1 files changed, 66 insertions, 0 deletions
diff --git a/app/services/packages/debian/parse_debian822_service.rb b/app/services/packages/debian/parse_debian822_service.rb
new file mode 100644
index 00000000000..665929d2324
--- /dev/null
+++ b/app/services/packages/debian/parse_debian822_service.rb
@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+module Packages
+  module Debian
+    # Parse String as Debian RFC822 control data format
+    # https://manpages.debian.org/unstable/dpkg-dev/deb822.5
+    class ParseDebian822Service
+      InvalidDebian822Error = Class.new(StandardError)
+
+      def initialize(input)
+        @input = input
+      end
+
+      def execute
+        output = {}
+        @input.each_line('', chomp: true) do |block|
+          section = {}
+          section_name, field = nil
+          block.each_line(chomp: true) do |line|
+            next if comment_line?(line)
+
+            if continuation_line?(line)
+              raise InvalidDebian822Error, "Parse error. Unexpected continuation line" if field.nil?
+
+              section[field] += "\n"
+              section[field] += line[1..] unless paragraph_separator?(line)
+            elsif match = match_section_line(line)
+              section_name = match[:name] if section_name.nil?
+              field = match[:field].to_sym
+
+              raise InvalidDebian822Error, "Duplicate field '#{field}' in section '#{section_name}'" if section.include?(field)
+
+              section[field] = match[:value]
+            else
+              raise InvalidDebian822Error, "Parse error on line #{line}"
+            end
+          end
+
+          raise InvalidDebian822Error, "Duplicate section '#{section_name}'" if output[section_name]
+
+          output[section_name] = section
+        end
+
+        output
+      end
+
+      private
+
+      def comment_line?(line)
+        line.match?(/^#/)
+      end
+
+      def continuation_line?(line)
+        line.match?(/^ /)
+      end
+
+      def paragraph_separator?(line)
+        line == ' .'
+      end
+
+      def match_section_line(line)
+        line.match(/(?<name>(?<field>^\S+):\s*(?<value>.*))/)
+      end
+    end
+  end
+end