After "make all", running "julia helloworld.jl" causes abort due to "attempt to free invalid pointer". However, running "./test_main" works.

helloworld.jl

# replace the string below with the absolute path to libtest.so
ccall((:helloworld, "[abosolute path to the libtest.so]"), Void, ())

Makefile

all: libtest.so test_main

CXX = g++ -std=c++14

test.pb: test.proto
        protoc --cpp_out=. test.proto

test.pb.h: test.pb
test.pb.cc : test.pb

test.o: test.c test.pb.h
        $(CXX) -fPIC $(CFLAGS) -c $< -o $@

test_main: test_main.c
        gcc $< -ldl -o $@

test.pb.o: test.pb.cc
        $(CXX) -fPIC $(CFLAGS) -c $< -o $@

libtest.so: test.o test.pb.o
        gcc -shared -Wl,-soname,libtest.so.0 -o libtest.so.0.0 \
                $^ -lprotobuf -ltcmalloc
        ln -sf libtest.so.0.0 $@

clean:
        rm -f *.o test.pb.h test.pb.cc *.so *.so.* test_main

test.c

#include <iostream>

extern "C" {
  void helloworld() {
    std::cout << "hello world!" << std::endl;
  }
}

test.proto

package test;
message Test {
  required int32 index = 1;
  required string value = 2;
}

test_main.c

#include <dlfcn.h>
#include <stdio.h>

int main(int argc, char *argv[]) {
  dlerror();
  void *lib = dlopen("/home/ubuntu/test_protobuf/libtest.so", RTLD_LAZY | RTLD_GLOBAL | RTLD_DEEPBIND);
  if (lib == NULL) {
    const char* err_msg = dlerror();
    printf("something wrong: %s\n", err_msg);
    return 1;
  }
  void *void_fptr = dlsym(lib, "helloworld");
  void (*fptr)(void);
  fptr = (void (*)(void)) void_fptr;
  if (void_fptr == NULL) {
    const char* err_msg = dlerror();
    printf("something wrong: %s\n", err_msg);
    return 1;
  }
  fptr();
  dlclose(lib);
}