CODEWITHSUNDEEP
cpostgresqldebian
Martin Moore
Martin Moore

Reputation: 733

C library gives '__gxx_personality_v0 ' error in Postgres

I'm building a new 64bit Debian Squeeze server, and Postgres 8.4 reports the well documented 'undefined __gxx_personality_v0' error when I try to restore a database.

The lib builds/installs fine.

However, the source is c, not c++ which seems to be where __gxx_personality_v0 belongs.

The code is from a 32bit Etch/postgres 8.1 environmnet.

I'm kind of stuck - but I bet the solution is very simple!

Upvotes: 0

Views: 261

Answers (1)

Craig Ringer
Craig Ringer

Reputation: 324375

Test to see whether the issue is actually related to PostgreSQL, or if it is a problem with your library build. Here's a simple program you can use to dlopen() your library and resolve a symbol. Compile it with:

gcc dlopentest.c -o dlopentest -ldl

... and run it as:

./dlopentest /path/to/my/lib.so somesymbol

or for more info prefix LD_DEBUG=symbols (for other options LD_DEBUG=help) eg:

LD_DEBUG=symbols ./dlopentest /path/to/my/lib somesymbol

Which symbol to look for depends on your code and what it's for. You haven't provided enough information to say.

This test program won't work with any library that requires symbols from the postgresql executable in order to load and init, so if your code is (for example) a procedural language it won't load. Most simple modules load fine, though.

You should also examine the output of:

ldd /path/to/your/library.so

to see if it's linking to libstdc++ or anything else you don't expect.

Here's the test program:

// Compile with a c99 compiler; I don't use oldstyle declarations
#include <stdlib.h>
#include <stdio.h>
#include <dlfcn.h>

int main(int argc, char * argv[]) {

  if (argc != 3) {
    printf("Usage: %s /path/to/lib/to/load symbol_to_resolve\n", argv[0]);
    printf("   eg: %s libc.so.6 gettimeofday\n", argv[0]);
    return 1;
  }

  char * err;
  const char * const libname = argv[1];
  const char * const symname = argv[2];

  dlerror();  // clear dl error state before starting work

  void * libhandle = dlopen(libname, RTLD_LAZY);
  if ( (err = dlerror()) != NULL ) {
    printf("Failed to load library: %s\n", err);
    return 2;
  }

  void * symhandle = dlsym(libhandle, symname);
  if ( (err = dlerror()) != NULL ) {
    printf("Failed to load symbol: %s\n", err);
    return 2;
  }
  printf("Successfully retrieved symbol %s from library %s\n", symname, libname);

  // Optional since we're existing, but good for testing:
  if ( (err = dlerror()) != NULL ) {
    printf("Failed to close lib during exit: %s\n", err);
    return 2;
  }

  return 0;
}

Upvotes: 2

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