node-signpdf/dist/helpers/plainAddPlaceholder/readRefTable.js

DEPRECATED. Have a look at @signpdf/signpdf instead.

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.getXref = exports.getLastTrailerPosition = exports.getFullXrefTable = exports.default = void 0;

var _SignPdfError = _interopRequireDefault(require("../../SignPdfError"));

var _xrefToRefMap = _interopRequireDefault(require("./xrefToRefMap"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

const getLastTrailerPosition = pdf => {
  const trailerStart = pdf.lastIndexOf(Buffer.from('trailer', 'utf8'));
  const trailer = pdf.slice(trailerStart, pdf.length - 6);
  const xRefPosition = trailer.slice(trailer.lastIndexOf(Buffer.from('startxref', 'utf8')) + 10).toString();
  return parseInt(xRefPosition);
};

exports.getLastTrailerPosition = getLastTrailerPosition;

const getXref = (pdf, position) => {
  let refTable = pdf.slice(position); // slice starting from where xref starts

  const realPosition = refTable.indexOf(Buffer.from('xref', 'utf8'));

  if (realPosition === -1) {
    throw new _SignPdfError.default(`Could not find xref anywhere at or after ${position}.`, _SignPdfError.default.TYPE_PARSE);
  }

  if (realPosition > 0) {
    const prefix = refTable.slice(0, realPosition);

    if (prefix.toString().replace(/\s*/g, '') !== '') {
      throw new _SignPdfError.default(`Expected xref at ${position} but found other content.`, _SignPdfError.default.TYPE_PARSE);
    }
  }

  const nextEofPosition = refTable.indexOf(Buffer.from('%%EOF', 'utf8'));

  if (nextEofPosition === -1) {
    throw new _SignPdfError.default('Expected EOF after xref and trailer but could not find one.', _SignPdfError.default.TYPE_PARSE);
  }

  refTable = refTable.slice(0, nextEofPosition);
  refTable = refTable.slice(realPosition + 4); // move ahead with the "xref"

  refTable = refTable.slice(refTable.indexOf('\n') + 1); // move after the next new line
  // extract the size

  let size = refTable.toString().split('/Size')[1];

  if (!size) {
    throw new _SignPdfError.default('Size not found in xref table.', _SignPdfError.default.TYPE_PARSE);
  }

  size = /^\s*(\d+)/.exec(size);

  if (size === null) {
    throw new _SignPdfError.default('Failed to parse size of xref table.', _SignPdfError.default.TYPE_PARSE);
  }

  size = parseInt(size[1]);
  const [objects, infos] = refTable.toString().split('trailer');
  const isContainingPrev = infos.split('/Prev')[1] != null;
  let prev;

  if (isContainingPrev) {
    const pagesRefRegex = /Prev (\d+)/g;
    const match = pagesRefRegex.exec(infos);
    const [, prevPosition] = match;
    prev = prevPosition;
  }

  const xRefContent = (0, _xrefToRefMap.default)(objects);
  return {
    size,
    prev,
    xRefContent
  };
};

exports.getXref = getXref;

const getFullXrefTable = pdf => {
  const lastTrailerPosition = getLastTrailerPosition(pdf);
  const lastXrefTable = getXref(pdf, lastTrailerPosition);

  if (lastXrefTable.prev === undefined) {
    return lastXrefTable.xRefContent;
  }

  const pdfWithoutLastTrailer = pdf.slice(0, lastTrailerPosition);
  const partOfXrefTable = getFullXrefTable(pdfWithoutLastTrailer);
  const mergedXrefTable = new Map([...partOfXrefTable, ...lastXrefTable.xRefContent]);
  return mergedXrefTable;
};
/**
 * @param {Buffer} pdfBuffer
 * @returns {object}
 */


exports.getFullXrefTable = getFullXrefTable;

const readRefTable = pdf => {
  const fullXrefTable = getFullXrefTable(pdf);
  const startingIndex = 0;
  const maxIndex = Math.max(...fullXrefTable.keys());
  return {
    startingIndex,
    maxIndex,
    offsets: fullXrefTable
  };
};

var _default = readRefTable;
exports.default = _default;