Adding new services fails

[dishkakrauch]

Hello there!

Has anybody complied C code as custom service for c-icap-server ever? I didn't find any suggestion how to do it correctly.
Just trying to use this simple function for saving data which ICAP server gets:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

int save_to_disk(char *data, int length) {
    time_t current_time;
    struct tm *local_time;
    char filename[100];
    FILE *file;

    time(&current_time);
    local_time = localtime(&current_time);

    snprintf(filename, 100, "output_%02d%02d%02d.txt", local_time->tm_hour, local_time->tm_min, local_time->tm_sec);

    file = fopen(filename, "w");
    if (file == NULL) {
        return -1;
    }

    fwrite(data, 1, length, file);

    fclose(file);

    return 0;
}

I've build this code with gcc and placed to the right place as svc_echo.so service.

gcc -shared -o /usr/local/c-icap/lib/c_icap/save_data.so -fPIC save_data.c
But c-icap-server can't start with my own service which was added to c-icap.conf:

Service save_data save_data.so

It throws an error:

Loading service: save_data path save_data.so
Found handler C_handler for service with extension: .so
Not found symbol "service" in library, unload it
Error while loading service save_data.so
Error loading service save_data.so
Fatal error while parsing config file: "/usr/local/c-icap/etc/c-icap.conf" line: 868
The line is: Service save_data save_data.so

I understand that my code doesn't have all neccessary method but I can't find template for doing custom services in this repo.
My task is really simple - to create a custom service that will be saving each message from ICAP server to anywhere (local storage or S3).

Any thoughts?