Extract the `Zip::File::split` code into its own module.

This code is rarely used and may not even be correct according to the
standard. Also this de-clutters the `File` class.

.rubocop_todo.yml

@@ -75,6 +75,7 @@ Style/IfUnlessModifier:
   Exclude:
     - 'lib/zip/entry.rb'
     - 'lib/zip/file.rb'
+    - 'lib/zip/file_split.rb'
     - 'lib/zip/filesystem/dir.rb'
     - 'lib/zip/filesystem/file.rb'
     - 'lib/zip/pass_thru_decompressor.rb'
@@ -100,6 +101,7 @@ Style/NumericPredicate:
     - 'lib/zip/extra_field/universal_time.rb'
     - 'lib/zip/extra_field/unix.rb'
     - 'lib/zip/file.rb'
+    - 'lib/zip/file_split.rb'
     - 'lib/zip/filesystem/file.rb'
     - 'lib/zip/input_stream.rb'
     - 'lib/zip/ioextras.rb'
@@ -114,6 +116,7 @@ Style/OptionalBooleanParameter:
   Exclude:
     - 'lib/zip/entry.rb'
     - 'lib/zip/file.rb'
+    - 'lib/zip/file_split.rb'
     - 'lib/zip/output_stream.rb'
 
 # Offense count: 29

lib/zip/file.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require_relative 'file_split'
+
 module Zip
   # ZipFile is modeled after java.util.zip.ZipFile from the Java SDK.
   # The most important methods are those inherited from
@@ -45,12 +47,9 @@ module Zip
   # interface for accessing the filesystem, ie. the File and Dir classes.
 
   class File < CentralDirectory
+    extend FileSplit
+
     CREATE               = true
-    SPLIT_SIGNATURE      = 0x08074b50
-    ZIP64_EOCD_SIGNATURE = 0x06064b50
-    MAX_SEGMENT_SIZE     = 3_221_225_472
-    MIN_SEGMENT_SIZE     = 65_536
-    DATA_BUFFER_SIZE     = 8192
     IO_METHODS           = [:tell, :seek, :read, :eof, :close].freeze
 
     attr_reader :name
@@ -172,82 +171,6 @@ module Zip
           zip_file.each(&block)
         end
       end
-
-      def get_segment_size_for_split(segment_size)
-        if MIN_SEGMENT_SIZE > segment_size
-          MIN_SEGMENT_SIZE
-        elsif MAX_SEGMENT_SIZE < segment_size
-          MAX_SEGMENT_SIZE
-        else
-          segment_size
-        end
-      end
-
-      def get_partial_zip_file_name(zip_file_name, partial_zip_file_name)
-        unless partial_zip_file_name.nil?
-          partial_zip_file_name = zip_file_name.sub(/#{::File.basename(zip_file_name)}\z/,
-                                                    partial_zip_file_name + ::File.extname(zip_file_name))
-        end
-        partial_zip_file_name ||= zip_file_name
-        partial_zip_file_name
-      end
-
-      def get_segment_count_for_split(zip_file_size, segment_size)
-        (zip_file_size / segment_size).to_i + (zip_file_size % segment_size == 0 ? 0 : 1)
-      end
-
-      def put_split_signature(szip_file, segment_size)
-        signature_packed = [SPLIT_SIGNATURE].pack('V')
-        szip_file << signature_packed
-        segment_size - signature_packed.size
-      end
-
-      #
-      # TODO: Make the code more understandable
-      #
-      def save_splited_part(zip_file, partial_zip_file_name, zip_file_size, szip_file_index, segment_size, segment_count)
-        ssegment_size  = zip_file_size - zip_file.pos
-        ssegment_size  = segment_size if ssegment_size > segment_size
-        szip_file_name = "#{partial_zip_file_name}.#{format('%03d', szip_file_index)}"
-        ::File.open(szip_file_name, 'wb') do |szip_file|
-          if szip_file_index == 1
-            ssegment_size = put_split_signature(szip_file, segment_size)
-          end
-          chunk_bytes = 0
-          until ssegment_size == chunk_bytes || zip_file.eof?
-            segment_bytes_left = ssegment_size - chunk_bytes
-            buffer_size        = segment_bytes_left < DATA_BUFFER_SIZE ? segment_bytes_left : DATA_BUFFER_SIZE
-            chunk              = zip_file.read(buffer_size)
-            chunk_bytes += buffer_size
-            szip_file << chunk
-            # Info for track splitting
-            yield segment_count, szip_file_index, chunk_bytes, ssegment_size if block_given?
-          end
-        end
-      end
-
-      # Splits an archive into parts with segment size
-      def split(zip_file_name, segment_size = MAX_SEGMENT_SIZE, delete_zip_file = true, partial_zip_file_name = nil)
-        raise Error, "File #{zip_file_name} not found" unless ::File.exist?(zip_file_name)
-        raise Errno::ENOENT, zip_file_name unless ::File.readable?(zip_file_name)
-
-        zip_file_size = ::File.size(zip_file_name)
-        segment_size  = get_segment_size_for_split(segment_size)
-        return if zip_file_size <= segment_size
-
-        segment_count = get_segment_count_for_split(zip_file_size, segment_size)
-        ::Zip::File.open(zip_file_name) {} # Check for correct zip structure.
-        partial_zip_file_name = get_partial_zip_file_name(zip_file_name, partial_zip_file_name)
-        szip_file_index       = 0
-        ::File.open(zip_file_name, 'rb') do |zip_file|
-          until zip_file.eof?
-            szip_file_index += 1
-            save_splited_part(zip_file, partial_zip_file_name, zip_file_size, szip_file_index, segment_size, segment_count)
-          end
-        end
-        ::File.delete(zip_file_name) if delete_zip_file
-        szip_file_index
-      end
     end
 
     # Returns an input stream to the specified entry. If a block is passed

lib/zip/file_split.rb

@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+module Zip
+  module FileSplit #:nodoc:
+    SPLIT_SIGNATURE      = 0x08074b50
+    MAX_SEGMENT_SIZE     = 3_221_225_472
+    MIN_SEGMENT_SIZE     = 65_536
+    DATA_BUFFER_SIZE     = 8192
+
+    def get_segment_size_for_split(segment_size)
+      if MIN_SEGMENT_SIZE > segment_size
+        MIN_SEGMENT_SIZE
+      elsif MAX_SEGMENT_SIZE < segment_size
+        MAX_SEGMENT_SIZE
+      else
+        segment_size
+      end
+    end
+
+    def get_partial_zip_file_name(zip_file_name, partial_zip_file_name)
+      unless partial_zip_file_name.nil?
+        partial_zip_file_name = zip_file_name.sub(/#{::File.basename(zip_file_name)}\z/,
+                                                  partial_zip_file_name + ::File.extname(zip_file_name))
+      end
+      partial_zip_file_name ||= zip_file_name
+      partial_zip_file_name
+    end
+
+    def get_segment_count_for_split(zip_file_size, segment_size)
+      (zip_file_size / segment_size).to_i + (zip_file_size % segment_size == 0 ? 0 : 1)
+    end
+
+    def put_split_signature(szip_file, segment_size)
+      signature_packed = [SPLIT_SIGNATURE].pack('V')
+      szip_file << signature_packed
+      segment_size - signature_packed.size
+    end
+
+    #
+    # TODO: Make the code more understandable
+    #
+    def save_splited_part(zip_file, partial_zip_file_name, zip_file_size, szip_file_index, segment_size, segment_count)
+      ssegment_size  = zip_file_size - zip_file.pos
+      ssegment_size  = segment_size if ssegment_size > segment_size
+      szip_file_name = "#{partial_zip_file_name}.#{format('%03d', szip_file_index)}"
+      ::File.open(szip_file_name, 'wb') do |szip_file|
+        if szip_file_index == 1
+          ssegment_size = put_split_signature(szip_file, segment_size)
+        end
+        chunk_bytes = 0
+        until ssegment_size == chunk_bytes || zip_file.eof?
+          segment_bytes_left = ssegment_size - chunk_bytes
+          buffer_size        = segment_bytes_left < DATA_BUFFER_SIZE ? segment_bytes_left : DATA_BUFFER_SIZE
+          chunk              = zip_file.read(buffer_size)
+          chunk_bytes += buffer_size
+          szip_file << chunk
+          # Info for track splitting
+          yield segment_count, szip_file_index, chunk_bytes, ssegment_size if block_given?
+        end
+      end
+    end
+
+    # Splits an archive into parts with segment size
+    def split(zip_file_name, segment_size = MAX_SEGMENT_SIZE, delete_zip_file = true, partial_zip_file_name = nil)
+      raise Error, "File #{zip_file_name} not found" unless ::File.exist?(zip_file_name)
+      raise Errno::ENOENT, zip_file_name unless ::File.readable?(zip_file_name)
+
+      zip_file_size = ::File.size(zip_file_name)
+      segment_size  = get_segment_size_for_split(segment_size)
+      return if zip_file_size <= segment_size
+
+      segment_count = get_segment_count_for_split(zip_file_size, segment_size)
+      ::Zip::File.open(zip_file_name) {} # Check for correct zip structure.
+      partial_zip_file_name = get_partial_zip_file_name(zip_file_name, partial_zip_file_name)
+      szip_file_index       = 0
+      ::File.open(zip_file_name, 'rb') do |zip_file|
+        until zip_file.eof?
+          szip_file_index += 1
+          save_splited_part(zip_file, partial_zip_file_name, zip_file_size, szip_file_index, segment_size, segment_count)
+        end
+      end
+      ::File.delete(zip_file_name) if delete_zip_file
+      szip_file_index
+    end
+  end
+end

test/file_split_test.rb

@@ -33,7 +33,7 @@ class ZipFileSplitTest < MiniTest::Test
 
     Dir["#{TEST_ZIP.zip_name}.*"].sort.each_with_index do |zip_file_name, index|
       File.open(zip_file_name, 'rb') do |zip_file|
-        zip_file.read([::Zip::File::SPLIT_SIGNATURE].pack('V').size) if index == 0
+        zip_file.read([::Zip::FileSplit::SPLIT_SIGNATURE].pack('V').size) if index == 0
         File.open(UNSPLITTED_FILENAME, 'ab') do |file|
           file << zip_file.read
         end