zlib: invalid distance too far back on `inflateRaw` with custom dictionary

[thusoy]

• Version: 4.5.0 and 6.5.0
• Platform: OSX and Linux (didn't test windows)
• Subsystem: zlib

The following script fails:

const zlib = require('zlib');

const serialized = new Buffer('mytexttocompresshere');
const zlibDictionary = new Buffer('texttocompress');
const zlibOptions = {dictionary: zlibDictionary};

const deflated = zlib.deflateRawSync(serialized, zlibOptions);
const inflated = zlib.inflateRawSync(deflated, zlibOptions);
console.log(inflated.equals(serialized));

With the following traceback (the crash comes from the inflateRawSync line):

zlib.js:535
      throw error;
      ^

Error: invalid distance too far back
    at Zlib._handle.onerror (zlib.js:363:17)
    at InflateRaw.Zlib._processChunk (zlib.js:525:30)
    at zlibBufferSync (zlib.js:239:17)
    at Object.exports.inflateRawSync (zlib.js:187:10)
    at Object.<anonymous> (~/testRawDeflate.js:8:23)
    at Module._compile (module.js:435:26)
    at Object.Module._extensions..js (module.js:442:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:311:12)
    at Function.Module.runMain (module.js:467:10)

If the dictionary argument is removed it works, and similarly the non-raw alternatives work (outputs true as expected). Not sure if relevant, but all test cases was against zlib 1.2.8 (console.log(process.binding('zlib').ZLIB_VERSION);).

The same problem exists for the async functions too.

[thusoy]

I'm not particularly familiar with the codebase, but I added a test case similar to the existing test-zlib-dictionary case, just swapping createInflate/createDeflate for their createInflateRaw/createDeflateRaw counterparts and the error persist. Debugging what happens during execution it appears that if inflate is called for a raw stream that requires a dictionary, it returns Z_DATA_ERROR instead of the expected Z_NEED_DICT.

The docs says that in raw mode inflateSetDictionary can be called right after inflateInit2, so I tried to set the dictionary before inflate() if the mode is INFLATERAW, which seems to work, PR coming.