Fix frozen error caused by frozen string literal

[taichi-ishitani]

Hi,

I got FrozenError when I use rubyzip gem --enable-frozen-string-literal option.

     FrozenError:
       can't modify frozen String: ""
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/crypto/decrypted_io.rb:18:in `replace'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/crypto/decrypted_io.rb:18:in `read'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/inflater.rb:32:in `produce_input'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/inflater.rb:15:in `read'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/input_stream.rb:84:in `sysread'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/entry.rb:619:in `block (2 levels) in create_file'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/entry.rb:534:in `get_input_stream'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/entry.rb:615:in `block in create_file'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/entry.rb:614:in `open'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/entry.rb:614:in `create_file'
     # ./vendor/bundle/ruby/2.7.0/gems/rubyzip-2.2.0/lib/zip/entry.rb:182:in `extract'

This PR is to fix the above error.

[coveralls]

Coverage remained the same at 95.674% when pulling 976dbd3 on taichi-ishitani:fix_frozen_error into ecd641e on rubyzip:master.

[jdleesmiller]

Good spot, thanks!

All but one of these changes look good to me (see comment).

[jdleesmiller]

Suggested change

	entryName = +entryName.to_s
	entryName = entryName.dup.to_s

I am not sure about this one --- I think the dup here is not necessarily to get an unfrozen entryName but instead to avoid mutating the entryName argument. + does not duplicate the string if it's not frozen.

[taichi-ishitani]

@jaredbeck ,
Thank you for your comment !
OK, I will revert this change.

[taichi-ishitani]

Done!

[jdleesmiller]

(And I have not forgotten about our discussion in #390 (comment) --- we should really get that linter set up!)

[hainesr]

@jdleesmiller I have a branch in my local repo where I've done a ton of work getting rubocop up to date. I'll try and get that sorted and get a PR out this weekend.

[jdleesmiller]

Thanks 👍