Uncompressing Gzip buffer in JavaScript

Question

I've got a data buffer compressed by the php function gzcompress and I need to uncompress it in js (nodejs).

gzcompress(serialize($slot[$i]['advanced_details']),8)

I've tried Class: zlib.Gunzip from https://nodejs.org/api/zlib.html#zlib_class_zlib_gunzip

But it throws:

{ [Error: incorrect header check] errno: -3, code: 'Z_DATA_ERROR' }

Full buffer here

My code:

nodeZlib.gunzip(rows[0]['Slot'+(i+1)+'AdvancedDetails'], 8, function(error, data) {
                if(!error) {
                    console.log = data.toString();
                } else {
                    console.log('Error unzipping:');
                    console.log(error);
                }
            });

What am I doing wrong?

score 2 · Accepted Answer · answered Dec 06 '16 at 03:06

2

You are confusing formats. Your confusion is aided by the horrible naming of the functions in PHP. PHP's gzcompress() produces the zlib format, whereas node.js's gunzip is expecting the gzip format. You could use gzencode() in PHP instead to generate the gzip format, or you could use node.js's zlib.inflate to decompress the zlib format.

answered Dec 06 '16 at 03:06

Mark Adler

101,978
13
118
158

Wow if it's that... gonna check right now and I'll validate the answer if correct. Thanks. – Jesús Fuentes Dec 06 '16 at 17:17
Aaaaaand perfect! – Jesús Fuentes Dec 06 '16 at 17:57

score 1 · Answer 2 · answered Nov 19 '18 at 13:22

I was trying to minify a json output from a shell command. It was too long without encoding it.

The solution I arrived to:

$content = ['sample', 'data'];

$data = base64_encode(gzencode(
    json_encode($content, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_QUOT | JSON_HEX_AMP | JSON_UNESCAPED_UNICODE),
    8,
    FORCE_DEFLATE
));

// then send $data to node

and retrieve the data in Node:

const zlib = require('zlib');

let data = zlib.inflateSync(new Buffer(data.min, 'base64')).toString();

Uncompressing Gzip buffer in JavaScript

2 Answers2