Issue #5929 has been reported by Eric Hodel.

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Bug #5929: Zlib::Inflate#set_dictionary does not work with short input
https://bugs.ruby-lang.org/issues/5929

Author: Eric Hodel
Status: Open
Priority: Normal
Assignee: 
Category: ext
Target version: 2.0.0
ruby -v: ruby 2.0.0dev (2012-01-26 trunk 34377) [x86_64-darwin11.2.0]


=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



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