dbus-message.c

/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-message.c  DBusMessage object
 *
 * Copyright (C) 2002, 2003, 2004, 2005  Red Hat Inc.
 * Copyright (C) 2002, 2003  CodeFactory AB
 *
 * 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
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include <config.h>
#include "dbus-internals.h"
#include "dbus-marshal-recursive.h"
#include "dbus-marshal-validate.h"
#include "dbus-marshal-byteswap.h"
#include "dbus-marshal-header.h"
#include "dbus-signature.h"
#include "dbus-message-private.h"
#include "dbus-object-tree.h"
#include "dbus-memory.h"
#include "dbus-list.h"
#include "dbus-threads-internal.h"
#ifdef HAVE_UNIX_FD_PASSING
#include "dbus-sysdeps.h"
#include "dbus-sysdeps-unix.h"
#endif

#include <string.h>

#define _DBUS_TYPE_IS_STRINGLIKE(type) \
  (type == DBUS_TYPE_STRING || type == DBUS_TYPE_SIGNATURE || \
   type == DBUS_TYPE_OBJECT_PATH)

static void dbus_message_finalize (DBusMessage *message);

#ifdef DBUS_BUILD_TESTS
static dbus_bool_t
_dbus_enable_message_cache (void)
{
  static int enabled = -1;

  if (enabled < 0)
    {
      const char *s = _dbus_getenv ("DBUS_MESSAGE_CACHE");

      enabled = TRUE;

      if (s && *s)
        {
          if (*s == '0')
            enabled = FALSE;
          else if (*s == '1')
            enabled = TRUE;
          else
            _dbus_warn ("DBUS_MESSAGE_CACHE should be 0 or 1 if set, not '%s'",
                s);
        }
    }

  return enabled;
}
#else
    /* constant expression, should be optimized away */
#   define _dbus_enable_message_cache() (TRUE)
#endif

#ifndef _dbus_message_trace_ref
void
_dbus_message_trace_ref (DBusMessage *message,
                         int          old_refcount,
                         int          new_refcount,
                         const char  *why)
{
  static int enabled = -1;

  _dbus_trace_ref ("DBusMessage", message, old_refcount, new_refcount, why,
      "DBUS_MESSAGE_TRACE", &enabled);
}
#endif

/* Not thread locked, but strictly const/read-only so should be OK
 */
_DBUS_STRING_DEFINE_STATIC(_dbus_empty_signature_str,  "");

/* these have wacky values to help trap uninitialized iterators;
 * but has to fit in 3 bits
 */
enum {
  DBUS_MESSAGE_ITER_TYPE_READER = 3,
  DBUS_MESSAGE_ITER_TYPE_WRITER = 7
};

typedef struct DBusMessageRealIter DBusMessageRealIter;

struct DBusMessageRealIter
{
  DBusMessage *message; 
  dbus_uint32_t changed_stamp : CHANGED_STAMP_BITS; 
  dbus_uint32_t iter_type : 3;      
  dbus_uint32_t sig_refcount : 8;   
  union
  {
    DBusTypeWriter writer; 
    DBusTypeReader reader; 
  } u; 
};

static void
get_const_signature (DBusHeader        *header,
                     const DBusString **type_str_p,
                     int               *type_pos_p)
{
  if (_dbus_header_get_field_raw (header,
                                  DBUS_HEADER_FIELD_SIGNATURE,
                                  type_str_p,
                                  type_pos_p))
    {
      *type_pos_p += 1; /* skip the signature length which is 1 byte */
    }
  else
    {
      *type_str_p = &_dbus_empty_signature_str;
      *type_pos_p = 0;
    }
}

static void
_dbus_message_byteswap (DBusMessage *message)
{
  const DBusString *type_str;
  int type_pos;
  char byte_order;

  byte_order = _dbus_header_get_byte_order (&message->header);

  if (byte_order == DBUS_COMPILER_BYTE_ORDER)
    return;

  _dbus_verbose ("Swapping message into compiler byte order\n");
  
  get_const_signature (&message->header, &type_str, &type_pos);
  
  _dbus_marshal_byteswap (type_str, type_pos,
                          byte_order,
                          DBUS_COMPILER_BYTE_ORDER,
                          &message->body, 0);

  _dbus_header_byteswap (&message->header, DBUS_COMPILER_BYTE_ORDER);
  _dbus_assert (_dbus_header_get_byte_order (&message->header) ==
                DBUS_COMPILER_BYTE_ORDER);
}

#define ensure_byte_order(message) _dbus_message_byteswap (message)

void
_dbus_message_get_network_data (DBusMessage          *message,
                                const DBusString    **header,
                                const DBusString    **body)
{
  _dbus_assert (message->locked);

  *header = &message->header.data;
  *body = &message->body;
}

void _dbus_message_get_unix_fds(DBusMessage *message,
                                const int  **fds,
                                unsigned    *n_fds)
{
  _dbus_assert (message->locked);

#ifdef HAVE_UNIX_FD_PASSING
  *fds = message->unix_fds;
  *n_fds = message->n_unix_fds;
#else
  *fds = NULL;
  *n_fds = 0;
#endif
}

void 
dbus_message_set_serial (DBusMessage   *message,
                         dbus_uint32_t  serial)
{
  _dbus_return_if_fail (message != NULL);
  _dbus_return_if_fail (!message->locked);

  _dbus_header_set_serial (&message->header, serial);
}

void
_dbus_message_add_counter_link (DBusMessage  *message,
                                DBusList     *link)
{
  /* right now we don't recompute the delta when message
   * size changes, and that's OK for current purposes
   * I think, but could be important to change later.
   * Do recompute it whenever there are no outstanding counters,
   * since it's basically free.
   */
  if (message->counters == NULL)
    {
      message->size_counter_delta =
        _dbus_string_get_length (&message->header.data) +
        _dbus_string_get_length (&message->body);

#ifdef HAVE_UNIX_FD_PASSING
      message->unix_fd_counter_delta = message->n_unix_fds;
#endif

#if 0
      _dbus_verbose ("message has size %ld\n",
                     message->size_counter_delta);
#endif
    }

  _dbus_list_append_link (&message->counters, link);

  _dbus_counter_adjust_size (link->data, message->size_counter_delta);

#ifdef HAVE_UNIX_FD_PASSING
  _dbus_counter_adjust_unix_fd (link->data, message->unix_fd_counter_delta);
#endif
}

dbus_bool_t
_dbus_message_add_counter (DBusMessage *message,
                           DBusCounter *counter)
{
  DBusList *link;

  link = _dbus_list_alloc_link (counter);
  if (link == NULL)
    return FALSE;

  _dbus_counter_ref (counter);
  _dbus_message_add_counter_link (message, link);

  return TRUE;
}

void
_dbus_message_remove_counter (DBusMessage  *message,
                              DBusCounter  *counter)
{
  DBusList *link;

  link = _dbus_list_find_last (&message->counters,
                               counter);
  _dbus_assert (link != NULL);

  _dbus_list_remove_link (&message->counters, link);

  _dbus_counter_adjust_size (counter, - message->size_counter_delta);

#ifdef HAVE_UNIX_FD_PASSING
  _dbus_counter_adjust_unix_fd (counter, - message->unix_fd_counter_delta);
#endif

  _dbus_counter_notify (counter);
  _dbus_counter_unref (counter);
}

void
dbus_message_lock (DBusMessage  *message)
{
  if (!message->locked)
    {
      _dbus_header_update_lengths (&message->header,
                                   _dbus_string_get_length (&message->body));

      /* must have a signature if you have a body */
      _dbus_assert (_dbus_string_get_length (&message->body) == 0 ||
                    dbus_message_get_signature (message) != NULL);

      message->locked = TRUE;
    }
}

static dbus_bool_t
set_or_delete_string_field (DBusMessage *message,
                            int          field,
                            int          typecode,
                            const char  *value)
{
  if (value == NULL)
    return _dbus_header_delete_field (&message->header, field);
  else
    return _dbus_header_set_field_basic (&message->header,
                                         field,
                                         typecode,
                                         &value);
}

#if 0
/* Probably we don't need to use this */
static dbus_bool_t
_dbus_message_set_signature (DBusMessage *message,
                             const char  *signature)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (!message->locked, FALSE);
  _dbus_return_val_if_fail (signature == NULL ||
                            _dbus_check_is_valid_signature (signature));
  /* can't delete the signature if you have a message body */
  _dbus_return_val_if_fail (_dbus_string_get_length (&message->body) == 0 ||
                            signature != NULL);

  return set_or_delete_string_field (message,
                                     DBUS_HEADER_FIELD_SIGNATURE,
                                     DBUS_TYPE_SIGNATURE,
                                     signature);
}
#endif

/* Message Cache
 *
 * We cache some DBusMessage to reduce the overhead of allocating
 * them.  In my profiling this consistently made about an 8%
 * difference.  It avoids the malloc for the message, the malloc for
 * the slot list, the malloc for the header string and body string,
 * and the associated free() calls. It does introduce another global
 * lock which could be a performance issue in certain cases.
 *
 * For the echo client/server the round trip time goes from around
 * .000077 to .000069 with the message cache on my laptop. The sysprof
 * change is as follows (numbers are cumulative percentage):
 *
 *  with message cache implemented as array as it is now (0.000069 per):
 *    new_empty_header           1.46
 *      mutex_lock               0.56    # i.e. _DBUS_LOCK(message_cache)
 *      mutex_unlock             0.25
 *      self                     0.41
 *    unref                      2.24
 *      self                     0.68
 *      list_clear               0.43
 *      mutex_lock               0.33    # i.e. _DBUS_LOCK(message_cache)
 *      mutex_unlock             0.25
 *
 *  with message cache implemented as list (0.000070 per roundtrip):
 *    new_empty_header           2.72
 *      list_pop_first           1.88
 *    unref                      3.3
 *      list_prepend             1.63
 *
 * without cache (0.000077 per roundtrip):
 *    new_empty_header           6.7
 *      string_init_preallocated 3.43
 *        dbus_malloc            2.43
 *      dbus_malloc0             2.59
 *
 *    unref                      4.02
 *      string_free              1.82
 *        dbus_free              1.63
 *      dbus_free                0.71
 *
 * If you implement the message_cache with a list, the primary reason
 * it's slower is that you add another thread lock (on the DBusList
 * mempool).
 */

#define MAX_MESSAGE_SIZE_TO_CACHE 10 * _DBUS_ONE_KILOBYTE

#define MAX_MESSAGE_CACHE_SIZE    5

_DBUS_DEFINE_GLOBAL_LOCK (message_cache);
static DBusMessage *message_cache[MAX_MESSAGE_CACHE_SIZE];
static int message_cache_count = 0;
static dbus_bool_t message_cache_shutdown_registered = FALSE;

static void
dbus_message_cache_shutdown (void *data)
{
  int i;

  _DBUS_LOCK (message_cache);

  i = 0;
  while (i < MAX_MESSAGE_CACHE_SIZE)
    {
      if (message_cache[i])
        dbus_message_finalize (message_cache[i]);

      ++i;
    }

  message_cache_count = 0;
  message_cache_shutdown_registered = FALSE;

  _DBUS_UNLOCK (message_cache);
}

static DBusMessage*
dbus_message_get_cached (void)
{
  DBusMessage *message;
  int i;

  message = NULL;

  _DBUS_LOCK (message_cache);

  _dbus_assert (message_cache_count >= 0);

  if (message_cache_count == 0)
    {
      _DBUS_UNLOCK (message_cache);
      return NULL;
    }

  /* This is not necessarily true unless count > 0, and
   * message_cache is uninitialized until the shutdown is
   * registered
   */
  _dbus_assert (message_cache_shutdown_registered);

  i = 0;
  while (i < MAX_MESSAGE_CACHE_SIZE)
    {
      if (message_cache[i])
        {
          message = message_cache[i];
          message_cache[i] = NULL;
          message_cache_count -= 1;
          break;
        }
      ++i;
    }
  _dbus_assert (message_cache_count >= 0);
  _dbus_assert (i < MAX_MESSAGE_CACHE_SIZE);
  _dbus_assert (message != NULL);

  _dbus_assert (_dbus_atomic_get (&message->refcount) == 0);

  _dbus_assert (message->counters == NULL);
  
  _DBUS_UNLOCK (message_cache);

  return message;
}

#ifdef HAVE_UNIX_FD_PASSING
static void
close_unix_fds(int *fds, unsigned *n_fds)
{
  DBusError e;
  int i;

  if (*n_fds <= 0)
    return;

  dbus_error_init(&e);

  for (i = 0; i < *n_fds; i++)
    {
      if (!_dbus_close(fds[i], &e))
        {
          _dbus_warn("Failed to close file descriptor: %s\n", e.message);
          dbus_error_free(&e);
        }
    }

  *n_fds = 0;

  /* We don't free the array here, in case we can recycle it later */
}
#endif

static void
free_counter (void *element,
              void *data)
{
  DBusCounter *counter = element;
  DBusMessage *message = data;

  _dbus_counter_adjust_size (counter, - message->size_counter_delta);
#ifdef HAVE_UNIX_FD_PASSING
  _dbus_counter_adjust_unix_fd (counter, - message->unix_fd_counter_delta);
#endif

  _dbus_counter_notify (counter);
  _dbus_counter_unref (counter);
}

static void
dbus_message_cache_or_finalize (DBusMessage *message)
{
  dbus_bool_t was_cached;
  int i;

  _dbus_assert (_dbus_atomic_get (&message->refcount) == 0);

  /* This calls application code and has to be done first thing
   * without holding the lock
   */
  _dbus_data_slot_list_clear (&message->slot_list);

  _dbus_list_foreach (&message->counters,
                      free_counter, message);
  _dbus_list_clear (&message->counters);

#ifdef HAVE_UNIX_FD_PASSING
  close_unix_fds(message->unix_fds, &message->n_unix_fds);
#endif

  was_cached = FALSE;

  _DBUS_LOCK (message_cache);

  if (!message_cache_shutdown_registered)
    {
      _dbus_assert (message_cache_count == 0);

      if (!_dbus_register_shutdown_func (dbus_message_cache_shutdown, NULL))
        goto out;

      i = 0;
      while (i < MAX_MESSAGE_CACHE_SIZE)
        {
          message_cache[i] = NULL;
          ++i;
        }

      message_cache_shutdown_registered = TRUE;
    }

  _dbus_assert (message_cache_count >= 0);

  if (!_dbus_enable_message_cache ())
    goto out;

  if ((_dbus_string_get_length (&message->header.data) +
       _dbus_string_get_length (&message->body)) >
      MAX_MESSAGE_SIZE_TO_CACHE)
    goto out;

  if (message_cache_count >= MAX_MESSAGE_CACHE_SIZE)
    goto out;

  /* Find empty slot */
  i = 0;
  while (message_cache[i] != NULL)
    ++i;

  _dbus_assert (i < MAX_MESSAGE_CACHE_SIZE);

  _dbus_assert (message_cache[i] == NULL);
  message_cache[i] = message;
  message_cache_count += 1;
  was_cached = TRUE;
#ifndef DBUS_DISABLE_CHECKS
  message->in_cache = TRUE;
#endif

 out:
  _dbus_assert (_dbus_atomic_get (&message->refcount) == 0);

  _DBUS_UNLOCK (message_cache);
  
  if (!was_cached)
    dbus_message_finalize (message);
}

#ifndef DBUS_DISABLE_CHECKS
static dbus_bool_t
_dbus_message_iter_check (DBusMessageRealIter *iter)
{
  char byte_order;

  if (iter == NULL)
    {
      _dbus_warn_check_failed ("dbus message iterator is NULL\n");
      return FALSE;
    }

  byte_order = _dbus_header_get_byte_order (&iter->message->header);

  if (iter->iter_type == DBUS_MESSAGE_ITER_TYPE_READER)
    {
      if (iter->u.reader.byte_order != byte_order)
        {
          _dbus_warn_check_failed ("dbus message changed byte order since iterator was created\n");
          return FALSE;
        }
      /* because we swap the message into compiler order when you init an iter */
      _dbus_assert (iter->u.reader.byte_order == DBUS_COMPILER_BYTE_ORDER);
    }
  else if (iter->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER)
    {
      if (iter->u.writer.byte_order != byte_order)
        {
          _dbus_warn_check_failed ("dbus message changed byte order since append iterator was created\n");
          return FALSE;
        }
      /* because we swap the message into compiler order when you init an iter */
      _dbus_assert (iter->u.writer.byte_order == DBUS_COMPILER_BYTE_ORDER);
    }
  else
    {
      _dbus_warn_check_failed ("dbus message iterator looks uninitialized or corrupted\n");
      return FALSE;
    }

  if (iter->changed_stamp != iter->message->changed_stamp)
    {
      _dbus_warn_check_failed ("dbus message iterator invalid because the message has been modified (or perhaps the iterator is just uninitialized)\n");
      return FALSE;
    }

  return TRUE;
}
#endif /* DBUS_DISABLE_CHECKS */

dbus_bool_t
_dbus_message_iter_get_args_valist (DBusMessageIter *iter,
                                    DBusError       *error,
                                    int              first_arg_type,
                                    va_list          var_args)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;
  int spec_type, msg_type, i;
  dbus_bool_t retval;

  _dbus_assert (_dbus_message_iter_check (real));

  retval = FALSE;

  spec_type = first_arg_type;
  i = 0;

  while (spec_type != DBUS_TYPE_INVALID)
    {
      msg_type = dbus_message_iter_get_arg_type (iter);

      if (msg_type != spec_type)
        {
          dbus_set_error (error, DBUS_ERROR_INVALID_ARGS,
                          "Argument %d is specified to be of type \"%s\", but "
                          "is actually of type \"%s\"\n", i,
                          _dbus_type_to_string (spec_type),
                          _dbus_type_to_string (msg_type));

          goto out;
        }

      if (spec_type == DBUS_TYPE_UNIX_FD)
        {
#ifdef HAVE_UNIX_FD_PASSING
          DBusBasicValue idx;
          int *pfd, nfd;

          pfd = va_arg (var_args, int*);
          _dbus_assert(pfd);

          _dbus_type_reader_read_basic(&real->u.reader, &idx);

          if (idx.u32 >= real->message->n_unix_fds)
            {
              dbus_set_error (error, DBUS_ERROR_INCONSISTENT_MESSAGE,
                              "Message refers to file descriptor at index %i,"
                              "but has only %i descriptors attached.\n",
                              idx.u32,
                              real->message->n_unix_fds);
              goto out;
            }

          if ((nfd = _dbus_dup(real->message->unix_fds[idx.u32], error)) < 0)
            goto out;

          *pfd = nfd;
#else
          dbus_set_error (error, DBUS_ERROR_NOT_SUPPORTED,
                          "Platform does not support file desciptor passing.\n");
          goto out;
#endif
        }
      else if (dbus_type_is_basic (spec_type))
        {
          DBusBasicValue *ptr;

          ptr = va_arg (var_args, DBusBasicValue*);

          _dbus_assert (ptr != NULL);

          _dbus_type_reader_read_basic (&real->u.reader,
                                        ptr);
        }
      else if (spec_type == DBUS_TYPE_ARRAY)
        {
          int element_type;
          int spec_element_type;
          const DBusBasicValue **ptr;
          int *n_elements_p;
          DBusTypeReader array;

          spec_element_type = va_arg (var_args, int);
          element_type = _dbus_type_reader_get_element_type (&real->u.reader);

          if (spec_element_type != element_type)
            {
              dbus_set_error (error, DBUS_ERROR_INVALID_ARGS,
                              "Argument %d is specified to be an array of \"%s\", but "
                              "is actually an array of \"%s\"\n",
                              i,
                              _dbus_type_to_string (spec_element_type),
                              _dbus_type_to_string (element_type));

              goto out;
            }

          if (dbus_type_is_fixed (spec_element_type) &&
              element_type != DBUS_TYPE_UNIX_FD)
            {
              ptr = va_arg (var_args, const DBusBasicValue**);
              n_elements_p = va_arg (var_args, int*);

              _dbus_assert (ptr != NULL);
              _dbus_assert (n_elements_p != NULL);

              _dbus_type_reader_recurse (&real->u.reader, &array);

              _dbus_type_reader_read_fixed_multi (&array,
                                                  (void *) ptr, n_elements_p);
            }
          else if (_DBUS_TYPE_IS_STRINGLIKE (spec_element_type))
            {
              char ***str_array_p;
              int n_elements;
              char **str_array;

              str_array_p = va_arg (var_args, char***);
              n_elements_p = va_arg (var_args, int*);

              _dbus_assert (str_array_p != NULL);
              _dbus_assert (n_elements_p != NULL);

              /* Count elements in the array */
              _dbus_type_reader_recurse (&real->u.reader, &array);

              n_elements = 0;
              while (_dbus_type_reader_get_current_type (&array) != DBUS_TYPE_INVALID)
                {
                  ++n_elements;
                  _dbus_type_reader_next (&array);
                }

              str_array = dbus_new0 (char*, n_elements + 1);
              if (str_array == NULL)
                {
                  _DBUS_SET_OOM (error);
                  goto out;
                }

              /* Now go through and dup each string */
              _dbus_type_reader_recurse (&real->u.reader, &array);

              i = 0;
              while (i < n_elements)
                {
                  const char *s;
                  _dbus_type_reader_read_basic (&array,
                                                (void *) &s);
                  
                  str_array[i] = _dbus_strdup (s);
                  if (str_array[i] == NULL)
                    {
                      dbus_free_string_array (str_array);
                      _DBUS_SET_OOM (error);
                      goto out;
                    }
                  
                  ++i;
                  
                  if (!_dbus_type_reader_next (&array))
                    _dbus_assert (i == n_elements);
                }

              _dbus_assert (_dbus_type_reader_get_current_type (&array) == DBUS_TYPE_INVALID);
              _dbus_assert (i == n_elements);
              _dbus_assert (str_array[i] == NULL);

              *str_array_p = str_array;
              *n_elements_p = n_elements;
            }
#ifndef DBUS_DISABLE_CHECKS
          else
            {
              _dbus_warn ("you can't read arrays of container types (struct, variant, array) with %s for now\n",
                          _DBUS_FUNCTION_NAME);
              goto out;
            }
#endif
        }
#ifndef DBUS_DISABLE_CHECKS
      else
        {
          _dbus_warn ("you can only read arrays and basic types with %s for now\n",
                      _DBUS_FUNCTION_NAME);
          goto out;
        }
#endif

      spec_type = va_arg (var_args, int);
      if (!_dbus_type_reader_next (&real->u.reader) && spec_type != DBUS_TYPE_INVALID)
        {
          dbus_set_error (error, DBUS_ERROR_INVALID_ARGS,
                          "Message has only %d arguments, but more were expected", i);
          goto out;
        }

      i++;
    }

  retval = TRUE;

 out:

  return retval;
}

dbus_uint32_t
dbus_message_get_serial (DBusMessage *message)
{
  _dbus_return_val_if_fail (message != NULL, 0);

  return _dbus_header_get_serial (&message->header);
}

dbus_bool_t
dbus_message_set_reply_serial (DBusMessage   *message,
                               dbus_uint32_t  reply_serial)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (!message->locked, FALSE);
  _dbus_return_val_if_fail (reply_serial != 0, FALSE); /* 0 is invalid */

  return _dbus_header_set_field_basic (&message->header,
                                       DBUS_HEADER_FIELD_REPLY_SERIAL,
                                       DBUS_TYPE_UINT32,
                                       &reply_serial);
}

dbus_uint32_t
dbus_message_get_reply_serial  (DBusMessage *message)
{
  dbus_uint32_t v_UINT32;

  _dbus_return_val_if_fail (message != NULL, 0);

  if (_dbus_header_get_field_basic (&message->header,
                                    DBUS_HEADER_FIELD_REPLY_SERIAL,
                                    DBUS_TYPE_UINT32,
                                    &v_UINT32))
    return v_UINT32;
  else
    return 0;
}

static void
dbus_message_finalize (DBusMessage *message)
{
  _dbus_assert (_dbus_atomic_get (&message->refcount) == 0);

  /* This calls application callbacks! */
  _dbus_data_slot_list_free (&message->slot_list);

  _dbus_list_foreach (&message->counters,
                      free_counter, message);
  _dbus_list_clear (&message->counters);

  _dbus_header_free (&message->header);
  _dbus_string_free (&message->body);

#ifdef HAVE_UNIX_FD_PASSING
  close_unix_fds(message->unix_fds, &message->n_unix_fds);
  dbus_free(message->unix_fds);
#endif

  _dbus_assert (_dbus_atomic_get (&message->refcount) == 0);

  dbus_free (message);
}

static DBusMessage*
dbus_message_new_empty_header (void)
{
  DBusMessage *message;
  dbus_bool_t from_cache;

  message = dbus_message_get_cached ();

  if (message != NULL)
    {
      from_cache = TRUE;
    }
  else
    {
      from_cache = FALSE;
      message = dbus_new0 (DBusMessage, 1);
      if (message == NULL)
        return NULL;
#ifndef DBUS_DISABLE_CHECKS
      message->generation = _dbus_current_generation;
#endif

#ifdef HAVE_UNIX_FD_PASSING
      message->unix_fds = NULL;
      message->n_unix_fds_allocated = 0;
#endif
    }

  _dbus_atomic_inc (&message->refcount);

  _dbus_message_trace_ref (message, 0, 1, "new_empty_header");

  message->locked = FALSE;
#ifndef DBUS_DISABLE_CHECKS
  message->in_cache = FALSE;
#endif
  message->counters = NULL;
  message->size_counter_delta = 0;
  message->changed_stamp = 0;

#ifdef HAVE_UNIX_FD_PASSING
  message->n_unix_fds = 0;
  message->n_unix_fds_allocated = 0;
  message->unix_fd_counter_delta = 0;
#endif

  if (!from_cache)
    _dbus_data_slot_list_init (&message->slot_list);

  if (from_cache)
    {
      _dbus_header_reinit (&message->header);
      _dbus_string_set_length (&message->body, 0);
    }
  else
    {
      if (!_dbus_header_init (&message->header))
        {
          dbus_free (message);
          return NULL;
        }

      if (!_dbus_string_init_preallocated (&message->body, 32))
        {
          _dbus_header_free (&message->header);
          dbus_free (message);
          return NULL;
        }
    }

  return message;
}

DBusMessage*
dbus_message_new (int message_type)
{
  DBusMessage *message;

  _dbus_return_val_if_fail (message_type != DBUS_MESSAGE_TYPE_INVALID, NULL);

  message = dbus_message_new_empty_header ();
  if (message == NULL)
    return NULL;

  if (!_dbus_header_create (&message->header,
                            DBUS_COMPILER_BYTE_ORDER,
                            message_type,
                            NULL, NULL, NULL, NULL, NULL))
    {
      dbus_message_unref (message);
      return NULL;
    }

  return message;
}

DBusMessage*
dbus_message_new_method_call (const char *destination,
                              const char *path,
                              const char *iface,
                              const char *method)
{
  DBusMessage *message;

  _dbus_return_val_if_fail (path != NULL, NULL);
  _dbus_return_val_if_fail (method != NULL, NULL);
  _dbus_return_val_if_fail (destination == NULL ||
                            _dbus_check_is_valid_bus_name (destination), NULL);
  _dbus_return_val_if_fail (_dbus_check_is_valid_path (path), NULL);
  _dbus_return_val_if_fail (iface == NULL ||
                            _dbus_check_is_valid_interface (iface), NULL);
  _dbus_return_val_if_fail (_dbus_check_is_valid_member (method), NULL);

  message = dbus_message_new_empty_header ();
  if (message == NULL)
    return NULL;

  if (!_dbus_header_create (&message->header,
                            DBUS_COMPILER_BYTE_ORDER,
                            DBUS_MESSAGE_TYPE_METHOD_CALL,
                            destination, path, iface, method, NULL))
    {
      dbus_message_unref (message);
      return NULL;
    }

  return message;
}

DBusMessage*
dbus_message_new_method_return (DBusMessage *method_call)
{
  DBusMessage *message;
  const char *sender;

  _dbus_return_val_if_fail (method_call != NULL, NULL);

  sender = dbus_message_get_sender (method_call);

  /* sender is allowed to be null here in peer-to-peer case */

  message = dbus_message_new_empty_header ();
  if (message == NULL)
    return NULL;

  if (!_dbus_header_create (&message->header,
                            DBUS_COMPILER_BYTE_ORDER,
                            DBUS_MESSAGE_TYPE_METHOD_RETURN,
                            sender, NULL, NULL, NULL, NULL))
    {
      dbus_message_unref (message);
      return NULL;
    }

  dbus_message_set_no_reply (message, TRUE);

  if (!dbus_message_set_reply_serial (message,
                                      dbus_message_get_serial (method_call)))
    {
      dbus_message_unref (message);
      return NULL;
    }

  return message;
}

DBusMessage*
dbus_message_new_signal (const char *path,
                         const char *iface,
                         const char *name)
{
  DBusMessage *message;

  _dbus_return_val_if_fail (path != NULL, NULL);
  _dbus_return_val_if_fail (iface != NULL, NULL);
  _dbus_return_val_if_fail (name != NULL, NULL);
  _dbus_return_val_if_fail (_dbus_check_is_valid_path (path), NULL);
  _dbus_return_val_if_fail (_dbus_check_is_valid_interface (iface), NULL);
  _dbus_return_val_if_fail (_dbus_check_is_valid_member (name), NULL);

  message = dbus_message_new_empty_header ();
  if (message == NULL)
    return NULL;

  if (!_dbus_header_create (&message->header,
                            DBUS_COMPILER_BYTE_ORDER,
                            DBUS_MESSAGE_TYPE_SIGNAL,
                            NULL, path, iface, name, NULL))
    {
      dbus_message_unref (message);
      return NULL;
    }

  dbus_message_set_no_reply (message, TRUE);

  return message;
}

DBusMessage*
dbus_message_new_error (DBusMessage *reply_to,
                        const char  *error_name,
                        const char  *error_message)
{
  DBusMessage *message;
  const char *sender;
  DBusMessageIter iter;

  _dbus_return_val_if_fail (reply_to != NULL, NULL);
  _dbus_return_val_if_fail (error_name != NULL, NULL);
  _dbus_return_val_if_fail (_dbus_check_is_valid_error_name (error_name), NULL);

  sender = dbus_message_get_sender (reply_to);

  /* sender may be NULL for non-message-bus case or
   * when the message bus is dealing with an unregistered
   * connection.
   */
  message = dbus_message_new_empty_header ();
  if (message == NULL)
    return NULL;

  if (!_dbus_header_create (&message->header,
                            DBUS_COMPILER_BYTE_ORDER,
                            DBUS_MESSAGE_TYPE_ERROR,
                            sender, NULL, NULL, NULL, error_name))
    {
      dbus_message_unref (message);
      return NULL;
    }

  dbus_message_set_no_reply (message, TRUE);

  if (!dbus_message_set_reply_serial (message,
                                      dbus_message_get_serial (reply_to)))
    {
      dbus_message_unref (message);
      return NULL;
    }

  if (error_message != NULL)
    {
      dbus_message_iter_init_append (message, &iter);
      if (!dbus_message_iter_append_basic (&iter,
                                           DBUS_TYPE_STRING,
                                           &error_message))
        {
          dbus_message_unref (message);
          return NULL;
        }
    }

  return message;
}

DBusMessage*
dbus_message_new_error_printf (DBusMessage *reply_to,
                               const char  *error_name,
                               const char  *error_format,
                               ...)
{
  va_list args;
  DBusString str;
  DBusMessage *message;

  _dbus_return_val_if_fail (reply_to != NULL, NULL);
  _dbus_return_val_if_fail (error_name != NULL, NULL);
  _dbus_return_val_if_fail (_dbus_check_is_valid_error_name (error_name), NULL);

  if (!_dbus_string_init (&str))
    return NULL;

  va_start (args, error_format);

  if (_dbus_string_append_printf_valist (&str, error_format, args))
    message = dbus_message_new_error (reply_to, error_name,
                                      _dbus_string_get_const_data (&str));
  else
    message = NULL;

  _dbus_string_free (&str);

  va_end (args);

  return message;
}


DBusMessage *
dbus_message_copy (const DBusMessage *message)
{
  DBusMessage *retval;

  _dbus_return_val_if_fail (message != NULL, NULL);

  retval = dbus_new0 (DBusMessage, 1);
  if (retval == NULL)
    return NULL;

  _dbus_atomic_inc (&retval->refcount);

  retval->locked = FALSE;
#ifndef DBUS_DISABLE_CHECKS
  retval->generation = message->generation;
#endif

  if (!_dbus_header_copy (&message->header, &retval->header))
    {
      dbus_free (retval);
      return NULL;
    }

  if (!_dbus_string_init_preallocated (&retval->body,
                                       _dbus_string_get_length (&message->body)))
    {
      _dbus_header_free (&retval->header);
      dbus_free (retval);
      return NULL;
    }

  if (!_dbus_string_copy (&message->body, 0,
                          &retval->body, 0))
    goto failed_copy;

#ifdef HAVE_UNIX_FD_PASSING
  retval->unix_fds = dbus_new(int, message->n_unix_fds);
  if (retval->unix_fds == NULL && message->n_unix_fds > 0)
    goto failed_copy;

  retval->n_unix_fds_allocated = message->n_unix_fds;

  for (retval->n_unix_fds = 0;
       retval->n_unix_fds < message->n_unix_fds;
       retval->n_unix_fds++)
    {
      retval->unix_fds[retval->n_unix_fds] = _dbus_dup(message->unix_fds[retval->n_unix_fds], NULL);

      if (retval->unix_fds[retval->n_unix_fds] < 0)
        goto failed_copy;
    }

#endif

  _dbus_message_trace_ref (retval, 0, 1, "copy");
  return retval;

 failed_copy:
  _dbus_header_free (&retval->header);
  _dbus_string_free (&retval->body);

#ifdef HAVE_UNIX_FD_PASSING
  close_unix_fds(retval->unix_fds, &retval->n_unix_fds);
  dbus_free(retval->unix_fds);
#endif

  dbus_free (retval);

  return NULL;
}


DBusMessage *
dbus_message_ref (DBusMessage *message)
{
  dbus_int32_t old_refcount;

  _dbus_return_val_if_fail (message != NULL, NULL);
  _dbus_return_val_if_fail (message->generation == _dbus_current_generation, NULL);
  _dbus_return_val_if_fail (!message->in_cache, NULL);

  old_refcount = _dbus_atomic_inc (&message->refcount);
  _dbus_assert (old_refcount >= 1);
  _dbus_message_trace_ref (message, old_refcount, old_refcount + 1, "ref");

  return message;
}

void
dbus_message_unref (DBusMessage *message)
{
 dbus_int32_t old_refcount;

  _dbus_return_if_fail (message != NULL);
  _dbus_return_if_fail (message->generation == _dbus_current_generation);
  _dbus_return_if_fail (!message->in_cache);

  old_refcount = _dbus_atomic_dec (&message->refcount);

  _dbus_assert (old_refcount >= 1);

  _dbus_message_trace_ref (message, old_refcount, old_refcount - 1, "unref");

  if (old_refcount == 1)
    {
      /* Calls application callbacks! */
      dbus_message_cache_or_finalize (message);
    }
}

int
dbus_message_get_type (DBusMessage *message)
{
  _dbus_return_val_if_fail (message != NULL, DBUS_MESSAGE_TYPE_INVALID);

  return _dbus_header_get_message_type (&message->header);
}

dbus_bool_t
dbus_message_append_args (DBusMessage *message,
                          int          first_arg_type,
                          ...)
{
  dbus_bool_t retval;
  va_list var_args;

  _dbus_return_val_if_fail (message != NULL, FALSE);

  va_start (var_args, first_arg_type);
  retval = dbus_message_append_args_valist (message,
                                            first_arg_type,
                                            var_args);
  va_end (var_args);

  return retval;
}

dbus_bool_t
dbus_message_append_args_valist (DBusMessage *message,
                                 int          first_arg_type,
                                 va_list      var_args)
{
  int type;
  DBusMessageIter iter;

  _dbus_return_val_if_fail (message != NULL, FALSE);

  type = first_arg_type;

  dbus_message_iter_init_append (message, &iter);

  while (type != DBUS_TYPE_INVALID)
    {
      if (dbus_type_is_basic (type))
        {
          const DBusBasicValue *value;
          value = va_arg (var_args, const DBusBasicValue*);

          if (!dbus_message_iter_append_basic (&iter,
                                               type,
                                               value))
            goto failed;
        }
      else if (type == DBUS_TYPE_ARRAY)
        {
          int element_type;
          DBusMessageIter array;
          char buf[2];

          element_type = va_arg (var_args, int);
              
          buf[0] = element_type;
          buf[1] = '\0';
          if (!dbus_message_iter_open_container (&iter,
                                                 DBUS_TYPE_ARRAY,
                                                 buf,
                                                 &array))
            goto failed;

          if (dbus_type_is_fixed (element_type) &&
              element_type != DBUS_TYPE_UNIX_FD)
            {
              const DBusBasicValue **value;
              int n_elements;

              value = va_arg (var_args, const DBusBasicValue**);
              n_elements = va_arg (var_args, int);
              
              if (!dbus_message_iter_append_fixed_array (&array,
                                                         element_type,
                                                         value,
                                                         n_elements)) {
                dbus_message_iter_abandon_container (&iter, &array);
                goto failed;
              }
            }
          else if (_DBUS_TYPE_IS_STRINGLIKE (element_type))
            {
              const char ***value_p;
              const char **value;
              int n_elements;
              int i;
              
              value_p = va_arg (var_args, const char***);
              n_elements = va_arg (var_args, int);

              value = *value_p;
              
              i = 0;
              while (i < n_elements)
                {
                  if (!dbus_message_iter_append_basic (&array,
                                                       element_type,
                                                       &value[i])) {
                    dbus_message_iter_abandon_container (&iter, &array);
                    goto failed;
                  }
                  ++i;
                }
            }
          else
            {
              _dbus_warn ("arrays of %s can't be appended with %s for now\n",
                          _dbus_type_to_string (element_type),
                          _DBUS_FUNCTION_NAME);
              goto failed;
            }

          if (!dbus_message_iter_close_container (&iter, &array))
            goto failed;
        }
#ifndef DBUS_DISABLE_CHECKS
      else
        {
          _dbus_warn ("type %s isn't supported yet in %s\n",
                      _dbus_type_to_string (type), _DBUS_FUNCTION_NAME);
          goto failed;
        }
#endif

      type = va_arg (var_args, int);
    }

  return TRUE;

 failed:
  return FALSE;
}

dbus_bool_t
dbus_message_get_args (DBusMessage     *message,
                       DBusError       *error,
                       int              first_arg_type,
                       ...)
{
  dbus_bool_t retval;
  va_list var_args;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_error_is_set (error, FALSE);

  va_start (var_args, first_arg_type);
  retval = dbus_message_get_args_valist (message, error, first_arg_type, var_args);
  va_end (var_args);

  return retval;
}

dbus_bool_t
dbus_message_get_args_valist (DBusMessage     *message,
                              DBusError       *error,
                              int              first_arg_type,
                              va_list          var_args)
{
  DBusMessageIter iter;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_error_is_set (error, FALSE);

  dbus_message_iter_init (message, &iter);
  return _dbus_message_iter_get_args_valist (&iter, error, first_arg_type, var_args);
}

static void
_dbus_message_iter_init_common (DBusMessage         *message,
                                DBusMessageRealIter *real,
                                int                  iter_type)
{
  _dbus_assert (sizeof (DBusMessageRealIter) <= sizeof (DBusMessageIter));

  /* Since the iterator will read or write who-knows-what from the
   * message, we need to get in the right byte order
   */
  ensure_byte_order (message);
  
  real->message = message;
  real->changed_stamp = message->changed_stamp;
  real->iter_type = iter_type;
  real->sig_refcount = 0;
}

dbus_bool_t
dbus_message_iter_init (DBusMessage     *message,
                        DBusMessageIter *iter)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;
  const DBusString *type_str;
  int type_pos;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (iter != NULL, FALSE);

  get_const_signature (&message->header, &type_str, &type_pos);

  _dbus_message_iter_init_common (message, real,
                                  DBUS_MESSAGE_ITER_TYPE_READER);

  _dbus_type_reader_init (&real->u.reader,
                          _dbus_header_get_byte_order (&message->header),
                          type_str, type_pos,
                          &message->body,
                          0);

  return _dbus_type_reader_get_current_type (&real->u.reader) != DBUS_TYPE_INVALID;
}

dbus_bool_t
dbus_message_iter_has_next (DBusMessageIter *iter)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;

  _dbus_return_val_if_fail (_dbus_message_iter_check (real), FALSE);
  _dbus_return_val_if_fail (real->iter_type == DBUS_MESSAGE_ITER_TYPE_READER, FALSE);

  return _dbus_type_reader_has_next (&real->u.reader);
}

dbus_bool_t
dbus_message_iter_next (DBusMessageIter *iter)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;

  _dbus_return_val_if_fail (_dbus_message_iter_check (real), FALSE);
  _dbus_return_val_if_fail (real->iter_type == DBUS_MESSAGE_ITER_TYPE_READER, FALSE);

  return _dbus_type_reader_next (&real->u.reader);
}

int
dbus_message_iter_get_arg_type (DBusMessageIter *iter)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;

  _dbus_return_val_if_fail (_dbus_message_iter_check (real), DBUS_TYPE_INVALID);
  _dbus_return_val_if_fail (real->iter_type == DBUS_MESSAGE_ITER_TYPE_READER, FALSE);

  return _dbus_type_reader_get_current_type (&real->u.reader);
}

int
dbus_message_iter_get_element_type (DBusMessageIter *iter)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;

  _dbus_return_val_if_fail (_dbus_message_iter_check (real), DBUS_TYPE_INVALID);
  _dbus_return_val_if_fail (real->iter_type == DBUS_MESSAGE_ITER_TYPE_READER, DBUS_TYPE_INVALID);
  _dbus_return_val_if_fail (dbus_message_iter_get_arg_type (iter) == DBUS_TYPE_ARRAY, DBUS_TYPE_INVALID);

  return _dbus_type_reader_get_element_type (&real->u.reader);
}

void
dbus_message_iter_recurse (DBusMessageIter  *iter,
                           DBusMessageIter  *sub)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;
  DBusMessageRealIter *real_sub = (DBusMessageRealIter *)sub;

  _dbus_return_if_fail (_dbus_message_iter_check (real));
  _dbus_return_if_fail (sub != NULL);

  *real_sub = *real;
  _dbus_type_reader_recurse (&real->u.reader, &real_sub->u.reader);
}

char *
dbus_message_iter_get_signature (DBusMessageIter *iter)
{
  const DBusString *sig;
  DBusString retstr;
  char *ret;
  int start, len;
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;

  _dbus_return_val_if_fail (_dbus_message_iter_check (real), NULL);

  if (!_dbus_string_init (&retstr))
    return NULL;

  _dbus_type_reader_get_signature (&real->u.reader, &sig,
                                   &start, &len);
  if (!_dbus_string_append_len (&retstr,
                                _dbus_string_get_const_data (sig) + start,
                                len))
    return NULL;
  if (!_dbus_string_steal_data (&retstr, &ret))
    return NULL;
  _dbus_string_free (&retstr);
  return ret;
}

void
dbus_message_iter_get_basic (DBusMessageIter  *iter,
                             void             *value)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;

  _dbus_return_if_fail (_dbus_message_iter_check (real));
  _dbus_return_if_fail (value != NULL);

  if (dbus_message_iter_get_arg_type (iter) == DBUS_TYPE_UNIX_FD)
    {
#ifdef HAVE_UNIX_FD_PASSING
      DBusBasicValue idx;

      _dbus_type_reader_read_basic(&real->u.reader, &idx);

      if (idx.u32 >= real->message->n_unix_fds) {
        /* Hmm, we cannot really signal an error here, so let's make
           sure to return an invalid fd. */
        *((int*) value) = -1;
        return;
      }

      *((int*) value) = _dbus_dup(real->message->unix_fds[idx.u32], NULL);
#else
      *((int*) value) = -1;
#endif
    }
  else
    {
      _dbus_type_reader_read_basic (&real->u.reader,
                                    value);
    }
}

int
dbus_message_iter_get_array_len (DBusMessageIter *iter)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;

  _dbus_return_val_if_fail (_dbus_message_iter_check (real), 0);

  return _dbus_type_reader_get_array_length (&real->u.reader);
}

void
dbus_message_iter_get_fixed_array (DBusMessageIter  *iter,
                                   void             *value,
                                   int              *n_elements)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;
#ifndef DBUS_DISABLE_CHECKS
  int subtype = _dbus_type_reader_get_current_type(&real->u.reader);

  _dbus_return_if_fail (_dbus_message_iter_check (real));
  _dbus_return_if_fail (value != NULL);
  _dbus_return_if_fail ((subtype == DBUS_TYPE_INVALID) ||
                        (dbus_type_is_fixed (subtype) && subtype != DBUS_TYPE_UNIX_FD));
#endif

  _dbus_type_reader_read_fixed_multi (&real->u.reader,
                                      value, n_elements);
}

void
dbus_message_iter_init_append (DBusMessage     *message,
                               DBusMessageIter *iter)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;

  _dbus_return_if_fail (message != NULL);
  _dbus_return_if_fail (iter != NULL);

  _dbus_message_iter_init_common (message, real,
                                  DBUS_MESSAGE_ITER_TYPE_WRITER);

  /* We create the signature string and point iterators at it "on demand"
   * when a value is actually appended. That means that init() never fails
   * due to OOM.
   */
  _dbus_type_writer_init_types_delayed (&real->u.writer,
                                        _dbus_header_get_byte_order (&message->header),
                                        &message->body,
                                        _dbus_string_get_length (&message->body));
}

static dbus_bool_t
_dbus_message_iter_open_signature (DBusMessageRealIter *real)
{
  DBusString *str;
  const DBusString *current_sig;
  int current_sig_pos;

  _dbus_assert (real->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER);

  if (real->u.writer.type_str != NULL)
    {
      _dbus_assert (real->sig_refcount > 0);
      real->sig_refcount += 1;
      return TRUE;
    }

  str = dbus_new (DBusString, 1);
  if (str == NULL)
    return FALSE;

  if (!_dbus_header_get_field_raw (&real->message->header,
                                   DBUS_HEADER_FIELD_SIGNATURE,
                                   &current_sig, &current_sig_pos))
    current_sig = NULL;

  if (current_sig)
    {
      int current_len;

      current_len = _dbus_string_get_byte (current_sig, current_sig_pos);
      current_sig_pos += 1; /* move on to sig data */

      if (!_dbus_string_init_preallocated (str, current_len + 4))
        {
          dbus_free (str);
          return FALSE;
        }

      if (!_dbus_string_copy_len (current_sig, current_sig_pos, current_len,
                                  str, 0))
        {
          _dbus_string_free (str);
          dbus_free (str);
          return FALSE;
        }
    }
  else
    {
      if (!_dbus_string_init_preallocated (str, 4))
        {
          dbus_free (str);
          return FALSE;
        }
    }

  real->sig_refcount = 1;

  _dbus_type_writer_add_types (&real->u.writer,
                               str, _dbus_string_get_length (str));
  return TRUE;
}

static dbus_bool_t
_dbus_message_iter_close_signature (DBusMessageRealIter *real)
{
  DBusString *str;
  const char *v_STRING;
  dbus_bool_t retval;

  _dbus_assert (real->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER);
  _dbus_assert (real->u.writer.type_str != NULL);
  _dbus_assert (real->sig_refcount > 0);

  real->sig_refcount -= 1;

  if (real->sig_refcount > 0)
    return TRUE;
  _dbus_assert (real->sig_refcount == 0);

  retval = TRUE;

  str = real->u.writer.type_str;

  v_STRING = _dbus_string_get_const_data (str);
  if (!_dbus_header_set_field_basic (&real->message->header,
                                     DBUS_HEADER_FIELD_SIGNATURE,
                                     DBUS_TYPE_SIGNATURE,
                                     &v_STRING))
    retval = FALSE;

  _dbus_type_writer_remove_types (&real->u.writer);
  _dbus_string_free (str);
  dbus_free (str);

  return retval;
}

static void
_dbus_message_iter_abandon_signature (DBusMessageRealIter *real)
{
  DBusString *str;

  _dbus_assert (real->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER);
  _dbus_assert (real->u.writer.type_str != NULL);
  _dbus_assert (real->sig_refcount > 0);

  real->sig_refcount -= 1;

  if (real->sig_refcount > 0)
    return;
  _dbus_assert (real->sig_refcount == 0);

  str = real->u.writer.type_str;

  _dbus_type_writer_remove_types (&real->u.writer);
  _dbus_string_free (str);
  dbus_free (str);
}

#ifndef DBUS_DISABLE_CHECKS
static dbus_bool_t
_dbus_message_iter_append_check (DBusMessageRealIter *iter)
{
  if (!_dbus_message_iter_check (iter))
    return FALSE;

  if (iter->message->locked)
    {
      _dbus_warn_check_failed ("dbus append iterator can't be used: message is locked (has already been sent)\n");
      return FALSE;
    }

  return TRUE;
}
#endif /* DBUS_DISABLE_CHECKS */

#ifdef HAVE_UNIX_FD_PASSING
static int *
expand_fd_array(DBusMessage *m,
                unsigned     n)
{
  _dbus_assert(m);

  /* This makes space for adding n new fds to the array and returns a
     pointer to the place were the first fd should be put. */

  if (m->n_unix_fds + n > m->n_unix_fds_allocated)
    {
      unsigned k;
      int *p;

      /* Make twice as much space as necessary */
      k = (m->n_unix_fds + n) * 2;

      /* Allocate at least four */
      if (k < 4)
        k = 4;

      p = dbus_realloc(m->unix_fds, k * sizeof(int));
      if (p == NULL)
        return NULL;

      m->unix_fds = p;
      m->n_unix_fds_allocated = k;
    }

  return m->unix_fds + m->n_unix_fds;
}
#endif

dbus_bool_t
dbus_message_iter_append_basic (DBusMessageIter *iter,
                                int              type,
                                const void      *value)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;
  dbus_bool_t ret;

  _dbus_return_val_if_fail (_dbus_message_iter_append_check (real), FALSE);
  _dbus_return_val_if_fail (real->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER, FALSE);
  _dbus_return_val_if_fail (dbus_type_is_basic (type), FALSE);
  _dbus_return_val_if_fail (value != NULL, FALSE);

#ifndef DBUS_DISABLE_CHECKS
  switch (type)
    {
      const char * const *string_p;
      const dbus_bool_t *bool_p;

      case DBUS_TYPE_STRING:
        string_p = value;
        _dbus_return_val_if_fail (_dbus_check_is_valid_utf8 (*string_p), FALSE);
        break;

      case DBUS_TYPE_OBJECT_PATH:
        string_p = value;
        _dbus_return_val_if_fail (_dbus_check_is_valid_path (*string_p), FALSE);
        break;

      case DBUS_TYPE_SIGNATURE:
        string_p = value;
        _dbus_return_val_if_fail (_dbus_check_is_valid_signature (*string_p), FALSE);
        break;

      case DBUS_TYPE_BOOLEAN:
        bool_p = value;
        _dbus_return_val_if_fail (*bool_p == 0 || *bool_p == 1, FALSE);
        break;

      default:
          {
            /* nothing to check, all possible values are allowed */
          }
    }
#endif

  if (!_dbus_message_iter_open_signature (real))
    return FALSE;

  if (type == DBUS_TYPE_UNIX_FD)
    {
#ifdef HAVE_UNIX_FD_PASSING
      int *fds;
      dbus_uint32_t u;

      /* First step, include the fd in the fd list of this message */
      if (!(fds = expand_fd_array(real->message, 1)))
        return FALSE;

      *fds = _dbus_dup(*(int*) value, NULL);
      if (*fds < 0)
        return FALSE;

      u = real->message->n_unix_fds;

      /* Second step, write the index to the fd */
      if (!(ret = _dbus_type_writer_write_basic (&real->u.writer, DBUS_TYPE_UNIX_FD, &u))) {
        _dbus_close(*fds, NULL);
        return FALSE;
      }

      real->message->n_unix_fds += 1;
      u += 1;

      /* Final step, update the header accordingly */
      ret = _dbus_header_set_field_basic (&real->message->header,
                                          DBUS_HEADER_FIELD_UNIX_FDS,
                                          DBUS_TYPE_UINT32,
                                          &u);

      /* If any of these operations fail the message is
         hosed. However, no memory or fds should be leaked since what
         has been added to message has been added to the message, and
         can hence be accounted for when the message is being
         freed. */
#else
      ret = FALSE;
#endif
    }
  else
    {
      ret = _dbus_type_writer_write_basic (&real->u.writer, type, value);
    }

  if (!_dbus_message_iter_close_signature (real))
    ret = FALSE;

  return ret;
}

dbus_bool_t
dbus_message_iter_append_fixed_array (DBusMessageIter *iter,
                                      int              element_type,
                                      const void      *value,
                                      int              n_elements)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;
  dbus_bool_t ret;

  _dbus_return_val_if_fail (_dbus_message_iter_append_check (real), FALSE);
  _dbus_return_val_if_fail (real->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER, FALSE);
  _dbus_return_val_if_fail (dbus_type_is_fixed (element_type) && element_type != DBUS_TYPE_UNIX_FD, FALSE);
  _dbus_return_val_if_fail (real->u.writer.container_type == DBUS_TYPE_ARRAY, FALSE);
  _dbus_return_val_if_fail (value != NULL, FALSE);
  _dbus_return_val_if_fail (n_elements >= 0, FALSE);
  _dbus_return_val_if_fail (n_elements <=
                            DBUS_MAXIMUM_ARRAY_LENGTH / _dbus_type_get_alignment (element_type),
                            FALSE);

#ifndef DBUS_DISABLE_CHECKS
  if (element_type == DBUS_TYPE_BOOLEAN)
    {
      const dbus_bool_t * const *bools = value;
      int i;

      for (i = 0; i < n_elements; i++)
        {
          _dbus_return_val_if_fail ((*bools)[i] == 0 || (*bools)[i] == 1, FALSE);
        }
    }
#endif

  ret = _dbus_type_writer_write_fixed_multi (&real->u.writer, element_type, value, n_elements);

  return ret;
}

dbus_bool_t
dbus_message_iter_open_container (DBusMessageIter *iter,
                                  int              type,
                                  const char      *contained_signature,
                                  DBusMessageIter *sub)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;
  DBusMessageRealIter *real_sub = (DBusMessageRealIter *)sub;
  DBusString contained_str;

  _dbus_return_val_if_fail (_dbus_message_iter_append_check (real), FALSE);
  _dbus_return_val_if_fail (real->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER, FALSE);
  _dbus_return_val_if_fail (dbus_type_is_container (type), FALSE);
  _dbus_return_val_if_fail (sub != NULL, FALSE);
  _dbus_return_val_if_fail ((type == DBUS_TYPE_STRUCT &&
                             contained_signature == NULL) ||
                            (type == DBUS_TYPE_DICT_ENTRY &&
                             contained_signature == NULL) ||
                            (type == DBUS_TYPE_VARIANT &&
                             contained_signature != NULL) ||
                            (type == DBUS_TYPE_ARRAY &&
                             contained_signature != NULL), FALSE);
  
  /* this would fail if the contained_signature is a dict entry, since
   * dict entries are invalid signatures standalone (they must be in
   * an array)
   */
  _dbus_return_val_if_fail ((type == DBUS_TYPE_ARRAY && contained_signature && *contained_signature == DBUS_DICT_ENTRY_BEGIN_CHAR) ||
                            (contained_signature == NULL ||
                             _dbus_check_is_valid_signature (contained_signature)),
                            FALSE);

  if (!_dbus_message_iter_open_signature (real))
    return FALSE;

  *real_sub = *real;

  if (contained_signature != NULL)
    {
      _dbus_string_init_const (&contained_str, contained_signature);

      return _dbus_type_writer_recurse (&real->u.writer,
                                        type,
                                        &contained_str, 0,
                                        &real_sub->u.writer);
    }
  else
    {
      return _dbus_type_writer_recurse (&real->u.writer,
                                        type,
                                        NULL, 0,
                                        &real_sub->u.writer);
    } 
}


dbus_bool_t
dbus_message_iter_close_container (DBusMessageIter *iter,
                                   DBusMessageIter *sub)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;
  DBusMessageRealIter *real_sub = (DBusMessageRealIter *)sub;
  dbus_bool_t ret;

  _dbus_return_val_if_fail (_dbus_message_iter_append_check (real), FALSE);
  _dbus_return_val_if_fail (real->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER, FALSE);
  _dbus_return_val_if_fail (_dbus_message_iter_append_check (real_sub), FALSE);
  _dbus_return_val_if_fail (real_sub->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER, FALSE);

  ret = _dbus_type_writer_unrecurse (&real->u.writer,
                                     &real_sub->u.writer);

  if (!_dbus_message_iter_close_signature (real))
    ret = FALSE;

  return ret;
}

void
dbus_message_iter_abandon_container (DBusMessageIter *iter,
                                     DBusMessageIter *sub)
{
  DBusMessageRealIter *real = (DBusMessageRealIter *)iter;
#ifndef DBUS_DISABLE_CHECKS
  DBusMessageRealIter *real_sub = (DBusMessageRealIter *)sub;

  _dbus_return_if_fail (_dbus_message_iter_append_check (real));
  _dbus_return_if_fail (real->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER);
  _dbus_return_if_fail (_dbus_message_iter_append_check (real_sub));
  _dbus_return_if_fail (real_sub->iter_type == DBUS_MESSAGE_ITER_TYPE_WRITER);
#endif

  _dbus_message_iter_abandon_signature (real);
}

void
dbus_message_set_no_reply (DBusMessage *message,
                           dbus_bool_t  no_reply)
{
  _dbus_return_if_fail (message != NULL);
  _dbus_return_if_fail (!message->locked);

  _dbus_header_toggle_flag (&message->header,
                            DBUS_HEADER_FLAG_NO_REPLY_EXPECTED,
                            no_reply);
}

dbus_bool_t
dbus_message_get_no_reply (DBusMessage *message)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);

  return _dbus_header_get_flag (&message->header,
                                DBUS_HEADER_FLAG_NO_REPLY_EXPECTED);
}

void
dbus_message_set_auto_start (DBusMessage *message,
                             dbus_bool_t  auto_start)
{
  _dbus_return_if_fail (message != NULL);
  _dbus_return_if_fail (!message->locked);

  _dbus_header_toggle_flag (&message->header,
                            DBUS_HEADER_FLAG_NO_AUTO_START,
                            !auto_start);
}

dbus_bool_t
dbus_message_get_auto_start (DBusMessage *message)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);

  return !_dbus_header_get_flag (&message->header,
                                 DBUS_HEADER_FLAG_NO_AUTO_START);
}


dbus_bool_t
dbus_message_set_path (DBusMessage   *message,
                       const char    *object_path)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (!message->locked, FALSE);
  _dbus_return_val_if_fail (object_path == NULL ||
                            _dbus_check_is_valid_path (object_path),
                            FALSE);

  return set_or_delete_string_field (message,
                                     DBUS_HEADER_FIELD_PATH,
                                     DBUS_TYPE_OBJECT_PATH,
                                     object_path);
}

const char*
dbus_message_get_path (DBusMessage   *message)
{
  const char *v;

  _dbus_return_val_if_fail (message != NULL, NULL);

  v = NULL; /* in case field doesn't exist */
  _dbus_header_get_field_basic (&message->header,
                                DBUS_HEADER_FIELD_PATH,
                                DBUS_TYPE_OBJECT_PATH,
                                (void *) &v);
  return v;
}

dbus_bool_t
dbus_message_has_path (DBusMessage   *message,
                       const char    *path)
{
  const char *msg_path;
  msg_path = dbus_message_get_path (message);
  
  if (msg_path == NULL)
    {
      if (path == NULL)
        return TRUE;
      else
        return FALSE;
    }

  if (path == NULL)
    return FALSE;
   
  if (strcmp (msg_path, path) == 0)
    return TRUE;

  return FALSE;
}

dbus_bool_t
dbus_message_get_path_decomposed (DBusMessage   *message,
                                  char        ***path)
{
  const char *v;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (path != NULL, FALSE);

  *path = NULL;

  v = dbus_message_get_path (message);
  if (v != NULL)
    {
      if (!_dbus_decompose_path (v, strlen (v),
                                 path, NULL))
        return FALSE;
    }
  return TRUE;
}

dbus_bool_t
dbus_message_set_interface (DBusMessage  *message,
                            const char   *iface)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (!message->locked, FALSE);
  _dbus_return_val_if_fail (iface == NULL ||
                            _dbus_check_is_valid_interface (iface),
                            FALSE);

  return set_or_delete_string_field (message,
                                     DBUS_HEADER_FIELD_INTERFACE,
                                     DBUS_TYPE_STRING,
                                     iface);
}

const char*
dbus_message_get_interface (DBusMessage *message)
{
  const char *v;

  _dbus_return_val_if_fail (message != NULL, NULL);

  v = NULL; /* in case field doesn't exist */
  _dbus_header_get_field_basic (&message->header,
                                DBUS_HEADER_FIELD_INTERFACE,
                                DBUS_TYPE_STRING,
                                (void *) &v);
  return v;
}

dbus_bool_t
dbus_message_has_interface (DBusMessage   *message,
                            const char    *iface)
{
  const char *msg_interface;
  msg_interface = dbus_message_get_interface (message);
   
  if (msg_interface == NULL)
    {
      if (iface == NULL)
        return TRUE;
      else
        return FALSE;
    }

  if (iface == NULL)
    return FALSE;
     
  if (strcmp (msg_interface, iface) == 0)
    return TRUE;

  return FALSE;

}

dbus_bool_t
dbus_message_set_member (DBusMessage  *message,
                         const char   *member)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (!message->locked, FALSE);
  _dbus_return_val_if_fail (member == NULL ||
                            _dbus_check_is_valid_member (member),
                            FALSE);

  return set_or_delete_string_field (message,
                                     DBUS_HEADER_FIELD_MEMBER,
                                     DBUS_TYPE_STRING,
                                     member);
}

const char*
dbus_message_get_member (DBusMessage *message)
{
  const char *v;

  _dbus_return_val_if_fail (message != NULL, NULL);

  v = NULL; /* in case field doesn't exist */
  _dbus_header_get_field_basic (&message->header,
                                DBUS_HEADER_FIELD_MEMBER,
                                DBUS_TYPE_STRING,
                                (void *) &v);
  return v;
}

dbus_bool_t
dbus_message_has_member (DBusMessage   *message,
                         const char    *member)
{
  const char *msg_member;
  msg_member = dbus_message_get_member (message);
 
  if (msg_member == NULL)
    {
      if (member == NULL)
        return TRUE;
      else
        return FALSE;
    }

  if (member == NULL)
    return FALSE;
    
  if (strcmp (msg_member, member) == 0)
    return TRUE;

  return FALSE;

}

dbus_bool_t
dbus_message_set_error_name (DBusMessage  *message,
                             const char   *error_name)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (!message->locked, FALSE);
  _dbus_return_val_if_fail (error_name == NULL ||
                            _dbus_check_is_valid_error_name (error_name),
                            FALSE);

  return set_or_delete_string_field (message,
                                     DBUS_HEADER_FIELD_ERROR_NAME,
                                     DBUS_TYPE_STRING,
                                     error_name);
}

const char*
dbus_message_get_error_name (DBusMessage *message)
{
  const char *v;

  _dbus_return_val_if_fail (message != NULL, NULL);

  v = NULL; /* in case field doesn't exist */
  _dbus_header_get_field_basic (&message->header,
                                DBUS_HEADER_FIELD_ERROR_NAME,
                                DBUS_TYPE_STRING,
                                (void *) &v);
  return v;
}

dbus_bool_t
dbus_message_set_destination (DBusMessage  *message,
                              const char   *destination)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (!message->locked, FALSE);
  _dbus_return_val_if_fail (destination == NULL ||
                            _dbus_check_is_valid_bus_name (destination),
                            FALSE);

  return set_or_delete_string_field (message,
                                     DBUS_HEADER_FIELD_DESTINATION,
                                     DBUS_TYPE_STRING,
                                     destination);
}

const char*
dbus_message_get_destination (DBusMessage *message)
{
  const char *v;

  _dbus_return_val_if_fail (message != NULL, NULL);

  v = NULL; /* in case field doesn't exist */
  _dbus_header_get_field_basic (&message->header,
                                DBUS_HEADER_FIELD_DESTINATION,
                                DBUS_TYPE_STRING,
                                (void *) &v);
  return v;
}

dbus_bool_t
dbus_message_set_sender (DBusMessage  *message,
                         const char   *sender)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (!message->locked, FALSE);
  _dbus_return_val_if_fail (sender == NULL ||
                            _dbus_check_is_valid_bus_name (sender),
                            FALSE);

  return set_or_delete_string_field (message,
                                     DBUS_HEADER_FIELD_SENDER,
                                     DBUS_TYPE_STRING,
                                     sender);
}

const char*
dbus_message_get_sender (DBusMessage *message)
{
  const char *v;

  _dbus_return_val_if_fail (message != NULL, NULL);

  v = NULL; /* in case field doesn't exist */
  _dbus_header_get_field_basic (&message->header,
                                DBUS_HEADER_FIELD_SENDER,
                                DBUS_TYPE_STRING,
                                (void *) &v);
  return v;
}

const char*
dbus_message_get_signature (DBusMessage *message)
{
  const DBusString *type_str;
  int type_pos;

  _dbus_return_val_if_fail (message != NULL, NULL);

  get_const_signature (&message->header, &type_str, &type_pos);

  return _dbus_string_get_const_data_len (type_str, type_pos, 0);
}

static dbus_bool_t
_dbus_message_has_type_interface_member (DBusMessage *message,
                                         int          type,
                                         const char  *iface,
                                         const char  *member)
{
  const char *n;

  _dbus_assert (message != NULL);
  _dbus_assert (iface != NULL);
  _dbus_assert (member != NULL);

  if (dbus_message_get_type (message) != type)
    return FALSE;

  /* Optimize by checking the short member name first
   * instead of the longer interface name
   */

  n = dbus_message_get_member (message);

  if (n && strcmp (n, member) == 0)
    {
      n = dbus_message_get_interface (message);

      if (n == NULL || strcmp (n, iface) == 0)
        return TRUE;
    }

  return FALSE;
}

dbus_bool_t
dbus_message_is_method_call (DBusMessage *message,
                             const char  *iface,
                             const char  *method)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (iface != NULL, FALSE);
  _dbus_return_val_if_fail (method != NULL, FALSE);
  /* don't check that interface/method are valid since it would be
   * expensive, and not catch many common errors
   */

  return _dbus_message_has_type_interface_member (message,
                                                  DBUS_MESSAGE_TYPE_METHOD_CALL,
                                                  iface, method);
}

dbus_bool_t
dbus_message_is_signal (DBusMessage *message,
                        const char  *iface,
                        const char  *signal_name)
{
  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (iface != NULL, FALSE);
  _dbus_return_val_if_fail (signal_name != NULL, FALSE);
  /* don't check that interface/name are valid since it would be
   * expensive, and not catch many common errors
   */

  return _dbus_message_has_type_interface_member (message,
                                                  DBUS_MESSAGE_TYPE_SIGNAL,
                                                  iface, signal_name);
}

dbus_bool_t
dbus_message_is_error (DBusMessage *message,
                       const char  *error_name)
{
  const char *n;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (error_name != NULL, FALSE);
  /* don't check that error_name is valid since it would be expensive,
   * and not catch many common errors
   */

  if (dbus_message_get_type (message) != DBUS_MESSAGE_TYPE_ERROR)
    return FALSE;

  n = dbus_message_get_error_name (message);

  if (n && strcmp (n, error_name) == 0)
    return TRUE;
  else
    return FALSE;
}

dbus_bool_t
dbus_message_has_destination (DBusMessage  *message,
                              const char   *name)
{
  const char *s;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (name != NULL, FALSE);
  /* don't check that name is valid since it would be expensive, and
   * not catch many common errors
   */

  s = dbus_message_get_destination (message);

  if (s && strcmp (s, name) == 0)
    return TRUE;
  else
    return FALSE;
}

dbus_bool_t
dbus_message_has_sender (DBusMessage  *message,
                         const char   *name)
{
  const char *s;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (name != NULL, FALSE);
  /* don't check that name is valid since it would be expensive, and
   * not catch many common errors
   */

  s = dbus_message_get_sender (message);

  if (s && strcmp (s, name) == 0)
    return TRUE;
  else
    return FALSE;
}

dbus_bool_t
dbus_message_has_signature (DBusMessage   *message,
                            const char    *signature)
{
  const char *s;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (signature != NULL, FALSE);
  /* don't check that signature is valid since it would be expensive,
   * and not catch many common errors
   */

  s = dbus_message_get_signature (message);

  if (s && strcmp (s, signature) == 0)
    return TRUE;
  else
    return FALSE;
}

dbus_bool_t
dbus_set_error_from_message (DBusError   *error,
                             DBusMessage *message)
{
  const char *str;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_error_is_set (error, FALSE);

  if (dbus_message_get_type (message) != DBUS_MESSAGE_TYPE_ERROR)
    return FALSE;

  str = NULL;
  dbus_message_get_args (message, NULL,
                         DBUS_TYPE_STRING, &str,
                         DBUS_TYPE_INVALID);

  dbus_set_error (error, dbus_message_get_error_name (message),
                  str ? "%s" : NULL, str);

  return TRUE;
}

dbus_bool_t
dbus_message_contains_unix_fds(DBusMessage *message)
{
#ifdef HAVE_UNIX_FD_PASSING
  _dbus_assert(message);

  return message->n_unix_fds > 0;
#else
  return FALSE;
#endif
}

#define INITIAL_LOADER_DATA_LEN 32

DBusMessageLoader*
_dbus_message_loader_new (void)
{
  DBusMessageLoader *loader;

  loader = dbus_new0 (DBusMessageLoader, 1);
  if (loader == NULL)
    return NULL;
  
  loader->refcount = 1;

  loader->corrupted = FALSE;
  loader->corruption_reason = DBUS_VALID;

  /* this can be configured by the app, but defaults to the protocol max */
  loader->max_message_size = DBUS_MAXIMUM_MESSAGE_LENGTH;

  /* We set a very relatively conservative default here since due to how
  SCM_RIGHTS works we need to preallocate an fd array of the maximum
  number of unix fds we want to receive in advance. A
  try-and-reallocate loop is not possible. */
  loader->max_message_unix_fds = DBUS_DEFAULT_MESSAGE_UNIX_FDS;

  if (!_dbus_string_init (&loader->data))
    {
      dbus_free (loader);
      return NULL;
    }

  /* preallocate the buffer for speed, ignore failure */
  _dbus_string_set_length (&loader->data, INITIAL_LOADER_DATA_LEN);
  _dbus_string_set_length (&loader->data, 0);

#ifdef HAVE_UNIX_FD_PASSING
  loader->unix_fds = NULL;
  loader->n_unix_fds = loader->n_unix_fds_allocated = 0;
  loader->unix_fds_outstanding = FALSE;
#endif

  return loader;
}

DBusMessageLoader *
_dbus_message_loader_ref (DBusMessageLoader *loader)
{
  loader->refcount += 1;

  return loader;
}

void
_dbus_message_loader_unref (DBusMessageLoader *loader)
{
  loader->refcount -= 1;
  if (loader->refcount == 0)
    {
#ifdef HAVE_UNIX_FD_PASSING
      close_unix_fds(loader->unix_fds, &loader->n_unix_fds);
      dbus_free(loader->unix_fds);
#endif
      _dbus_list_foreach (&loader->messages,
                          (DBusForeachFunction) dbus_message_unref,
                          NULL);
      _dbus_list_clear (&loader->messages);
      _dbus_string_free (&loader->data);
      dbus_free (loader);
    }
}

void
_dbus_message_loader_get_buffer (DBusMessageLoader  *loader,
                                 DBusString        **buffer)
{
  _dbus_assert (!loader->buffer_outstanding);

  *buffer = &loader->data;

  loader->buffer_outstanding = TRUE;
}

void
_dbus_message_loader_return_buffer (DBusMessageLoader  *loader,
                                    DBusString         *buffer,
                                    int                 bytes_read)
{
  _dbus_assert (loader->buffer_outstanding);
  _dbus_assert (buffer == &loader->data);

  loader->buffer_outstanding = FALSE;
}

dbus_bool_t
_dbus_message_loader_get_unix_fds(DBusMessageLoader  *loader,
                                  int               **fds,
                                  unsigned           *max_n_fds)
{
#ifdef HAVE_UNIX_FD_PASSING
  _dbus_assert (!loader->unix_fds_outstanding);

  /* Allocate space where we can put the fds we read. We allocate
     space for max_message_unix_fds since this is an
     upper limit how many fds can be received within a single
     message. Since SCM_RIGHTS doesn't allow a reallocate+retry logic
     we are allocating the maximum possible array size right from the
     beginning. This sucks a bit, however unless SCM_RIGHTS is fixed
     there is no better way. */

  if (loader->n_unix_fds_allocated < loader->max_message_unix_fds)
    {
      int *a = dbus_realloc(loader->unix_fds,
                            loader->max_message_unix_fds * sizeof(loader->unix_fds[0]));

      if (!a)
        return FALSE;

      loader->unix_fds = a;
      loader->n_unix_fds_allocated = loader->max_message_unix_fds;
    }

  *fds = loader->unix_fds + loader->n_unix_fds;
  *max_n_fds = loader->n_unix_fds_allocated - loader->n_unix_fds;

  loader->unix_fds_outstanding = TRUE;
  return TRUE;
#else
  _dbus_assert_not_reached("Platform doesn't support unix fd passing");
  return FALSE;
#endif
}

void
_dbus_message_loader_return_unix_fds(DBusMessageLoader  *loader,
                                     int                *fds,
                                     unsigned            n_fds)
{
#ifdef HAVE_UNIX_FD_PASSING
  _dbus_assert(loader->unix_fds_outstanding);
  _dbus_assert(loader->unix_fds + loader->n_unix_fds == fds);
  _dbus_assert(loader->n_unix_fds + n_fds <= loader->n_unix_fds_allocated);

  loader->n_unix_fds += n_fds;
  loader->unix_fds_outstanding = FALSE;

  if (n_fds && loader->unix_fds_change)
    loader->unix_fds_change (loader->unix_fds_change_data);
#else
  _dbus_assert_not_reached("Platform doesn't support unix fd passing");
#endif
}

/*
 * FIXME when we move the header out of the buffer, that memmoves all
 * buffered messages. Kind of crappy.
 *
 * Also we copy the header and body, which is kind of crappy.  To
 * avoid this, we have to allow header and body to be in a single
 * memory block, which is good for messages we read and bad for
 * messages we are creating. But we could move_len() the buffer into
 * this single memory block, and move_len() will just swap the buffers
 * if you're moving the entire buffer replacing the dest string.
 *
 * We could also have the message loader tell the transport how many
 * bytes to read; so it would first ask for some arbitrary number like
 * 256, then if the message was incomplete it would use the
 * header/body len to ask for exactly the size of the message (or
 * blocks the size of a typical kernel buffer for the socket). That
 * way we don't get trailing bytes in the buffer that have to be
 * memmoved. Though I suppose we also don't have a chance of reading a
 * bunch of small messages at once, so the optimization may be stupid.
 *
 * Another approach would be to keep a "start" index into
 * loader->data and only delete it occasionally, instead of after
 * each message is loaded.
 *
 * load_message() returns FALSE if not enough memory OR the loader was corrupted
 */
static dbus_bool_t
load_message (DBusMessageLoader *loader,
              DBusMessage       *message,
              int                byte_order,
              int                fields_array_len,
              int                header_len,
              int                body_len)
{
  dbus_bool_t oom;
  DBusValidity validity;
  const DBusString *type_str;
  int type_pos;
  DBusValidationMode mode;
  dbus_uint32_t n_unix_fds = 0;

  mode = DBUS_VALIDATION_MODE_DATA_IS_UNTRUSTED;
  
  oom = FALSE;

#if 0
  _dbus_verbose_bytes_of_string (&loader->data, 0, header_len /* + body_len */);
#endif

  /* 1. VALIDATE AND COPY OVER HEADER */
  _dbus_assert (_dbus_string_get_length (&message->header.data) == 0);
  _dbus_assert ((header_len + body_len) <= _dbus_string_get_length (&loader->data));

  if (!_dbus_header_load (&message->header,
                          mode,
                          &validity,
                          byte_order,
                          fields_array_len,
                          header_len,
                          body_len,
                          &loader->data, 0,
                          _dbus_string_get_length (&loader->data)))
    {
      _dbus_verbose ("Failed to load header for new message code %d\n", validity);

      /* assert here so we can catch any code that still uses DBUS_VALID to indicate
         oom errors.  They should use DBUS_VALIDITY_UNKNOWN_OOM_ERROR instead */
      _dbus_assert (validity != DBUS_VALID);

      if (validity == DBUS_VALIDITY_UNKNOWN_OOM_ERROR)
        oom = TRUE;
      else
        {
          loader->corrupted = TRUE;
          loader->corruption_reason = validity;
        }
      goto failed;
    }

  _dbus_assert (validity == DBUS_VALID);

  /* 2. VALIDATE BODY */
  if (mode != DBUS_VALIDATION_MODE_WE_TRUST_THIS_DATA_ABSOLUTELY)
    {
      get_const_signature (&message->header, &type_str, &type_pos);
      
      /* Because the bytes_remaining arg is NULL, this validates that the
       * body is the right length
       */
      validity = _dbus_validate_body_with_reason (type_str,
                                                  type_pos,
                                                  byte_order,
                                                  NULL,
                                                  &loader->data,
                                                  header_len,
                                                  body_len);
      if (validity != DBUS_VALID)
        {
          _dbus_verbose ("Failed to validate message body code %d\n", validity);

          loader->corrupted = TRUE;
          loader->corruption_reason = validity;
          
          goto failed;
        }
    }

  /* 3. COPY OVER UNIX FDS */
  _dbus_header_get_field_basic(&message->header,
                               DBUS_HEADER_FIELD_UNIX_FDS,
                               DBUS_TYPE_UINT32,
                               &n_unix_fds);

#ifdef HAVE_UNIX_FD_PASSING

  if (n_unix_fds > loader->n_unix_fds)
    {
      _dbus_verbose("Message contains references to more unix fds than were sent %u != %u\n",
                    n_unix_fds, loader->n_unix_fds);

      loader->corrupted = TRUE;
      loader->corruption_reason = DBUS_INVALID_MISSING_UNIX_FDS;
      goto failed;
    }

  /* If this was a recycled message there might still be
     some memory allocated for the fds */
  dbus_free(message->unix_fds);

  if (n_unix_fds > 0)
    {
      message->unix_fds = _dbus_memdup(loader->unix_fds, n_unix_fds * sizeof(message->unix_fds[0]));
      if (message->unix_fds == NULL)
        {
          _dbus_verbose ("Failed to allocate file descriptor array\n");
          oom = TRUE;
          goto failed;
        }

      message->n_unix_fds_allocated = message->n_unix_fds = n_unix_fds;
      loader->n_unix_fds -= n_unix_fds;
      memmove (loader->unix_fds, loader->unix_fds + n_unix_fds, loader->n_unix_fds * sizeof (loader->unix_fds[0]));

      if (loader->unix_fds_change)
        loader->unix_fds_change (loader->unix_fds_change_data);
    }
  else
    message->unix_fds = NULL;

#else

  if (n_unix_fds > 0)
    {
      _dbus_verbose ("Hmm, message claims to come with file descriptors "
                     "but that's not supported on our platform, disconnecting.\n");

      loader->corrupted = TRUE;
      loader->corruption_reason = DBUS_INVALID_MISSING_UNIX_FDS;
      goto failed;
    }

#endif

  /* 3. COPY OVER BODY AND QUEUE MESSAGE */

  if (!_dbus_list_append (&loader->messages, message))
    {
      _dbus_verbose ("Failed to append new message to loader queue\n");
      oom = TRUE;
      goto failed;
    }

  _dbus_assert (_dbus_string_get_length (&message->body) == 0);
  _dbus_assert (_dbus_string_get_length (&loader->data) >=
                (header_len + body_len));

  if (!_dbus_string_copy_len (&loader->data, header_len, body_len, &message->body, 0))
    {
      _dbus_verbose ("Failed to move body into new message\n");
      oom = TRUE;
      goto failed;
    }

  _dbus_string_delete (&loader->data, 0, header_len + body_len);

  /* don't waste more than 2k of memory */
  _dbus_string_compact (&loader->data, 2048);

  _dbus_assert (_dbus_string_get_length (&message->header.data) == header_len);
  _dbus_assert (_dbus_string_get_length (&message->body) == body_len);

  _dbus_verbose ("Loaded message %p\n", message);

  _dbus_assert (!oom);
  _dbus_assert (!loader->corrupted);
  _dbus_assert (loader->messages != NULL);
  _dbus_assert (_dbus_list_find_last (&loader->messages, message) != NULL);

  return TRUE;

 failed:

  /* Clean up */

  /* does nothing if the message isn't in the list */
  _dbus_list_remove_last (&loader->messages, message);
  
  if (oom)
    _dbus_assert (!loader->corrupted);
  else
    _dbus_assert (loader->corrupted);

  _dbus_verbose_bytes_of_string (&loader->data, 0, _dbus_string_get_length (&loader->data));

  return FALSE;
}

dbus_bool_t
_dbus_message_loader_queue_messages (DBusMessageLoader *loader)
{
  while (!loader->corrupted &&
         _dbus_string_get_length (&loader->data) >= DBUS_MINIMUM_HEADER_SIZE)
    {
      DBusValidity validity;
      int byte_order, fields_array_len, header_len, body_len;

      if (_dbus_header_have_message_untrusted (loader->max_message_size,
                                               &validity,
                                               &byte_order,
                                               &fields_array_len,
                                               &header_len,
                                               &body_len,
                                               &loader->data, 0,
                                               _dbus_string_get_length (&loader->data)))
        {
          DBusMessage *message;

          _dbus_assert (validity == DBUS_VALID);

          message = dbus_message_new_empty_header ();
          if (message == NULL)
            return FALSE;

          if (!load_message (loader, message,
                             byte_order, fields_array_len,
                             header_len, body_len))
            {
              dbus_message_unref (message);
              /* load_message() returns false if corrupted or OOM; if
               * corrupted then return TRUE for not OOM
               */
              return loader->corrupted;
            }

          _dbus_assert (loader->messages != NULL);
          _dbus_assert (_dbus_list_find_last (&loader->messages, message) != NULL);
        }
      else
        {
          _dbus_verbose ("Initial peek at header says we don't have a whole message yet, or data broken with invalid code %d\n",
                         validity);
          if (validity != DBUS_VALID)
            {
              loader->corrupted = TRUE;
              loader->corruption_reason = validity;
            }
          return TRUE;
        }
    }

  return TRUE;
}

DBusMessage*
_dbus_message_loader_peek_message (DBusMessageLoader *loader)
{
  if (loader->messages)
    return loader->messages->data;
  else
    return NULL;
}

DBusMessage*
_dbus_message_loader_pop_message (DBusMessageLoader *loader)
{
  return _dbus_list_pop_first (&loader->messages);
}

DBusList*
_dbus_message_loader_pop_message_link (DBusMessageLoader *loader)
{
  return _dbus_list_pop_first_link (&loader->messages);
}

void
_dbus_message_loader_putback_message_link (DBusMessageLoader  *loader,
                                           DBusList           *link)
{
  _dbus_list_prepend_link (&loader->messages, link);
}

dbus_bool_t
_dbus_message_loader_get_is_corrupted (DBusMessageLoader *loader)
{
  _dbus_assert ((loader->corrupted && loader->corruption_reason != DBUS_VALID) ||
                (!loader->corrupted && loader->corruption_reason == DBUS_VALID));
  return loader->corrupted;
}

DBusValidity
_dbus_message_loader_get_corruption_reason (DBusMessageLoader *loader)
{
  _dbus_assert ((loader->corrupted && loader->corruption_reason != DBUS_VALID) ||
                (!loader->corrupted && loader->corruption_reason == DBUS_VALID));

  return loader->corruption_reason;
}

void
_dbus_message_loader_set_max_message_size (DBusMessageLoader  *loader,
                                           long                size)
{
  if (size > DBUS_MAXIMUM_MESSAGE_LENGTH)
    {
      _dbus_verbose ("clamping requested max message size %ld to %d\n",
                     size, DBUS_MAXIMUM_MESSAGE_LENGTH);
      size = DBUS_MAXIMUM_MESSAGE_LENGTH;
    }
  loader->max_message_size = size;
}

long
_dbus_message_loader_get_max_message_size (DBusMessageLoader  *loader)
{
  return loader->max_message_size;
}

void
_dbus_message_loader_set_max_message_unix_fds (DBusMessageLoader  *loader,
                                               long                n)
{
  if (n > DBUS_MAXIMUM_MESSAGE_UNIX_FDS)
    {
      _dbus_verbose ("clamping requested max message unix_fds %ld to %d\n",
                     n, DBUS_MAXIMUM_MESSAGE_UNIX_FDS);
      n = DBUS_MAXIMUM_MESSAGE_UNIX_FDS;
    }
  loader->max_message_unix_fds = n;
}

long
_dbus_message_loader_get_max_message_unix_fds (DBusMessageLoader  *loader)
{
  return loader->max_message_unix_fds;
}

static DBusDataSlotAllocator slot_allocator;
_DBUS_DEFINE_GLOBAL_LOCK (message_slots);

int
_dbus_message_loader_get_pending_fds_count (DBusMessageLoader *loader)
{
#ifdef HAVE_UNIX_FD_PASSING
  return loader->n_unix_fds;
#else
  return 0;
#endif
}

void
_dbus_message_loader_set_pending_fds_function (DBusMessageLoader *loader,
                                               void (* callback) (void *),
                                               void *data)
{
#ifdef HAVE_UNIX_FD_PASSING
  loader->unix_fds_change = callback;
  loader->unix_fds_change_data = data;
#endif
}

dbus_bool_t
dbus_message_allocate_data_slot (dbus_int32_t *slot_p)
{
  return _dbus_data_slot_allocator_alloc (&slot_allocator,
                                          &_DBUS_LOCK_NAME (message_slots),
                                          slot_p);
}

void
dbus_message_free_data_slot (dbus_int32_t *slot_p)
{
  _dbus_return_if_fail (*slot_p >= 0);

  _dbus_data_slot_allocator_free (&slot_allocator, slot_p);
}

dbus_bool_t
dbus_message_set_data (DBusMessage     *message,
                       dbus_int32_t     slot,
                       void            *data,
                       DBusFreeFunction free_data_func)
{
  DBusFreeFunction old_free_func;
  void *old_data;
  dbus_bool_t retval;

  _dbus_return_val_if_fail (message != NULL, FALSE);
  _dbus_return_val_if_fail (slot >= 0, FALSE);

  retval = _dbus_data_slot_list_set (&slot_allocator,
                                     &message->slot_list,
                                     slot, data, free_data_func,
                                     &old_free_func, &old_data);

  if (retval)
    {
      /* Do the actual free outside the message lock */
      if (old_free_func)
        (* old_free_func) (old_data);
    }

  return retval;
}

void*
dbus_message_get_data (DBusMessage   *message,
                       dbus_int32_t   slot)
{
  void *res;

  _dbus_return_val_if_fail (message != NULL, NULL);

  res = _dbus_data_slot_list_get (&slot_allocator,
                                  &message->slot_list,
                                  slot);

  return res;
}

int
dbus_message_type_from_string (const char *type_str)
{
  if (strcmp (type_str, "method_call") == 0)
    return DBUS_MESSAGE_TYPE_METHOD_CALL;
  if (strcmp (type_str, "method_return") == 0)
    return DBUS_MESSAGE_TYPE_METHOD_RETURN;
  else if (strcmp (type_str, "signal") == 0)
    return DBUS_MESSAGE_TYPE_SIGNAL;
  else if (strcmp (type_str, "error") == 0)
    return DBUS_MESSAGE_TYPE_ERROR;
  else
    return DBUS_MESSAGE_TYPE_INVALID;
}

const char *
dbus_message_type_to_string (int type)
{
  switch (type)
    {
    case DBUS_MESSAGE_TYPE_METHOD_CALL:
      return "method_call";
    case DBUS_MESSAGE_TYPE_METHOD_RETURN:
      return "method_return";
    case DBUS_MESSAGE_TYPE_SIGNAL:
      return "signal";
    case DBUS_MESSAGE_TYPE_ERROR:
      return "error";
    default:
      return "invalid";
    }
}

dbus_bool_t
dbus_message_marshal (DBusMessage  *msg,
                      char        **marshalled_data_p,
                      int          *len_p)
{
  DBusString tmp;
  dbus_bool_t was_locked;

  _dbus_return_val_if_fail (msg != NULL, FALSE);
  _dbus_return_val_if_fail (marshalled_data_p != NULL, FALSE);
  _dbus_return_val_if_fail (len_p != NULL, FALSE);
  
  if (!_dbus_string_init (&tmp))
    return FALSE;

  /* Ensure the message is locked, to ensure the length header is filled in. */
  was_locked = msg->locked;

  if (!was_locked)
    dbus_message_lock (msg);

  if (!_dbus_string_copy (&(msg->header.data), 0, &tmp, 0))
    goto fail;

  *len_p = _dbus_string_get_length (&tmp);

  if (!_dbus_string_copy (&(msg->body), 0, &tmp, *len_p))
    goto fail;

  *len_p = _dbus_string_get_length (&tmp);

  if (!_dbus_string_steal_data (&tmp, marshalled_data_p))
    goto fail;

  _dbus_string_free (&tmp);

  if (!was_locked)
    msg->locked = FALSE;

  return TRUE;

 fail:
  _dbus_string_free (&tmp);

  if (!was_locked)
    msg->locked = FALSE;

  return FALSE;
}

DBusMessage *
dbus_message_demarshal (const char *str,
                        int         len,
                        DBusError  *error)
{
  DBusMessageLoader *loader;
  DBusString *buffer;
  DBusMessage *msg;

  _dbus_return_val_if_fail (str != NULL, NULL);

  loader = _dbus_message_loader_new ();

  if (loader == NULL)
    return NULL;

  _dbus_message_loader_get_buffer (loader, &buffer);
  _dbus_string_append_len (buffer, str, len);
  _dbus_message_loader_return_buffer (loader, buffer, len);

  if (!_dbus_message_loader_queue_messages (loader))
    goto fail_oom;

  if (_dbus_message_loader_get_is_corrupted (loader))
    goto fail_corrupt;

  msg = _dbus_message_loader_pop_message (loader);

  if (!msg)
    goto fail_oom;

  _dbus_message_loader_unref (loader);
  return msg;

 fail_corrupt:
  dbus_set_error (error, DBUS_ERROR_INVALID_ARGS, "Message is corrupted (%s)",
                  _dbus_validity_to_error_message (loader->corruption_reason));
  _dbus_message_loader_unref (loader);
  return NULL;

 fail_oom:
  _DBUS_SET_OOM (error);
  _dbus_message_loader_unref (loader);
  return NULL;
}

int 
dbus_message_demarshal_bytes_needed(const char *buf, 
                                    int         len)
{
  DBusString str;
  int byte_order, fields_array_len, header_len, body_len;
  DBusValidity validity = DBUS_VALID;
  int have_message;

  if (!buf || len < DBUS_MINIMUM_HEADER_SIZE)
    return 0;

  if (len > DBUS_MAXIMUM_MESSAGE_LENGTH)
    len = DBUS_MAXIMUM_MESSAGE_LENGTH;
  _dbus_string_init_const_len (&str, buf, len);
  
  validity = DBUS_VALID;
  have_message
    = _dbus_header_have_message_untrusted(DBUS_MAXIMUM_MESSAGE_LENGTH,
                                          &validity, &byte_order,
                                          &fields_array_len,
                                          &header_len,
                                          &body_len,
                                          &str, 0,
                                          len);
  _dbus_string_free (&str);

  if (validity == DBUS_VALID)
    {
      _dbus_assert (have_message || (header_len + body_len) > len);
      (void) have_message; /* unused unless asserting */
      return header_len + body_len;
    }
  else
    {
      return -1; /* broken! */
    }
}

/* tests in dbus-message-util.c */