Archive:PackagingDrafts/RubyGem with C code

Proposal for package Ruby Gem including extension library written in C

Current status

Current packaging guidelines on Fedora about Ruby Gems are mainly written on https://fedoraproject.org/wiki/Packaging/Ruby#Ruby_Gems

The guideline says:

The install should be performed with the command
$ gem install --local --install-dir %{buildroot}%{gemdir} --force %{SOURCE0}

Problem

This causes some problems especially when Ruby Gem contains extension libraries written in C because of the following reason.

A-1

First of all the above procedure will cause the error like following.

+ /usr/lib/rpm/check-buildroot
Binary file /home/tasaka1/rpmbuild/INSTROOT/rubygem-zoom-0.4.1-4.fc9p-root-tasaka1/usr/lib/debug/usr/lib/ruby/site_ruby/1.8/i386-linux/zoom.so.debug matches
Found '/home/tasaka1/rpmbuild/INSTROOT/rubygem-zoom-0.4.1-4.fc9p-root-tasaka1' in installed files; aborting
error: Bad exit status from /home/tasaka1/rpmbuild/INSTROOT/rpm-tmp.84251 (%install)

This is because with above command:

• gem first unpacks files in the gem file under %{buildroot}%{gemdir}
• Then gem (actually gcc) compiles C source files installed under there.

So the rebuilt C library may contain %{buildroot} string.

A-2

So to avoid this error some maintainers on Fedora of rubygems including extension written in C simply strip compiled C libraries before %install stage ends.

• Of course this won't create debuginfo file correctly.
• Also, when Gem is directly installed under %{buildroot} and %prep is blank, find_debuginfo.sh won't be called anyway because %{buildsubdir} is not defined (this is because debugXXX.list can't be written when %{_builddir}/%{buildsubdir} is missing).

Solution to A

The problem written in A can be resolved when Ruby Gems are installed under %{_builddir} first.

B

Currently there is no mention about how to pass Fedora specific compilation flags correctly.

Solution to B

Usually ruby extension uses ruby script file named extconf.rb which has require 'mkmf'. mkmf.rb module accepts CONFIGURE_ARGS environment to specify CFLAGS so using this is preferred.

Proposition

When Ruby Gem contains extension libraries written in C,

• First %{_builddir}/%{buildsubdir} must be created at %prep stage.
• The following line should be used to pass CFLAGS to Makefile to be created correctly.

export CONFIGURE_ARGS="--with-cflags='%{optflags}'"

• Then the Ruby Gem must be installed under %{_builddir}/%{buildsubdir} at %build stage to get C libraries compiled under the directory.
• When using gem command to install Gem file, using -V option is recommend to check if CFLAGS is correctly honored.
• Finally at %install stage the whole tree under %{_builddir}/%{buildsubdir}%{gemdir} should be copied (not moved) to under %{buildroot}%{gemdir}.
  • When all tree under %{_builddir}/%{buildsubdir} is moved to under %{buildroot}, find_debuginfo.sh will complain that the corresponding source files are missing.
• Installed C codes (usually under %{geminstdir}/etc) may be removed even if gem contents %{gemname} reports that installed C codes should be found there.

Note

The current guideline

If the Gem contains binary content (e.g., for a database driver), it must be marked 
as architecture specific, and all architecture specific content must be moved 
from the %{gemdir} to the [#ruby_sitearch %{ruby_sitearch} directory] during %install

must still apply.

Example

%prep
%setup -q -T -c

%build
mkdir -p ./%{gemdir}
export CONFIGURE_ARGS="--with-cflags='%{optflags}'"
gem install --local --install-dir ./%{gemdir} -V --force %{SOURCE0}

%install
rm -rf %{buildroot}
mkdir -p %{buildroot}%{gemdir}
cp -a ./%{gemdir}/* %{buildroot}%{gemdir}

mkdir -p %{buildroot}%{ruby_sitearch}
mv %{buildroot}%{geminstdir}/lib/*.so %{buildroot}%{ruby_sitearch}
rm -rf %{buildroot}%{geminstdir}/ext

%clean
rm -rf %{buildroot}

%files
%defattr(-,root,root,-)
%{ruby_sitearch}/*.so
%{geminstdir}/
%{gemdir}/cache/%{gemname}-%{version}.gem
%{gemdir}/specifications/%{gemname}-%{version}.gemspec

Issues

SOLVED: Installed C codes

Currently all C codes (in Gem file) are also installed with gem install (usually under %{geminstdir}/ext). In my recognition these files are used only for creating C libraries and are not needed anymore. So actually some packagers simply remove these files.

• Note that when also non-Gem type of source archive is provided, when using non-Gem version such C codes are usually not installed.

However Gem has its own metadata and Gem actually reports that these files should have been installed.

• Example
  • Currently in rubygem-pam rpm no files are under %{geminstdir}/ext (on i386 this is currently /usr/lib/ruby/gems/1.8/gems/pam-1.5.3/ext).
  • However gem contents pam actually returns some files under this directory.

How should we treat these files?

• simply don't remove these files
• ignore gem report in this case and remove these anyway
• seperate these files into subpackages (e.g. -source subpackage)
• or anything else

To pass CFLAGS correctly

I noticed that even for non-Gem Ruby packages, many packages containing C shared libraries

• have extconf.rb in the source archives
• or have Rakefile which create extconf.rb

which usually contain require mkmf. In such case

export CONFIGURE_ARGS="--with-cflags='%{optflags}'"

can be used.

• A package which uses extconf.rb directly can take --with-cflags= argument directly, like ruby extconf.rb --with-cflags="%{optflags}", however in the case that Rakefile creates extconf.rb, usually rake build does not accept --with-cflags= argument.

So, maybe the part of how to pass CFLAGS correctly in the proposal written above can be replaced by more general guideline like following.

Alternative proposal (for both Gem and non-Gem)

• For packages which creates C shared libraries using extconf.rb

export CONFIGURE_ARGS="--with-cflags='%{optflags}'"

should be used to pass CFLAGS to Makefile correctly. This also applies to Ruby Gems.