char *strsep(char **sp, char *sep) {
  char *p, *s;
  if(sp == NULL || *sp == NULL || **sp == '\0')
    return(NULL);
  s = *sp;
  p = s + strcspn(s, sep);
  if(*p != '\0')
    *p++ = '\0';
  *sp = p;
  return(s);
}
Unknown