Skip site navigation (1)Skip section navigation (2) 
Date:      Tue, 1 Sep 1998 07:33:33 -0400 (EDT)
From:      Brian Feldman <green@unixhelp.org>
To:        current@FreeBSD.ORG
Subject:   E-day problems: rtld-elf dlsym() broken?
Message-ID:  <Pine.BSD.4.00.9809010729170.18315-200000@feldman.dyn.ml.org>
next in thread | raw e-mail | index | archive | help 

[-- Attachment #1 --]
As a start, I'd like to say great job to John Birrell and everyone else
involved, going to ELF worked almost without a hitch, I'm impressed! But
there is a problem now: dlsym, for me, seems to have stopped working.
Entirely.... Returning NULL always it seems. I've attached a program (yes,
it's a start on a basic debugger, I'm implementing rtld functions first)
which should show the problem to anyone interested. 

Brian Feldman
green@unixhelp.org
-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GCM/CS/SS d- s+:+ a--- C++(++++) UB++++ P---- L- E---(+) W+++ N@ o? K- W--- O M- V-- PS+ PE-() Y+ PGP(+) t+ 5-- X++ R+ mtv b++(+++) D+ D++ G e* h(+) r+(-) z- 
-------END GEEK CODE BLOCK-----

[-- Attachment #2 --]
/*-
 * Copyright (c) 1998 Brian Fundakowski Feldman
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

static const char copyright[] = "@(#) Copyright 1998 Brian Fundakowski Feldman.\
	All rights reserved.";

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>

#include <readline/readline.h>
#include <readline/history.h>

void doline(char *);
void help(void *);
void copyrightf(void *);
void lookup(void *);
void quit(void *);

int
main(int argc, char **argv) {
	char *line;
	signal(SIGINT, (sig_t)&exit);
	signal(SIGTERM, (sig_t)&exit);
	while ((line = readline("(dl) ")) != NULL)
		doline(line);
	exit(0);
}

struct binds {
	char *name;
	void (*func)(void *);
	char *desc;
};

struct binds bindz[] = {
	{ "quit", &quit, "Quit this program." },
	{ "help", &help, "Command help." },
	{ "copyright", &copyrightf, "Copyright info." },
	{ "lookup", &lookup, "Look up a symbol." },
};

#define BINDS (sizeof(bindz) / sizeof(struct binds))

void
doline(char *line) {
	char c, *d, *oline;

	oline = strdup(line);
	if ((d = index(oline, ' ')) != (char *)NULL)
		*d = 0;
	for (c = 0; c < BINDS; c++)
		if (!strcmp(oline, bindz[c].name)) {
			(*bindz[c].func)(line);
			free(oline);
			break;
		}
	if (c == BINDS) {
		printf("%s: command unknown\n", line);
		free(line);
	}
}

void
lookup(void *line) {
	void *lameptr;
	char *baz;

	if ((void *)index(line, '\0') < line + 8 ||
	    (lameptr = (void *)dlsym(NULL, baz = (char *)line + 7)) == NULL)
		printf("%s: not found\n", *baz ? baz : "");
	else
		printf("%s: 0x%x\n", line + 7, lameptr);
	free(line);
}

void
copyrightf(void *line) {
	printf("%s\n", copyright + 5);
	free(line);
}

void
help(void *line) {
	char c;

	printf("Help:\n");
	for (c = 0; c < BINDS; c++)
		printf("\t%s\t%s\n", bindz[c].name, bindz[c].desc);
	free(line);
}

void
quit(void *line) {
	free(line);
	exit(0);
}

Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSD.4.00.9809010729170.18315-200000>