin(), md5.end()};
 
    // Offset will be reset when it's baked
    entry.offset = 0;
}
 
bool PCK::bake(const std::string& outputDir_, BakeOptions options, const EntryCallback& callback) {
    // Get the proper file output folder
    std::string outputDir = this->getBakeOutputDir(outputDir_);
    std::string outputPath = outputDir + '/' + this->getFilename();
 
    // Reconstruct data for ease of access
    std::vector<std::pair<std::string, Entry*>> entriesToBake;
    this->runForAllEntriesInternal([&entriesToBake](const std::string& path, Entry& entry) {
        entriesToBake.emplace_back(path, &entry);
    });
 
    // Read data before overwriting, we don't know if we're writing to ourself
    std::vector<std::byte> fileData;
    for (auto& [path, entry] : entriesToBake) {
        if (auto binData = this->readEntry(path)) {
            entry->offset = fileData.size();
 
            fileData.insert(fileData.end(), binData->begin(), binData->end());
            const auto padding = math::paddingForAlignment(PCK_FILE_DATA_PADDING, static_cast<int>(entry->length));
            for (int i = 0; i < padding; i++) {
                fileData.push_back(static_cast<std::byte>(0));
            }
        } else {
            entry->offset = 0;
            entry->length = 0;
        }
    }
 
    // If this is an embedded pck, read the executable data first
    std::vector<std::byte> exeData;
    if (this->startOffset > 0) {
        FileStream stream{this->fullFilePath};
        if (!stream) {
            return false;
        }
        stream.seek_in(0);
        exeData = stream.read_bytes(this->startOffset);
    }
 
    // Write data
    {
        FileStream stream{outputPath, FileStream::OPT_TRUNCATE | FileStream::OPT_CREATE_IF_NONEXISTENT};
        stream.seek_out(0);
 
        if (!exeData.empty()) {
            stream.write(exeData);
        }
 
        // Signature
        stream.write(PCK_SIGNATURE);
 
        // Header
        stream.write(this->header.packVersion);
        stream.write(this->header.godotVersionMajor);
        stream.write(this->header.godotVersionMinor);
        stream.write(this->header.godotVersionPatch);
 
        if (this->header.packVersion > 1) {
            stream.write(this->header.flags);
            stream.write<uint64_t>(0);
        }
 
        // Reserved
        stream.write(std::array<int32_t, 16>{});
 
        // Directory start
        stream.write(static_cast<uint32_t>(entriesToBake.size()));
 
        // Dry-run to get the length of the directory section
        this->dataOffset = stream.tell_out();
        for (const auto& path : std::views::keys(entriesToBake)) {
            const auto entryPath = std::string{PCK_PATH_PREFIX} + path;
            const auto padding = math::paddingForAlignment(PCK_DIRECTORY_STRING_PADDING, static_cast<int>(entryPath.length()));
            this->dataOffset +=
                    sizeof(uint32_t) +             // Path length
                    entryPath.length() + padding + // Path
                    (sizeof(std::size_t) * 2) +    // Offset, Length
                    (sizeof(std::byte) * 16);      // MD5
 
            if (this->header.packVersion > 1) {
                this->dataOffset += sizeof(uint32_t); // Flags
            }
        }
 
        // Directory
        for (const auto& [path, entry] : entriesToBake) {
            auto entryPath = path;
            if (this->header.godotVersionMajor <= 4 && this->header.godotVersionMinor <= 3) {
                entryPath = std::string{PCK_PATH_PREFIX} + entryPath; // NOLINT(*-inefficient-string-concatenation)
            }
            const auto padding = math::paddingForAlignment(PCK_DIRECTORY_STRING_PADDING, static_cast<int>(entryPath.length()));
            stream.write(static_cast<uint32_t>(entryPath.length() + padding));
            stream.write(entryPath, false, entryPath.length() + padding);
 
            entry->offset += this->dataOffset;
            stream.write(entry->offset);
            stream.write(entry->length);
            stream.write(entry->extraData);
 
            if (this->header.packVersion > 1) {
                stream.write(entry->flags);
            }
 
            if (callback) {
                callback(path, *entry);
            }
        }
 
        // File data
        stream.write(fileData);
 
        // Write offset to start
        if (this->startOffset > 0) {
            stream.write(stream.tell_out() - startOffset);
            stream.write(PCK_SIGNATURE);
        }
    }
 
    // Clean up
    this->mergeUnbakedEntries();
    PackFile::setFullFilePath(outputDir);
    return true;
}
 
Attribute PCK::getSupportedEntryAttributes() const {
    using enum Attribute;
    return LENGTH | PCK_MD5;
}
 
PCK::operator std::string() const {
    auto out = PackFile::operator std::string() + std::format(" | Version v{} | Godot Version v{}.{}.{}", this->header.packVersion, this->header.godotVersionMajor, this->header.godotVersionMinor, this->header.godotVersionPatch);
    if (this->startOffset > 0) {
        out += " | Embedded";
    }
    if (this->header.flags & FLAG_DIR_ENCRYPTED) {
        out += " | Encrypted";
    }
    return out;
}
 
uint32_t PCK::getVersion() const {
    return this->header.packVersion;
}
 
void PCK::setVersion(uint32_t version) {
    if (version == 1 || version == 2) {
        this->header.packVersion = version;
    }
}
 
std::tuple<uint32_t, uint32_t, uint32_t> PCK::getGodotVersion() const {
    return {this->header.godotVersionMajor, this->header.godotVersionMinor, this->header.godotVersionPatch};
}
 
void PCK::setGodotVersion(uint32_t major, uint32_t minor, uint32_t patch) {
    this->header.godotVersionMajor = major;
    this->header.godotVersionMinor = minor;
    this->header.godotVersionPatch = patch;
}