Hiding symbols in a dynamic library without modifying source code

I found a solution that works... I created a shim library that redirects calls to the third-party library allowing code outside the library to see protbuf v2.4 symbols while code inside the third-party library sees protobuf v2.3 symbols. This workaround was based on the idea posted here: http://www.linuxjournal.com/article/7795

I had to modify the dlopen flags to include RTLD_LAZY | RTLD_LOCAL | RTLD_DEEPBIND. The RTLD_LOCAL flag keeps symbols inside the third-party library from being seen outside the shim library (prevents symbols leaking out). The RTLD_DEEPBIND forces calls from inside the 3rd party library to see only the internal version of the symbols (keeps symbols from leaking in).

To be concrete, here is an example excerpt from my shim library.

#include <stdio.h>
#include <stdint.h>
#include <dlfcn.h>
#include "libhdfs/hdfs.h"

//#define PRINT_DEBUG_STUFF

// Helper function to retrieve a function pointer to a function from libMapRClient
// while isolating the symbols used internally from those already linked externaly
// to workaround symbol collision problem with the current version of libMapRClient.
void* GetFunc(const char* name){
  #ifdef PRINT_DEBUG_STUFF
    printf("redirecting %s\n", name);
  #endif
  void *handle;
  char *error;

  handle = dlopen("/opt/mapr/lib/libMapRClient.so", RTLD_LAZY | RTLD_LOCAL | RTLD_DEEPBIND);

  if (!handle) {
    fputs(dlerror(), stderr);
    exit(1);
  }
  void* fp = dlsym(handle, name);
  if ((error = dlerror()) != 0) {
    fprintf(stderr, "%s\n", error);
    exit(1);
  }
  return fp;
}


hdfsFS hdfsConnect(const char* host, tPort port) {
  typedef hdfsFS (*FP) (const char* host, tPort port);
  static FP ext = 0;
  if (!ext) {
    ext = (FP)GetFunc("hdfsConnect");
  }
  return ext(host, port);
}


int hdfsCloseFile(hdfsFS fs, hdfsFile file) {
  typedef int (*FP) (hdfsFS fs, hdfsFile file);
  static FP ext = 0;
  if (!ext) {
    ext = (FP)GetFunc("hdfsCloseFile");
  }
  return ext(fs, file);
}

... and so on for the other public API functions