Sunday, February 24, 2013

RTEMS Texinfo Tools Update

A couple of years ago, Chris Johns and I began to discuss that RTEMS has had a long and successful history as a free software project. One aspect of this discussion resulted in the Open Source and Generational Differences. This post reflected on how new developers can have a tendency to avoid projects that use "uncool" tools. They want to be on the leading edge of technology. However, another aspect of using uncool tools is that they are old. RTEMS-based applications often have lifespans measured in decades from development, through fielding, to long term sustainment. This insight lead us to begin to review the tools we depended upon for long-term viability and that they continued to offer a high quality solution. The transition from CVS to git has been the most visible outcome of this effort.

But lurking within the RTEMS source tree was a dependency on a long dead tool - texi2www. RTEMS was the last user of this and had to include the source code in our own tree. This was exactly the type of situation Chris and I had realized could happen and it already had without us noticing. In November 2011, I posted to the GNU Texinfo Help Mailing list asking for advice on converting to the more modern texi2html program. Unfortunately, I learned that texi2html was considered deprecated and being re-implemented in Perl and the new implementation would be known as texi2any. This led to me converting us away from the stone cold dead texi2www to texi2html. With the recent release of texinfo 5.0, I began to ensure that our documentation would build with either texi2html 1,82 or texi2any from texinfo 5.0 and that the build infrastructure could detect which to use.

The goal of this post is to point out how we invoke tools, initialization file differences and the minor changes to our documentation required to support both tools. The other tools in the texinfo package such as makeinfo did require us to make changes to the source but did not change their invocation. I will detail the changes to our texinfo source files after showing the command line differences for the html converters.

The commands executed by our build infrastructure are generated by an autoconf based build infrastructure. This sometimes leads to longer than absolutely necessary command lines. I have made no attempt to shorten or clean these command lines up. These are for the RTEMS C User's Guide whose main texinfo file is c_user.texi.

The following is the invocation of texi2html 1.82:
 texi2html -D use-html --split node --node-files -o ./ --top-file index.html --init-file=../texi2html_init \  
   -I /home/joel/rtems-4.11-work/rtems//doc/user -I /home/joel/rtems-4.11-work/rtems//doc \  
   -I .. -I . --menu /home/joel/rtems-4.11-work/rtems//doc/user/c_user.texi \  

This is the corresponding invocation of texi2any from texinfo 5.0:
 texi2any --html -D use-html --split node -o ./ --init-file=../texi2any_init \  
   -I /home/joel/rtems-4.11-work/rtems//doc/user -I /home/joel/rtems-4.11-work/rtems//doc \  
   -I .. -I . /home/joel/rtems-4.11-work/rtems//doc/user/c_user.texi  

Notice that both command lines are quite similar. However, texi2html requires the --node-files argument to produce individual html file names which are based on the section or chapter name. By default, they will be named using a pattern line DOC_nnn.html.

The other thing to note is that they both accept initialization files. However, the format of the initialization files is very different between the two implementations. Texinfo supports hierarchically structured documents and allows the author to provide links to the next section, previous section, and the section that contains or is logically above the current one. The RTEMS Project has a tool which automatically constructs the node markups based on chapter, section, and subsection headings. Thus, the RTEMS documentation is fully hierarchically linked with no manual node definition required. The RTEMS documentation build system uses the initialization file to define a custom header, footer and to modify the navigation buttons.

This is the file texi2html_init generated by our build infrastructure:
 my $button_text = '<a href="../index.html">Library</a>';  
 push @SECTION_BUTTONS, \$button_text;  
 push @CHAPTER_BUTTONS, \$button_text;  
 push @MISC_BUTTONS, \$button_text;  
 push @TOP_BUTTONS, \$button_text;  
 '<A HREF="" target="Text Frame">  
 <IMG align=right BORDER=0 SRC="../images/rtems_logo.jpg" ALT="RTEMS  
 Logo"> </A>  
 <H1>RTEMS On-Line Library</H1>  
 'Copyright &copy; 1988-2011  
 <A HREF="" target="Text Frame">OAR Corporation</A>  

The initialization files reflects the internal implementation of the two programs and the format used by texi2any is different. We have an initialization file which accomplishes similar things in the generated HTML files but looks different. For example, the texi2html output has navigation icons while the texi2any output has textual links.

This is the file texi2any_init generated by our build infrastructure:
 set_from_init_file ('AFTER_BODY_OPEN',  
 '<A HREF="" target="Text Frame">  
 <IMG align=right BORDER=0 SRC="../images/rtems_logo.jpg" ALT="RTEMS  
 Logo">  </A>  
 <H1>RTEMS On-Line Library</H1>  
 texinfo_register_handler('setup', \&add_button);  
 my $button_text = '<a href="../dir.html">Directory</a>';  
 sub add_button($)  
  my $self = shift;  
  foreach my $button_type ('SECTION_BUTTONS', 'CHAPTER_BUTTONS',   
               'MISC_BUTTONS', 'TOP_BUTTONS') {  
   my $buttons = $self->get_conf($button_type);  
   push @$buttons, \$button_text;  
  return 1;  

There were only a couple of issues encountered with our use of texinfo which required modifying the source.
  • Missing @item in @itemize lists now results in warnings. 
  • The order of menu definition, @top and its @node, and file @include statements in the top level texinfo files had to be reordered. Texinfo 5.0 is not as forgiving on this.
In addition, I spotted mistakes in our documentation when reviewing the various output forms. The entire range of patches can be viewed online here.
NOTE: As of 24 February 2013, these have not been committed. When they are committed, links will be provided to the git repository.

We would like to take advantage of features in the newer tools and are investigating using a print on demand service for RTEMS manuals. I hope there is experience in the texinfo community about this but, if not, I suppose I will pester the maintainers until the results are satisfactory and report on what I had to do.

Thanks to the Texinfo maintainers Patrice Dumas, Karl Berry, and Eli Zaretskii folyzr being incredibly patient and helpful through this process.

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