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.. _mozilla_projects_nss_building:
Building NSS
`Introduction <#introduction>`__
.. container::
This page has detailed information on how to build NSS. Because NSS is a
cross-platform library that builds on many different platforms and has many
options, it may be complex to build._ Two build systems are maintained
concurrently: a ``Make`` based and a ``gyp`` based system.
.. _build_environment:
`Prerequisites <#build_environment>`__
.. container::
NSS needs a C and C++ compiler. It has minimal dependencies, including only
standard C and C++ libraries, plus `zlib <>`__.
For building, you also need `make <>`__.
Ideally, also install `gyp-next <>`__ and `ninja
<>`__ and put them on your path. This is
recommended, as the build is faster and more reliable.
Please, note that we ``gyp`` is currently unmaintained and that our support for
``gyp-next`` is experimental and might be unstable.
To install prerequisites on different platforms, one can run the following
**On Linux:**
.. code::
sudo apt install mercurial git ninja-build python3-pip
python3 -m pip install gyp-next
**On MacOS:**
.. code::
brew install mercurial git ninja python3-pip
python3 -m pip install gyp-next
It is also necessary to make sure that a `python` (not just `python3`)
executable is in the path.
The Homebrew Python installation has the necessary symlink but may require
explicit adding to the PATH variable, for example like this:
.. code::
export PATH="/opt/homebrew/opt/python/libexec/bin:$PATH"
**On Windows:**
.. code::
.. note::
To retrieve the source code from the project repositories, users will need to
download a release or pull the source code with their favourite Version
Control System (git or Mercurial). Installing a VCS is not necessary to build
an NSS release when downloaded as a compressed archive.
By default Mozilla uses a Mercurial repository for NSS. If you whish to
contribute to NSS and use ``git`` instead of Mercurial, we encourage you to
install `git-cinnabar <>`__.
`Windows <#windows>`__
.. container::
NSS compilation on Windows uses the same shared build system as Mozilla
Firefox. You must first install the `Windows Prerequisites
including **MozillaBuild**.
You can also build NSS on the Windows Subsystem for Linux, but the resulting binaries aren't
usable by other Windows applications.
.. _get_the_source:
`Source code <#get_the_source>`__
.. container::
NSS and NSPR use Mercurial for source control like other Mozilla projects. To
check out the latest sources for NSS and NSPR--which may not be part of a
stable release--use the following commands:
.. code::
**To get the source of a specific release, see:**
ref:`mozilla_projects_nss_releases` **.**
To download the source using ``git-cinnabar`` instead:
.. code::
`Build with gyp and ninja <#build>`__
.. container::
Build NSS and NSPR using our build script from the ``nss`` directory:
.. code::
cd nss
This builds both NSPR and NSS in a parent directory called ``dist``.
Build options are available for this script: ``-o`` will build in **Release**
mode instead of the **Debug** mode and ``-c`` will **clean** the ``dist``
directory before the build.
Other build options can be displayed by running ``./ --help``
.. _build_with_make:
`Build with make <#build_with_make>`__
.. container::
Alternatively, there is a ``make`` target, which produces a similar
result. This supports some alternative options, but can be a lot slower.
.. code::
USE_64=1 make -j
The make-based build system for NSS uses a variety of variables to control
the build. Below are some of the variables, along with possible values they
may be set to.
.. csv-table::
:header: "BUILD_OPT", ""
:widths: 10,50
"0", "Build a debug (non-optimized) version of NSS. **This is the default.**"
"1", "Build an optimized (non-debug) version of NSS."
.. csv-table::
:header: "USE_64", ""
:widths: 10,50
"0", "Build for a 32-bit environment/ABI. **This is the default.**"
"1", "Build for a 64-bit environment/ABI. *This is recommended.*"
.. csv-table::
:header: "USE_ASAN", ""
:widths: 10,50
"0", "Do not create an `AddressSanitizer
<>`__ build. **This is the default.**"
"1", "Create an AddressSanitizer build."
.. _unit_testing:
`Unit testing <#unit_testing>`__
.. container::
NSS contains extensive unit tests. Scripts to run these are found in the ``tests`` directory.
Run the standard suite by:
.. code::
HOST=localhost DOMSUF=localdomain USE_64=1 ./tests/
.. _unit_test_configuration:
`Unit test configuration <#unit_test_configuration>`__
.. container::
NSS tests are configured using environment variables.
The scripts will attempt to infer values for ``HOST`` and ``DOMSUF``, but
can fail. Replace ``localhost`` and ``localdomain`` with the hostname and
domain suffix for your host. You need to be able to connect to
If you don't have a domain suffix you can add an entry to ``/etc/hosts`` (on
Windows,\ ``c:\Windows\System32\drivers\etc\hosts``) as follows:
.. code:: localhost.localdomain
Validate this opening a command shell and typing: ``ping localhost.localdomain``.
Remove the ``USE_64=1`` override if using a 32-bit build.
.. _test_results:
`Test results <#test_results>`__
.. container::
Running all tests can take a considerable amount of time.
Test output is stored in ``tests_results/security/$HOST.$NUMBER/``. The file
``results.html`` summarizes the results, ``output.log`` captures all the test
Other subdirectories of ``nss/tests`` contain scripts that run a subset of
the full suite. Those can be run directly instead of ````, which might
save some time at the cost of coverage.