Is there anyway to override the date (Checksum of zip mismatched) ?

I’m writing a file to zip on upload:

/**
   * @method compressAndHash
   * @description Returns an object that has the compressed file in a buffer, and the representing md5 checksum
   * @param buffer
   * @param fileName The name of the output file in the zip
   */
  private compressAndHash(buffer: Buffer, fileName: string) {
    const zip = new admZip();
    zip.addFile(fileName, buffer);
    const bufferedZip = zip.toBuffer();
    return {
      compressedFile: bufferedZip,
      hash: this.createHash(bufferedZip)
    };
  }

  /**
   * @method createHash
   * @description Generates md5 for a given buffer
   * @param buffer
   */
  private createHash(buffer: Buffer) {
    const hash = crypt
      .createHash('md5')
      .update(buffer)
      .digest('base64');
    return hash;
  }
}

But it looks like the “date” is part of the checksum. Is there anyway to override the date? Similar to the issue/solution mentioned in https://github.com/archiverjs/node-archiver/issues/82 so we can get consistent checksums?

[pxlprfct]

Hi @ClaytonAstrom,

I recently ran into this exact issue. I ended up mocking the date use in date.Now() which is used inside amd-zip. We now get a consistent now get a checksum.

Apparently dates are apart of the zip spec, and adm-zip isn’t doing anything out of the ordinary here.

Hopefully this is useful! Thanks, Ollie

describe('/zip/', ()=> {
    let clock;

    // date.now() needs to be mocked, as it's stored in the output zip and causes the zips to differ ever-so-slightly
    beforeEach(async function() {
        const date = new Date(2013, 3, 1);
        clock = sinon.useFakeTimers(date.getTime());
    });

    afterEach(function() {
        clock.restore();
    });

    it('zipped data exactly matches expected output', async ()=> {
        const result = zip.zipFile(xml);

        expect(result).to.equal(encodedZip);
    });
});

[5saviahv]

adm-zip wraps internal structures so you cant see them directly. one idea is after you call:

zip.addfile(filename, ...);

you also call

zip.getEntry(filename).header.time = new Date("some known date");

and after that you call toBuffer()