Bug #15662: Fix CSV delegation to missing StringIO

• Status: Closed
• Assignee: kou (Kouhei Sutou)
• Target version: -
• Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN

[gsamokovarov (Genadi Samokovarov)]

If you create a CSV from raw content like:

  csv = CSV.new("h1,h2")

You'll get method missing when calling csv.path but still, get true when you call csv.respond_to?(:path).

This tricks 3rd party libraries like carrierwave which try to call path on their input if it responds to it.

See https://github.com/carrierwaveuploader/carrierwave/blob/a91ab69fdd8052cdf5a5e48ef8baf40939e441fb/lib/carrierwave/sanitized_file.rb#L109-L123

This stops me from passing CSV objects as StringIO's into carrierwave uploads, for example, but the problem can also be manifested in other 3rd party libraries, as responding to a method and returning a NoMethodError when calling it is still an unexpected behavior.

I have gone through the CSV delegation scheme and made sure that every method that StringIO doesn't respond to returns a meaningful zero value and does not raise a NoMethodError while used through a CSV Instance.

[gsamokovarov (Genadi Samokovarov)]

I have opened a PR on GitHub's tracker with the changes: https://github.com/ruby/ruby/pull/2094

[kou (Kouhei Sutou)]

• Status changed from Open to Assigned
• Assignee set to kou (Kouhei Sutou)

Could you use https://github.com/ruby/csv instead of ruby/ruby?
ruby/csv is the upstream repository.

[gsamokovarov (Genadi Samokovarov)]

We resolved it in https://github.com/ruby/csv/pull/80. Thank you @kou (Kouhei Sutou) 🙇‍♂️!

[kou (Kouhei Sutou)]

• Status changed from Assigned to Closed

Thanks!