word-extractor/lib/ole-header.js

Node.js package to read Word .doc files

const HEADER_DATA = Buffer.from('D0CF11E0A1B11AE1', 'hex');

class Header {

  constructor() {}

  load(buffer) {
    for(let i = 0; i < HEADER_DATA.length; i++) {
      if (HEADER_DATA[i] != buffer[i])
        return false;
    }
  
    this.secSize        = 1 << buffer.readInt16LE(30);  // Size of sectors
    this.shortSecSize   = 1 << buffer.readInt16LE(32);  // Size of short sectors
    this.SATSize        =      buffer.readInt32LE(44);  // Number of sectors used for the Sector Allocation Table
    this.dirSecId       =      buffer.readInt32LE(48);  // Starting Sec ID of the directory stream
    this.shortStreamMax =      buffer.readInt32LE(56);  // Maximum size of a short stream
    this.SSATSecId      =      buffer.readInt32LE(60);  // Starting Sec ID of the Short Sector Allocation Table
    this.SSATSize       =      buffer.readInt32LE(64);  // Number of sectors used for the Short Sector Allocation Table
    this.MSATSecId      =      buffer.readInt32LE(68);  // Starting Sec ID of the Master Sector Allocation Table
    this.MSATSize       =      buffer.readInt32LE(72);  // Number of sectors used for the Master Sector Allocation Table
  
    // The first 109 sectors of the MSAT
    this.partialMSAT = new Array(109);
    for(let i = 0; i < 109; i++)
      this.partialMSAT[i] = buffer.readInt32LE(76 + i * 4);
  
    return true;  
  }

}

module.exports = Header;