mirror of
https://sourceware.org/git/glibc.git
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cf197e41e7
2000-04-02 Ulrich Drepper <drepper@redhat.com>
* elf/dl-fini.c (_dl_fini): Increment j counter after swapping in
element at this position.
* elf/Versions [ld.so] (GLIBC_2.2): Export _dl_load_lock.
* elf/link.h (struct link_map): Add l_reldepsmax, l_reldepsact, and
l_reldeps elements.
* elf/dl-lookup.c (add_dependency): New function.
(_dl_lookup_symbol): Use it whenever symbol was found in a global,
dynamically loaded object.
(_dl_lookup_symbol_skip): Likewise.
(_dl_lookup_versioned_symbol): Likewise.
(_dl_lookup_versioned_symbol_skip): Likewise.
* elf/dl-open.c: Don't define _dl_load_lock here...
* elf/rtld.c: ...but here...
* elf/dl-support.c: ...and here.
* elf/dl-close.c (_dl_close): Close also dependent objects introduce
through relocation.
* elf/dl-fini.c (_dl_fini): Also take dependencies introduced through
relocations.
* dlfcn/Makefile (glrefmain.out): Test is not expected to fail
anymore.
* dlfcn/glrefmain.c: Add one more debug message.
* Makeconfig (preprocess-versions): Don't add $(CPPFLAGS) to compiler
command line.
* Makerules (sysd-versions): Use ( ) instead of { }.
* elf/dl-load.c: Use __builtin_expect to signal that compiler should
optimize for the non-debugging case.
* elf/dl-lookup.c: Likewise.
* sysdeps/generic/libc-start.c: Likewise.
549 lines
18 KiB
C
549 lines
18 KiB
C
/* Look up a symbol in the loaded objects.
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Copyright (C) 1995,96,97,98,99,2000 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 <alloca.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <ldsodefs.h>
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#include "dl-hash.h"
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#include <dl-machine.h>
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#include <bits/libc-lock.h>
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#include <assert.h>
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#define VERSTAG(tag) (DT_NUM + DT_PROCNUM + DT_VERSIONTAGIDX (tag))
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/* We need this string more than once. */
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static const char undefined_msg[] = "undefined symbol: ";
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struct sym_val
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{
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const ElfW(Sym) *s;
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struct link_map *m;
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};
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#define make_string(string, rest...) \
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({ \
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const char *all[] = { string, ## rest }; \
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size_t len, cnt; \
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char *result, *cp; \
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\
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len = 1; \
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for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \
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len += strlen (all[cnt]); \
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\
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cp = result = alloca (len); \
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for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \
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cp = __stpcpy (cp, all[cnt]); \
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\
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result; \
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})
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/* Statistics function. */
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unsigned long int _dl_num_relocations;
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/* During the program run we must not modify the global data of
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loaded shared object simultanously in two threads. Therefore we
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protect `_dl_open' and `_dl_close' in dl-close.c.
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This must be a recursive lock since the initializer function of
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the loaded object might as well require a call to this function.
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At this time it is not anymore a problem to modify the tables. */
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__libc_lock_define (extern, _dl_load_lock)
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/* We have two different situations when looking up a simple: with or
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without versioning. gcc is not able to optimize a single function
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definition serving for both purposes so we define two functions. */
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#define VERSIONED 0
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#include "do-lookup.h"
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#define VERSIONED 1
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#include "do-lookup.h"
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/* Add extra dependency on MAP to UNDEF_MAP. */
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static int
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add_dependency (struct link_map *undef_map, struct link_map *map)
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{
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struct link_map **list;
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unsigned act;
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unsigned int i;
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int result = 0;
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/* Make sure nobody can unload the object while we are at it. */
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__libc_lock_lock (_dl_load_lock);
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/* Determine whether UNDEF_MAP already has a reference to MAP. First
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look in the normal dependencies. */
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list = undef_map->l_searchlist.r_list;
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act = undef_map->l_searchlist.r_nlist;
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for (i = 0; i < act; ++i)
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if (list[i] == map)
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break;
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if (__builtin_expect (i, act) == act)
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{
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/* No normal dependency. See whether we already had to add it
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to the special list of dynamic dependencies. */
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list = undef_map->l_reldeps;
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act = undef_map->l_reldepsact;
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for (i = 0; i < act; ++i)
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if (list[i] == map)
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break;
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if (i == act)
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{
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/* The object is not yet in the dependency list. Before we add
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it make sure just one more time the object we are about to
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reference is still available. There is a brief period in
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which the object could have been removed since we found the
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definition. */
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struct link_map *runp = _dl_loaded;
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while (runp != NULL && runp != map)
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runp = runp->l_next;
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if (runp != NULL)
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{
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/* The object is still available. Add the reference now. */
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if (act >= undef_map->l_reldepsmax)
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{
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/* Allocate more memory for the dependency list. Since
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this can never happen during the startup phase we can
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use `realloc'. */
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void *newp;
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undef_map->l_reldepsmax += 5;
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newp = realloc (undef_map->l_reldeps,
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undef_map->l_reldepsmax);
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if (__builtin_expect (newp != NULL, 1))
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undef_map->l_reldeps = (struct link_map **) newp;
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else
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/* Correct the addition. */
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undef_map->l_reldepsmax -= 5;
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}
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/* If we didn't manage to allocate memory for the list this
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is no fatal mistake. We simply increment the use counter
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of the referenced object and don't record the dependencies.
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This means this increment can never be reverted and the
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object will never be unloaded. This is semantically the
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correct behaviour. */
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if (act < undef_map->l_reldepsmax)
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undef_map->l_reldeps[undef_map->l_reldepsact++] = map;
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/* And increment the counter in the referenced object. */
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++map->l_opencount;
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/* Display information if we are debugging. */
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if (__builtin_expect (_dl_debug_files, 0))
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_dl_debug_message (1, "\nfile=",
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map->l_name[0] ? map->l_name : _dl_argv[0],
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"; needed by ",
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undef_map->l_name[0]
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? undef_map->l_name : _dl_argv[0],
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" (relocation dependency)\n\n", NULL);
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}
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else
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/* Whoa, that was bad luck. We have to search again. */
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result = -1;
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}
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}
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/* Release the lock. */
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__libc_lock_unlock (_dl_load_lock);
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return result;
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}
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/* Search loaded objects' symbol tables for a definition of the symbol
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UNDEF_NAME. */
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ElfW(Addr)
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internal_function
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_dl_lookup_symbol (const char *undef_name, struct link_map *undef_map,
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const ElfW(Sym) **ref, struct r_scope_elem *symbol_scope[],
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int reloc_type)
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{
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const char *reference_name = undef_map ? undef_map->l_name : NULL;
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const unsigned long int hash = _dl_elf_hash (undef_name);
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struct sym_val current_value = { NULL, NULL };
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struct r_scope_elem **scope;
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++_dl_num_relocations;
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/* Search the relevant loaded objects for a definition. */
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for (scope = symbol_scope; *scope; ++scope)
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if (do_lookup (undef_name, undef_map, hash, *ref, ¤t_value,
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*scope, 0, NULL, reloc_type))
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{
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/* We have to check whether this would bind UNDEF_MAP to an object
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in the global scope which was dynamically loaded. In this case
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we have to prevent the latter from being unloaded unless the
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UNDEF_MAP object is also unloaded. */
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if (current_value.m->l_global
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&& (__builtin_expect (current_value.m->l_type, lt_library)
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== lt_loaded)
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&& undef_map != current_value.m
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/* Add UNDEF_MAP to the dependencies. */
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&& add_dependency (undef_map, current_value.m) < 0)
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/* Something went wrong. Perhaps the object we tried to reference
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was just removed. Try finding another definition. */
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return _dl_lookup_symbol (undef_name, undef_map, ref, symbol_scope,
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reloc_type);
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break;
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}
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if (current_value.s == NULL)
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{
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if (*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)
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/* We could find no value for a strong reference. */
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_dl_signal_cerror (0, (reference_name && reference_name[0]
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? reference_name
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: (_dl_argv[0] ?: "<main program>")),
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make_string (undefined_msg, undef_name));
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*ref = NULL;
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return 0;
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}
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if (__builtin_expect (_dl_debug_bindings, 0))
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_dl_debug_message (1, "binding file ",
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(reference_name && reference_name[0]
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? reference_name
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: (_dl_argv[0] ?: "<main program>")),
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" to ", current_value.m->l_name[0]
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? current_value.m->l_name : _dl_argv[0],
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": symbol `", undef_name, "'\n", NULL);
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*ref = current_value.s;
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return current_value.m->l_addr;
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}
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/* This function is nearly the same as `_dl_lookup_symbol' but it
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skips in the first list all objects until SKIP_MAP is found. I.e.,
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it only considers objects which were loaded after the described
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object. If there are more search lists the object described by
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SKIP_MAP is only skipped. */
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ElfW(Addr)
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internal_function
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_dl_lookup_symbol_skip (const char *undef_name,
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struct link_map *undef_map, const ElfW(Sym) **ref,
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struct r_scope_elem *symbol_scope[],
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struct link_map *skip_map)
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{
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const char *reference_name = undef_map ? undef_map->l_name : NULL;
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const unsigned long int hash = _dl_elf_hash (undef_name);
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struct sym_val current_value = { NULL, NULL };
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struct r_scope_elem **scope;
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size_t i;
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++_dl_num_relocations;
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/* Search the relevant loaded objects for a definition. */
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scope = symbol_scope;
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for (i = 0; (*scope)->r_duplist[i] != skip_map; ++i)
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assert (i < (*scope)->r_nduplist);
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if (i < (*scope)->r_nlist
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&& do_lookup (undef_name, undef_map, hash, *ref, ¤t_value,
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*scope, i, skip_map, 0))
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{
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/* We have to check whether this would bind UNDEF_MAP to an object
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in the global scope which was dynamically loaded. In this case
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we have to prevent the latter from being unloaded unless the
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UNDEF_MAP object is also unloaded. */
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if (current_value.m->l_global
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&& (__builtin_expect (current_value.m->l_type, lt_library)
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== lt_loaded)
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&& undef_map != current_value.m
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/* Add UNDEF_MAP to the dependencies. */
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&& add_dependency (undef_map, current_value.m) < 0)
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/* Something went wrong. Perhaps the object we tried to reference
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was just removed. Try finding another definition. */
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return _dl_lookup_symbol_skip (undef_name, undef_map, ref,
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symbol_scope, skip_map);
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}
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else
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while (*++scope)
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if (do_lookup (undef_name, undef_map, hash, *ref, ¤t_value,
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*scope, 0, skip_map, 0))
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{
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/* We have to check whether this would bind UNDEF_MAP to an object
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in the global scope which was dynamically loaded. In this case
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we have to prevent the latter from being unloaded unless the
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UNDEF_MAP object is also unloaded. */
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if (current_value.m->l_global
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&& (__builtin_expect (current_value.m->l_type, lt_library)
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== lt_loaded)
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&& undef_map != current_value.m
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/* Add UNDEF_MAP to the dependencies. */
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&& add_dependency (undef_map, current_value.m) < 0)
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/* Something went wrong. Perhaps the object we tried to reference
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was just removed. Try finding another definition. */
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return _dl_lookup_symbol_skip (undef_name, undef_map, ref,
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symbol_scope, skip_map);
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break;
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}
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if (current_value.s == NULL)
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{
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*ref = NULL;
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return 0;
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}
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if (__builtin_expect (_dl_debug_bindings, 0))
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_dl_debug_message (1, "binding file ",
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(reference_name && reference_name[0]
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? reference_name
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: (_dl_argv[0] ?: "<main program>")),
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" to ", current_value.m->l_name[0]
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? current_value.m->l_name : _dl_argv[0],
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": symbol `", undef_name, "' (skip)\n", NULL);
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*ref = current_value.s;
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return current_value.m->l_addr;
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}
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/* This function works like _dl_lookup_symbol but it takes an
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additional arguement with the version number of the requested
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symbol.
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XXX We'll see whether we need this separate function. */
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ElfW(Addr)
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internal_function
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_dl_lookup_versioned_symbol (const char *undef_name,
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struct link_map *undef_map, const ElfW(Sym) **ref,
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struct r_scope_elem *symbol_scope[],
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const struct r_found_version *version,
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int reloc_type)
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{
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const char *reference_name = undef_map ? undef_map->l_name : NULL;
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const unsigned long int hash = _dl_elf_hash (undef_name);
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struct sym_val current_value = { NULL, NULL };
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struct r_scope_elem **scope;
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++_dl_num_relocations;
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/* Search the relevant loaded objects for a definition. */
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for (scope = symbol_scope; *scope; ++scope)
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{
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int res = do_lookup_versioned (undef_name, undef_map, hash, *ref,
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¤t_value, *scope, 0, version, NULL,
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reloc_type);
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if (res > 0)
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{
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/* We have to check whether this would bind UNDEF_MAP to an object
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in the global scope which was dynamically loaded. In this case
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we have to prevent the latter from being unloaded unless the
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UNDEF_MAP object is also unloaded. */
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if (current_value.m->l_global
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&& (__builtin_expect (current_value.m->l_type, lt_library)
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== lt_loaded)
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&& undef_map != current_value.m
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/* Add UNDEF_MAP to the dependencies. */
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&& add_dependency (undef_map, current_value.m) < 0)
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/* Something went wrong. Perhaps the object we tried to reference
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was just removed. Try finding another definition. */
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return _dl_lookup_versioned_symbol (undef_name, undef_map, ref,
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symbol_scope, version,
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reloc_type);
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break;
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}
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if (res < 0)
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{
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/* Oh, oh. The file named in the relocation entry does not
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contain the needed symbol. */
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_dl_signal_cerror (0, (reference_name && reference_name[0]
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? reference_name
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: (_dl_argv[0] ?: "<main program>")),
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make_string ("symbol ", undef_name, ", version ",
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version->name,
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" not defined in file ",
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version->filename,
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" with link time reference",
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res == -2
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? " (no version symbols)" : ""));
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*ref = NULL;
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return 0;
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}
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}
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if (current_value.s == NULL)
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{
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if (*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)
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/* We could find no value for a strong reference. */
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_dl_signal_cerror (0, (reference_name && reference_name[0]
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? reference_name
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: (_dl_argv[0] ?: "<main program>")),
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make_string (undefined_msg, undef_name,
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", version ", version->name ?: NULL));
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*ref = NULL;
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return 0;
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}
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if (__builtin_expect (_dl_debug_bindings, 0))
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_dl_debug_message (1, "binding file ",
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(reference_name && reference_name[0]
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? reference_name
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: (_dl_argv[0] ?: "<main program>")),
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" to ", current_value.m->l_name[0]
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? current_value.m->l_name : _dl_argv[0],
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": symbol `", undef_name, "' [", version->name,
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"]\n", NULL);
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*ref = current_value.s;
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return current_value.m->l_addr;
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}
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/* Similar to _dl_lookup_symbol_skip but takes an additional argument
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with the version we are looking for. */
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ElfW(Addr)
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internal_function
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_dl_lookup_versioned_symbol_skip (const char *undef_name,
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struct link_map *undef_map,
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const ElfW(Sym) **ref,
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struct r_scope_elem *symbol_scope[],
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const struct r_found_version *version,
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struct link_map *skip_map)
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{
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const char *reference_name = undef_map ? undef_map->l_name : NULL;
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const unsigned long int hash = _dl_elf_hash (undef_name);
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struct sym_val current_value = { NULL, NULL };
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struct r_scope_elem **scope;
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size_t i;
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++_dl_num_relocations;
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/* Search the relevant loaded objects for a definition. */
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scope = symbol_scope;
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for (i = 0; (*scope)->r_duplist[i] != skip_map; ++i)
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assert (i < (*scope)->r_nduplist);
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if (i < (*scope)->r_nlist
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&& do_lookup_versioned (undef_name, undef_map, hash, *ref,
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¤t_value, *scope, i, version, skip_map, 0))
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{
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/* We have to check whether this would bind UNDEF_MAP to an object
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in the global scope which was dynamically loaded. In this case
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we have to prevent the latter from being unloaded unless the
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UNDEF_MAP object is also unloaded. */
|
|
if (current_value.m->l_global
|
|
&& (__builtin_expect (current_value.m->l_type, lt_library)
|
|
== lt_loaded)
|
|
&& undef_map != current_value.m
|
|
/* Add UNDEF_MAP to the dependencies. */
|
|
&& add_dependency (undef_map, current_value.m) < 0)
|
|
/* Something went wrong. Perhaps the object we tried to reference
|
|
was just removed. Try finding another definition. */
|
|
return _dl_lookup_versioned_symbol_skip (undef_name, undef_map, ref,
|
|
symbol_scope, version,
|
|
skip_map);
|
|
}
|
|
else
|
|
while (*++scope)
|
|
if (do_lookup_versioned (undef_name, undef_map, hash, *ref,
|
|
¤t_value, *scope, 0, version, skip_map,
|
|
0))
|
|
{
|
|
/* We have to check whether this would bind UNDEF_MAP to an object
|
|
in the global scope which was dynamically loaded. In this case
|
|
we have to prevent the latter from being unloaded unless the
|
|
UNDEF_MAP object is also unloaded. */
|
|
if (current_value.m->l_global
|
|
&& (__builtin_expect (current_value.m->l_type, lt_library)
|
|
== lt_loaded)
|
|
&& undef_map != current_value.m
|
|
/* Add UNDEF_MAP to the dependencies. */
|
|
&& add_dependency (undef_map, current_value.m) < 0)
|
|
/* Something went wrong. Perhaps the object we tried to reference
|
|
was just removed. Try finding another definition. */
|
|
return _dl_lookup_versioned_symbol_skip (undef_name, undef_map,
|
|
ref, symbol_scope,
|
|
version, skip_map);
|
|
break;
|
|
}
|
|
|
|
if (current_value.s == NULL)
|
|
{
|
|
if (*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)
|
|
{
|
|
/* We could find no value for a strong reference. */
|
|
const size_t len = strlen (undef_name);
|
|
char buf[sizeof undefined_msg + len];
|
|
__mempcpy (__mempcpy (buf, undefined_msg, sizeof undefined_msg - 1),
|
|
undef_name, len + 1);
|
|
_dl_signal_cerror (0, (reference_name && reference_name[0]
|
|
? reference_name
|
|
: (_dl_argv[0] ?: "<main program>")), buf);
|
|
}
|
|
*ref = NULL;
|
|
return 0;
|
|
}
|
|
|
|
if (__builtin_expect (_dl_debug_bindings, 0))
|
|
_dl_debug_message (1, "binding file ",
|
|
(reference_name && reference_name[0]
|
|
? reference_name
|
|
: (_dl_argv[0] ?: "<main program>")),
|
|
" to ",
|
|
current_value.m->l_name[0]
|
|
? current_value.m->l_name : _dl_argv[0],
|
|
": symbol `", undef_name, "' [", version->name,
|
|
"] (skip)\n", NULL);
|
|
|
|
*ref = current_value.s;
|
|
return current_value.m->l_addr;
|
|
}
|
|
|
|
|
|
/* Cache the location of MAP's hash table. */
|
|
|
|
void
|
|
internal_function
|
|
_dl_setup_hash (struct link_map *map)
|
|
{
|
|
Elf_Symndx *hash;
|
|
Elf_Symndx nchain;
|
|
|
|
if (!map->l_info[DT_HASH])
|
|
return;
|
|
hash = (void *)(map->l_addr + map->l_info[DT_HASH]->d_un.d_ptr);
|
|
|
|
map->l_nbuckets = *hash++;
|
|
nchain = *hash++;
|
|
map->l_buckets = hash;
|
|
hash += map->l_nbuckets;
|
|
map->l_chain = hash;
|
|
}
|