Exploit of character breaking bug in https://github.com/EBvi/dev-matrix/blob/master/dev-test.md

smpstring.java

// NOTE: This example uses tengwar glyph in Unicode SMP.
// To properly render all glyph, you need font which support
// U+16080-160FF range.
//
// Here is modified FreeMonoTengwar font for that purpose.
// http://galadriel.gentoo.moe/tengwar-SMP/

class smptest
{
  public static void main(String args[])
  {
    // Tengwar in SMP. WARN: TENTATIVELY ALLOCATED CODEPOINT
    // This string is 32 * 2 + 1 byte in UTF-16
    char[] arr = "𖂑𖃄𖂢𖂄𖃄𖂠𖂥𖃄 𖂑𖃄𖂢𖂄𖃄𖂠𖂥𖃄".toCharArray();
    StringBuffer sb = new StringBuffer();
    int size = 0;

    for (char c : arr)
      {
        size += (c > 255) ? 2 : 1; //Is it 2byte?
        sb.append(c);

        // It will break Tehtar U+160C4
        if(size >= 63)
          break;
      }

    System.out.println(sb);
    //Output: 𖂑𖃄𖂢𖂄𖃄𖂠𖂥𖃄 𖂑𖃄𖂢𖂄𖃄𖂠𖂥?
  }
}