Only use the Zip64 CDIR end locator if needed.

Previously the central directory Zip64 data was written even if it wasn't strictly needed. The standard allows for entries to include Zip64 data (say, if they are streamed and their size is unknown when writing the file data) without needing any Zip64 data in the central directory. So now we only write central directory Zip64 data if there are over 65535 files or the file data is huge.
hainesr · Nov 17, 2022 · c9ddf28 · c9ddf28
1 parent 1aac89b
commit c9ddf28
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Showing 2 changed files with 13 additions and 34 deletions.
diff --git a/lib/zip/central_directory.rb b/lib/zip/central_directory.rb
@@ -44,14 +44,10 @@ def write_to_stream(io) #:nodoc:
       @entry_set.each { |entry| entry.write_c_dir_entry(io) }
       eocd_offset = io.tell
       cdir_size = eocd_offset - cdir_offset
-      if ::Zip.write_zip64_support
-        need_zip64_eocd = cdir_offset > 0xFFFFFFFF || cdir_size > 0xFFFFFFFF \
-                          || @entry_set.size > 0xFFFF
-        need_zip64_eocd ||= @entry_set.any?(&:zip64?)
-        if need_zip64_eocd
-          write_64_e_o_c_d(io, cdir_offset, cdir_size)
-          write_64_eocd_locator(io, eocd_offset)
-        end
+      if Zip.write_zip64_support &&
+         (cdir_offset > 0xFFFFFFFF || cdir_size > 0xFFFFFFFF || @entry_set.size > 0xFFFF)
+        write_64_e_o_c_d(io, cdir_offset, cdir_size)
+        write_64_eocd_locator(io, eocd_offset)
       end
       write_e_o_c_d(io, cdir_offset, cdir_size)
     end

diff --git a/test/central_directory_test.rb b/test/central_directory_test.rb
@@ -87,43 +87,26 @@ def test_write_to_stream
     assert_equal(cdir.entries.sort, cdir_readback.entries.sort)
   end
 
-  def test_write64_to_stream
-    entries = [
-      ::Zip::Entry.new(
-        'file.zip', 'file1-little', comment: 'comment1', size: 200,
-        compressed_size: 200, crc: 101,
-        compression_method: ::Zip::Entry::STORED
-      ),
-      ::Zip::Entry.new(
-        'file.zip', 'file2-big', comment: 'comment2',
-        size: 20_000_000_000, compressed_size: 18_000_000_000, crc: 102
-      ),
-      ::Zip::Entry.new(
-        'file.zip', 'file3-alsobig', comment: 'comment3',
-        size: 21_000_000_000, compressed_size: 15_000_000_000, crc: 103
-      ),
-      ::Zip::Entry.new(
-        'file.zip', 'file4-little', comment: 'comment4',
-        size: 121, compressed_size: 100, crc: 104
-      )
-    ]
+  def test_write64_to_stream_65536_entries
+    skip unless ENV['FULL_ZIP64_TEST']
 
-    [0, 250, 18_000_000_300, 33_000_000_350].each_with_index do |offset, index|
-      entries[index].local_header_offset = offset
+    entries = []
+    0x10000.times do |i|
+      entries << Zip::Entry.new('file.zip', "#{i}.txt")
     end
 
-    cdir = ::Zip::CentralDirectory.new(entries, 'zip comment')
+    cdir = Zip::CentralDirectory.new(entries)
     File.open('test/data/generated/cdir64test.bin', 'wb') do |f|
       cdir.write_to_stream(f)
     end
 
-    cdir_readback = ::Zip::CentralDirectory.new
+    cdir_readback = Zip::CentralDirectory.new
     File.open('test/data/generated/cdir64test.bin', 'rb') do |f|
       cdir_readback.read_from_stream(f)
     end
 
-    assert_equal(cdir.entries.sort, cdir_readback.entries.sort)
-    assert_equal(::Zip::VERSION_NEEDED_TO_EXTRACT_ZIP64, cdir_readback.instance_variable_get(:@version_needed_for_extract))
+    assert_equal(0x10000, cdir_readback.size)
+    assert_equal(Zip::VERSION_NEEDED_TO_EXTRACT_ZIP64, cdir_readback.instance_variable_get(:@version_needed_for_extract))
   end
 
   def test_equality