eradicate the use of the base64 library

CHANGELOG.adoc

@@ -54,6 +54,7 @@ Bug Fixes::
 * remove deprecated, undocumented `svg-font-family` theme key (the correct key is `svg-fallback-font-family`)
 * major improvement to OTF support following release of ttfunk 1.8.0 (automatic transitive dependency of prawn)
 * propagate source location to table cell for description in horizontal dlist so it is included in truncation warning message (#2502)
+* eradicate use of the base64 library to fix waarning about base64 gem when using Ruby >= 3.3
 * upgrade prawn-svg to 0.34 to fix warning about base64 gem when using Ruby >= 3.3; apply additional patch to fix bug in prawn-svg
 
 == 2.3.13 (2024-02-16) - @mojavelinux

Gemfile

@@ -8,7 +8,6 @@ gemspec
 gem 'asciidoctor', ENV['ASCIIDOCTOR_VERSION'], require: false if ENV.key? 'ASCIIDOCTOR_VERSION'
 gem 'asciidoctor-diagram', ENV['ASCIIDOCTOR_DIAGRAM_VERSION'], require: false if ENV.key? 'ASCIIDOCTOR_DIAGRAM_VERSION'
 gem 'asciidoctor-kroki', ENV['ASCIIDOCTOR_KROKI_VERSION'], require: false if ENV.key? 'ASCIIDOCTOR_KROKI_VERSION'
-gem 'base64', require: false if (Gem::Version.new RUBY_VERSION) >= (Gem::Version.new '3.3.0') # required until asciidoctor 2.0.22 is out
 gem 'coderay', '~> 1.1.0', require: false
 gem 'ffi-icu', ENV['FFI_ICU_VERSION'], require: false if ENV.key? 'FFI_ICU_VERSION'
 gem 'open-uri-cached', '~> 1.0.0', require: false

lib/asciidoctor/pdf/converter.rb

@@ -1738,7 +1738,7 @@ def convert_image node, opts = {}
         if image_format == 'gif' && !(defined? ::GMagick::Image)
           log :warn, %(GIF image format not supported. Install the prawn-gmagick gem or convert #{target} to PNG.)
           image_path = nil
-        elsif ::Base64 === target
+        elsif ::Asciidoctor::Image::Base64Encoded === target
           image_path = target
         elsif (image_path = resolve_image_path node, target, image_format, (opts.fetch :relative_to_imagesdir, true))
           if image_format == 'pdf'
@@ -1807,8 +1807,8 @@ def convert_image node, opts = {}
           rendered_h = rendered_w = nil
           span_page_width_if align_to_page do
             if image_format == 'svg'
-              if ::Base64 === image_path
-                svg_data = ::Base64.decode64 image_path
+              if ::Asciidoctor::Image::Base64Encoded === image_path
+                svg_data = image_path.unpack1 'm'
                 file_request_root = false
               else
                 svg_data = ::File.read image_path, mode: 'r:UTF-8'
@@ -1858,8 +1858,8 @@ def convert_image node, opts = {}
             else
               # FIXME: this code really needs to be better organized!
               # NOTE: use low-level API to access intrinsic dimensions; build_image_object caches image data previously loaded
-              image_obj, image_info = ::Base64 === image_path ?
-                  ::StringIO.open((::Base64.decode64 image_path), 'rb') {|fd| build_image_object fd } :
+              image_obj, image_info = ::Asciidoctor::Image::Base64Encoded === image_path ?
+                  ::StringIO.open((image_path.unpack1 'm'), 'rb') {|fd| build_image_object fd } :
                   ::File.open(image_path, 'rb') {|fd| build_image_object fd }
               actual_w = to_pt image_info.width, :px
               width = actual_w * scale if scale
@@ -4344,11 +4344,11 @@ def resolve_image_path node, image_path, image_format, relative_to = true
           imagesdir = relative_to
         end
         # NOTE: base64 logic currently used for inline images
-        if ::Base64 === image_path
+        if ::Asciidoctor::Image::Base64Encoded === image_path
           return @tmp_files[image_path] if @tmp_files.key? image_path
           tmp_image = ::Tempfile.create %W(image- .#{image_format})
           tmp_image.binmode unless image_format == 'svg'
-          tmp_image.write ::Base64.decode64 image_path
+          tmp_image.write image_path.unpack1 'm'
           tmp_image.close
           @tmp_files[image_path] = tmp_image.path
         # NOTE: this will catch a classloader resource path on JRuby (e.g., uri:classloader:/path/to/image)

lib/asciidoctor/pdf/ext/asciidoctor/image.rb

@@ -2,6 +2,7 @@
 
 module Asciidoctor
   module Image
+    Base64Encoded = ::Module.new
     DataUriRx = %r(^data:image/(?<fmt>png|jpe?g|gif|pdf|bmp|tiff|svg\+xml);base64,(?<data>.*)$)
     FormatAliases = { 'jpg' => 'jpeg', 'svg+xml' => 'svg' }
 
@@ -11,7 +12,7 @@ def self.format image_path
 
     def self.target_and_format image_path, attributes = nil
       if (image_path.start_with? 'data:') && (m = DataUriRx.match image_path)
-        [(m[:data].extend ::Base64), (FormatAliases.fetch m[:fmt], m[:fmt])]
+        [(m[:data].extend Base64Encoded), (FormatAliases.fetch m[:fmt], m[:fmt])]
       else
         [image_path, (attributes&.[] 'format') || ((ext = ::File.extname image_path).downcase.slice 1, ext.length)]
       end
@@ -20,7 +21,7 @@ def self.target_and_format image_path, attributes = nil
     def target_and_format
       image_path = inline? ? target : (attr 'target')
       if (image_path.start_with? 'data:') && (m = DataUriRx.match image_path)
-        [(m[:data].extend ::Base64), (FormatAliases.fetch m[:fmt], m[:fmt])]
+        [(m[:data].extend Base64Encoded), (FormatAliases.fetch m[:fmt], m[:fmt])]
       else
         [image_path, (attr 'format', nil, false) || ((ext = ::File.extname image_path).downcase.slice 1, ext.length)]
       end