コード例 #1
0
ファイル: break-loader.c プロジェクト: mirsal/dbus
static void
randomly_set_extreme_ints (const DBusString *orig_data,
                           DBusString       *mutated)
{
  int i;
  int byte_order;
  const char *d;
  dbus_uint32_t orig;
  static int which = 0;
  unsigned int extreme_ints[] = {
    _DBUS_INT_MAX,
    _DBUS_UINT_MAX,
    _DBUS_INT_MAX - 1,
    _DBUS_UINT_MAX - 1,
    _DBUS_INT_MAX - 2,
    _DBUS_UINT_MAX - 2,
    _DBUS_INT_MAX - 17,
    _DBUS_UINT_MAX - 17,
    _DBUS_INT_MAX / 2,
    _DBUS_INT_MAX / 3,
    _DBUS_UINT_MAX / 2,
    _DBUS_UINT_MAX / 3,
    0, 1, 2, 3,
    (unsigned int) -1,
    (unsigned int) -2,
    (unsigned int) -3
  };
    
  if (orig_data != mutated)
    {
      _dbus_string_set_length (mutated, 0);
      
      if (!_dbus_string_copy (orig_data, 0, mutated, 0))
        _dbus_assert_not_reached ("out of mem");
    }

  if (_dbus_string_get_length (mutated) < 12)
    return;
  
  d = _dbus_string_get_const_data (mutated);

  if (!(*d == DBUS_LITTLE_ENDIAN ||
        *d == DBUS_BIG_ENDIAN))
    return;

  byte_order = *d;
  
  i = random_int_in_range (4, _dbus_string_get_length (mutated) - 8);
  i = _DBUS_ALIGN_VALUE (i, 4);

  orig = _dbus_demarshal_uint32 (mutated, byte_order, i, NULL);

  which = random_int_in_range (0, _DBUS_N_ELEMENTS (extreme_ints));

  _dbus_assert (which >= 0);
  _dbus_assert (which < _DBUS_N_ELEMENTS (extreme_ints));
  
  _dbus_marshal_set_uint32 (mutated, byte_order, i,
                            extreme_ints[which]);
}
コード例 #2
0
static dbus_bool_t
generate_many_bodies_inner (DBusMessageDataIter *iter,
                            DBusMessage        **message_p)
{
  DBusMessage *message;
  DBusString signature;
  DBusString body;
  char byte_order;

  /* Keeping this small makes things go faster */
  message = dbus_message_new_method_call ("o.z.F",
                                          "/",
                                          "o.z.B",
                                          "Nah");
  if (message == NULL)
    _dbus_assert_not_reached ("oom");

  byte_order = _dbus_header_get_byte_order (&message->header);

  set_reply_serial (message);

  if (!_dbus_string_init (&signature) || !_dbus_string_init (&body))
    _dbus_assert_not_reached ("oom");
  
  if (dbus_internal_do_not_use_generate_bodies (iter_get_sequence (iter),
                                                byte_order,
                                                &signature, &body))
    {
      const char *v_SIGNATURE;

      v_SIGNATURE = _dbus_string_get_const_data (&signature);
      if (!_dbus_header_set_field_basic (&message->header,
                                         DBUS_HEADER_FIELD_SIGNATURE,
                                         DBUS_TYPE_SIGNATURE,
                                         &v_SIGNATURE))
        _dbus_assert_not_reached ("oom");

      if (!_dbus_string_move (&body, 0, &message->body, 0))
        _dbus_assert_not_reached ("oom");

      _dbus_marshal_set_uint32 (&message->header.data, BODY_LENGTH_OFFSET,
                                _dbus_string_get_length (&message->body),
                                byte_order);
      
      *message_p = message;
    }
  else
    {
      dbus_message_unref (message);
      *message_p = NULL;
    }
  
  _dbus_string_free (&signature);
  _dbus_string_free (&body);

  return *message_p != NULL;
}
コード例 #3
0
/**
 * Fills in the correct body length.
 *
 * @param header the header
 * @param body_len the length of the body
 */
void
_dbus_header_update_lengths (DBusHeader *header,
                             int         body_len)
{
  _dbus_marshal_set_uint32 (&header->data,
                            BODY_LENGTH_OFFSET,
                            body_len,
                            header->byte_order);
}
コード例 #4
0
/**
 * Sets the serial number of a header.  This can only be done once on
 * a header.
 *
 * @param header the header
 * @param serial the serial
 */
void
_dbus_header_set_serial (DBusHeader    *header,
                         dbus_uint32_t  serial)
{
  /* we use this function to set the serial on outgoing
   * messages, and to reset the serial in dbus_message_copy;
   * this assertion should catch a double-set on outgoing.
   */
  _dbus_assert (_dbus_header_get_serial (header) == 0 ||
                serial == 0);

  _dbus_marshal_set_uint32 (&header->data,
                            SERIAL_OFFSET,
			    serial,
                            header->byte_order);
}
コード例 #5
0
ファイル: break-loader.c プロジェクト: mirsal/dbus
static void
randomly_modify_length (const DBusString *orig_data,
                        DBusString       *mutated)
{
  int i;
  int byte_order;
  const char *d;
  dbus_uint32_t orig;
  int delta;
  
  if (orig_data != mutated)
    {
      _dbus_string_set_length (mutated, 0);
      
      if (!_dbus_string_copy (orig_data, 0, mutated, 0))
        _dbus_assert_not_reached ("out of mem");
    }

  if (_dbus_string_get_length (mutated) < 12)
    return;
  
  d = _dbus_string_get_const_data (mutated);

  if (!(*d == DBUS_LITTLE_ENDIAN ||
        *d == DBUS_BIG_ENDIAN))
    return;

  byte_order = *d;
  
  i = random_int_in_range (4, _dbus_string_get_length (mutated) - 8);
  i = _DBUS_ALIGN_VALUE (i, 4);

  orig = _dbus_demarshal_uint32 (mutated, byte_order, i, NULL);

  delta = random_int_in_range (-10, 10);  
  
  _dbus_marshal_set_uint32 (mutated, byte_order, i,
                            (unsigned) (orig + delta));
}
コード例 #6
0
static dbus_bool_t
generate_wrong_length (DBusMessageDataIter *iter,
                       DBusString          *data,
                       DBusValidity        *expected_validity)
{
  int lengths[] = { -42, -17, -16, -15, -9, -8, -7, -6, -5, -4, -3, -2, -1,
                    1, 2, 3, 4, 5, 6, 7, 8, 9, 15, 16, 30 };
  int adjust;
  int len_seq;

 restart:
  len_seq = iter_get_sequence (iter);
  if (len_seq == _DBUS_N_ELEMENTS (lengths))
    return FALSE;

  _dbus_assert (len_seq < _DBUS_N_ELEMENTS (lengths));
  
  iter_recurse (iter);
  if (!generate_many_bodies (iter, data, expected_validity))
    {
      iter_set_sequence (iter, 0); /* reset to first body */
      iter_unrecurse (iter);
      iter_next (iter);            /* next length adjustment */
      goto restart;
    }
  iter_unrecurse (iter);

  adjust = lengths[len_seq];

  if (adjust < 0)
    {
      if ((_dbus_string_get_length (data) + adjust) < DBUS_MINIMUM_HEADER_SIZE)
        _dbus_string_set_length (data, DBUS_MINIMUM_HEADER_SIZE);
      else
        _dbus_string_shorten (data, - adjust);
      *expected_validity = DBUS_INVALID_FOR_UNKNOWN_REASON;
    }
  else
    {      
      if (!_dbus_string_lengthen (data, adjust))
        _dbus_assert_not_reached ("oom");
      *expected_validity = DBUS_INVALID_TOO_MUCH_DATA;
    }

  /* Fixup lengths */
  {
    int old_body_len;
    int new_body_len;
    int byte_order;
    
    _dbus_assert (_dbus_string_get_length (data) >= DBUS_MINIMUM_HEADER_SIZE);
    
    byte_order = _dbus_string_get_byte (data, BYTE_ORDER_OFFSET);
    old_body_len = _dbus_marshal_read_uint32 (data,
                                              BODY_LENGTH_OFFSET,
                                              byte_order,
                                              NULL);
    _dbus_assert (old_body_len < _dbus_string_get_length (data));
    new_body_len = old_body_len + adjust;
    if (new_body_len < 0)
      {
        new_body_len = 0;
        /* we just munged the header, and aren't sure how */
        *expected_validity = DBUS_VALIDITY_UNKNOWN;
      }

    _dbus_verbose ("changing body len from %u to %u by adjust %d\n",
                   old_body_len, new_body_len, adjust);
    
    _dbus_marshal_set_uint32 (data, BODY_LENGTH_OFFSET,
                              new_body_len,
                              byte_order);
  }

  return TRUE;
}
コード例 #7
0
static dbus_bool_t
generate_special (DBusMessageDataIter   *iter,
                  DBusString            *data,
                  DBusValidity          *expected_validity)
{
  int item_seq;
  DBusMessage *message;
  int pos;
  dbus_int32_t v_INT32;

  _dbus_assert (_dbus_string_get_length (data) == 0);
  
  message = NULL;
  pos = -1;
  v_INT32 = 42;
  item_seq = iter_get_sequence (iter);

  if (item_seq == 0)
    {
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");
                                     
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);
      
      /* set an invalid typecode */
      _dbus_string_set_byte (data, pos + 1, '$');

      *expected_validity = DBUS_INVALID_UNKNOWN_TYPECODE;
    }
  else if (item_seq == 1)
    {
      char long_sig[DBUS_MAXIMUM_TYPE_RECURSION_DEPTH+2];
      const char *v_STRING;
      int i;
      
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");

      i = 0;
      while (i < (DBUS_MAXIMUM_TYPE_RECURSION_DEPTH + 1))
        {
          long_sig[i] = DBUS_TYPE_ARRAY;
          ++i;
        }
      long_sig[i] = DBUS_TYPE_INVALID;

      v_STRING = long_sig;
      if (!_dbus_header_set_field_basic (&message->header,
                                         DBUS_HEADER_FIELD_SIGNATURE,
                                         DBUS_TYPE_SIGNATURE,
                                         &v_STRING))
        _dbus_assert_not_reached ("oom");
      
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);
      
      *expected_validity = DBUS_INVALID_EXCEEDED_MAXIMUM_ARRAY_RECURSION;
    }
  else if (item_seq == 2)
    {
      char long_sig[DBUS_MAXIMUM_TYPE_RECURSION_DEPTH*2+4];
      const char *v_STRING;
      int i;
      
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");

      i = 0;
      while (i <= (DBUS_MAXIMUM_TYPE_RECURSION_DEPTH + 1))
        {
          long_sig[i] = DBUS_STRUCT_BEGIN_CHAR;
          ++i;
        }

      long_sig[i] = DBUS_TYPE_INT32;
      ++i;

      while (i < (DBUS_MAXIMUM_TYPE_RECURSION_DEPTH*2 + 3))
        {
          long_sig[i] = DBUS_STRUCT_END_CHAR;
          ++i;
        }
      long_sig[i] = DBUS_TYPE_INVALID;
      
      v_STRING = long_sig;
      if (!_dbus_header_set_field_basic (&message->header,
                                         DBUS_HEADER_FIELD_SIGNATURE,
                                         DBUS_TYPE_SIGNATURE,
                                         &v_STRING))
        _dbus_assert_not_reached ("oom");
      
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);
      
      *expected_validity = DBUS_INVALID_EXCEEDED_MAXIMUM_STRUCT_RECURSION;
    }
  else if (item_seq == 3)
    {
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");
                                     
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);
      
      _dbus_string_set_byte (data, pos + 1, DBUS_STRUCT_BEGIN_CHAR);
      
      *expected_validity = DBUS_INVALID_STRUCT_STARTED_BUT_NOT_ENDED;
    }
  else if (item_seq == 4)
    {
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");
                                     
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);
      
      _dbus_string_set_byte (data, pos + 1, DBUS_STRUCT_END_CHAR);
      
      *expected_validity = DBUS_INVALID_STRUCT_ENDED_BUT_NOT_STARTED;
    }
  else if (item_seq == 5)
    {
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");
                                     
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);
      
      _dbus_string_set_byte (data, pos + 1, DBUS_STRUCT_BEGIN_CHAR);
      _dbus_string_set_byte (data, pos + 2, DBUS_STRUCT_END_CHAR);
      
      *expected_validity = DBUS_INVALID_STRUCT_HAS_NO_FIELDS;
    }
  else if (item_seq == 6)
    {
      message = simple_method_call ();
      generate_from_message (data, expected_validity, message);
      
      _dbus_string_set_byte (data, TYPE_OFFSET, DBUS_MESSAGE_TYPE_INVALID);
      
      *expected_validity = DBUS_INVALID_BAD_MESSAGE_TYPE;
    }
  else if (item_seq == 7)
    {
      /* Messages of unknown type are considered valid */
      message = simple_method_call ();
      generate_from_message (data, expected_validity, message);
      
      _dbus_string_set_byte (data, TYPE_OFFSET, 100);
      
      *expected_validity = DBUS_VALID;
    }
  else if (item_seq == 8)
    {
      char byte_order;

      message = simple_method_call ();
      byte_order = _dbus_header_get_byte_order (&message->header);
      generate_from_message (data, expected_validity, message);
      
      _dbus_marshal_set_uint32 (data, BODY_LENGTH_OFFSET,
                                DBUS_MAXIMUM_MESSAGE_LENGTH / 2 + 4,
                                byte_order);
      _dbus_marshal_set_uint32 (data, FIELDS_ARRAY_LENGTH_OFFSET,
                                DBUS_MAXIMUM_MESSAGE_LENGTH / 2 + 4,
                                byte_order);
      *expected_validity = DBUS_INVALID_MESSAGE_TOO_LONG;
    }
  else if (item_seq == 9)
    {
      const char *v_STRING = "not a valid bus name";
      message = simple_method_call ();

      if (!_dbus_header_set_field_basic (&message->header,
                                         DBUS_HEADER_FIELD_SENDER,
                                         DBUS_TYPE_STRING, &v_STRING))
        _dbus_assert_not_reached ("oom");
      
      generate_from_message (data, expected_validity, message);

      *expected_validity = DBUS_INVALID_BAD_SENDER;
    }
  else if (item_seq == 10)
    {
      message = simple_method_call ();

      if (!dbus_message_set_interface (message, DBUS_INTERFACE_LOCAL))
        _dbus_assert_not_reached ("oom");
      
      generate_from_message (data, expected_validity, message);

      *expected_validity = DBUS_INVALID_USES_LOCAL_INTERFACE;
    }
  else if (item_seq == 11)
    {
      message = simple_method_call ();

      if (!dbus_message_set_path (message, DBUS_PATH_LOCAL))
        _dbus_assert_not_reached ("oom");
      
      generate_from_message (data, expected_validity, message);

      *expected_validity = DBUS_INVALID_USES_LOCAL_PATH;
    }
  else if (item_seq == 12)
    {
      /* Method calls don't have to have interface */
      message = simple_method_call ();

      if (!dbus_message_set_interface (message, NULL))
        _dbus_assert_not_reached ("oom");
      
      generate_from_message (data, expected_validity, message);
      
      *expected_validity = DBUS_VALID;
    }
  else if (item_seq == 13)
    {
      /* Signals require an interface */
      message = simple_signal ();

      if (!dbus_message_set_interface (message, NULL))
        _dbus_assert_not_reached ("oom");
      
      generate_from_message (data, expected_validity, message);
      
      *expected_validity = DBUS_INVALID_MISSING_INTERFACE;
    }
  else if (item_seq == 14)
    {
      message = simple_method_return ();

      if (!_dbus_header_delete_field (&message->header, DBUS_HEADER_FIELD_REPLY_SERIAL))
        _dbus_assert_not_reached ("oom");
      
      generate_from_message (data, expected_validity, message);
      
      *expected_validity = DBUS_INVALID_MISSING_REPLY_SERIAL;
    }
  else if (item_seq == 15)
    {
      message = simple_error ();

      if (!dbus_message_set_error_name (message, NULL))
        _dbus_assert_not_reached ("oom");
      
      generate_from_message (data, expected_validity, message);
      
      *expected_validity = DBUS_INVALID_MISSING_ERROR_NAME;
    }
  else if (item_seq == 16)
    {
      char long_sig[DBUS_MAXIMUM_TYPE_RECURSION_DEPTH*4+10];
      const char *v_STRING;
      int i;
      int n_begins;
      
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");

      i = 0;
      while (i <= (DBUS_MAXIMUM_TYPE_RECURSION_DEPTH*3 + 3))
        {
          long_sig[i] = DBUS_TYPE_ARRAY;
          ++i;
          long_sig[i] = DBUS_DICT_ENTRY_BEGIN_CHAR;
          ++i;
          long_sig[i] = DBUS_TYPE_INT32;
          ++i;
        }
      n_begins = i / 3;

      long_sig[i] = DBUS_TYPE_INT32;
      ++i;
      
      while (n_begins > 0)
        {
          long_sig[i] = DBUS_DICT_ENTRY_END_CHAR;
          ++i;
          n_begins -= 1;
        }
      long_sig[i] = DBUS_TYPE_INVALID;
      
      v_STRING = long_sig;
      if (!_dbus_header_set_field_basic (&message->header,
                                         DBUS_HEADER_FIELD_SIGNATURE,
                                         DBUS_TYPE_SIGNATURE,
                                         &v_STRING))
        _dbus_assert_not_reached ("oom");
      
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);
      
      *expected_validity = DBUS_INVALID_EXCEEDED_MAXIMUM_DICT_ENTRY_RECURSION;
    }
  else if (item_seq == 17)
    {
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");
                                     
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);

      _dbus_string_set_byte (data, pos + 1, DBUS_TYPE_ARRAY);
      _dbus_string_set_byte (data, pos + 2, DBUS_DICT_ENTRY_BEGIN_CHAR);
      
      *expected_validity = DBUS_INVALID_DICT_ENTRY_STARTED_BUT_NOT_ENDED;
    }
  else if (item_seq == 18)
    {
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");
                                     
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);
      
      _dbus_string_set_byte (data, pos + 1, DBUS_DICT_ENTRY_END_CHAR);
      
      *expected_validity = DBUS_INVALID_DICT_ENTRY_ENDED_BUT_NOT_STARTED;
    }
  else if (item_seq == 19)
    {
      message = simple_method_call ();
      if (!dbus_message_append_args (message,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INT32, &v_INT32,
                                     DBUS_TYPE_INVALID))
        _dbus_assert_not_reached ("oom");
                                     
      _dbus_header_get_field_raw (&message->header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  NULL, &pos);
      generate_from_message (data, expected_validity, message);

      _dbus_string_set_byte (data, pos + 1, DBUS_TYPE_ARRAY);
      _dbus_string_set_byte (data, pos + 2, DBUS_DICT_ENTRY_BEGIN_CHAR);
      _dbus_string_set_byte (data, pos + 3, DBUS_DICT_ENTRY_END_CHAR);
      
      *expected_validity = DBUS_INVALID_DICT_ENTRY_HAS_NO_FIELDS;
    }
  else if (item_seq == 20)
    {
      /* 64 levels of nesting is OK */
      message = message_with_nesting_levels(64);

      generate_from_message (data, expected_validity, message);

      *expected_validity = DBUS_VALID;
    }
  else if (item_seq == 21)
    {
      /* 65 levels of nesting is not OK */
      message = message_with_nesting_levels(65);

      generate_from_message (data, expected_validity, message);

      *expected_validity = DBUS_INVALID_NESTED_TOO_DEEPLY;
    }
  else
    {
      return FALSE;
    }

  if (message)
    dbus_message_unref (message);

  iter_next (iter);
  return TRUE;
}
コード例 #8
0
static dbus_bool_t
generate_uint32_changed (DBusMessageDataIter *iter,
                         DBusString          *data,
                         DBusValidity        *expected_validity)
{
  int body_seq;
  int byte_seq;
  int change_seq;
  dbus_uint32_t v_UINT32;
  int byte_order;
  const UIntChange *change;
  int base_depth;

  /* Outer loop is each body, next loop is each change,
   * inner loop is each change location
   */

  base_depth = iter->depth;
  
 next_body:
  _dbus_assert (iter->depth == (base_depth + 0));
  _dbus_string_set_length (data, 0);
  body_seq = iter_get_sequence (iter);
  
  if (!generate_many_bodies (iter, data, expected_validity))
    return FALSE;

  _dbus_assert (iter->depth == (base_depth + 0));

  iter_set_sequence (iter, body_seq); /* undo the "next" from generate_many_bodies */
  iter_recurse (iter);
 next_change:
  _dbus_assert (iter->depth == (base_depth + 1));
  change_seq = iter_get_sequence (iter);
  
  if (change_seq == _DBUS_N_ELEMENTS (uint32_changes))
    {
      /* Reset change count */
      iter_set_sequence (iter, 0);
      iter_unrecurse (iter);
      iter_next (iter);
      goto next_body;
    }

  _dbus_assert (iter->depth == (base_depth + 1));
  
  iter_recurse (iter);
  _dbus_assert (iter->depth == (base_depth + 2));
  byte_seq = iter_get_sequence (iter);
  /* skip 4 bytes at a time */
  iter_next (iter);
  iter_next (iter);
  iter_next (iter);
  iter_next (iter);
  iter_unrecurse (iter);

  _dbus_assert (_DBUS_ALIGN_VALUE (byte_seq, 4) == (unsigned) byte_seq);
  if (byte_seq >= (_dbus_string_get_length (data) - 4))
    {
      /* reset byte count */
      _dbus_assert (iter->depth == (base_depth + 1));
      iter_recurse (iter);
      _dbus_assert (iter->depth == (base_depth + 2));
      iter_set_sequence (iter, 0);
      iter_unrecurse (iter);
      _dbus_assert (iter->depth == (base_depth + 1));
      iter_next (iter);
      goto next_change;
    }
  
  _dbus_assert (byte_seq <= (_dbus_string_get_length (data) - 4));

  byte_order = _dbus_string_get_byte (data, BYTE_ORDER_OFFSET);
  
  v_UINT32 = _dbus_marshal_read_uint32 (data, byte_seq, byte_order, NULL);

  change = &uint32_changes[change_seq];

  if (change->type == CHANGE_TYPE_ADJUST)
    {
      v_UINT32 += (int) change->value;
    }
  else
    {
      v_UINT32 = change->value;
    }

#if 0
  printf ("body %d change %d pos %d ",
          body_seq, change_seq, byte_seq);

  if (change->type == CHANGE_TYPE_ADJUST)
    printf ("adjust by %d", (int) change->value);
  else
    printf ("set to %u", change->value);
  
  printf (" \t%u -> %u\n",
          _dbus_marshal_read_uint32 (data, byte_seq, byte_order, NULL),
          v_UINT32);
#endif
  
  _dbus_marshal_set_uint32 (data, byte_seq, v_UINT32, byte_order);
  *expected_validity = DBUS_VALIDITY_UNKNOWN;

  _dbus_assert (iter->depth == (base_depth + 1));
  iter_unrecurse (iter);
  _dbus_assert (iter->depth == (base_depth + 0));
          
  return TRUE;
}