fs.js

var nodeFs = require("fs");

var fs = {};

fs.readFile = function (path, callback) {
    nodeFs.readFile(path, callback);
};

fs.readChunk = function (path, start, end, callback) {
    var stream = nodeFs.createReadStream(path, {
        start: start,
        end: end - 1
    });
    var chunks = [];
    stream.on("readable", function () {
        var chunk = stream.read();
        if (chunk === null) {
            callback(null, join(chunks));
        } else {
            chunks.push(chunk);
        }
    });
    stream.on("error", function (error) {
        callback(error);
    });
};

fs.writeFile = function (path, binary, callback) {
    nodeFs.writeFile(path, binary, callback);
};

fs.readDir = function (path, callback) {
    nodeFs.readdir(path, callback);
};

function join(buffers) {
    var length = 0;
    var at;
    var index;
    var count = buffers.length;
    var buffer;
    var result;
    for (index = 0; index < count; index++) {
        buffer = buffers[index];
        length += buffer.length;
    }
    result = new Buffer(length);
    at = 0;
    for (index = 0; index < count; index++) {
        buffer = buffers[index];
        buffer.copy(result, at, 0);
        at += buffer.length;
    }
    buffers.splice(0, count, result);
    return result;
}