236 lines
6.2 KiB
C
236 lines
6.2 KiB
C
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/* loader-dlopen.c -- dynamic linking with dlopen/dlsym
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Copyright (C) 1998, 1999, 2000, 2004, 2006,
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2007, 2008 Free Software Foundation, Inc.
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Written by Thomas Tanner, 1998
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NOTE: The canonical source of this file is maintained with the
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GNU Libtool package. Report bugs to bug-libtool@gnu.org.
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GNU Libltdl is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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As a special exception to the GNU Lesser General Public License,
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if you distribute this file as part of a program or library that
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is built using GNU Libtool, you may include this file under the
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same distribution terms that you use for the rest of that program.
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GNU Libltdl is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with GNU Libltdl; see the file COPYING.LIB. If not, a
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copy can be downloaded from http://www.gnu.org/licenses/lgpl.html,
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or obtained by writing to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "lt__private.h"
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#include "lt_dlloader.h"
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/* Use the preprocessor to rename non-static symbols to avoid namespace
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collisions when the loader code is statically linked into libltdl.
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Use the "<module_name>_LTX_" prefix so that the symbol addresses can
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be fetched from the preloaded symbol list by lt_dlsym(): */
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#define get_vtable dlopen_LTX_get_vtable
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LT_BEGIN_C_DECLS
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LT_SCOPE lt_dlvtable *get_vtable (lt_user_data loader_data);
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LT_END_C_DECLS
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/* Boilerplate code to set up the vtable for hooking this loader into
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libltdl's loader list: */
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static int vl_exit (lt_user_data loader_data);
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static lt_module vm_open (lt_user_data loader_data, const char *filename,
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lt_dladvise advise);
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static int vm_close (lt_user_data loader_data, lt_module module);
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static void * vm_sym (lt_user_data loader_data, lt_module module,
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const char *symbolname);
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static lt_dlvtable *vtable = 0;
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/* Return the vtable for this loader, only the name and sym_prefix
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attributes (plus the virtual function implementations, obviously)
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change between loaders. */
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lt_dlvtable *
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get_vtable (lt_user_data loader_data)
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{
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if (!vtable)
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{
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vtable = (lt_dlvtable *) lt__zalloc (sizeof *vtable);
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}
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if (vtable && !vtable->name)
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{
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vtable->name = "lt_dlopen";
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#if defined(DLSYM_USCORE)
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vtable->sym_prefix = "_";
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#endif
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vtable->module_open = vm_open;
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vtable->module_close = vm_close;
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vtable->find_sym = vm_sym;
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vtable->dlloader_exit = vl_exit;
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vtable->dlloader_data = loader_data;
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vtable->priority = LT_DLLOADER_PREPEND;
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}
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if (vtable && (vtable->dlloader_data != loader_data))
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{
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LT__SETERROR (INIT_LOADER);
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return 0;
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}
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return vtable;
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}
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/* --- IMPLEMENTATION --- */
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#if defined(HAVE_DLFCN_H)
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# include <dlfcn.h>
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#endif
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#if defined(HAVE_SYS_DL_H)
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# include <sys/dl.h>
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#endif
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/* We may have to define LT_LAZY_OR_NOW in the command line if we
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find out it does not work in some platform. */
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#if !defined(LT_LAZY_OR_NOW)
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# if defined(RTLD_LAZY)
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# define LT_LAZY_OR_NOW RTLD_LAZY
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# else
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# if defined(DL_LAZY)
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# define LT_LAZY_OR_NOW DL_LAZY
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# endif
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# endif /* !RTLD_LAZY */
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#endif
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#if !defined(LT_LAZY_OR_NOW)
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# if defined(RTLD_NOW)
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# define LT_LAZY_OR_NOW RTLD_NOW
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# else
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# if defined(DL_NOW)
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# define LT_LAZY_OR_NOW DL_NOW
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# endif
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# endif /* !RTLD_NOW */
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#endif
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#if !defined(LT_LAZY_OR_NOW)
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# define LT_LAZY_OR_NOW 0
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#endif /* !LT_LAZY_OR_NOW */
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/* We only support local and global symbols from modules for loaders
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that provide such a thing, otherwise the system default is used. */
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#if !defined(RTLD_GLOBAL)
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# if defined(DL_GLOBAL)
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# define RTLD_GLOBAL DL_GLOBAL
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# endif
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#endif /* !RTLD_GLOBAL */
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#if !defined(RTLD_LOCAL)
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# if defined(DL_LOCAL)
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# define RTLD_LOCAL DL_LOCAL
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# endif
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#endif /* !RTLD_LOCAL */
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#if defined(HAVE_DLERROR)
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# define DLERROR(arg) dlerror ()
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#else
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# define DLERROR(arg) LT__STRERROR (arg)
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#endif
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#define DL__SETERROR(errorcode) \
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LT__SETERRORSTR (DLERROR (errorcode))
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/* A function called through the vtable when this loader is no
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longer needed by the application. */
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static int
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vl_exit (lt_user_data LT__UNUSED loader_data)
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{
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vtable = NULL;
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return 0;
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}
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/* A function called through the vtable to open a module with this
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loader. Returns an opaque representation of the newly opened
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module for processing with this loader's other vtable functions. */
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static lt_module
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vm_open (lt_user_data LT__UNUSED loader_data, const char *filename,
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lt_dladvise advise)
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{
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int module_flags = LT_LAZY_OR_NOW;
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lt_module module;
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if (advise)
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{
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#ifdef RTLD_GLOBAL
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/* If there is some means of asking for global symbol resolution,
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do so. */
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if (advise->is_symglobal)
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module_flags |= RTLD_GLOBAL;
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#else
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/* Otherwise, reset that bit so the caller can tell it wasn't
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acted on. */
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advise->is_symglobal = 0;
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#endif
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/* And similarly for local only symbol resolution. */
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#ifdef RTLD_LOCAL
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if (advise->is_symlocal)
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module_flags |= RTLD_LOCAL;
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#else
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advise->is_symlocal = 0;
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#endif
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}
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module = dlopen (filename, module_flags);
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if (!module)
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{
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DL__SETERROR (CANNOT_OPEN);
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}
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return module;
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}
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/* A function called through the vtable when a particular module
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should be unloaded. */
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static int
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vm_close (lt_user_data LT__UNUSED loader_data, lt_module module)
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{
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int errors = 0;
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if (dlclose (module) != 0)
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{
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DL__SETERROR (CANNOT_CLOSE);
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++errors;
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}
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return errors;
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}
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/* A function called through the vtable to get the address of
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a symbol loaded from a particular module. */
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static void *
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vm_sym (lt_user_data LT__UNUSED loader_data, lt_module module, const char *name)
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{
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void *address = dlsym (module, name);
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if (!address)
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{
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DL__SETERROR (SYMBOL_NOT_FOUND);
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}
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return address;
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}
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