Realloc fail on union

Projects Programming
8

ok, i've try this:

unsigned char MyString::changeBuffer(unsigned int maxStrLen)
{
  Serial.print("change buffer sixe: "); Serial.println(maxStrLen);
  char *newbuffer = nullptr;
  if ( !buffer.longString.data ) {
    newbuffer = (char*) malloc (maxStrLen + 1);
    Serial.println("try malloc");
  }
  else newbuffer = (char *)realloc(buffer.longString.data, maxStrLen + 1);
  if (newbuffer) {
    Serial.println("alocation succed");
    buffer.longString.data = newbuffer;
    buffer.longString.capacity = maxStrLen;
    return 1;
  }
  return 0;

malloc have been tried, but failed to.

It failed on the newbuffer pointer... I really do not understand....