iso-spider/lib/iso9660/parse/volume-descriptor.js

'use strict';

const Buffer = require("safe-buffer").Buffer;

const createBufferReader = require("../buffer-reader");
const parseBootRecord = require("./descriptors/boot-record");
const parsePrimaryVolumeDescriptor = require("./descriptors/primary-volume");
const parseSupplementaryVolumeDescriptor = require("./descriptors/supplementary-volume");
const parseVolumePartitionDescriptor = require("./descriptors/volume-partition");
const parseVolumeDescriptorSetTerminator = require("./descriptors/descriptor-set-terminator");

let identifierCD001 = Buffer.from("CD001");

function getVolumeDescriptorType(typeNumber) {
    if (typeNumber === 0) {
        return "boot";
    } else if (typeNumber === 1) {
        return "primary";
    } else if (typeNumber === 2) {
        return "supplementary";
    } else if (typeNumber === 3) {
        return "partition";
    } else if (typeNumber >= 4 && typeNumber <= 254) {
        return "reserved";
    } else if (typeNumber === 255) {
        return "terminator";
    } else {
        throw new Error("Unknown volume descriptor type");
    }
}

function parseVolumeDescriptorData(type, dataBuffer) {
    if (type === "boot") {
        return parseBootRecord(dataBuffer);
    } else if (type === "primary") {
        return parsePrimaryVolumeDescriptor(dataBuffer);
    } else if (type === "supplementary") {
        return parseSupplementaryVolumeDescriptor(dataBuffer);
    } else if (type === "partition") {
        return parseVolumePartitionDescriptor(dataBuffer);
    } else if (type === "terminator") {
        return parseVolumeDescriptorSetTerminator(dataBuffer);
    }
}

module.exports = function parseVolumeDescriptor(data) {
    if (!data.slice(1, 6).equals(identifierCD001)) {
        throw new Error("Not a valid volume descriptor - CD001 identifier is missing");
    }

    let buffer = createBufferReader(data);

    let descriptorType = getVolumeDescriptorType(buffer.int8(0));

    return {
        type: descriptorType,
        version: buffer.int8(6),
        data: parseVolumeDescriptorData(descriptorType, data.slice(7, 2048))
    }
};