OO7.cpp

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#include <vpkpp/format/OO7.h>
 
#include <filesystem>
 
#include <FileStream.h>
#include <miniz.h>
#include <sourcepp/crypto/MD5.h>
 
using namespace sourcepp;
using namespace vpkpp;
 
std::unique_ptr<PackFile> OO7::open(const std::string& path, const EntryCallback& callback) {
    if (!std::filesystem::exists(path)) {
        // File does not exist
        return nullptr;
    }
 
    auto* oo7 = new OO7{path};
    auto packFile = std::unique_ptr<PackFile>(oo7);
 
    FileStream reader{oo7->fullFilePath};
    reader.seek_in(0);
 
    reader >> oo7->majorVersion >> oo7->minorVersion;
    if (oo7->majorVersion != 1 || (oo7->minorVersion != 1 && oo7->minorVersion != 3)) {
        // We only support v1.1 and v1.3
        return nullptr;
    }
 
    std::vector<std::string> v3EntriesFixup;
 
    // Read the file tree recursively
    std::function<void(const std::string&, bool)> readDir;
    readDir = [&callback, &oo7, &reader, &v3EntriesFixup, &readDir](const std::string& parentPath, bool root) {
        auto currentPath = parentPath + '/' + reader.read_string(reader.read<uint32_t>(), false);
        if (root) {
            currentPath = ""; // The root folder gets ignored
        }
        auto subDirCount = reader.read<uint32_t>();
        if (oo7->minorVersion == 3) {
            reader.skip_in<uint32_t>(); // File count
        }
        while (1) {
            auto filenameSize = reader.read<uint32_t>();
            if (!filenameSize) {
                break;
            }
 
            Entry entry = createNewEntry();
 
            auto entryPath = oo7->cleanEntryPath(currentPath + '/' + reader.read_string(filenameSize, false));
 
            bool compressed = reader.read<uint8_t>();
            entry.length = reader.read<uint32_t>();
            if (compressed) {
                entry.compressedLength = reader.read<uint32_t>();
            } else {
                reader.skip_in<uint32_t>();
            }
 
            if (oo7->minorVersion == 1) {
                entry.offset = reader.tell_in();
 
                if (compressed) {
                    reader.skip_in(entry.compressedLength);
                } else {
                    reader.skip_in(entry.length);
                }
            } else {
                v3EntriesFixup.push_back(entryPath);
            }
 
            oo7->entries.emplace(entryPath, entry);
 
            if (callback) {
                callback(entryPath, entry);
            }
        }
        for (uint32_t i = 0; i < subDirCount; i++) {
            readDir(currentPath, false);
        }
    };
    readDir("", true);
 
    for (const auto& entryPath : v3EntriesFixup) {
        auto& entry = oo7->entries.at(entryPath);
        entry.offset = reader.tell_in();
        if (!entry.compressedLength) {
            reader.skip_in(entry.length);
        } else {
            reader.skip_in(entry.compressedLength);
        }
    }
 
    // Absolutely no idea what the demo checksum is calculated from, and if it's
    // the file tree minus file data that is insane. It technically has one, but
    // I'm not going to advertise that to users of this library.
    if (oo7->minorVersion == 3 && reader.read<uint32_t>() == 16) {
        oo7->hasChecksum = true;
        reader >> oo7->checksum;
    }
 
    return packFile;
}
 
bool OO7::hasPackFileChecksum() const {
    return this->hasChecksum;
}
 
bool OO7::verifyPackFileChecksum() const {
    if (!this->hasChecksum) {
        return true;
    }
 
    // Looping here is faster than parsing the tree again
    // We're assuming the first entry on disk is directly after the tree
    if (this->entries.empty()) {
        return true;
    }
    uint32_t minOffset = UINT32_MAX;
    this->runForAllEntries([&minOffset](const std::string&, const Entry& entry) {
        minOffset = (entry.offset < minOffset) ? entry.offset : minOffset;
    });
    auto data = fs::readFileBuffer(this->fullFilePath, sizeof(uint32_t) * 2);
    data.resize(minOffset - (sizeof(uint32_t) * 2));
    return crypto::computeMD5(data) == this->checksum;
}
 
std::optional<std::vector<std::byte>> OO7::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);
    if (!entry->compressedLength) {
        return stream.read_bytes(entry->length);
    }
 
    // Decompress
    auto compressedData = stream.read_bytes(entry->compressedLength);
    mz_ulong uncompressedLength = entry->length;
    std::vector<std::byte> uncompressedData(uncompressedLength);
    if (mz_uncompress(reinterpret_cast<unsigned char*>(uncompressedData.data()), &uncompressedLength, reinterpret_cast<const unsigned char*>(compressedData.data()), entry->compressedLength) != MZ_OK) {
        return std::nullopt;
    }
    return uncompressedData;
}
 
Attribute OO7::getSupportedEntryAttributes() const {
    using enum Attribute;
    return LENGTH;
}
 
OO7::operator std::string() const {
    return PackFileReadOnly::operator std::string() +
        " | Version v" + std::to_string(this->majorVersion) + '.' + std::to_string(this->minorVersion);
}