Libzim

The Libzim is the reference implementation for the ZIM file format. It's a software library to read and write ZIM files on many systems and architectures. More information about the ZIM format and the openZIM project at https://openzim.org/.

Disclaimer

This document assumes you have a little knowledge about software compilation. If you experience difficulties with the dependencies or with the Libzim compilation itself, we recommend to have a look to kiwix-build.

Preamble

Although the Libzim can be compiled/cross-compiled on/for many systems, the following documentation explains how to do it on POSIX ones. It is primarily though for GNU/Linux systems and has been tested on recent releases of Ubuntu and Fedora.

Dependencies

The Libzim relies on many third party software libraries. They are prerequisites to the Kiwix library compilation. Following libraries need to be available:

• LZMA (package liblzma-dev on Ubuntu)
• ICU (package libicu-dev on Ubuntu)
• Zstd (package libzstd-dev on Ubuntu)
• Xapian - optional (package libxapian-dev on Ubuntu)

To test the code:

• Google Test (package googletest on Ubuntu)
• ZIM Testing Suite - Reference test data set

To build the documentations you need the packages:

• Doxygen
• Python packages for Sphinx, Sphinx rtd theme, Breathe and Exhale (packages Sphinx, sphinx_rtd_theme, Breathe and Exhale while using pip)

These dependencies may or may not be packaged by your operating system. They may also be packaged but only in an older version. The compilation script will tell you if one of them is missing or too old. In the worse case, you will have to download and compile a more recent version by hand.

If you want to install these dependencies locally, then ensure that Meson (through pkg-config) will properly find them.

Environment

The Libzim builds using Meson version 0.43 or higher. Meson relies itself on Ninja, Pkg-config and few other compilation tools. Install them first:

• Meson
• Ninja
• Pkg-config

These tools should be packaged if you use a cutting edge operating system. If not, have a look to the Troubleshooting section.

Compilation

Once all dependencies are installed, you can compile Libzim with:

meson . build
ninja -C build

By default, it will compile dynamic linked libraries. All binary files will be created in the build directory created automatically by Meson. If you want statically linked libraries, you can add --default-library=static option to the Meson command.

If you want to build the documentation, we need to pass the -Ddoc=true option and run the doc target:

meson . build -Ddoc=true
ninja -C build doc

Depending on your system, ninja command may be called ninja-build.

By default, Libzim tries to compile with Xapian (and will generate an error if Xapian is not found). You can build without Xapian by passing the option -Dwith_xapian=false :

meson . build -Dwith_xapian=false
ninja -C build doc

If Libzim is compiled without Xapian, all search API are removed. You can test if an installed version of Libzim is compiled with or without xapian by testing the define LIBZIM_WITH_XAPIAN.

Testing

ZIM files needed by unit-tests are not included in this repository. By default, Meson will use an internal directory in your build directory, but you can specify another directory with option test_data_dir:

meson . build -Dtest_data_dir=<A_DIR_WITH_TEST_DATA>

Whatever you specify a directory or not, you need a extra step to download the data. At choice:

• Get the data from the repository openzim/zim-testing-suite and put it yourself in the directory.
• Use the script download_test_data.py which will download and extract the data for you.
• As ninja to do it for you with ninja download_test_data once the project is configured.

The simple workflow is:

meson . build # Configure the project (using default directory for test data)
cd build
ninja # Build
ninja download_test_data # Download the test data
meson test # Test

It is possible to deactivate all tests using test data zim files by passing none to the test_data_dir option:

meson . build -Dtest_data_dir=none
cd build
ninja
meson test # Run tests but tests needing test zim files.

If the automated tests fail or timeout, you need to be aware that some tests need up to 16GB of memory. You can skip those specific tests with:

SKIP_BIG_MEMORY_TEST=1 meson test

Some tests are checking error detection in multithread environment and they need to sleep to let threads working (and detect error). How many time to wait depends of your computer. If you have error_in_creator test failing, you probably need to extend the waiting time. This can be done by setting the env variable WAIT_TIME_FACTOR_TEST to a float factor. The waiting time will multiplied by this factor.

WAIT_TIME_FACTOR_TEST=2 meson test

Installation

If you want to install the Libzim and the headers you just have compiled on your system, here we go:

ninja -C build install

You might need to run the command as root (or using sudo), depending where you want to install the libraries. After the installation succeeded, you may need to run ldconfig (as root).

Uninstallation

If you want to uninstall the Libzim:

ninja -C build uninstall

Like for the installation, you might need to run the command as root (or using sudo).

Troubleshooting

If you need to install Meson "manually":

virtualenv -p python3 ./ # Create virtualenv
source bin/activate      # Activate the virtualenv
pip3 install meson       # Install Meson
hash -r                  # Refresh bash paths

If you need to install Ninja "manually":

git clone git://github.com/ninja-build/ninja.git
cd ninja
git checkout release
./configure.py --bootstrap
mkdir ../bin
cp ninja ../bin
cd ..

If the compilation still fails, you might need to get a more recent version of a dependency than the one packaged by your Linux distribution. Try then with a source tarball distributed by the problematic upstream project or even directly from the source code repository.

License

GPLv2 or later, see COPYING for more details.