Bug #5929: Zlib::Inflate#set_dictionary does not work with short input

• Status: Closed
• Assignee: -
• Target version: 2.0.0
• ruby -v: ruby 2.0.0dev (2012-01-26 trunk 34377) [x86_64-darwin11.2.0]

[drbrain (Eric Hodel)]

=begin
If a deflate stream requires a dictionary and the block of data is short it is impossible to decompress the data without modifying the returned bytes. Upon receiving a Zlib::NeedDict exception the documentation for Zlib::Inflate#inflate states:

Set the dictionary by Zlib::Inflate#set_dictionary and then
call this method again with an empty string

Calling inflate with an empty string does not decompress any further bytes due to (({do_inflate()})) ignoring zero-byte strings to avoid a Z_BUF_ERROR.

The attached patch alters the (({do_inflate()})) to inflate more data when either more data was provided by the user or (({z->stream.avail_in})) is nonzero.

Reading (({zstream_run()})) it appears that (({z->stream.avail_in})) will be set to zero upon consuming a chunk of data, so providing an empty string in the middle of a non-dictionary stream will be OK, but please check it.
=end

[drbrain (Eric Hodel)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r34552.
Eric, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• ext/zlib/zlib.c (do_inflate): Inflate more data if buffered data
  exists. Allows Zlib::Inflate#set_dictionary to work.
  [ruby-trunk - Bug #5929]