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/* loader-dlopen.c -- dynamic linking with dlopen/dlsym |
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|
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Copyright (C) 1998-2000, 2004, 2006-2008, 2011-2019, 2021-2022 Free |
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Software Foundation, Inc. |
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Written by Thomas Tanner, 1998 |
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|
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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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|
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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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|
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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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|
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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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|
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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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|
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#include "lt__private.h" |
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#include "lt_dlloader.h" |
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|
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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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|
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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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|
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|
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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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|
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static lt_dlvtable *vtable = 0; |
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|
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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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|
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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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|
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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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|
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return vtable; |
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} |
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|
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|
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|
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/* --- IMPLEMENTATION --- */ |
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|
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|
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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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|
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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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|
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|
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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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|
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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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|
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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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|
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#define DL__SETERROR(errorcode) \ |
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LT__SETERRORSTR (DLERROR (errorcode)) |
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|
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|
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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 loader_data LT__UNUSED) |
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{ |
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vtable = NULL; |
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return 0; |
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} |
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|
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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 loader_data LT__UNUSED, 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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#ifdef RTLD_MEMBER |
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int len = LT_STRLEN (filename); |
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#endif |
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|
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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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|
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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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|
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#ifdef RTLD_MEMBER /* AIX */ |
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if (len >= 4) /* at least "l(m)" */ |
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{ |
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/* Advise loading an archive member only if the filename really |
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contains both the opening and closing parent, and a member. */ |
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if (filename[len-1] == ')') |
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{ |
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const char *opening = strrchr(filename, '('); |
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if (opening && opening < (filename+len-2) && strchr(opening+1, '/') == NULL) |
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module_flags |= RTLD_MEMBER; |
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} |
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} |
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#endif |
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|
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module = dlopen (filename, module_flags); |
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|
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#if defined RTLD_MEMBER && defined LT_SHARED_LIB_MEMBER |
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if (!module && len && !(module_flags & RTLD_MEMBER) && errno == ENOEXEC) |
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{ |
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/* Loading without a member specified failed with "Exec format error". |
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So the file is there, but either has wrong bitwidth, or is an |
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archive eventually containing the default shared archive member. |
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Retry with default member, getting same error in worst case. */ |
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const char *member = LT_SHARED_LIB_MEMBER; |
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|
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char *attempt = MALLOC (char, len + strlen (member) + 1); |
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if (!attempt) |
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{ |
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LT__SETERROR (NO_MEMORY); |
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return module; |
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} |
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|
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sprintf (attempt, "%s%s", filename, member); |
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module = vm_open (loader_data, attempt, advise); |
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FREE (attempt); |
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return module; |
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} |
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#endif |
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|
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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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|
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return module; |
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} |
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|
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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 loader_data LT__UNUSED, lt_module module) |
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{ |
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int errors = 0; |
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|
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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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|
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return errors; |
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} |
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|
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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 loader_data LT__UNUSED, lt_module module, const char *name) |
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{ |
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void *address = dlsym (module, name); |
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|
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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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|
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return address; |
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} |
