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glibc/elf/dl-lookup.c
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/* Look up a symbol in the loaded objects. | |
Copyright (C) 1995, 1996, 1997, 1998, 1999 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 Library General Public License as | |
published by the Free Software Foundation; either version 2 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 | |
Library General Public License for more details. | |
You should have received a copy of the GNU Library General Public | |
License along with the GNU C Library; see the file COPYING.LIB. If not, | |
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
Boston, MA 02111-1307, USA. */ | |
#include <alloca.h> | |
#include <string.h> | |
#include <unistd.h> | |
#include <elf/ldsodefs.h> | |
#include "dl-hash.h" | |
#include <dl-machine.h> | |
#include <assert.h> | |
#define VERSTAG(tag) (DT_NUM + DT_PROCNUM + DT_VERSIONTAGIDX (tag)) | |
/* We need this string more than once. */ | |
static const char undefined_msg[] = "undefined symbol: "; | |
struct sym_val | |
{ | |
const ElfW(Sym) *s; | |
struct link_map *m; | |
}; | |
#define make_string(string, rest...) \ | |
({ \ | |
const char *all[] = { string, ## rest }; \ | |
size_t len, cnt; \ | |
char *result, *cp; \ | |
\ | |
len = 1; \ | |
for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \ | |
len += strlen (all[cnt]); \ | |
\ | |
cp = result = alloca (len); \ | |
for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \ | |
cp = __stpcpy (cp, all[cnt]); \ | |
\ | |
result; \ | |
}) | |
/* Statistics function. */ | |
unsigned long int _dl_num_relocations; | |
/* We have two different situations when looking up a simple: with or | |
without versioning. gcc is not able to optimize a single function | |
definition serving for both purposes so we define two functions. */ | |
#define VERSIONED 0 | |
#include "do-lookup.h" | |
#define VERSIONED 1 | |
#include "do-lookup.h" | |
/* Search loaded objects' symbol tables for a definition of the symbol | |
UNDEF_NAME. */ | |
ElfW(Addr) | |
internal_function | |
_dl_lookup_symbol (const char *undef_name, struct link_map *undef_map, | |
const ElfW(Sym) **ref, struct r_scope_elem *symbol_scope[], | |
int reloc_type) | |
{ | |
const char *reference_name = undef_map ? undef_map->l_name : NULL; | |
const unsigned long int hash = _dl_elf_hash (undef_name); | |
struct sym_val current_value = { NULL, NULL }; | |
struct r_scope_elem **scope; | |
++_dl_num_relocations; | |
/* Search the relevant loaded objects for a definition. */ | |
for (scope = symbol_scope; *scope; ++scope) | |
if (do_lookup (undef_name, undef_map, hash, *ref, ¤t_value, | |
*scope, 0, NULL, reloc_type)) | |
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. */ | |
_dl_signal_cerror (0, (reference_name && reference_name[0] | |
? reference_name | |
: (_dl_argv[0] ?: "<main program>")), | |
make_string (undefined_msg, undef_name)); | |
*ref = NULL; | |
return 0; | |
} | |
if (_dl_debug_bindings) | |
_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, "'\n", NULL); | |
*ref = current_value.s; | |
return current_value.m->l_addr; | |
} | |
/* This function is nearly the same as `_dl_lookup_symbol' but it | |
skips in the first list all objects until SKIP_MAP is found. I.e., | |
it only considers objects which were loaded after the described | |
object. If there are more search lists the object described by | |
SKIP_MAP is only skipped. */ | |
ElfW(Addr) | |
internal_function | |
_dl_lookup_symbol_skip (const char *undef_name, | |
struct link_map *undef_map, const ElfW(Sym) **ref, | |
struct r_scope_elem *symbol_scope[], | |
struct link_map *skip_map) | |
{ | |
const char *reference_name = undef_map ? undef_map->l_name : NULL; | |
const unsigned long int hash = _dl_elf_hash (undef_name); | |
struct sym_val current_value = { NULL, NULL }; | |
struct r_scope_elem **scope; | |
size_t i; | |
++_dl_num_relocations; | |
/* Search the relevant loaded objects for a definition. */ | |
scope = symbol_scope; | |
for (i = 0; (*scope)->r_duplist[i] != skip_map; ++i) | |
assert (i < (*scope)->r_nduplist); | |
if (i >= (*scope)->r_nlist | |
|| ! do_lookup (undef_name, undef_map, hash, *ref, ¤t_value, | |
*scope, i, skip_map, 0)) | |
while (*++scope) | |
if (do_lookup (undef_name, undef_map, hash, *ref, ¤t_value, | |
*scope, 0, skip_map, 0)) | |
break; | |
if (current_value.s == NULL) | |
{ | |
*ref = NULL; | |
return 0; | |
} | |
if (_dl_debug_bindings) | |
_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, "' (skip)\n", NULL); | |
*ref = current_value.s; | |
return current_value.m->l_addr; | |
} | |
/* This function works like _dl_lookup_symbol but it takes an | |
additional arguement with the version number of the requested | |
symbol. | |
XXX We'll see whether we need this separate function. */ | |
ElfW(Addr) | |
internal_function | |
_dl_lookup_versioned_symbol (const char *undef_name, | |
struct link_map *undef_map, const ElfW(Sym) **ref, | |
struct r_scope_elem *symbol_scope[], | |
const struct r_found_version *version, | |
int reloc_type) | |
{ | |
const char *reference_name = undef_map ? undef_map->l_name : NULL; | |
const unsigned long int hash = _dl_elf_hash (undef_name); | |
struct sym_val current_value = { NULL, NULL }; | |
struct r_scope_elem **scope; | |
++_dl_num_relocations; | |
/* Search the relevant loaded objects for a definition. */ | |
for (scope = symbol_scope; *scope; ++scope) | |
{ | |
int res = do_lookup_versioned (undef_name, undef_map, hash, *ref, | |
¤t_value, *scope, 0, version, NULL, | |
reloc_type); | |
if (res > 0) | |
break; | |
if (res < 0) | |
{ | |
/* Oh, oh. The file named in the relocation entry does not | |
contain the needed symbol. */ | |
_dl_signal_cerror (0, (reference_name && reference_name[0] | |
? reference_name | |
: (_dl_argv[0] ?: "<main program>")), | |
make_string ("symbol ", undef_name, ", version ", | |
version->name, | |
" not defined in file ", | |
version->filename, | |
" with link time reference", | |
res == -2 | |
? " (no version symbols)" : "")); | |
*ref = NULL; | |
return 0; | |
} | |
} | |
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. */ | |
_dl_signal_cerror (0, (reference_name && reference_name[0] | |
? reference_name | |
: (_dl_argv[0] ?: "<main program>")), | |
make_string (undefined_msg, undef_name, | |
", version ", version->name ?: NULL)); | |
*ref = NULL; | |
return 0; | |
} | |
if (_dl_debug_bindings) | |
_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, | |
"]\n", NULL); | |
*ref = current_value.s; | |
return current_value.m->l_addr; | |
} | |
/* Similar to _dl_lookup_symbol_skip but takes an additional argument | |
with the version we are looking for. */ | |
ElfW(Addr) | |
internal_function | |
_dl_lookup_versioned_symbol_skip (const char *undef_name, | |
struct link_map *undef_map, | |
const ElfW(Sym) **ref, | |
struct r_scope_elem *symbol_scope[], | |
const struct r_found_version *version, | |
struct link_map *skip_map) | |
{ | |
const char *reference_name = undef_map ? undef_map->l_name : NULL; | |
const unsigned long int hash = _dl_elf_hash (undef_name); | |
struct sym_val current_value = { NULL, NULL }; | |
struct r_scope_elem **scope; | |
size_t i; | |
++_dl_num_relocations; | |
/* Search the relevant loaded objects for a definition. */ | |
scope = symbol_scope; | |
for (i = 0; (*scope)->r_duplist[i] != skip_map; ++i) | |
assert (i < (*scope)->r_nduplist); | |
if (i >= (*scope)->r_nlist | |
|| ! do_lookup_versioned (undef_name, undef_map, hash, *ref, | |
¤t_value, *scope, i, version, skip_map, | |
0)) | |
while (*++scope) | |
if (do_lookup_versioned (undef_name, undef_map, hash, *ref, | |
¤t_value, *scope, 0, version, skip_map, | |
0)) | |
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 (_dl_debug_bindings) | |
_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; | |
} |