/*-------------------------------------------------------------------------
 *
 * dynloader.c--
 *    Dynamic Loader for Postgres for Linux, generated from those for
 *    Ultrix.
 *
 *    You need to install the dld library on your Linux system!
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    /usr/local/devel/pglite/cvs/src/backend/port/linux/dynloader.c,v 1.1.1.1 1994/11/07 05:19:37 andrew Exp
 *
 *-------------------------------------------------------------------------
 */
#include <stdio.h>
#include <dld.h>
#include "postgres.h"
#include "port-protos.h"
#include "utils/elog.h"
#include "fmgr.h"

extern char pg_pathname[];

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

    /*
     * 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 (dld_init (dld_find_executable (pg_pathname))) {
	    return NULL;
	}
	/*
	 * if there are undefined symbols, we want dl to search from the
	 * following libraries also.
	 */
	dl_initialized= 1;
    }

    /*
     * link the file, then check for undefined symbols!
     */
    if (dld_link(filename)) {
	return NULL;
    }

    /*
     * If undefined symbols: try to link with the C and math libraries!
     * This could be smarter, if the dynamic linker was able to handle
     * shared libs!
     */
    if(dld_undefined_sym_count > 0) {
	if (dld_link("/usr/lib/libc.a")) {
	    elog(NOTICE, "dld: Cannot link C library!");
	    return NULL;
	}
	if(dld_undefined_sym_count > 0) {
	    if (dld_link("/usr/lib/libm.a")) {
		elog(NOTICE, "dld: Cannot link math library!");
		return NULL;
	    }
	    if(dld_undefined_sym_count > 0) {
		int count = dld_undefined_sym_count;
		char **list= dld_list_undefined_sym();

		/* list the undefined symbols, if any */
		elog(NOTICE, "dld: Undefined:");
		do {
		    elog(NOTICE, "  %s", *list);
		    list++;
		    count--;
		} while(count > 0);

		dld_unlink_by_file(filename, 1);
		return NULL;
	    }
	}
    }

    return (void *) strdup(filename);
}

char *
pg_dlerror()
{
    return dld_strerror(dld_errno);
}