Function WebBundleHasIntegrityBlock

go/integrityblock/integrityblock.go:211–227

WebBundleHasIntegrityBlock is a helper function that can be called with any file path to check if it has an integrtiy block. Basically this checks if the bytes fileBytes[2:10] match with the magic bytes.

(bundleFile io.ReadSeeker)

// WebBundleHasIntegrityBlock is a helper function that can be called with any file path to check if it has
// an integrtiy block. Basically this checks if the bytes fileBytes[2:10] match with the magic bytes.
func WebBundleHasIntegrityBlock(bundleFile io.ReadSeeker) (bool, error) {
	bundleFile.Seek(2, io.SeekStart)

	possibleMagic := make([]byte, len(IntegrityBlockMagic))
	numBytesRead, err := io.ReadFull(bundleFile, possibleMagic)
	if err != nil {
		return false, err
	}
	if numBytesRead != len(IntegrityBlockMagic) {
		return false, nil
	}

	// Return to the start of the file.
	bundleFile.Seek(0, io.SeekStart)

	return bytes.Compare(IntegrityBlockMagic, possibleMagic) == 0, nil
}