rem: add_field_list (const char *c_str)
add: add_field_list (char *str)
context: add_field_list (const char *c_str){  char *p, *str;  /* Make a writable copy of c_str.  */  str = (char *) alloca (strlen (c_str) + 1);  strcpy (str, c_str);  p = str;  do    {      int invalid;      int file_index, field_index;      char *spec_item = p;      p = strpbrk (p, ", \t");      if (p)        *p++ = 0;      invalid = decode_field_spec (spec_item, &file_index, &field_index);      if (invalid)	return 1;      add_field (file_index, field_index);      uni_blank.nfields = max (uni_blank.nfields, field_index);    }  while (p);  return 0;}