bit7z

A C++ static library offering a clean and simple interface to the 7-zip shared libraries

        
     

⚡️ Introduction

bit7z is a cross-platform C++ static library that allows the compression/extraction of archive files through a clean and simple wrapper interface to the dynamic libraries from the 7-zip project.
It supports compression and extraction to and from the filesystem or the memory, reading archives metadata, updating existing ones, creating multi-volume archives, operation progress callbacks, and many other functionalities.

🎯 Supported Features

• Compression using the following archive formats: 7z, XZ, BZIP2, GZIP, TAR, ZIP, and WIM.
• Extraction of many archive formats: 7z, AR, ARJ, BZIP2, CAB, CHM, CPIO, CramFS, DEB, DMG, EXT, FAT, GPT, GZIP, HFS, HXS, IHEX, ISO, LZH, LZMA, MBR, MSI, NSIS, NTFS, QCOW2, RAR, RAR5, RPM, SquashFS, TAR, UDF, UEFI, VDI, VHD, VMDK, WIM, XAR, XZ, Z, and ZIP.
• Reading metadata of archives and their content.
• Testing archives for errors.
• Updating existing file archives with new files.
• Renaming, updating, or deleting old items in existing file archives.
• Compression and extraction to and from memory and C++ standard streams.
• Compression using custom path aliases for the items in the output archives.
• Selective extraction of only specified files/folders using wildcards and regular expressions.
• Creation of encrypted archives (strong AES-256 encryption; only for 7z and ZIP formats).
• Archive header encryption (only for 7z format).
• Possibility to choose the compression level (if supported by the archive format), the compression method (supported methods), the dictionary size, and the word size.
• Automatic input archive format detection.
• Solid archives (only for 7z).
• Multi-volume archives.
• Operation callbacks for obtaining real-time information about ongoing operations.
• Canceling or pausing the current operation.

Notes

The presence or not of some of the above features depends on the particular shared library used along with bit7z.
For example, 7z.dll should support all these features, 7za.dll should work only with the 7z file format, and 7zxa.dll can only extract 7z files. For more information about the 7-zip DLLs, please check this wiki page.

In the end, some other features (e.g., automatic format detection and selective extraction using regular expressions) are disabled by default, and macro definitions must be used during compilation to have them available (wiki).

🔥 Getting Started (Library Usage)

Below are a few examples that show how to use some of the main features of bit7z.

📂 Extracting Files from an Archive

#include <bit7z/bitfileextractor.hpp>
 
try { // bit7z classes can throw BitException objects
    using namespace bit7z;
 
    Bit7zLibrary lib{ "7za.dll" };
    BitFileExtractor extractor{ lib, BitFormat::SevenZip };
 
    // Extracting a simple archive
    extractor.extract( "path/to/archive.7z", "out/dir/" );
 
    // Extracting a specific file
    extractor.extractMatching( "path/to/archive.7z", "file.pdf", "out/dir/" );
 
    // Extracting the first file of an archive to a buffer
    std::vector< byte_t > buffer;
    extractor.extract( "path/to/archive.7z", buffer );
 
    // Extracting an encrypted archive
    extractor.setPassword( "password" );
    extractor.extract( "path/to/another/archive.7z", "out/dir/" );
} catch ( const bit7z::BitException& ex ) { /* Do something with ex.what()...*/ }

Alternatively, if you only need to work on a single archive:

#include <bit7z/bitarchivereader.hpp>
 
try { // bit7z classes can throw BitException objects
    using namespace bit7z;
 
    Bit7zLibrary lib{ "7z.dll" };
 
    // Opening the archive
    BitArchiveReader archive{ lib, "path/to/archive.gz", BitFormat::GZip };
 
    // Testing the archive
    archive.test();
 
    // Extracting the archive
    archive.extractTo( "out/dir/" );
} catch ( const bit7z::BitException& ex ) { /* Do something with ex.what()...*/ }

💼 Compressing Files into an Archive

#include <bit7z/bitfilecompressor.hpp>
 
try { // bit7z classes can throw BitException objects
    using namespace bit7z;
 
    Bit7zLibrary lib{ "7z.dll" };
    BitFileCompressor compressor{ lib, BitFormat::Zip };
 
    std::vector< std::string > files = { "path/to/file1.jpg", "path/to/file2.pdf" };
 
    // Creating a simple zip archive
    compressor.compress( files, "output_archive.zip" );
 
    // Creating a zip archive with a custom directory structure
    std::map< std::string, std::string > files_map = {
        { "path/to/file1.jpg", "alias/path/file1.jpg" },
        { "path/to/file2.pdf", "alias/path/file2.pdf" }
    };
    compressor.compress( files_map, "output_archive2.zip" );
 
    // Compressing a directory
    compressor.compressDirectory( "dir/path/", "dir_archive.zip" );
 
    // Creating an encrypted zip archive of two files
    compressor.setPassword( "password" );
    compressor.compressFiles( files, "protected_archive.zip" );
 
    // Updating an existing zip archive
    compressor.setUpdateMode( UpdateMode::Append );
    compressor.compressFiles( files, "existing_archive.zip" );
 
    // Compressing a single file into a buffer
    std::vector< bit7z::byte_t > buffer;
    BitFileCompressor compressor2{ lib, BitFormat::BZip2 };
    compressor2.compressFile( files[0], buffer );
} catch ( const bit7z::BitException& ex ) { /* Do something with ex.what()...*/ }

Alternatively, if you only need to work on a single archive:

#include <bit7z/bitarchivewriter.hpp>
 
try { // bit7z classes can throw BitException objects
    using namespace bit7z;
 
    Bit7zLibrary lib{ "7z.dll" };
    BitArchiveWriter archive{ lib, BitFormat::SevenZip };
 
    // Adding the items to be compressed (no compression is performed here)
    archive.addFile( "path/to/file.txt" );
    archive.addDirectory( "path/to/dir/" );
 
    // Compressing the added items to the output archive
    archive.compressTo( "output.7z" );
} catch ( const bit7z::BitException& ex ) { /* Do something with ex.what()...*/ }

📑 Reading Archive Metadata

#include <bit7z/bitarchivereader.hpp>
 
try { // bit7z classes can throw BitException objects
    using namespace bit7z;
 
    Bit7zLibrary lib{ "7za.dll" };
    BitArchiveReader arc{ lib, "archive.7z", BitFormat::SevenZip };
 
    // Printing archive metadata
    std::cout << "Archive properties" << std::endl;
    std::cout << "  Items count: "   << arc.itemsCount() << std::endl;
    std::cout << "  Folders count: " << arc.foldersCount() << std::endl;
    std::cout << "  Files count: "   << arc.filesCount() << std::endl;
    std::cout << "  Size: "          << arc.size() << std::endl;
    std::cout << "  Packed size: "   << arc.packSize() << std::endl;
    std::cout << std::endl;
 
    // Printing the metadata of the archived items
    std::cout << "Archived items";
    auto arc_items = arc.items();
    for ( auto& item : arc_items ) {
        std::cout << std::endl;
        std::cout << "  Item index: "   << item.index() << std::endl;
        std::cout << "    Name: "        << item.name() << std::endl;
        std::cout << "    Extension: "   << item.extension() << std::endl;
        std::cout << "    Path: "        << item.path() << std::endl;
        std::cout << "    IsDir: "       << item.isDir() << std::endl;
        std::cout << "    Size: "        << item.size() << std::endl;
        std::cout << "    Packed size: " << item.packSize() << std::endl;
        std::cout << "    CRC: "         << item.crc() << std::endl;
    }
} catch ( const bit7z::BitException& ex ) { /* Do something with ex.what()...*/ }

A complete API reference is available in the wiki section.

🚀 Upgrading from bit7z v3 to v4

The newest bit7z v4 introduced some significant breaking changes to the library's API.

Expand for more details!

• By default, the project now follows the UTF-8 Everywhere Manifesto:
  • The default string type is std::string (instead of std::wstring), so users can use the library in cross-platform projects more easily (v4 introduced Linux/macOS support too).
  • Input std::strings will be considered as UTF-8 encoded.
  • You can still achieve the old behavior on Windows using the -DBIT7Z_USE_NATIVE_STRING CMake option.
• The old BitExtractor class is now called BitFileExtractor.
  • Now BitExtractor is just the name of a template class for all the extraction classes.
• The old BitCompressor class is now called BitFileCompressor.
  • Now BitCompressor is just the name of a template class for all the compression classes.
• The ProgressCallback now must return a bool value indicating whether the current operation can continue (true) or not (false).
• The project structure changed:
  • Public API headers moved from include/ to the include/bit7z/ folder, so #include directives now need to prepend bit7z/ to the included header name (e.g., #include <bit7z/bitfileextractor.hpp>).
    • Even though it is a bit verbose, it is a typical structure for C and C++ libraries, and it makes explicit which third-party library a header file belongs to.
  • By default, the output folder of bit7z is now lib/<architecture>/; if the CMake generator is multi-config (e.g., Visual Studio generators), the default output folder is lib/<architecture>/<build type>/.
    • Optionally, you can force using the "Visual Studio style" output path by enabling the BIT7Z_VS_LIBNAME_OUTDIR_STYLE CMake option.
  • Third-party dependencies are no longer handled using git submodules but are automatically downloaded using CPM.cmake when configuring/using the library via CMake.

💾 Download

Each released package contains:

• A pre-compiled version of bit7z (both in debug and release mode);
• The public API headers needed to use the library in your program;

Packages are available for both x86 and x64 architectures.

You can also clone/download this repository and build the library yourself (please, read the wiki).

🧰 Requirements

• Operating System: Windows, Linux, macOS, Android[^1].
• Architecture: x86, x86_64, arm, arm64.
• Language Standard: C++11 (for using the library), C++14 (for building the library).
• Compiler: MSVC 2015 or later[^2], MinGW v6.4 or later, GCC v4.9 or later, Clang 3.6 or later.
• Shared Library: a 7-zip .dll library on Windows, a 7-zip/p7zip .so library on Unix[^3].

[^1]: On Windows, you should link your program also with oleaut32 (e.g., -lbit7z -loleaut32).
On Linux and macOS, you should link your program also with dl (e.g., -lbit7z -ldl).
If you are using the library via CMake, these dependencies will be linked automatically to your project.

[^2]: MSVC 2010 was supported until v2.x, MSVC 2012/2013 until v3.x.

[^3]: bit7z doesn't ship with the 7-zip shared libraries. You can build them from the source code available at 7-zip.org.

⚙️ Building and Using bit7z

For building the library:

cd <bit7z folder>
mkdir build && cd build
cmake ../ -DCMAKE_BUILD_TYPE=Release
cmake --build . -j --config Release

A more detailed guide on how to build this library is available here.

You can also directly integrate the library into your project via CMake:

• Download bit7z and copy it into a sub-directory of your project (e.g., third_party), or add it as a git submodule of your repository.
• Then, use the command add_subdirectory() in your CMakeLists.txt to include bit7z.
• Finally, link the bit7z library using the target_link_libraries() command.

For example:

add_subdirectory( ${CMAKE_SOURCE_DIR}/third_party/bit7z )
target_link_libraries( ${YOUR_TARGET} PRIVATE bit7z )

The library is highly customizable: for a detailed list of the available build options, please refer to the wiki.

📑 7-zip Version

While configuring bit7z via CMake, it automatically downloads the latest version of 7-zip currently supported by the library.

Optionally, you can specify a different version of 7-zip via the CMake option BIT7Z_7ZIP_VERSION (e.g., -DBIT7Z_7ZIP_VERSION="22.01").

Alternatively, you can specify a custom path containing the 7-zip source code via the option BIT7Z_CUSTOM_7ZIP_PATH.

Please note that, in general, it is best to use the same version of 7-zip of the shared libraries that you will use at runtime.

Using 7-zip v23.01 on Linux and macOS

Expand for more details!

On Linux and macOS, 7-zip v23.01 introduced breaking changes to the IUnknown interface. If you build bit7z for such a version of 7-zip (the default), it will not support using the shared libraries from previous versions of 7-zip (or from p7zip). Conversely, bit7z made for earlier versions of 7-zip or for p7zip is incompatible with the shared libraries from 7-zip v23.01 and later.

You can build the shared libraries of 7-zip v23.01 in a backward-compatible mode by defining the macro Z7_USE_VIRTUAL_DESTRUCTOR_IN_IUNKNOWN. If this is your case, you can build bit7z for v23.01 using the option BIT7Z_USE_LEGACY_IUNKNOWN (in this case, bit7z will be compatible also with previous versions of 7-zip/p7zip).

🌐 String Encoding

By default, bit7z follows the UTF-8 Everywhere Manifesto to simplify the use of the library within cross-platform projects. In short, this means that:

• The default path string type is std::string.
• Input std::strings are considered as UTF-8 encoded; output std::strings are UTF-8 encoded.

Expand for more details and for other string encoding options!

On POSIX systems, std::strings are usually already UTF-8 encoded, and no configuration is needed.

The situation is a bit more complex on Windows since, by default, Windows treats std::strings as encoded using the system code page, which may not necessarily be UTF-8, like, for example, Windows-1252.

If your program deals exclusively with ASCII-only strings, you should be fine with the default bit7z settings (as ASCII characters are also UTF-8).

However, if you need to handle non-ASCII/Unicode characters, as it is likely, you have the following options:

• Enforcing using the UTF-8 code page for your whole application, as explained by Microsoft here:
  • Recommended, but supported only since Windows 10 1903 and later.
• Manually ensuring the encoding of the std::strings passed to bit7z:
  • You can use some string encoding library or C++11's UTF-8 string literals for input strings.
  • User-input strings (e.g., the password of an archive) can be handled as explained here; in short: read the input as an UTF-16 wide string (e.g., via ReadConsoleW), and convert it to UTF-8 (bit7z provides a utility function for this, bit7z::to_tstring).
  • You can correctly print the UTF-8 output strings from bit7z (e.g., the path/name metadata of a file in an archive) to the console by calling SetConsoleOutputCP(CP_UTF8) before.
• Configuring bit7z to use UTF-16 encoded wide strings (i.e., std::wstring) by enabling the BIT7Z_USE_NATIVE_STRING option via CMake.
  • If your program is Windows-only, or you already use wide strings on Windows, this might be the best choice since it will avoid any internal string conversions (7-zip always uses wide strings).
  • This option makes developing cross-platform applications slightly inconvenient since you'll still have to use std::string on POSIX systems.
  • The library provides a type alias bit7z::tstring and a macro function BIT7Z_STRING for defining wide string variables and literals on Windows and narrow ones on other platforms.

  • You must programmatically set the standard input and output encoding to UTF-16 to correctly read and print Unicode characters:

    #include <fcntl.h> //for _O_U16TEXT
    #include <io.h>  //for _setmode
     
    _setmode(_fileno(stdout), _O_U16TEXT); // setting the stdout encoding to UTF16
    _setmode(_fileno(stdin), _O_U16TEXT); // setting the stdin encoding to UTF16

• Configuring bit7z to use the system code page encoding for std::string by enabling the BIT7Z_USE_SYSTEM_CODEPAGE option via CMake.
  • Not recommended: using this option, your program will be limited in the set of characters it can pass to and read from bit7z.

☕️ Donate

If you have found this project helpful, please consider supporting me with a small donation so that I can keep improving it! Thank you! :pray:

  

📜 License

This project is licensed under the terms of the Mozilla Public License v2.0.
For more details, please check:

• The LICENSE file.
• Mozilla's MPL-2.0 FAQ

Older versions (v3.x and earlier) of bit7z were released under the GNU General Public License v2.

Copyright © 2014 - 2023 Riccardo Ostani (@rikyoz)