If strdup and strndup is not present

strdup.c

char * 
strdup (const char *s)
{
  size_t len = strlen (s) + 1;
  void *new = malloc (len);

  if(NULL == new) return NULL;

  return (char *) memcpy (new, s, len);
}

char *
strndup (const char *s, size_t n)
{
  size_t len = strnlen (s, n);
  char *new = (char *) malloc (len + 1);

  if(NULL == new) return NULL;

  new[len] = '\0';
  return (char *) memcpy (new, s, len);
}