как перехватить подключение библиотеки?

~$ cat 1.c 2.c 3.c 4.c
int main() {
	printf( "%d\n", foo() );
	printf( "%d\n", a() );
	printf( "%d\n", b() );
}

int a() {
	return foo();
}
int b() {
	return foo();
}
int foo() {
	return D;
}

~$ gcc 4.c -shared -o foo.so.1 -DD=1 -Wl,-soname,foo.so.1 -Wl,--default-symver
~$ gcc 4.c -shared -o foo.so.2 -DD=2 -Wl,-soname,foo.so.2 -Wl,--default-symver
~$ gcc 4.c -shared -o foo.so.3 -DD=3 -Wl,-soname,foo.so.3 -Wl,--default-symver
~$ gcc 2.c -shared -fPIC -o 1.so foo.so.2
~$ gcc 3.c -shared -fPIC -o 2.so foo.so.3
~$ gcc 1.c 1.so 2.so foo.so.1 -Wl,-rpath,/home/igor
~$ ./a.out 
1
2
3

./run.sh 
#!/bin/bash

cat run.sh
echo "***dlopen.c***"
cat dlopen.c
echo "***lib1.c, lib2.c***"
cat lib1.c lib2.c
echo "***main.c***"
cat main.c
echo "***test.c***"
cat test.c

gcc -fPIC -shared -Wl,-soname,dlopen.so -o dlopen.so dlopen.c

gcc -fPIC -shared -Wl,-soname,test.so -o test.so test.c
gcc -fPIC -shared -o lib1.so lib1.c
gcc -fPIC -shared -o lib2.so lib2.c
gcc main.c -o main -ldl

export LD_PRELOAD=$(pwd)/dlopen.so
export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:.
echo "***./main***"
./main

***dlopen.c***
#define _GNU_SOURCE
#include <dlfcn.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>

#include <execinfo.h>
#include <stdlib.h>
#include <unistd.h>

int test(void)
{
  int res=1;
  int j, nptrs;
#define SIZE 3
  void *buffer[SIZE];
  char **strings;

  nptrs = backtrace(buffer, SIZE);
  //printf("backtrace() returned %d addresses\n", nptrs);

  strings = backtrace_symbols(buffer, nptrs);
  if (strings == NULL) {
    perror("backtrace_symbols");
    exit(EXIT_FAILURE);
  }

  //for (j = 0; j < nptrs; j++)
  //  printf("%s\n", strings[j]);
  if(nptrs==3)
    res=memcmp("test.so",strings[2],7);

  free(strings);
  return res;
}

static void* (*real_dlopen)(const char *filename, int flag) = 0;
void *dlopen(const char *filename, int flag)
{
  if(!real_dlopen) real_dlopen = dlsym(RTLD_NEXT, "dlopen");
  printf("dlopen(%s,%i)\n",filename,flag);
  if(test()==0)
    return real_dlopen("lib2.so", flag);
  else
    return real_dlopen(filename, flag);
}
***lib1.c, lib2.c***
#include <stdio.h>

void fun()
{
  printf("fun from lib1.so\n");
}
#include <stdio.h>

void fun()
{
  printf("fun from lib2.so\n");
}
***main.c***
#include <dlfcn.h>
#include <stdio.h>

typedef void (*tfun)();
void test_fun()
{
  void* lib = dlopen("lib1.so", RTLD_LAZY);
  if(lib)
  {
    tfun fun = (tfun)dlsym(lib,"fun");
    if(fun) fun();
  }
}
void call_lib()
{
  void* lib = dlopen("test.so", RTLD_LAZY);
  if(lib)
  {
    tfun fun = (tfun)dlsym(lib,"fun");
    if(fun)
      fun();
  }
}
int main()
{
  test_fun();
  call_lib();

  return 0;
}
***test.c***
#include <dlfcn.h>
#include <stdio.h>

typedef void (*tfun)();
void fun()
{
  void* lib = dlopen("lib1.so", RTLD_LAZY);
  if(lib)
  {
    tfun fun = (tfun)dlsym(lib,"fun");
    if(fun) fun();
  }
}
***./main***
dlopen(lib1.so,1)
fun from lib1.so
dlopen(test.so,1)
dlopen(lib1.so,1)
fun from lib2.so