static gboolean
update_cache (CamelGroupwiseJournal *groupwise_journal, CamelMimeMessage *message,
	      const CamelMessageInfo *mi, char **updated_uid, CamelException *ex)
{
	CamelOfflineJournal *journal = (CamelOfflineJournal *) groupwise_journal;
	CamelGroupwiseFolder *groupwise_folder = (CamelGroupwiseFolder *) journal->folder;
	CamelFolder *folder = (CamelFolder *) journal->folder;
	CamelMessageInfo *info;
	CamelStream *cache;
	guint32 nextuid;
	char *uid;

	if (groupwise_folder->cache == NULL) {
		camel_exception_set (ex, CAMEL_EXCEPTION_SYSTEM,
				     _("Cannot append message in offline mode: cache unavailable"));
		return FALSE;
	}

	nextuid = camel_folder_summary_next_uid (folder->summary);
	uid = g_strdup_printf ("-%u", nextuid);

	if (!(cache = camel_data_cache_add (groupwise_folder->cache, "cache", uid, ex))) {
		folder->summary->nextuid--;
		g_free (uid);
		return FALSE;
	}

	if (camel_data_wrapper_write_to_stream ((CamelDataWrapper *) message, cache) == -1
	    || camel_stream_flush (cache) == -1) {
		camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
				      _("Cannot append message in offline mode: %s"),
				      g_strerror (errno));
		camel_data_cache_remove (groupwise_folder->cache, "cache", uid, NULL);
		folder->summary->nextuid--;
		camel_object_unref (cache);
		g_free (uid);
		return FALSE;
	}

	camel_object_unref (cache);

	info = camel_folder_summary_info_new_from_message (folder->summary, message);
	g_free(info->uid);
	info->uid = g_strdup (uid);

	gw_message_info_dup_to ((CamelMessageInfoBase *) info, (CamelMessageInfoBase *) mi);

	camel_folder_summary_add (folder->summary, info);

	if (updated_uid)
		*updated_uid = g_strdup (uid);

	g_free (uid);

	return TRUE;
}
static CamelStream *
nntp_folder_download_message (CamelNNTPFolder *nntp_folder, const char *id, const char *msgid, CamelException *ex)
{
	CamelNNTPStore *nntp_store = (CamelNNTPStore *) ((CamelFolder *) nntp_folder)->parent_store;
	CamelStream *stream = NULL;
	int ret;
	char *line;

	ret = camel_nntp_command (nntp_store, ex, nntp_folder, &line, "article %s", id);
	if (ret == 220) {
		stream = camel_data_cache_add (nntp_store->cache, "cache", msgid, NULL);
		if (stream) {
			if (camel_stream_write_to_stream ((CamelStream *) nntp_store->stream, stream) == -1)
				goto fail;
			if (camel_stream_reset (stream) == -1)
				goto fail;
		} else {
			stream = (CamelStream *) nntp_store->stream;
			camel_object_ref (stream);
		}
	} else if (ret == 423 || ret == 430) {
		camel_exception_setv (ex, CAMEL_EXCEPTION_FOLDER_INVALID_UID, _("Cannot get message %s: %s"), msgid, line);
	} else if (ret != -1) {
		camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM, _("Cannot get message %s: %s"), msgid, line);
	}

	return stream;

 fail:
	if (errno == EINTR)
		camel_exception_setv (ex, CAMEL_EXCEPTION_USER_CANCEL, _("User canceled"));
	else
		camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM, _("Cannot get message %s: %s"), msgid, g_strerror (errno));

	return NULL;
}
static CamelStream *
nntp_folder_download_message (CamelNNTPFolder *nntp_folder,
                              const gchar *id,
                              const gchar *msgid,
                              GCancellable *cancellable,
                              GError **error)
{
	CamelFolder *folder;
	CamelStore *parent_store;
	CamelDataCache *nntp_cache;
	CamelNNTPStore *nntp_store;
	CamelNNTPStream *nntp_stream = NULL;
	CamelStream *stream = NULL;
	gint ret;
	gchar *line;

	folder = CAMEL_FOLDER (nntp_folder);
	parent_store = camel_folder_get_parent_store (folder);

	nntp_store = CAMEL_NNTP_STORE (parent_store);
	nntp_cache = camel_nntp_store_ref_cache (nntp_store);

	ret = camel_nntp_command (
		nntp_store, cancellable, error,
		nntp_folder, &line, "article %s", id);

	if (ret == 220) {
		GIOStream *base_stream;

		nntp_stream = camel_nntp_store_ref_stream (nntp_store);

		base_stream = camel_data_cache_add (
			nntp_cache, "cache", msgid, NULL);
		if (base_stream != NULL) {
			gboolean success;

			stream = camel_stream_new (base_stream);
			g_object_unref (base_stream);

			success = (camel_stream_write_to_stream (
				CAMEL_STREAM (nntp_stream),
				stream, cancellable, error) != -1);
			if (!success)
				goto fail;

			success = g_seekable_seek (
				G_SEEKABLE (stream), 0,
				G_SEEK_SET, cancellable, error);
			if (!success)
				goto fail;
		} else {
			stream = g_object_ref (nntp_stream);
		}

	} else if (ret == 423 || ret == 430) {
		g_set_error (
			error, CAMEL_FOLDER_ERROR,
			CAMEL_FOLDER_ERROR_INVALID_UID,
			_("Cannot get message %s: %s"), msgid, line);

	} else if (ret != -1) {
		g_set_error (
			error, CAMEL_ERROR, CAMEL_ERROR_GENERIC,
			_("Cannot get message %s: %s"), msgid, line);
	}

	goto exit;

fail:
	camel_data_cache_remove (nntp_cache, "cache", msgid, NULL);
	g_prefix_error (error, _("Cannot get message %s: "), msgid);

	g_clear_object (&stream);

exit:
	g_clear_object (&nntp_cache);
	g_clear_object (&nntp_stream);

	return stream;
}