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https://sourceware.org/git/glibc.git
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3d76e77847
1998-03-11 Ulrich Drepper <drepper@cygnus.com> * nss/nss_db/db-XXX.c (lookup): Copy data to safe place before parsing it.
447 lines
14 KiB
C
447 lines
14 KiB
C
/* Look up a symbol in the loaded objects.
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Copyright (C) 1995, 1996, 1997, 1998 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 <link.h>
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#include <assert.h>
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#include <string.h>
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#include <unistd.h>
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#include "dl-hash.h"
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#include <dl-machine.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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/* 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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do_lookup (const char *undef_name, unsigned long int hash,
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const ElfW(Sym) *ref, struct sym_val *result,
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struct link_map *scope, size_t i, const char *reference_name,
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const struct r_found_version *version, struct link_map *skip,
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int reloc_type)
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{
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struct link_map **list = scope->l_searchlist;
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size_t n = scope->l_nsearchlist;
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struct link_map *map;
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for (; i < n; ++i)
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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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ElfW(Symndx) symidx;
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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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/* Skip objects that could not be opened, which can occur in trace
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mode. */
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if (map->l_opencount == 0)
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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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/* Skip objects without symbol tables. */
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if (map->l_info[DT_SYMTAB] == NULL)
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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 = ((void *) map->l_addr + map->l_info[DT_SYMTAB]->d_un.d_ptr);
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strtab = ((void *) map->l_addr + map->l_info[DT_STRTAB]->d_un.d_ptr);
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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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const ElfW(Sym) *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 (version == NULL)
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{
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/* No specific version is selected. When the object
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file also does not define a version we have a match.
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Otherwise we only accept the default version, i.e.,
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the version which name is "". */
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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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continue;
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}
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}
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else
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{
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if (verstab == NULL)
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{
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/* We need a versioned system but haven't found any.
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If this is the object which is referenced in the
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verneed entry it is a bug in the library since a
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symbol must not simply disappear. */
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if (version->filename != NULL
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&& _dl_name_match_p (version->filename, map))
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return -2;
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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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}
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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
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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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/* There cannot be another entry for this symbol so stop here. */
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break;
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}
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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 != NULL && version->filename != NULL
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&& _dl_name_match_p (version->filename, map))
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return -1;
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}
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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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/* 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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_dl_lookup_symbol (const char *undef_name, const ElfW(Sym) **ref,
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struct link_map *symbol_scope[],
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const char *reference_name,
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int reloc_type)
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{
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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 link_map **scope;
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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, hash, *ref, ¤t_value,
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*scope, 0, reference_name, NULL, NULL, reloc_type))
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break;
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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_error (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 (_dl_debug_bindings)
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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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_dl_lookup_symbol_skip (const char *undef_name, const ElfW(Sym) **ref,
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struct link_map *symbol_scope[],
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const char *reference_name,
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struct link_map *skip_map)
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{
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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 link_map **scope;
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size_t i;
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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)->l_dupsearchlist[i] != skip_map; ++i)
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assert (i < (*scope)->l_ndupsearchlist);
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if (! do_lookup (undef_name, hash, *ref, ¤t_value,
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*scope, i, reference_name, NULL, skip_map, 0))
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while (*++scope)
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if (do_lookup (undef_name, hash, *ref, ¤t_value,
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*scope, 0, reference_name, NULL, skip_map, 0))
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break;
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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 (_dl_debug_bindings)
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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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_dl_lookup_versioned_symbol (const char *undef_name, const ElfW(Sym) **ref,
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struct link_map *symbol_scope[],
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const char *reference_name,
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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 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 link_map **scope;
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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 (undef_name, hash, *ref, ¤t_value,
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*scope, 0, reference_name, version, NULL, reloc_type);
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if (res > 0)
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break;
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if (res < 0)
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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_error (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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}
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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_error (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 (_dl_debug_bindings)
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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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_dl_lookup_versioned_symbol_skip (const char *undef_name,
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const ElfW(Sym) **ref,
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struct link_map *symbol_scope[],
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const char *reference_name,
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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 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 link_map **scope;
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size_t i;
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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)->l_dupsearchlist[i] != skip_map; ++i)
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assert (i < (*scope)->l_ndupsearchlist);
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if (! do_lookup (undef_name, hash, *ref, ¤t_value,
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*scope, i, reference_name, version, skip_map, 0))
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while (*++scope)
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if (do_lookup (undef_name, hash, *ref, ¤t_value,
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*scope, 0, reference_name, version, skip_map, 0))
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break;
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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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{
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/* We could find no value for a strong reference. */
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const size_t len = strlen (undef_name);
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char buf[sizeof undefined_msg + len];
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__mempcpy (__mempcpy (buf, undefined_msg, sizeof undefined_msg - 1),
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undef_name, len + 1);
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_dl_signal_error (0, (reference_name && reference_name[0]
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? reference_name
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: (_dl_argv[0] ?: "<main program>")), buf);
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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 (_dl_debug_bindings)
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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 ",
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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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"] (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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/* Cache the location of MAP's hash table. */
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void
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_dl_setup_hash (struct link_map *map)
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{
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ElfW(Symndx) *hash;
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ElfW(Symndx) nchain;
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if (!map->l_info[DT_HASH])
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return;
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hash = (void *)(map->l_addr + map->l_info[DT_HASH]->d_un.d_ptr);
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map->l_nbuckets = *hash++;
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nchain = *hash++;
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map->l_buckets = hash;
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hash += map->l_nbuckets;
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map->l_chain = hash;
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}
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