readmongo/node_modules/get-stream/index.js

'use strict';
const pump = require('pump');
const bufferStream = require('./buffer-stream');

class MaxBufferError extends Error {
	constructor() {
		super('maxBuffer exceeded');
		this.name = 'MaxBufferError';
	}
}

function getStream(inputStream, options) {
	if (!inputStream) {
		return Promise.reject(new Error('Expected a stream'));
	}

	options = Object.assign({maxBuffer: Infinity}, options);

	const {maxBuffer} = options;

	let stream;
	return new Promise((resolve, reject) => {
		const rejectPromise = error => {
			if (error) { // A null check
				error.bufferedData = stream.getBufferedValue();
			}
			reject(error);
		};

		stream = pump(inputStream, bufferStream(options), error => {
			if (error) {
				rejectPromise(error);
				return;
			}

			resolve();
		});

		stream.on('data', () => {
			if (stream.getBufferedLength() > maxBuffer) {
				rejectPromise(new MaxBufferError());
			}
		});
	}).then(() => stream.getBufferedValue());
}

module.exports = getStream;
module.exports.buffer = (stream, options) => getStream(stream, Object.assign({}, options, {encoding: 'buffer'}));
module.exports.array = (stream, options) => getStream(stream, Object.assign({}, options, {array: true}));
module.exports.MaxBufferError = MaxBufferError;