Node: [Android] TypeError in Buffer.concat()

[imkiva]

Please excuse my poor English.

I've already ported node-v4.1.1 to my Android device, but I got the following error:

$ node-v4.1.1 trans.js "hello"
buffer.js:238
    buf.copy(buffer, pos);

TypeError: buf.copy is not a function
    at Function.Buffer.concat (buffer.js:238:9)
    at IncomingMessage.<anonymous> (/data/local/trans.js:20:22)
    at emitNone (event.js:72:20)
    at IncomingMessage.emit (event.js:166:7)
    at endReadableNT (_stream_readable.js:893:12)
    at doNTCallback2 (node.js:429:9)
    at process._tickCallback (node.js:343:17)

But there's no problem with v0.12.7

$ node-v0.12.7 trans.js "hello"
您好

Here is the content of trans.js:

var api = 'http://openapi.baidu.com/public/2.0/bmt/translate?client_id=wo99UGjCxweEkgKrKFuf7N0n&from=auto&to=auto&q=';
var http = require("http");
var qs = require("querystring");


function translate(text, callback) {
    var getstr = api + qs.escape(text);

    http.get(getstr, function(res) {
        var buffer = [];
        res.setEncoding('utf-8');

        res.on('data', function(chunk) {
            buffer.push(chunk);
        });

        res.on('end', function() {
            var body = Buffer.concat(buffer).toString();
            var json = JSON.parse(body);

            callback(json);
        });
    });
}


function showResult(json) {
    var res = json.trans_result;

    res.forEach(function(item) {
        console.log(item.dst);
    });
}

if (process.argv.length <= 2) {
    console.log("Usage: translate.js <string-to-translate>");
    process.exit(1);
}

var argv = process.argv.slice(2);
translate(argv[0], showResult);

[ChALkeR]

`buffer.push(chunk);`` — could you log chunks at this point?

[brycebaril]

The res.setEncoding('utf-8') causes your buffer to be an array of strings (in this case, a single string) and Buffer.concat([<String>]) is causing problems. If you remove the res.setEncoding this example works.

Here is a simpler repro case:

var a = ['abc']
Buffer.concat(a)

The API docs don't indicate that Buffer.concat([<String>]) should be supported, but it's also not listed as one of the breaking changes https://github.com/nodejs/node/wiki/API-changes-between-v0.10-and-v4

[imkiva]

thanks, I removed res.setEncoding, and now it works. :+1:

[ChALkeR]

@brycebaril Did Buffer.concat([<String>]) work in 0.10 and/or 0.12?

[brycebaril]

@ChALkeR when I test the 2-line repro script it works in every version of node from 0.8 up until io.js 3.0.0.

This is either a regression or an API change.

[ChALkeR]

@trevnorris Should this be mentioned in the API changes or fixed?

[trevnorris]

@ChALkeR I just went though code back to v0.8. I don't see how this ever could have worked. Just tried it on v0.12 myself:

$ ./node -v
v0.12.7
$ ./node
> Buffer.concat(['abc', 'def'])
TypeError: undefined is not a function

This may have been a bug in setEncoding() in v0.12. Not sure though.

[brycebaril]

@trevnorris it only worked in the past if a.length === 1

bryce@x1c:~/boneyard$ node -v
v0.12.7
bryce@x1c:~/boneyard$ node
> Buffer.concat(['abc'])
'abc'
> Buffer.concat(['abc', 'def'])
TypeError: undefined is not a function
    at Function.Buffer.concat (buffer.js:215:9)
    at repl:1:8
    at REPLServer.defaultEval (repl.js:132:27)
    at bound (domain.js:254:14)
    at REPLServer.runBound [as eval] (domain.js:267:12)
    at REPLServer.<anonymous> (repl.js:279:12)
    at REPLServer.emit (events.js:107:17)
    at REPLServer.Interface._onLine (readline.js:214:10)
    at REPLServer.Interface._line (readline.js:553:8)
    at REPLServer.Interface._ttyWrite (readline.js:830:14)

[trevnorris]

@brycebaril ah. because of a previous API stupidity where it would simply return the same value. instead of making a copy. that's been fixed.

[brycebaril]

@trevnorris got it, since it used to be documented I'd be happy if the resolution to this was to get it included in @Fishrock123's API change list

edit: actually looking at @Fishrock123's list it _does_ mention it:

Buffer.concat() now always creates a new buffer, even if only called with one element.

That language isn't extremely clear because it doesn't point out the old behavior, but perhaps it's enough?

[Fishrock123]

Maybe someone could edit in another point under mine about this? It _is_ a wiki. :)

[brycebaril]

@Fishrock123 edited, thanks for the nudge ;)

I'd say this can be closed now.