notif_subscribe_example.c

/**
 * @file notif_subscribe_example.c
 * @author Michal Vasko <mvasko@cesnet.cz>
 * @brief example of an application subscribing to a notification
 *
 * @copyright
 * Copyright (c) 2019 CESNET, z.s.p.o.
 *
 * This source code is licensed under BSD 3-Clause License (the "License").
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://opensource.org/licenses/BSD-3-Clause
 */

#define _QNX_SOURCE /* sleep() */
#define _GNU_SOURCE

#include <inttypes.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <libyang/libyang.h>

#include "sysrepo.h"

volatile int exit_application = 0;

static void
print_val(const sr_val_t *value)
{
    if (NULL == value) {
        return;
    }

    printf("%s ", value->xpath);

    switch (value->type) {
    case SR_CONTAINER_T:
    case SR_CONTAINER_PRESENCE_T:
        printf("(container)");
        break;
    case SR_LIST_T:
        printf("(list instance)");
        break;
    case SR_STRING_T:
        printf("= %s", value->data.string_val);
        break;
    case SR_BOOL_T:
        printf("= %s", value->data.bool_val ? "true" : "false");
        break;
    case SR_DECIMAL64_T:
        printf("= %g", value->data.decimal64_val);
        break;
    case SR_INT8_T:
        printf("= %" PRId8, value->data.int8_val);
        break;
    case SR_INT16_T:
        printf("= %" PRId16, value->data.int16_val);
        break;
    case SR_INT32_T:
        printf("= %" PRId32, value->data.int32_val);
        break;
    case SR_INT64_T:
        printf("= %" PRId64, value->data.int64_val);
        break;
    case SR_UINT8_T:
        printf("= %" PRIu8, value->data.uint8_val);
        break;
    case SR_UINT16_T:
        printf("= %" PRIu16, value->data.uint16_val);
        break;
    case SR_UINT32_T:
        printf("= %" PRIu32, value->data.uint32_val);
        break;
    case SR_UINT64_T:
        printf("= %" PRIu64, value->data.uint64_val);
        break;
    case SR_IDENTITYREF_T:
        printf("= %s", value->data.identityref_val);
        break;
    case SR_INSTANCEID_T:
        printf("= %s", value->data.instanceid_val);
        break;
    case SR_BITS_T:
        printf("= %s", value->data.bits_val);
        break;
    case SR_BINARY_T:
        printf("= %s", value->data.binary_val);
        break;
    case SR_ENUM_T:
        printf("= %s", value->data.enum_val);
        break;
    case SR_LEAF_EMPTY_T:
        printf("(empty leaf)");
        break;
    default:
        printf("(unprintable)");
        break;
    }

    switch (value->type) {
    case SR_UNKNOWN_T:
    case SR_CONTAINER_T:
    case SR_CONTAINER_PRESENCE_T:
    case SR_LIST_T:
    case SR_LEAF_EMPTY_T:
        printf("\n");
        break;
    default:
        printf("%s\n", value->dflt ? " [default]" : "");
        break;
    }
}

static void
notif_cb(sr_session_ctx_t *session, const sr_ev_notif_type_t notif_type, uint32_t sub_id, const char *path,
        const sr_val_t *values, const size_t values_cnt, struct timespec *timestamp, void *private_data)
{
    size_t i;

    (void)session;
    (void)notif_type;
    (void)sub_id;
    (void)timestamp;
    (void)private_data;

    printf("\n\n ========== NOTIFICATION \"%s\" RECEIVED =======================\n\n", path);

    for (i = 0; i < values_cnt; ++i) {
        print_val(&values[i]);
    }
}

static void
sigint_handler(int signum)
{
    (void)signum;

    exit_application = 1;
}

int
main(int argc, char **argv)
{
    sr_conn_ctx_t *connection = NULL;
    sr_session_ctx_t *session = NULL;
    sr_subscription_ctx_t *subscription = NULL;
    int rc = SR_ERR_OK;
    const char *mod_name, *xpath = NULL;

    if ((argc < 2) || (argc > 3)) {
        printf("%s <module-with-notifications> [<xpath-filtering-notifications>]\n", argv[0]);
        return EXIT_FAILURE;
    }
    mod_name = argv[1];
    if (argc == 3) {
        xpath = argv[2];
    }

    printf("Application will subscribe to \"%s\" notifications.\n\n", mod_name);

    /* turn logging on */
    sr_log_stderr(SR_LL_WRN);

    /* connect to sysrepo */
    rc = sr_connect(0, &connection);
    if (rc != SR_ERR_OK) {
        goto cleanup;
    }

    /* start session */
    rc = sr_session_start(connection, SR_DS_RUNNING, &session);
    if (rc != SR_ERR_OK) {
        goto cleanup;
    }

    /* subscribe for the notifications */
    rc = sr_notif_subscribe(session, mod_name, xpath, NULL, NULL, notif_cb, NULL, 0, &subscription);
    if (rc != SR_ERR_OK) {
        goto cleanup;
    }

    printf("\n\n ========== LISTENING FOR NOTIFICATIONS ==========\n\n");

    /* loop until ctrl-c is pressed / SIGINT is received */
    signal(SIGINT, sigint_handler);
    signal(SIGPIPE, SIG_IGN);
    while (!exit_application) {
        sleep(1000);
    }

    printf("Application exit requested, exiting.\n");

cleanup:
    sr_disconnect(connection);
    return rc ? EXIT_FAILURE : EXIT_SUCCESS;
}