YANG data modeling language library
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The project uses 2 main branches
devel. Other branches should not be cloned. In
masterthere are files of the last official release. Any latest improvements and changes, which were tested at least briefly are found in
devel. On every new release,
develis merged into
This means that when only stable official releases are to be used, either
mastercan be used or specific releases downloaded. If all the latest bugfixes should be applied,
develbranch is the one to be used. Note that whenever a new issue is created and it occurs on the
masterbranch, the first response will likely be to use
develbefore any further provided support.
Look into the documentation and the section
Transition Manual. That should help with basic migration and the ability to compile a project. But to actually make use of the new features, it is required to read through the whole documentation and the API.
Binary RPM or DEB packages of the latest release can be built locally using
apkg, look into
$ mkdir build; cd build $ cmake .. $ make # make install
$ CC=/usr/bin/clang cmake ..
To change the prefix where the library, headers and any other files are installed, set
$ cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr ..
Default prefix is
There are two build modes: * Release. This generates library for the production use without any debug information. * Debug. This generates library with the debug information and disables optimization of the code.
Debugmode is currently used as the default one. to switch to the
Releasemode, enter at the command line:
$ cmake -D CMAKE_BUILD_TYPE:String="Release" ..
As for YANG extensions, libyang allows loading extension plugins. By default, the directory to store the plugins is LIBDIR/libyang. To change it, use the following cmake option with the value specifying the desired directory:
$ cmake -DPLUGINS_DIR:PATH=`pwd`"/src/extensions/" ..
The directory path can be also changed runtime via environment variable, e.g.:
$ LIBYANG_EXTENSIONS_PLUGINS_DIR=`pwd`/my/relative/path yanglint
Whenever the latest revision of a schema is supposed to be loaded (import without specific revision), it is performed in the standard way, the first time. By default, every other time when the latest revision of the same schema is needed, the one initially loaded is reused. If you know this can cause problems meaning the latest available revision of a schema can change during operation, you can force libyang to always search for the schema anew by:
$ cmake -DENABLE_LATEST_REVISIONS=OFF ..
Note that, with CMake, if you want to change the compiler or its options after you already ran CMake, you need to clear its cache first - the most simple way to do it is to remove all content from the 'build' directory.
All libyang functions are available via the main header: ```
To compile your program with libyang, it is necessary to link it with libyang using the following linker parameters:
Note, that it may be necessary to call
ldconfig(8)after library installation and if the library was installed into a non-standard path, the path to libyang must be specified to the linker. To help with setting all the compiler's options, there is
pkg-config(1)available in the source tree. The file is installed with the library.
If you are using
cmakein you project, it is also possible to use the provided
FindLibYANG.cmakefile to detect presence of the libyang library in the system.
There are no bindings for other languages directly in this project but they are available separately.
libyang project includes a feature-rich tool called
yanglint(1)for validation and conversion of the schemas and YANG modeled data. The source codes are located at
/tools/lintand can be used to explore how an application is supposed to use the libyang library.
yanglint(1)binary as well as its man page are installed together with the library itself.
There is also README describing some examples of using
libyang includes several tests built with cmocka. The tests can be found in
testssubdirectory and they are designed for checking library functionality after code changes. Additional regression tests done with a corpus of fuzzing inputs that previously caused crashes are done. Those are available in
tests/fuzzand are built automatically with the cmocka unit tests.
The tests are by default built in the
Debugbuild mode by running
In case of the
Releasemode, the tests are not built by default (it requires additional dependency), but they can be enabled via cmake option:
$ cmake -DENABLE_TESTS=ON ..
Note that if the necessary cmocka headers are not present in the system include paths, tests are not available despite the build mode or cmake's options.
Tests can be run by the make's
$ make test
There is a performance measurement tool included that prints information about the time required to execute common use-cases of working with YANG instance data.
To enable this test, use an option and to get representative results, enable Release build type:
$ cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_PERF_TESTS=ON ..and to run the test with seeing its output run:
$ make $ ctest -V -R ly_perf
Based on the tests run, it is possible to generate code coverage report. But it must be enabled and these commands are needed to generate the report:
$ cmake -DENABLE_COVERAGE=ON .. $ make $ make coverage
Multiple YANG fuzzing targets and fuzzing instructions are available in the
All of the targets can be fuzzed with LLVM's LibFuzzer and AFL, and new targets can easily be added. Asciinema examples which describe the fuzzing setup for both AFL (https://asciinema.org/a/311060) and LibFuzzer (https://asciinema.org/a/311035) are available.