xcom_input_request.h

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/* Copyright (c) 2018, 2022, Oracle and/or its affiliates.
 
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   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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   This program is distributed in the hope that it will be useful,
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.
 
   You should have received a copy of the GNU General Public License
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef XCOM_INPUT_REQUEST_H
#define XCOM_INPUT_REQUEST_H
 
#include "xcom/pax_msg.h"
 
/**
 * A request directed to XCom through the input channel.
 */
struct xcom_input_request;
typedef struct xcom_input_request *xcom_input_request_ptr;
 
/**
 * The function type that XCom will use to reply to a request.
 */
typedef void (*xcom_input_reply_function_ptr)(void *reply_arg,
                                              pax_msg *payload);
 
/**
 * Creates a new XCom request.
 *
 * Takes ownership of @c a.
 *
 * @param a the request's app_data payload
 * @param reply_function the function used to reply to the request
 * @param reply_arg opaque argument to the reply_function
 * @retval xcom_input_request_ptr if successful
 * @retval NULL if unsuccessful
 */
xcom_input_request_ptr xcom_input_request_new(
    app_data_ptr a, xcom_input_reply_function_ptr reply_function,
    void *reply_arg);
 
/**
 * Frees the given request and its payload.
 *
 * @param request the request to free
 */
void xcom_input_request_free(xcom_input_request_ptr request);
 
/**
 * Links @c request to the list of requests @c next.
 *
 * @param request the request to link
 * @param next the list to be linked to
 */
void xcom_input_request_set_next(xcom_input_request_ptr request,
                                 xcom_input_request_ptr next);
 
/**
 * Unlinks @c request from its list.
 *
 * @param request the request to unlink
 * @returns the tail of the list the request was unlinked from
 */
xcom_input_request_ptr xcom_input_request_extract_next(
    xcom_input_request_ptr request);
 
/**
 * Extract the given request's payload.
 *
 * Transfers ownership of the result to the caller.
 *
 * @param request the request from which to extract the payload
 * @returns the request's app_data payload
 */
app_data_ptr xcom_input_request_extract_app_data(
    xcom_input_request_ptr request);
 
/**
 * Replies to the request using the strategy chosen by the request's origin.
 *
 * @param request the request to reply to
 * @param payload the payload of the reply
 */
void xcom_input_request_reply(xcom_input_request_ptr request, pax_msg *payload);
 
#endif /* XCOM_INPUT_REQUEST_H */