ttsuki/nanonzip

A study for unzip program

nano𝒏zip

A study for simple unzip program (with optional zlib/bzip2).

for zip files as game application assets bundle.

features

• zip64 extension support.
• basic password encrypted zip file support.
• crc32 calculation support.
• store algorithm (= method 0) support.
• deflate algorithm (= method 8) support (with built-in implementation or zlib).
• bzip2 compress algorithm (= method 12) support (with bzip2).
• open zip file from memory (or user defined file-reading function).

files

• nanonzip.h: public api header
• nanonzip.cpp: all implementation
• test/:
  • test/nanonzip.test.cpp: a sample unzip program

library look and feel

from test/nanonzip.test.cpp

  const std::filesystem::path zip_file_path = std::filesystem::u8path(argv[1]);
  const std::string password = argv[2] ? argv[2] : "";

  // zip file
  nanonzip::zip_file_reader zip(zip_file_path);

  const auto extract_root = std::filesystem::weakly_canonical(std::filesystem::current_path());

  for (const auto& info : zip.files())
  {
    const auto target_path = std::filesystem::weakly_canonical(extract_root / info.path);

    if (bool target_path_is_outside_of_extract_root = /* ... */)
      throw std::runtime_error("target path is out side of extract_root directory.");

    if (info.path.u8string().back() == '/')
    {
      // directory
      std::filesystem::create_directories(target_path);
    }
    else
    {
      // file
      auto file = zip.open_file(info.path, password);

      std::filesystem::create_directories(target_path.parent_path());
      std::ofstream out(target_path, std::ios::out | std::ios::binary);

      std::streamoff total = 0;
      while (total < file.size())
      {
        std::vector<char> buf(1048576);
        size_t r = file.read(buf.data(), buf.size());
        out.write(buf.data(), static_cast<std::streamsize>(r));
        total += static_cast<std::streamsize>(r);
      }
    }
  }

build

env

• C++17
• zlib (optional, for instead of built-in inflate algorithm implementation)
• bzip2 (optional, to support compression_type=12)

Visual Studio

• test/nanonzip.test.sln with vcpkg integration
  • vcpkg install zlib and #define NANONZIP_ENABLE_ZLIB (optional)
  • vcpkg install bzip2 and #define NANONZIP_ENABLE_BZIP2 (optional)

• To define macros, Directory.Build.props can be used.
  google it: Directory.Build.props

g++

• g++-11

  g++ -std=c++17 -I. nanonzip.cpp test/nanonzip.test.cpp 

  or

  g++ -std=c++17 -I. \
    -DNANONZIP_ENABLE_ZLIB -DNANONZIP_ENABLE_BZIP2 \
    nanonzip.cpp test/nanonzip.test.cpp -lz -lbz2

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MIT License Copyright (c) 2023 ttsuki