build.sh

#!/bin/sh

gcc -c mod.c -o mod.o
gcc -c main.c -o main.o
g++ -c mod_loader.cc -o mod_loader.o
g++ mod.o main.o mod_loader.o -o test

main.c

#include <stdio.h>
#include "mod.h"

DEFINE_LOG_ID(TestApp);

int main()
{
    printf("Hello World\n");
}

mod.c

#include <stdio.h>
#include "mod.h"

extern char const * logging_init_data[]; 

void init_logger()
{
    logging_create_module_info(logging_init_data[0], logging_init_data[1], logging_init_data[2] );    
}

void*
logging_create_module_info (const char* header_location,
                            const char* stream_location,
                            const char* id)
{ 
    printf( "C init func called\n"
            "header_location: %s\n" 
            "stream_location: %s\n"
            "id:              %s\n", header_location, stream_location, id);
}

mod.h

#ifndef LIBLOG_LOG_H_INCLUDED
#define LIBLOG_LOG_H_INCLUDED

void*
logging_create_module_info (const char* header_location,
                            const char* stream_location,
                            const char* id);

#define DEFINE_LOG_ID_IMPL(HEADER_LOCATION, ID) \
char const * logging_init_data[] = { HEADER_LOCATION, __BASE_FILE__, # ID }

#define DEFINE_LOG_ID(ID) \
DEFINE_LOG_ID_IMPL (__FILE__, ID)

#endif

mod_loader.cc

extern "C" void init_logger();

namespace {

struct init_it{ init_it(){ init_logger(); } };

static init_it do_init;

}