gunzipstream.js

var fs = require('fs'),
    sys = require('sys'),
    gzbz2 = require('gzbz2'),
    stream = require('stream');

/**
 * wrap an readable stream (for binary data) with gunzip
 */
var GunzipStream = function(readStream, enc) {
    stream.Stream.call(this);
    var self = this;

    self.stream = readStream;
    self.gz = new gzbz2.Gunzip();
    self.gz.init({encoding: enc});

    self.ondata = function(data) {
        try {
            var inflated = self.gz.inflate(data);
        } catch (err) {
            return self.onerror(err);
        }
        self.emit('data', inflated);
    };
    self.onclose = function() {
        self.gz.end();
        self.emit('close');
        self._cleanup();
    };
    self.onend = function() {
        self.gz.end();
        self.emit('end');
        self._cleanup();
    };
    self.onerror = function(err) {
        self.gz.end();
        self.emit('error', err);
        self._cleanup();
    };
    self.pause = function() {
        self.stream.pause();
    };
    self.resume = function() {
        self.stream.resume();
    };
    self._cleanup = function() {
        self.stream.removeListener('data', self.ondata);
        self.stream.removeListener('close', self.onclose);
        self.stream.removeListener('end', self.onend);
        self.stream.removeListener('error', self.onerror);
    };

    self.stream.addListener('data', self.ondata);
    self.stream.addListener('end', self.onend);
    self.stream.addListener('close', self.onclose);
    self.stream.addListener('error', self.onerror);
};
sys.inherits(GunzipStream, stream.Stream);
exports.GunzipStream = GunzipStream;

/**
 * this method accepts 4 main flavors:
 *
 * none             gunzip from stdin
 * ---------------------------------------------------------------
 * @param stream    ReadStream, if null/undefined, use stdin
 * ---------------------------------------------------------------
 * @param path      string pathname, if null/undefined: use stdin
 * ---------------------------------------------------------------
 * @param path      string pathname, if null/undefined && options.fd == null/undefined, use stdin
 * @param options   as would be given to fs.createReadStream()
 *
 * @return  a GunzipStream object, the underlying ReadStream is available as attribute named 'stream'
 */
exports.wrap = function() {
    // [stream] | [path, [options,]]
    var stream = arguments[0], options = arguments[1];
    var enc = options.encoding;
    if( stream == null ) {
        if( options.fd == null ) {
            stream = process.openStdin();
        }
    } else if( typeof stream == 'string' ) {
        if( options ) {
            // we want to use buffers
            options.encoding = null;
        }
        stream = fs.createReadStream(stream, options);
    } // else stream is all set, options (if provided) are ignored
    return new GunzipStream(stream, enc);
};