Resolve dlsym(3) and friends directly so that dlsym(RTLD_NEXT,...) works.
Previously dlsym resolved to the version in crt0.o or libc which would mean that the caller's shared object couldn't be determined correctly using __builtin_return_address(0). Mainly from FreeBSD, but adapted by me. Benefits of this solutions are: - backward comptibility maintained - existing broken binaries are fixed with a new ld.elf_so - __mainprog_obj can be removed from crt0.o - we do the same thing as FreeBSD Fixes PR 22067. OKed by Jason and Christos.
This commit is contained in:
skrll
parent
b4c1c6117c
commit
d900731978
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@ -1,4 +1,4 @@
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/* $NetBSD: common.c,v 1.12 2003/07/26 19:24:26 salo Exp $ */
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/* $NetBSD: common.c,v 1.13 2003/08/12 09:18:42 skrll Exp $ */
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/*
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* Copyright (c) 1995 Christopher G. Demetriou
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@ -74,13 +74,4 @@ _rtld_setup(cleanup, obj)
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atexit(cleanup);
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}
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#ifdef __weak_alias
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__weak_alias(dlopen,_dlopen);
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__weak_alias(dlclose,_dlclose);
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__weak_alias(dlsym,_dlsym);
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__weak_alias(dlerror,_dlerror);
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__weak_alias(dladdr,_dladdr);
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#endif
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#include <dlfcn_stubs.c>
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#endif /* DYNAMIC */
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@ -1,4 +1,4 @@
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/* $NetBSD: common.h,v 1.8 2003/07/26 19:24:26 salo Exp $ */
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/* $NetBSD: common.h,v 1.9 2003/08/12 09:18:42 skrll Exp $ */
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/*
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* Copyright (c) 1995 Christopher G. Demetriou
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@ -75,8 +75,6 @@ extern void _fini __P((void));
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#ifdef DYNAMIC
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void _rtld_setup __P((void (*)(void), const Obj_Entry *obj));
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const Obj_Entry *__mainprog_obj;
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/*
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* Arrange for _DYNAMIC to be weak and undefined (and therefore to show up
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* as being at address zero, unless something else defines it). That way,
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@ -1,4 +1,4 @@
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/* $NetBSD: dlfcn_elf.c,v 1.3 2002/07/20 08:54:04 yamt Exp $ */
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/* $NetBSD: dlfcn_elf.c,v 1.4 2003/08/12 09:18:43 skrll Exp $ */
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/*
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* Copyright (c) 2000 Takuya SHIOZAKI
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@ -27,7 +27,7 @@
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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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__RCSID("$NetBSD: dlfcn_elf.c,v 1.3 2002/07/20 08:54:04 yamt Exp $");
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__RCSID("$NetBSD: dlfcn_elf.c,v 1.4 2003/08/12 09:18:43 skrll Exp $");
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#endif /* LIBC_SCCS and not lint */
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#include "namespace.h"
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@ -35,11 +35,6 @@ __RCSID("$NetBSD: dlfcn_elf.c,v 1.3 2002/07/20 08:54:04 yamt Exp $");
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#define ELFSIZE ARCH_ELFSIZE
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#include "rtld.h"
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#ifdef __weak_extern
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__weak_extern(__mainprog_obj)
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#endif
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extern const Obj_Entry *__mainprog_obj;
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#ifdef __weak_alias
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__weak_alias(dlopen,__dlopen)
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__weak_alias(dlclose,__dlclose)
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@ -48,4 +43,54 @@ __weak_alias(dlerror,__dlerror)
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__weak_alias(dladdr,__dladdr)
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#endif
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#include <dlfcn_stubs.c>
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/*
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* For ELF, the dynamic linker directly resolves references to its
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* services to functions inside the dynamic linker itself. These
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* weak-symbol stubs are necessary so that "ld" won't complain about
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* undefined symbols. The stubs are executed only when the program is
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* linked statically, or when a given service isn't implemented in the
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* dynamic linker. They must return an error if called, and they must
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* be weak symbols so that the dynamic linker can override them.
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*/
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static char dlfcn_error[] = "Service unavailable";
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/*ARGSUSED*/
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void *
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dlopen(const char *name, int mode)
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{
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return NULL;
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}
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/*ARGSUSED*/
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int
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dlclose(void *fd)
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{
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return -1;
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}
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/*ARGSUSED*/
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void *
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dlsym(void *handle, const char *name)
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{
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return NULL;
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}
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/*ARGSUSED*/
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__aconst char *
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dlerror()
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{
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return dlfcn_error;
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}
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/*ARGSUSED*/
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int
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dladdr(const void *addr, Dl_info *dli)
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{
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return 0;
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}
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@ -1,102 +0,0 @@
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/* $NetBSD: dlfcn_stubs.c,v 1.4 2003/07/26 19:24:41 salo Exp $ */
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/*
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* Copyright (c) 1995 Christopher G. Demetriou
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed for the
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* NetBSD Project. See http://www.NetBSD.org/ for
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* information about NetBSD.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
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*/
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/*
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* NOT A STANDALONE FILE!
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*/
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void *
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dlopen(name, mode)
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const char *name;
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int mode;
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{
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if (__mainprog_obj == NULL)
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return NULL;
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return (__mainprog_obj->dlopen)(name, mode);
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}
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int
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dlclose(fd)
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void *fd;
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{
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if (__mainprog_obj == NULL)
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return -1;
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return (__mainprog_obj->dlclose)(fd);
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}
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void *
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dlsym(fd, name)
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void *fd;
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const char *name;
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{
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if (__mainprog_obj == NULL)
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return NULL;
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return (__mainprog_obj->dlsym)(fd, name);
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}
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#if 0 /* not supported for ELF shlibs, apparently */
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int
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dlctl(fd, cmd, arg)
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void *fd, *arg;
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int cmd;
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{
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if (__mainprog_obj == NULL)
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return -1;
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return (__mainprog_obj->dlctl)(fd, cmd, arg);
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}
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#endif
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__aconst char *
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dlerror()
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{
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if (__mainprog_obj == NULL)
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return ("Dynamic linker interface not available");
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return (__mainprog_obj->dlerror)();
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}
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int
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dladdr(const void *addr, Dl_info *dli)
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{
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if (__mainprog_obj == NULL)
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return -1;
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return (__mainprog_obj->dladdr)(addr, dli);
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}
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@ -1,4 +1,4 @@
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/* $NetBSD: reloc.c,v 1.80 2003/07/24 10:12:26 skrll Exp $ */
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/* $NetBSD: reloc.c,v 1.81 2003/08/12 09:18:46 skrll Exp $ */
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/*
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* Copyright 1996 John D. Polstra.
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@ -196,11 +196,11 @@ _rtld_relocate_objects(Obj_Entry *first, bool bind_now)
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obj->version = RTLD_VERSION;
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/* Fill in the dynamic linker entry points. */
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obj->dlopen = _rtld_dlopen;
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obj->dlsym = _rtld_dlsym;
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obj->dlerror = _rtld_dlerror;
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obj->dlclose = _rtld_dlclose;
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obj->dladdr = _rtld_dladdr;
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obj->dlopen = dlopen;
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obj->dlsym = dlsym;
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obj->dlerror = dlerror;
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obj->dlclose = dlclose;
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obj->dladdr = dladdr;
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dbg(("fixing up PLTGOT"));
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/* Set the special PLTGOT entries. */
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@ -1,4 +1,4 @@
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/* $NetBSD: rtld.c,v 1.98 2003/07/24 10:12:26 skrll Exp $ */
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/* $NetBSD: rtld.c,v 1.99 2003/08/12 09:18:48 skrll Exp $ */
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/*
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* Copyright 1996 John D. Polstra.
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@ -433,6 +433,9 @@ _rtld(Elf_Addr *sp, Elf_Addr relocbase)
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real_environ = _rtld_objmain_sym("environ");
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if (real_environ)
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*real_environ = environ;
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/*
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* Set __mainprog_obj for old binaries.
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*/
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real___mainprog_obj = _rtld_objmain_sym("__mainprog_obj");
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if (real___mainprog_obj)
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*real___mainprog_obj = _rtld_objmain;
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@ -458,7 +461,7 @@ _rtld(Elf_Addr *sp, Elf_Addr relocbase)
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void
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_rtld_die(void)
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{
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const char *msg = _rtld_dlerror();
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const char *msg = dlerror();
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if (msg == NULL)
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msg = "Fatal error";
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@ -573,7 +576,7 @@ _rtld_unref_dag(Obj_Entry *root)
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}
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int
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_rtld_dlclose(void *handle)
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dlclose(void *handle)
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{
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Obj_Entry *root = _rtld_dlcheck(handle);
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@ -593,7 +596,7 @@ _rtld_dlclose(void *handle)
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}
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char *
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_rtld_dlerror(void)
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dlerror(void)
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{
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char *msg = error_message;
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@ -602,7 +605,7 @@ _rtld_dlerror(void)
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}
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void *
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_rtld_dlopen(const char *name, int mode)
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dlopen(const char *name, int mode)
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{
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Obj_Entry **old_obj_tail = _rtld_objtail;
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Obj_Entry *obj = NULL;
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@ -659,7 +662,7 @@ _rtld_objmain_sym(const char *name)
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}
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void *
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_rtld_dlsym(void *handle, const char *name)
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dlsym(void *handle, const char *name)
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{
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const Obj_Entry *obj;
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unsigned long hash;
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@ -745,7 +748,7 @@ _rtld_dlsym(void *handle, const char *name)
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}
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int
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_rtld_dladdr(const void *addr, Dl_info *info)
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dladdr(const void *addr, Dl_info *info)
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{
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const Obj_Entry *obj;
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const Elf_Sym *def, *best_def;
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@ -1,4 +1,4 @@
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/* $NetBSD: rtld.h,v 1.69 2003/07/24 10:12:26 skrll Exp $ */
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/* $NetBSD: rtld.h,v 1.70 2003/08/12 09:18:49 skrll Exp $ */
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/*
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* Copyright 1996 John D. Polstra.
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@ -211,15 +211,20 @@ extern Objlist _rtld_list_main;
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extern Elf_Sym _rtld_sym_zero;
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/* rtld.c */
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/*
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* We export these symbols using _rtld_symbol_lookup and is_exported.
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*/
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char *dlerror(void);
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void *dlopen(const char *, int);
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void *dlsym(void *, const char *);
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int dlclose(void *);
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int dladdr(const void *, Dl_info *);
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void _rtld_error(const char *, ...)
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__attribute__((__format__(__printf__,1,2)));
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void _rtld_die(void);
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char *_rtld_dlerror(void);
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void *_rtld_dlopen(const char *, int);
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void *_rtld_objmain_sym(const char *);
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void *_rtld_dlsym(void *, const char *);
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int _rtld_dlclose(void *);
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int _rtld_dladdr(const void *, Dl_info *);
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void _rtld_debug_state(void);
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void _rtld_linkmap_add(Obj_Entry *);
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void _rtld_linkmap_delete(Obj_Entry *);
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@ -1,4 +1,4 @@
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/* $NetBSD: search.c,v 1.17 2003/07/24 10:12:26 skrll Exp $ */
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/* $NetBSD: search.c,v 1.18 2003/08/12 09:18:50 skrll Exp $ */
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/*
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* Copyright 1996 Matt Thomas <matt@3am-software.com>
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@ -127,7 +127,7 @@ _rtld_load_library(const char *name, const Obj_Entry *refobj, int mode)
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}
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dbg((" Searching for \"%s\" (%p)", name, refobj));
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tmperrorp = _rtld_dlerror();
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tmperrorp = dlerror();
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if (tmperrorp != NULL) {
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strncpy(tmperror, tmperrorp, sizeof tmperror);
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tmperrorp = tmperror;
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@ -165,7 +165,7 @@ pathfound:
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if (tmperrorp)
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_rtld_error("%s", tmperror);
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else
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(void)_rtld_dlerror();
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(void)dlerror();
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return obj;
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found:
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@ -1,4 +1,4 @@
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/* $NetBSD: symbol.c,v 1.32 2003/08/05 19:41:53 skrll Exp $ */
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/* $NetBSD: symbol.c,v 1.33 2003/08/12 09:18:50 skrll Exp $ */
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/*
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* Copyright 1996 John D. Polstra.
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@ -53,6 +53,29 @@
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#include "debug.h"
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#include "rtld.h"
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static bool
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_rtld_is_exported(const Elf_Sym *def)
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{
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static Elf_Addr _rtld_exports[] = {
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(Elf_Addr)dlopen,
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(Elf_Addr)dlclose,
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(Elf_Addr)dlsym,
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(Elf_Addr)dlerror,
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(Elf_Addr)dladdr,
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NULL
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};
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int i;
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Elf_Addr value;
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value = (Elf_Addr)(_rtld_objself.relocbase + def->st_value);
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for (i = 0; _rtld_exports[i] != NULL; i++) {
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if (value == _rtld_exports[i])
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return true;
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}
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return false;
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}
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/*
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* Hash function for symbol table lookup. Don't even think about changing
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* this. It is specified by the System V ABI.
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@ -225,6 +248,20 @@ _rtld_find_symdef(unsigned long symnum, const Obj_Entry *refobj,
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}
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}
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/*
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* Search the dynamic linker itself, and possibly resolve the
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* symbol from there. This is how the application links to
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* dynamic linker services such as dlopen. Only the values listed
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* in the "_rtld_exports" array can be resolved from the dynamic linker.
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*/
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if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
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symp = _rtld_symlook_obj(name, hash, &_rtld_objself, in_plt);
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if (symp != NULL && _rtld_is_exported(symp)) {
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def = symp;
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defobj = &_rtld_objself;
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}
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}
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/*
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* If we found no definition and the reference is weak, treat the
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* symbol as having the value zero.
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@ -1,4 +1,4 @@
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/* $NetBSD: ldd.c,v 1.19 2003/05/28 20:45:39 dsl Exp $ */
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/* $NetBSD: ldd.c,v 1.20 2003/08/12 09:18:38 skrll Exp $ */
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/*-
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* Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
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@ -197,7 +197,7 @@ _rtld_error(const char *fmt, ...)
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}
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char *
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_rtld_dlerror()
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dlerror()
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{
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char *msg = error_message;
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error_message = NULL;
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