dbus-marshal-byteswap.c 7.5 KB
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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
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/* dbus-marshal-byteswap.c  Swap a block of marshaled data
 *
 * Copyright (C) 2005 Red Hat, Inc.
 *
 * Licensed under the Academic Free License version 2.1
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
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 *
 */

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#include <config.h>
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#include "dbus-marshal-byteswap.h"
#include "dbus-marshal-basic.h"
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#include "dbus-signature.h"
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/**
 * @addtogroup DBusMarshal
 * @{
 */

static void
byteswap_body_helper (DBusTypeReader       *reader,
                      dbus_bool_t           walk_reader_to_end,
                      int                   old_byte_order,
                      int                   new_byte_order,
                      unsigned char        *p,
                      unsigned char       **new_p)
{
  int current_type;

  while ((current_type = _dbus_type_reader_get_current_type (reader)) != DBUS_TYPE_INVALID)
    {
      switch (current_type)
        {
        case DBUS_TYPE_BYTE:
          ++p;
          break;

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        case DBUS_TYPE_INT16:
        case DBUS_TYPE_UINT16:
          {
            p = _DBUS_ALIGN_ADDRESS (p, 2);
            *((dbus_uint16_t*)p) = DBUS_UINT16_SWAP_LE_BE (*((dbus_uint16_t*)p));
            p += 2;
          }
          break;
          
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        case DBUS_TYPE_BOOLEAN:
        case DBUS_TYPE_INT32:
        case DBUS_TYPE_UINT32:
          {
            p = _DBUS_ALIGN_ADDRESS (p, 4);
            *((dbus_uint32_t*)p) = DBUS_UINT32_SWAP_LE_BE (*((dbus_uint32_t*)p));
            p += 4;
          }
          break;
          
        case DBUS_TYPE_INT64:
        case DBUS_TYPE_UINT64:
        case DBUS_TYPE_DOUBLE:
          {
            p = _DBUS_ALIGN_ADDRESS (p, 8);
#ifdef DBUS_HAVE_INT64
            *((dbus_uint64_t*)p) = DBUS_UINT64_SWAP_LE_BE (*((dbus_uint64_t*)p));
#else
            _dbus_swap_array (p, 1, 8);
#endif
            p += 8;
          }
          break;

        case DBUS_TYPE_ARRAY:
        case DBUS_TYPE_STRING:
        case DBUS_TYPE_OBJECT_PATH:
          {
            dbus_uint32_t array_len;
            
            p = _DBUS_ALIGN_ADDRESS (p, 4);

            array_len = _dbus_unpack_uint32 (old_byte_order, p);
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            *((dbus_uint32_t*)p) = DBUS_UINT32_SWAP_LE_BE (*((dbus_uint32_t*)p));
            p += 4;

            if (current_type == DBUS_TYPE_ARRAY)
              {
                int elem_type;
                int alignment;

                elem_type = _dbus_type_reader_get_element_type (reader);
                alignment = _dbus_type_get_alignment (elem_type);

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		_dbus_assert ((array_len / alignment) < DBUS_MAXIMUM_ARRAY_LENGTH);

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                p = _DBUS_ALIGN_ADDRESS (p, alignment);
                
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                if (dbus_type_is_fixed (elem_type))
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                  {
                    if (alignment > 1)
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		      _dbus_swap_array (p, array_len / alignment, alignment);
		    p += array_len;
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                  }
                else
                  {
                    DBusTypeReader sub;
                    const unsigned char *array_end;

                    array_end = p + array_len;
                    
                    _dbus_type_reader_recurse (reader, &sub);

                    while (p < array_end)
                      {
                        byteswap_body_helper (&sub,
                                              FALSE,
                                              old_byte_order,
                                              new_byte_order,
                                              p, &p);
                      }
                  }
              }
            else
              {
                _dbus_assert (current_type == DBUS_TYPE_STRING ||
                              current_type == DBUS_TYPE_OBJECT_PATH);
                
                p += (array_len + 1); /* + 1 for nul */
              }
          }
          break;

        case DBUS_TYPE_SIGNATURE:
          {
            dbus_uint32_t sig_len;

            sig_len = *p;
            
            p += (sig_len + 2); /* +2 for len and nul */
          }
          break;

        case DBUS_TYPE_VARIANT:
          {
            /* 1 byte sig len, sig typecodes, align to
             * contained-type-boundary, values.
             */
            dbus_uint32_t sig_len;
            DBusString sig;
            DBusTypeReader sub;
            int contained_alignment;

            sig_len = *p;
            ++p;

            _dbus_string_init_const_len (&sig, p, sig_len);

            p += (sig_len + 1); /* 1 for nul */

            contained_alignment = _dbus_type_get_alignment (_dbus_first_type_in_signature (&sig, 0));
            
            p = _DBUS_ALIGN_ADDRESS (p, contained_alignment);

            _dbus_type_reader_init_types_only (&sub, &sig, 0);

            byteswap_body_helper (&sub, FALSE, old_byte_order, new_byte_order, p, &p);
          }
          break;

        case DBUS_TYPE_STRUCT:
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        case DBUS_TYPE_DICT_ENTRY:
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          {
            DBusTypeReader sub;

            p = _DBUS_ALIGN_ADDRESS (p, 8);
            
            _dbus_type_reader_recurse (reader, &sub);
            
            byteswap_body_helper (&sub, TRUE, old_byte_order, new_byte_order, p, &p);
          }
          break;

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        case DBUS_TYPE_UNIX_FD:
          /* fds can only be passed on a local machine, so byte order must always match */
          _dbus_assert_not_reached("attempted to byteswap unix fds which makes no sense");
          break;

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        default:
          _dbus_assert_not_reached ("invalid typecode in supposedly-validated signature");
          break;
        }

      if (walk_reader_to_end)
        _dbus_type_reader_next (reader);
      else
        break;
    }

  if (new_p)
    *new_p = p;
}

/**
 * Byteswaps the marshaled data in the given value_str.
 *
 * @param signature the types in the value_str
 * @param signature_start where in signature is the signature
 * @param old_byte_order the old byte order
 * @param new_byte_order the new byte order
 * @param value_str the string containing the body
 * @param value_pos where the values start
 */
void
_dbus_marshal_byteswap (const DBusString *signature,
                        int               signature_start,
                        int               old_byte_order,
                        int               new_byte_order,
                        DBusString       *value_str,
                        int               value_pos)
{
  DBusTypeReader reader;

  _dbus_assert (value_pos >= 0);
  _dbus_assert (value_pos <= _dbus_string_get_length (value_str));

  if (old_byte_order == new_byte_order)
    return;
  
  _dbus_type_reader_init_types_only (&reader,
                                     signature, signature_start);

  byteswap_body_helper (&reader, TRUE,
                        old_byte_order, new_byte_order,
                        _dbus_string_get_data_len (value_str, value_pos, 0),
                        NULL);
}

/** @} */

/* Tests in dbus-marshal-byteswap-util.c */