backport fix for #4561 remove use of base64 library to prevent warnin…

…g in Ruby >= 3.3

CHANGELOG.adoc

@@ -18,7 +18,9 @@ This project utilizes semantic versioning.
 // tag::compact[]
 == Unreleased
 
-_No changes since previous release._
+Compliance::
+
+  * Remove use of base64 library to prevent warning in Ruby >= 3.3 (#4561)
 
 == 2.0.21 (2024-02-20) - @mojavelinux
 

Gemfile

@@ -22,6 +22,7 @@ group :development do
   elsif (Gem::Version.new RUBY_VERSION) < (Gem::Version.new '2.6.0')
     gem 'nokogiri', '~> 1.12.0'
   end
+  gem 'minitest', '~> 5.14.0' if (Gem::Version.new RUBY_VERSION) < (Gem::Version.new '2.6.0')
 end
 
 group :docs do

asciidoctor.gemspec

@@ -39,7 +39,7 @@ Gem::Specification.new do |s|
   # erubi is needed for testing alternate eRuby impls
   s.add_development_dependency 'erubi', '~> 1.10.0'
   s.add_development_dependency 'haml', '~> 6.1.0'
-  s.add_development_dependency 'minitest', '~> 5.14.0'
+  s.add_development_dependency 'minitest', '~> 5.22.0'
   s.add_development_dependency 'nokogiri', '~> 1.13.0'
   s.add_development_dependency 'rake', '~> 12.3.0'
   s.add_development_dependency 'slim', '~> 4.1.0'

lib/asciidoctor.rb

@@ -6,7 +6,6 @@
   # this require is satisfied by the Asciidoctor.js build; it augments the Ruby environment for Asciidoctor.js
   require 'asciidoctor/js'
 else
-  autoload :Base64, 'base64'
   require 'cgi/util'
   autoload :OpenURI, 'open-uri'
   autoload :Pathname, 'pathname'

lib/asciidoctor/abstract_node.rb

@@ -354,8 +354,8 @@ def media_uri(target, asset_dir_key = 'imagesdir')
   #
   # First, and foremost, the target image path is cleaned if the document safe mode level
   # is set to at least SafeMode::SAFE (a condition which is true by default) to prevent access
-  # to ancestor paths in the filesystem. The image data is then read and converted to
-  # Base64. Finally, a data URI is built which can be used in an image tag.
+  # to ancestor paths in the filesystem. The image data is then read and converted to base64.
+  # Finally, a data URI is built which can be used in an image tag.
   #
   # target_image - A String path to the target image
   # asset_dir_key - The String attribute key used to lookup the directory where
@@ -376,8 +376,8 @@ def generate_data_uri(target_image, asset_dir_key = nil)
     end
 
     if ::File.readable? image_path
-      # NOTE base64 is autoloaded by reference to ::Base64
-      %(data:#{mimetype};base64,#{::Base64.strict_encode64 ::File.binread image_path})
+      # NOTE pack 'm0' is equivalent to Base64.strict_encode64
+      %(data:#{mimetype};base64,#{[(::File.binread image_path)].pack 'm0'})
     else
       logger.warn %(image to embed not found or not readable: #{image_path})
       %(data:#{mimetype};base64,)
@@ -410,8 +410,8 @@ def generate_data_uri_from_uri image_uri, cache_uri = false
 
     begin
       mimetype, bindata = ::OpenURI.open_uri(image_uri, URI_READ_MODE) {|f| [f.content_type, f.read] }
-      # NOTE base64 is autoloaded by reference to ::Base64
-      %(data:#{mimetype};base64,#{::Base64.strict_encode64 bindata})
+      # NOTE pack 'm0' is equivalent to Base64.strict_encode64
+      %(data:#{mimetype};base64,#{[bindata].pack 'm0'})
     rescue
       logger.warn %(could not retrieve image data from URI: #{image_uri})
       image_uri