GMA.cpp

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#include <vpkpp/format/GMA.h>
 
#include <filesystem>
#include <format>
 
#include <FileStream.h>
#include <sourcepp/crypto/CRC32.h>
#include <sourcepp/FS.h>
 
using namespace sourcepp;
using namespace vpkpp;
 
std::unique_ptr<PackFile> GMA::open(const std::string& path, const EntryCallback& callback) {
    if (!std::filesystem::exists(path)) {
        // File does not exist
        return nullptr;
    }
 
    auto* gma = new GMA{path};
    auto packFile = std::unique_ptr<PackFile>(gma);
 
    FileStream reader{gma->fullFilePath};
    reader.seek_in(0);
 
    reader.read(gma->header.signature);
    if (gma->header.signature != GMA_SIGNATURE) {
        // File is not a GMA
        return nullptr;
    }
    reader.read(gma->header.version);
    reader.read(gma->header.steamID);
    reader.read(gma->header.timestamp);
    reader.read(gma->header.requiredContent);
    reader.read(gma->header.addonName);
    reader.read(gma->header.addonDescription);
    reader.read(gma->header.addonAuthor);
    reader.read(gma->header.addonVersion);
 
    std::vector<std::pair<std::string, Entry>> entries;
    while (reader.read<uint32_t>() > 0) {
        Entry entry = createNewEntry();
 
        auto entryPath = gma->cleanEntryPath(reader.read_string());
 
        entry.length = reader.read<uint64_t>();
        reader.read(entry.crc32);
 
        entries.emplace_back(entryPath, entry);
    }
 
    // At this point we've reached the file data section, calculate the offsets and then add the entries
    std::size_t offset = reader.tell_in();
    for (auto& [entryPath, entry] : entries) {
        entry.offset = offset;
        offset += entry.length;
 
        gma->entries.emplace(entryPath, entry);
 
        if (callback) {
            callback(entryPath, entry);
        }
    }
 
    return packFile;
}
 
std::vector<std::string> GMA::verifyEntryChecksums() const {
    return this->verifyEntryChecksumsUsingCRC32();
}
 
bool GMA::hasPackFileChecksum() const {
    return true;
}
 
bool GMA::verifyPackFileChecksum() const {
    auto data = fs::readFileBuffer(this->fullFilePath);
    if (data.size() <= 4) {
        return true;
    }
 
    const auto checksum = *(reinterpret_cast<uint32_t*>(data.data() + data.size()) - 1);
    data.pop_back();
    data.pop_back();
    data.pop_back();
    data.pop_back();
    return checksum == crypto::computeCRC32(data);
}
 
std::optional<std::vector<std::byte>> GMA::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
    FileStream stream{this->fullFilePath};
    if (!stream) {
        return std::nullopt;
    }
    stream.seek_in_u(entry->offset);
    return stream.read_bytes(entry->length);
}
 
void GMA::addEntryInternal(Entry& entry, const std::string& path, std::vector<std::byte>& buffer, EntryOptions options) {
    entry.length = buffer.size();
    entry.crc32 = crypto::computeCRC32(buffer);
 
    // Offset will be reset when it's baked
    entry.offset = 0;
}
 
bool GMA::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)) {
            fileData.insert(fileData.end(), binData->begin(), binData->end());
        } else {
            entry->length = 0;
        }
    }
 
    {
        FileStream stream{outputPath, FileStream::OPT_TRUNCATE | FileStream::OPT_CREATE_IF_NONEXISTENT};
        stream.seek_out(0);
 
        // Header
        stream.write(this->header.signature);
        stream.write(this->header.version);
        stream.write(this->header.steamID);
        stream.write(this->header.timestamp);
        stream.write(this->header.requiredContent);
        stream.write(this->header.addonName);
        stream.write(this->header.addonDescription);
        stream.write(this->header.addonAuthor);
        stream.write(this->header.addonVersion);
 
        // File tree
        for (uint32_t i = 1; i <= entriesToBake.size(); i++) {
            stream.write(i);
            const auto& [path, entry] = entriesToBake[i - 1];
            stream.write(path);
            stream.write(entry->length);
            stream.write<uint32_t>(options.gma_writeCRCs ? entry->crc32 : 0);
 
            if (callback) {
                callback(path, *entry);
            }
        }
        stream.write<uint32_t>(0);
 
        // Fix offsets
        std::size_t offset = stream.tell_out();
        for (auto& [path, entry] : entriesToBake) {
            entry->offset = offset;
            offset += entry->length;
        }
 
        // File data
        stream.write(fileData);
    }
 
    // CRC of everything that's been written
    uint32_t crc = 0;
    if (options.gma_writeCRCs) {
        auto fileSize = std::filesystem::file_size(outputPath);
        FileStream stream{outputPath};
        stream.seek_in(0);
        crc = crypto::computeCRC32(stream.read_bytes(fileSize));
    }
    {
        FileStream stream{outputPath, FileStream::OPT_APPEND};
        stream.write(crc);
    }
 
    // Clean up
    this->mergeUnbakedEntries();
    PackFile::setFullFilePath(outputDir);
    return true;
}
 
Attribute GMA::getSupportedEntryAttributes() const {
    using enum Attribute;
    return LENGTH | CRC32;
}
 
GMA::operator std::string() const {
    return PackFile::operator std::string() + std::format(" | Version v{} | Addon Name: \"{}\"", this->header.version, this->header.addonName);
}