/*-------------------------------------------------------------------------
 *
 * dynloader.c--
 *	  This dynamic loader uses Andrew Yu's libdl-1.0 package for Ultrix 4.x.
 *	  (Note that pg_dlsym and pg_dlclose are actually macros defined in
 *	  "port-protos.h".)
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/port/ultrix4/Attic/dynloader.c,v 1.6 1998/02/26 04:34:39 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include <stdio.h>
#include <postgres.h>
#include "dl.h"
#include <utils/dynamic_loader.h>
#include "c.h"
#include "fmgr.h"
#include "port-protos.h"
#include "utils/elog.h"

extern char pg_pathname[];

void *
pg_dlopen(char *filename)
{
	static int	dl_initialized = 0;
	void	   *handle;

	/*
	 * initializes the dynamic loader with the executable's pathname.
	 * (only needs to do this the first time pg_dlopen is called.)
	 */
	if (!dl_initialized)
	{
		if (!dl_init(pg_pathname))
		{
			return NULL;
		}

		/*
		 * if there are undefined symbols, we want dl to search from the
		 * following libraries also.
		 */
		dl_setLibraries("/usr/lib/libm_G0.a:/usr/lib/libc_G0.a");
		dl_initialized = 1;
	}

	/*
	 * open the file. We do the symbol resolution right away so that we
	 * will know if there are undefined symbols. (This is in fact the same
	 * semantics as "ld -A". ie. you cannot have undefined symbols.
	 */
	if ((handle = dl_open(filename, DL_NOW)) == NULL)
	{
		int			count;
		char	  **list = dl_undefinedSymbols(&count);

		/* list the undefined symbols, if any */
		if (count)
		{
			elog(NOTICE, "dl: Undefined:");
			while (*list)
			{
				elog(NOTICE, "  %s", *list);
				list++;
			}
		}
	}

	return (void *) handle;
}
