detect.rb

#
# Instructions:
#
# * Download Microsoft Journal Sample code February 1997:
# 
#   http://globalfilesearch.com/download.aspx?path=ringtail.its.monash.edu.au/pub/msj/newfiles/MSJFEB97.EXE
#
# * Extract depends.exe from 'Under the Hood' folder and place along this script.
#
# * call it with 'ruby detect.rb'
#
# NOTE: Some gems contains fat-binaries, look for 1.8/ext.so, that means it has both (1.8 and 1.9)
#
require 'rubygems'

pattern = /ruby18/

# Iterate over all gems looking for path occurrences
Gem.source_index.each do |full_name, spec|
  if spec.extensions.any?
    reqs = spec.require_paths.join(',')
    lookout = File.join(spec.installation_path, 'gems', full_name, "{#{reqs}}", "**", "*.so")
    Dir.glob(lookout).each do |ext|
      output = `depends #{ext.gsub(File::SEPARATOR, File::ALT_SEPARATOR)}`
      if output =~ pattern
        warn "Gem #{full_name} extension '#{File.basename(File.dirname(ext))}/#{File.basename(ext)}' depends on supplied pattern."
      end
    end
  end

  spec.files.select { |f| f =~ /\.so$/ }.each do |ext|
    ext = File.join(spec.installation_path, 'gems', full_name, ext)
    output = `depends #{ext.gsub(File::SEPARATOR, File::ALT_SEPARATOR)}`
    if output =~ pattern
      warn "Gem #{full_name} extension '#{File.basename(File.dirname(ext))}/#{File.basename(ext)}' depends on supplied pattern."
    end
  end
end