qpdf/manual/packaging.rst

.. _packaging:

Notes for Packagers
===================

If you are packaging qpdf for an operating system distribution, this
chapter is for you. Otherwise, feel free to skip.

Build Options
-------------

- Perl must be present at build time. Prior to qpdf version 9.1.1,
  there was a runtime dependency on perl, but this is no longer the
  case.

- Make sure you are getting the intended behavior with regard to crypto
  providers. Read :ref:`crypto.build` for details.

- Passing :samp:`--enable-show-failed-test-output` to
  :command:`./configure` will cause any failed test
  output to be written to the console. This can be very useful for
  seeing test failures generated by autobuilders where you can't access
  qtest.log after the fact.

- If qpdf's build environment detects the presence of autoconf and
  related tools, it will check to ensure that automatically generated
  files are up-to-date with recorded checksums and fail if it detects a
  discrepancy. This feature is intended to prevent you from
  accidentally forgetting to regenerate automatic files after modifying
  their sources. If your packaging environment automatically refreshes
  automatic files, it can cause this check to fail. Suppress qpdf's
  checks by passing :samp:`--disable-check-autofiles`
  to :command:`/.configure`. This is safe since qpdf's
  :command:`autogen.sh` just runs autotools in the
  normal way.

- QPDF's :command:`make install` does not install completion files by
  default, but as a packager, it's good if you install them wherever
  your distribution expects such files to go. You can find completion
  files to install in the :file:`completions` directory.

- Packagers are encouraged to install the source files from the
  :file:`examples` directory along with qpdf development packages.

.. _packaging-doc:

Packaging Documentation
-----------------------

Starting in qpdf version 10.5, pre-built documentation is no longer
distributed with the qpdf source distribution. Here are a few options
you may want to consider for your packages:

- **Do nothing**

  When you run ``make install``, the file :file:`README-doc.txt` is
  installed in ``$(docdir)``. That file tells the reader where to find
  the documentation online and where to go to download offline copies
  of the documentation. This is the option selected by the debian
  packages.

- **Embed pre-built documentation**

  You can obtain pre-built documentation and extract its contents into
  your distribution. This is what the Windows binary distributions
  available from the qpdf release site do. You can find the pre-build
  documentation in the release area in the file
  :file:`qpdf-{version}-doc.zip`.

- **Build the documentation yourself**

  You can build the documentation as part of your build process. Be
  sure to pass ``--enable-doc-maintenance`` to ``./configure``, and
  install it with ``make doc-dist DOC_DEST=...``. This is what the
  AppImage build does. The latest version of Sphinx at the time of the
  initial conversion a sphinx-based documentation was 4.3.2. Older
  versions are not guaranteed to work.

Documentation Packaging Rationale
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This section describes the reason for things being the way they are.
It's for information only; you don't have to know any of this to
package qpdf.

What is the reason for this change? Prior to qpdf 10.5, the qpdf
manual was a docbook XML file. The generated documents were the
product of running the file through build-time style sheets and
contained no copyrighted material of their own. Starting with version
10.5, the manual is written produced with `Sphinx
<https://www.sphinx-doc.org>`__. This change was made to make it much
easier to automatically generate portions of the documentation and to
make the documentation easier to work with. The HTML output of Sphinx
is also much more readable, usable, and suitable for online
consumption than the output of the docbook style sheets. The downsides
are that the generated HTML documentation now contains Javascript code
and embedded fonts, and the PDF version of the documentation is no
longer as suitable for printing (at least as of the 10.5 distribution)
since external link targets are no longer shown and cross references
no longer contain page number information. The presence of copyrighted
material in the generated documentation, even though things are
licensed with MIT and BSD licenses, complicates the job of the
packager in various ways. For one thing, it means the
:file:`NOTICE.md` file in the source repository would have to keep up
with the copyright information for files that are not controlled in
the repository. Additionally, some distributions (notably
Debian/Ubuntu) discourage inclusion of sphinx-generated documentation
in packages, preferring you instead to build the documentation as part
of the package build process and to depend at runtime on a shared
package that contains the code. At the time of the conversion of the
qpdf manual from docbook to sphinx, newer versions of both sphinx and
the html theme were required than were available in some of most of
the Debian/Ubuntu versions for which qpdf was packaged.

Since always-on Internet connectivity is much more common than it used
to be, many users of qpdf would prefer to consume the documentation
online anyway, and the lack of pre-built documentation in the
distribution won't be as big of a deal. However there are still some
people who can't or choose not to view documentation online. For them,
pre-built documentation is still available.