203 lines
6.3 KiB
C
203 lines
6.3 KiB
C
/* Look up a symbol in the loaded objects.
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Copyright (C) 1995, 1996, 1997, 1998, 1999, 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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#if VERSIONED
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# define FCT do_lookup_versioned
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# define ARG const struct r_found_version *const version,
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#else
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# define FCT do_lookup
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# define ARG
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#endif
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/* Inner part of the lookup functions. We return a value > 0 if we
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found the symbol, the value 0 if nothing is found and < 0 if
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something bad happened. */
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static inline int
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FCT (const char *undef_name, struct link_map *undef_map,
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unsigned long int hash, const ElfW(Sym) *ref, struct sym_val *result,
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struct r_scope_elem *scope, size_t i, ARG struct link_map *skip,
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int reloc_type)
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{
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struct link_map **list = scope->r_list;
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size_t n = scope->r_nlist;
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struct link_map *map;
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do
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{
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const ElfW(Sym) *symtab;
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const char *strtab;
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const ElfW(Half) *verstab;
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Elf_Symndx symidx;
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const ElfW(Sym) *sym;
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#if ! VERSIONED
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int num_versions = 0;
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const ElfW(Sym) *versioned_sym = NULL;
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#endif
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map = list[i];
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/* Here come the extra test needed for `_dl_lookup_symbol_skip'. */
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if (skip != NULL && map == skip)
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continue;
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/* Don't search the executable when resolving a copy reloc. */
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if (elf_machine_lookup_noexec_p (reloc_type)
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&& map->l_type == lt_executable)
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continue;
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/* Print some debugging info if wanted. */
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if (_dl_debug_symbols)
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_dl_debug_message (1, "symbol=", undef_name, "; lookup in file=",
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map->l_name[0] ? map->l_name : _dl_argv[0],
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"\n", NULL);
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symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
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strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
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verstab = map->l_versyms;
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/* Search the appropriate hash bucket in this object's symbol table
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for a definition for the same symbol name. */
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for (symidx = map->l_buckets[hash % map->l_nbuckets];
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symidx != STN_UNDEF;
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symidx = map->l_chain[symidx])
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{
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sym = &symtab[symidx];
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if (sym->st_value == 0 || /* No value. */
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(elf_machine_lookup_noplt_p (reloc_type) /* Reject PLT entry. */
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&& sym->st_shndx == SHN_UNDEF))
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continue;
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if (ELFW(ST_TYPE) (sym->st_info) > STT_FUNC)
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/* Ignore all but STT_NOTYPE, STT_OBJECT and STT_FUNC entries
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since these are no code/data definitions. */
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continue;
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if (sym != ref && strcmp (strtab + sym->st_name, undef_name))
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/* Not the symbol we are looking for. */
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continue;
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#if VERSIONED
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if (verstab == NULL)
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{
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/* We need a versioned symbol but haven't found any. If
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this is the object which is referenced in the verneed
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entry it is a bug in the library since a symbol must
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not simply disappear.
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It would also be a bug in the object since it means that
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the list of required versions is incomplete and so the
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tests in dl-version.c haven't found a problem.*/
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assert (version->filename == NULL
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|| ! _dl_name_match_p (version->filename, map));
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/* Otherwise we accept the symbol. */
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}
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else
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{
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/* We can match the version information or use the
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default one if it is not hidden. */
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ElfW(Half) ndx = verstab[symidx] & 0x7fff;
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if ((map->l_versions[ndx].hash != version->hash
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|| strcmp (map->l_versions[ndx].name, version->name))
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&& (version->hidden || map->l_versions[ndx].hash
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|| (verstab[symidx] & 0x8000)))
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/* It's not the version we want. */
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continue;
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}
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#else
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/* No specific version is selected. When the object file
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also does not define a version we have a match.
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Otherwise we accept the default version, or in case there
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is only one version defined, this one version. */
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if (verstab != NULL)
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{
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ElfW(Half) ndx = verstab[symidx] & 0x7fff;
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if (ndx > 2) /* map->l_versions[ndx].hash != 0) */
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{
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/* Don't accept hidden symbols. */
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if ((verstab[symidx] & 0x8000) == 0 && num_versions++ == 0)
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/* No version so far. */
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versioned_sym = sym;
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continue;
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}
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}
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#endif
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/* There cannot be another entry for this symbol so stop here. */
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goto found_it;
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}
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/* If we have seen exactly one versioned symbol while we are
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looking for an unversioned symbol and the version is not the
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default version we still accept this symbol since there are
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no possible ambiguities. */
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#if VERSIONED
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sym = NULL;
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#else
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sym = num_versions == 1 ? versioned_sym : NULL;
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#endif
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if (sym != NULL
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/* Don't allow binding if the symbol is hidden. When processor
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specific definitions for STV_INTERNAL are defined we might
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have to extend this conditional. */
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&& (ELFW(ST_VISIBILITY) (sym->st_other) != STV_HIDDEN
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|| map == undef_map))
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{
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found_it:
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switch (ELFW(ST_BIND) (sym->st_info))
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{
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case STB_GLOBAL:
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/* Global definition. Just what we need. */
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result->s = sym;
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result->m = map;
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return 1;
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case STB_WEAK:
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/* Weak definition. Use this value if we don't find another. */
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if (! result->s)
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{
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result->s = sym;
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result->m = map;
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}
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break;
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default:
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/* Local symbols are ignored. */
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break;
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}
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}
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#if VERSIONED
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/* If this current map is the one mentioned in the verneed entry
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and we have not found a weak entry, it is a bug. */
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if (symidx == STN_UNDEF && version->filename != NULL
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&& _dl_name_match_p (version->filename, map))
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return -1;
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#endif
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}
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while (++i < n);
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/* We have not found anything until now. */
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return 0;
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}
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#undef FCT
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#undef ARG
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#undef VERSIONED
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