| commit | f6461b82b932013f170acf357c4dd3468c923f73 | [log] [tgz] |
|---|---|---|
| author | brian m. carlson <sandals@crustytoothpaste.net> | Sun Sep 15 22:43:32 2019 +0000 |
| committer | Junio C Hamano <gitster@pobox.com> | Mon Sep 16 12:20:39 2019 -0700 |
| tree | 109766e05d6c22eb8163f41c4cf56ceb695414dd | |
| parent | 5fa0f5238b0cd46cfe7f6fa76c3f526ea98148d9 [diff] |
Documentation: fix build with Asciidoctor 2 Our documentation toolchain has traditionally been built around DocBook 4.5. This version of DocBook is the last DTD-based version of DocBook. In 2009, DocBook 5 was introduced using namespaces and its syntax is expressed in RELAX NG, which is more expressive and allows a wider variety of syntax forms. Asciidoctor, one of the alternatives for building our documentation, moved support for DocBook 4.5 out of core in its recent 2.0 release and now only supports DocBook 5 in the main release. The DocBoook 4.5 converter is still available as a separate component, but this is not available in most distro packages. This would not be a problem but for the fact that we use xmlto, which is still stuck in the DocBook 4.5 era. xmlto performs DTD validation as part of the build process. This is not problematic for DocBook 4.5, which has a valid DTD, but it clearly cannot work for DocBook 5, since no DTD can adequately express its full syntax. In addition, even if xmlto did support RELAX NG validation, that wouldn't be sufficient because it uses the libxml2-based xmllint to do so, which has known problems with validating interleaves in RELAX NG. Fortunately, there's an easy way forward: ask Asciidoctor to use its DocBook 5 backend and tell xmlto to skip validation. Asciidoctor has supported DocBook 5 since v0.1.4 in 2013 and xmlto has supported skipping validation for probably longer than that. We also need to teach xmlto how to use the namespaced DocBook XSLT stylesheets instead of the non-namespaced ones it usually uses. Normally these stylesheets are interchangeable, but the non-namespaced ones have a bug that causes them not to strip whitespace automatically from certain elements when namespaces are in use. This results in additional whitespace at the beginning of list elements, which is jarring and unsightly. We can do this by passing a custom stylesheet with the -x option that simply imports the namespaced stylesheets via a URL. Any system with support for XML catalogs will automatically look this URL up and reference a local copy instead without us having to know where this local copy is located. We know that anyone using xmlto will already have catalogs set up properly since the DocBook 4.5 DTD used during validation is also looked up via catalogs. All major Linux distributions distribute the necessary stylesheets and have built-in catalog support, and Homebrew does as well, albeit with a requirement to set an environment variable to enable catalog support. On the off chance that someone lacks support for catalogs, it is possible for xmlto (via xmllint) to download the stylesheets from the URLs in question, although this will likely perform poorly enough to attract attention. People still have the option of using the prebuilt documentation that we ship, so happily this should not be an impediment. Finally, we need to filter out some messages from other stylesheets that occur when invoking dblatex in the CI job. This tool strips namespaces much like the unnamespaced DocBook stylesheets and prints similar messages. If we permit these messages to be printed to standard error, our documentation CI job will fail because we check standard error for unexpected output. Due to dblatex's reliance on Python 2, we may need to revisit its use in the future, in which case this problem may go away, but this can be delayed until a future patch. The final message we filter is due to libxslt on modern Debian and Ubuntu. The patch which they use to implement reproducible ID generation also prints messages about the ID generation. While this doesn't affect our current CI images since they use Ubuntu 16.04 which lacks this patch, if we upgrade to Ubuntu 18.04 or a modern Debian, these messages will appear and, like the above messages, cause a CI failure. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see Documentation/giteveryday.txt for a useful minimum set of commands, and Documentation/git-<commandname>.txt for documentation of each command. If git has been correctly installed, then the tutorial can also be read with man gittutorial or git help tutorial, and the documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt (man gitcvs-migration or git help cvs-migration if git is installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just “subscribe git” in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://public-inbox.org/git/, http://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the “What's cooking” reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name “git” was given by Linus Torvalds when he wrote the very first version. He described the tool as “the stupid content tracker” and the name as (depending on your mood):