glibc/elf/dl-lookup.c
1999-08-01 18:04:40 +00:00

336 lines
10 KiB
C

/* 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, &current_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, &current_value,
*scope, i, skip_map, 0))
while (*++scope)
if (do_lookup (undef_name, undef_map, hash, *ref, &current_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,
&current_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,
&current_value, *scope, i, version, skip_map,
0))
while (*++scope)
if (do_lookup_versioned (undef_name, undef_map, hash, *ref,
&current_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;
}