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1999-02-03 Ulrich Drepper <drepper@cygnus.com> * elf/dlsym.c (dlsym_doit): If no symbol for RTLD_NEXT is found initialize ref element of args object so that dlsym does not dump a core. * elf/dlvsym.c (dlvsym_doit): Likewise.
100 lines
2.9 KiB
C
100 lines
2.9 KiB
C
/* Look up a symbol in a shared object loaded by `dlopen'.
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Copyright (C) 1995, 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <dlfcn.h>
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#include <setjmp.h>
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#include <stddef.h>
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#include <elf/ldsodefs.h>
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struct dlsym_args
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{
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/* The arguments to dlsym_doit. */
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void *handle;
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const char *name;
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struct r_found_version version;
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ElfW(Addr) caller;
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/* The return values of dlsym_doit. */
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ElfW(Addr) loadbase;
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const ElfW(Sym) *ref;
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};
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static void
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dlsym_doit (void *a)
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{
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struct dlsym_args *args = (struct dlsym_args *) a;
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args->ref = NULL;
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if (args->handle == RTLD_DEFAULT)
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/* Search the global scope. */
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args->loadbase = _dl_lookup_symbol (args->name, &args->ref,
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_dl_global_scope, NULL, 0);
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else if (args->handle == RTLD_NEXT)
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{
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struct link_map *l, *match;
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/* Find the highest-addressed object that CALLER is not below. */
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match = NULL;
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for (l = _dl_loaded; l; l = l->l_next)
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if (args->caller >= l->l_addr && (!match || match->l_addr < l->l_addr))
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match = l;
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if (! match)
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_dl_signal_error (0, NULL, _("\
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RTLD_NEXT used in code not dynamically loaded"));
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l = match;
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while (l->l_loader)
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l = l->l_loader;
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args->loadbase = _dl_lookup_symbol_skip (args->name, &args->ref,
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l->l_local_scope, NULL, match);
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if (args->loadbase == 0)
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{
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/* This means that no such symbol is defined. In this case we
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have to provide a phony Elfxx_Sym entry since the value is
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referenced in `dlsym'. */
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static const ElfW(Sym) null_result;
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args->ref = &null_result;
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}
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}
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else
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{
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/* Search the scope of the given object. */
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struct link_map *map = args->handle;
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args->loadbase = _dl_lookup_symbol (args->name, &args->ref,
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map->l_local_scope, map->l_name, 0);
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}
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}
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void *
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dlsym (void *handle, const char *name)
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{
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struct dlsym_args args;
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args.caller = (ElfW(Addr)) __builtin_return_address (0);
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args.handle = handle;
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args.name = name;
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return (_dlerror_run (dlsym_doit, &args)
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? NULL : (void *) (args.loadbase + args.ref->st_value));
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}
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