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Diffstat (limited to 'trunk/src/ld-do-lookup.h')
| -rw-r--r-- | trunk/src/ld-do-lookup.h | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/trunk/src/ld-do-lookup.h b/trunk/src/ld-do-lookup.h new file mode 100644 index 0000000..2d359d7 --- /dev/null +++ b/trunk/src/ld-do-lookup.h @@ -0,0 +1,232 @@ +/* Look up a symbol in the loaded objects. + Copyright (C) 1995,96,97,98,99,2000,2001,2002 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#if VERSIONED +# define FCT do_lookup_versioned +# define ARG const struct r_found_version *const version +#else +# define FCT do_lookup +# define ARG int flags +#endif + +/* Inner part of the lookup functions. We return a value > 0 if we + found the symbol, the value 0 if nothing is found and < 0 if + something bad happened. */ +static inline int +FCT (const char *undef_name, const ElfW(Sym) *ref, struct sym_val *result, + struct r_scope_elem *scope, size_t i, ARG, struct ldlibs_link_map *skip, + int type_class, int machine) +{ + struct ldlibs_link_map **list = scope->r_list; + size_t n = scope->r_nlist; + struct ldlibs_link_map *map; + + do + { + unsigned long int hash; + const ElfW(Sym) *symtab; + const char *strtab; + const ElfW(Half) *verstab; + Elf_Symndx symidx; + const ElfW(Sym) *sym; + int gnu_hash; +#if ! VERSIONED + int num_versions = 0; + const ElfW(Sym) *versioned_sym = NULL; +#endif + + map = list[i]; + + /* Here come the extra test needed for `_dl_lookup_symbol_skip'. */ + if (skip != NULL && map == skip) + continue; + + /* Don't search the executable when resolving a copy reloc. */ + if ((type_class & ELF_RTYPE_CLASS_COPY) && map->l_type == lt_executable) + continue; + + /* Print some debugging info if wanted. */ + if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_SYMBOLS, 0)) + INTUSE(_dl_debug_printf) ("symbol=%s; lookup in file=%s\n", + undef_name, (map->l_name[0] + ? map->l_name : rtld_progname)); + + symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]); + strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); + verstab = map->l_versyms; + gnu_hash = map->l_gnu_hash; + hash = rtld_elf_any_hash (undef_name, gnu_hash); + + /* Search the appropriate hash bucket in this object's symbol table + for a definition for the same symbol name. */ + for (symidx = do_lookup_get_first (map, hash, gnu_hash); + symidx != STN_UNDEF; + symidx = do_lookup_get_next (symidx, map, hash, gnu_hash)) + { + sym = &symtab[symidx]; + + assert (ELF_RTYPE_CLASS_PLT == 1); + if ((sym->st_value == 0 /* No value. */ +#ifdef USE_TLS + && ELFW(ST_TYPE) (sym->st_info) != STT_TLS +#endif + ) + || (machine == EM_MIPS + && sym->st_shndx == SHN_UNDEF + && !(sym->st_other & STO_MIPS_PLT)) + || (type_class & (sym->st_shndx == SHN_UNDEF))) + continue; + + if (ELFW(ST_TYPE) (sym->st_info) > STT_FUNC + && (machine != EM_ARM + || ELFW(ST_TYPE) (sym->st_info) != STT_ARM_TFUNC) +#ifdef USE_TLS + && ELFW(ST_TYPE) (sym->st_info) != STT_TLS +#endif + ) + /* Ignore all but STT_NOTYPE, STT_OBJECT and STT_FUNC + entries (and STT_TLS if TLS is supported) since these + are no code/data definitions. */ + continue; + + if (sym != ref && strcmp (strtab + sym->st_name, undef_name)) + /* Not the symbol we are looking for. */ + continue; + +#if VERSIONED + if (__builtin_expect (verstab == NULL, 0)) + { + /* We need a versioned symbol but haven't found any. If + this is the object which is referenced in the verneed + entry it is a bug in the library since a symbol must + not simply disappear. + + It would also be a bug in the object since it means that + the list of required versions is incomplete and so the + tests in dl-version.c haven't found a problem.*/ + assert (version->filename == NULL + || ! _dl_soname_match_p (version->filename, map)); + + /* Otherwise we accept the symbol. */ + } + else + { + /* We can match the version information or use the + default one if it is not hidden. */ + ElfW(Half) ndx = verstab[symidx] & 0x7fff; + if ((map->l_versions[ndx].hash != version->hash + || strcmp (map->l_versions[ndx].name, version->name)) + && (version->hidden || map->l_versions[ndx].hash + || (verstab[symidx] & 0x8000))) + /* It's not the version we want. */ + continue; + } +#else + /* No specific version is selected. There are two ways we + can got here: + + - a binary which does not include versioning information + is loaded + + - dlsym() instead of dlvsym() is used to get a symbol which + might exist in more than one form + + If the library does not provide symbol version + information there is no problem at at: we simply use the + symbol if it is defined. + + These two lookups need to be handled differently if the + library defines versions. In the case of the old + unversioned application the oldest (default) version + should be used. In case of a dlsym() call the latest and + public interface should be returned. */ + if (verstab != NULL) + { + if ((verstab[symidx] & 0x7fff) + >= ((flags & DL_LOOKUP_RETURN_NEWEST) ? 2 : 3)) + { + /* Don't accept hidden symbols. */ + if ((verstab[symidx] & 0x8000) == 0 && num_versions++ == 0) + /* No version so far. */ + versioned_sym = sym; + + continue; + } + } +#endif + + /* There cannot be another entry for this symbol so stop here. */ + goto found_it; + } + + /* If we have seen exactly one versioned symbol while we are + looking for an unversioned symbol and the version is not the + default version we still accept this symbol since there are + no possible ambiguities. */ +#if VERSIONED + sym = NULL; +#else + sym = num_versions == 1 ? versioned_sym : NULL; +#endif + + if (sym != NULL) + { + found_it: + switch (ELFW(ST_BIND) (sym->st_info)) + { + case STB_WEAK: + /* Weak definition. Use this value if we don't find another. */ + if (__builtin_expect (GL(dl_dynamic_weak), 0)) + { + if (! result->s) + { + result->s = sym; + result->m = map; + } + break; + } + /* FALLTHROUGH */ + case STB_GLOBAL: + /* Global definition. Just what we need. */ + result->s = sym; + result->m = map; + return 1; + default: + /* Local symbols are ignored. */ + break; + } + } + +#if VERSIONED + /* If this current map is the one mentioned in the verneed entry + and we have not found a weak entry, it is a bug. */ + if (symidx == STN_UNDEF && version->filename != NULL + && __builtin_expect (_dl_soname_match_p (version->filename, map), 0)) + return -1; +#endif + } + while (++i < n); + + /* We have not found anything until now. */ + return 0; +} + +#undef FCT +#undef ARG +#undef VERSIONED |