Using Zip.sort_entries appears to change file header in place when using block with File.open

[stadelmanma]

I ran into this when working with docx files and after refactoring some code the test fixtures were getting modified but for the life of me I couldn't tell how. The unzipped content of the archive is unchanged however the number of bytes slightly changes (which I assume is the file ordering?). Zip::File.open.each does not modify the file in place, nor does using Zip::File.open_buffer on the raw stream.

The block below can reproduce the error.

Zip.sort_entries = true # required to process document.xml before numbering.xml
Zip::File.open('../fixtures/conditionals_template.docx') do |docx_zip|
end

For a full demonstration of the problem you can pull down my branch of Sablon here (use the zip-modify-inplace branch) and then run bundle exec rake. Ignore the failing test and afterwards you can use git status to see all of the fixtures be modified.

[leandronsp]

@stadelmanma I realized the problem starts on lib/zip/entry_set.rb:71, exactly while calling @entry_set.sort. I guess the root cause resides on the way the @entry_set is being manipulated somewhere.

[hainesr]

It seems ridiculous that simply opening and closing a zip file with Zip.sort_entries = true should alter that file on disk.