Unhandled error: "invalid distance too far back"

When trying to unzip a large archive (about 45MB that should expand to about 100MB), it fails with this output:

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: invalid distance too far back
    at Zlib._binding.onerror (zlib.js:295:17)

Any idea what this means?

[coockoo]

For anyone who is looking for an answer. I accidentally bumped into this repo (maintainable fork of this one) https://github.com/ZJONSSON/node-unzipper I just replaced my dependency and require line and everything worked like a charm.

[MaximilianBuegler]

The problem isn’t in the unzip library. You were probably using the createReadStream method of the S3 getObject response. This seems to pack an http header in front of the zip file, which causes unzip to rightfully complain about this not being a zip file with the aforementioned error.

Solution is to take the Body of the response, which is a Buffer, convert that to a ReadStream and pipe it into unzip. The BufferStream converter class can be found here: https://gist.github.com/bennadel/b35f3a15cb3b03ddbcf8#file-test-js . (No idea why this isn’t available as a npm package)

So my solution then looks as follows (loose code snippet):

var s3 = new AWS.S3();
var params = {Bucket: s3bucket, Key: zipFileName};
s3.getObject(params,function(err, queryData) {
                if (err){
                    return reject("Loading file "+s3bucket+" : "+zipFileName+" failed. "+err);
                }
                else{
                    var stream=new BufferStream(queryData.Body);
                    var unzipStream=stream.pipe(unzip.Parse());
                    unzipStream.on('error', function(err){ return reject("Unzipping file "+s3bucket+" : "+zipFileName+" failed. "+err); });
                    unzipStream.on('entry', function (entry) {
                                ...

Hope this helps others with this issue.