glibc/elf/dl-sym.c
Ulrich Drepper 4e35ef2c71 * sysdeps/generic/ldsodefs.h: Define DL_LOOKUP_SCOPE_LOCK.
* elf/dl-lookup.c (add_dependency): If scope map is locked, unlock
	it before getting dl_load_lock and then relock.
	(_dl_lookup_symbol_x): Pass flags to add_dependency.
	When rerunning _dl_lookup_symbol_x, compute symbol_scope again in
	case we unlocked the scope.
	* elf/dl-runtime.c (_dl_fixup): Pass DL_LOOKUP_SCOPE_LOCK to
	_dl_lookup_symbol_x in case we locked the scope.
	(_dl_profile_fixup): Likewise.
	* elf/dl-sym.c (do_sym): In flags passed to call_dl_lookup, also
	set DL_LOOKUP_SCOPE_LOCK.
2007-01-15 20:48:56 +00:00

275 lines
7.4 KiB
C

/* Look up a symbol in a shared object loaded by `dlopen'.
Copyright (C) 1999-2002,2004,2006,2007 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. */
#include <assert.h>
#include <stddef.h>
#include <setjmp.h>
#include <libintl.h>
#include <dlfcn.h>
#include <ldsodefs.h>
#include <dl-hash.h>
#include <sysdep-cancel.h>
#include <dl-tls.h>
#ifdef SHARED
/* Systems which do not have tls_index also probably have to define
DONT_USE_TLS_INDEX. */
# ifndef __TLS_GET_ADDR
# define __TLS_GET_ADDR __tls_get_addr
# endif
/* Return the symbol address given the map of the module it is in and
the symbol record. This is used in dl-sym.c. */
static void *
internal_function
_dl_tls_symaddr (struct link_map *map, const ElfW(Sym) *ref)
{
# ifndef DONT_USE_TLS_INDEX
tls_index tmp =
{
.ti_module = map->l_tls_modid,
.ti_offset = ref->st_value
};
return __TLS_GET_ADDR (&tmp);
# else
return __TLS_GET_ADDR (map->l_tls_modid, ref->st_value);
# endif
}
#endif
struct call_dl_lookup_args
{
/* Arguments to do_dlsym. */
struct link_map *map;
const char *name;
struct r_found_version *vers;
int flags;
/* Return values of do_dlsym. */
lookup_t loadbase;
const ElfW(Sym) **refp;
};
static void
call_dl_lookup (void *ptr)
{
struct call_dl_lookup_args *args = (struct call_dl_lookup_args *) ptr;
args->map = GLRO(dl_lookup_symbol_x) (args->name, args->map, args->refp,
args->map->l_scope, args->vers, 0,
args->flags, NULL);
}
static void *
internal_function
do_sym (void *handle, const char *name, void *who,
struct r_found_version *vers, int flags)
{
const ElfW(Sym) *ref = NULL;
lookup_t result;
ElfW(Addr) caller = (ElfW(Addr)) who;
/* If the address is not recognized the call comes from the main
program (we hope). */
struct link_map *match = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
/* Find the highest-addressed object that CALLER is not below. */
for (Lmid_t ns = 0; ns < DL_NNS; ++ns)
for (struct link_map *l = GL(dl_ns)[ns]._ns_loaded; l != NULL;
l = l->l_next)
if (caller >= l->l_map_start && caller < l->l_map_end)
{
/* There must be exactly one DSO for the range of the virtual
memory. Otherwise something is really broken. */
match = l;
break;
}
if (handle == RTLD_DEFAULT)
{
/* Search the global scope. We have the simple case where
we look up in the scope of an object which was part of
the initial binary. And then the more complex part
where the object is dynamically loaded and the scope
array can change. */
if (match->l_type != lt_loaded || RTLD_SINGLE_THREAD_P)
result = GLRO(dl_lookup_symbol_x) (name, match, &ref,
match->l_scope, vers, 0,
flags | DL_LOOKUP_ADD_DEPENDENCY,
NULL);
else
{
__rtld_mrlock_lock (match->l_scope_lock);
struct call_dl_lookup_args args;
args.name = name;
args.map = match;
args.vers = vers;
args.flags = flags | DL_LOOKUP_ADD_DEPENDENCY | DL_LOOKUP_SCOPE_LOCK;
args.refp = &ref;
const char *objname;
const char *errstring = NULL;
bool malloced;
int err = GLRO(dl_catch_error) (&objname, &errstring, &malloced,
call_dl_lookup, &args);
__rtld_mrlock_unlock (match->l_scope_lock);
if (__builtin_expect (errstring != NULL, 0))
{
/* The lookup was unsuccessful. Rethrow the error. */
char *errstring_dup = strdupa (errstring);
char *objname_dup = strdupa (objname);
if (malloced)
free ((char *) errstring);
GLRO(dl_signal_error) (err, objname_dup, NULL, errstring_dup);
/* NOTREACHED */
}
result = args.map;
}
}
else if (handle == RTLD_NEXT)
{
if (__builtin_expect (match == GL(dl_ns)[LM_ID_BASE]._ns_loaded, 0))
{
if (match == NULL
|| caller < match->l_map_start
|| caller >= match->l_map_end)
GLRO(dl_signal_error) (0, NULL, NULL, N_("\
RTLD_NEXT used in code not dynamically loaded"));
}
struct link_map *l = match;
while (l->l_loader != NULL)
l = l->l_loader;
result = GLRO(dl_lookup_symbol_x) (name, match, &ref, l->l_local_scope,
vers, 0, 0, match);
}
else
{
/* Search the scope of the given object. */
struct link_map *map = handle;
result = GLRO(dl_lookup_symbol_x) (name, map, &ref, map->l_local_scope,
vers, 0, flags, NULL);
}
if (ref != NULL)
{
void *value;
#ifdef SHARED
if (ELFW(ST_TYPE) (ref->st_info) == STT_TLS)
/* The found symbol is a thread-local storage variable.
Return the address for to the current thread. */
value = _dl_tls_symaddr (result, ref);
else
#endif
value = DL_SYMBOL_ADDRESS (result, ref);
#ifdef SHARED
/* Auditing checkpoint: we have a new binding. Provide the
auditing libraries the possibility to change the value and
tell us whether further auditing is wanted. */
if (__builtin_expect (GLRO(dl_naudit) > 0, 0))
{
const char *strtab = (const char *) D_PTR (result,
l_info[DT_STRTAB]);
/* Compute index of the symbol entry in the symbol table of
the DSO with the definition. */
unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result,
l_info[DT_SYMTAB]));
if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0)
{
unsigned int altvalue = 0;
struct audit_ifaces *afct = GLRO(dl_audit);
/* Synthesize a symbol record where the st_value field is
the result. */
ElfW(Sym) sym = *ref;
sym.st_value = (ElfW(Addr)) value;
for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
{
if (afct->symbind != NULL
&& ((match->l_audit[cnt].bindflags & LA_FLG_BINDFROM)
!= 0
|| ((result->l_audit[cnt].bindflags & LA_FLG_BINDTO)
!= 0)))
{
unsigned int flags = altvalue | LA_SYMB_DLSYM;
uintptr_t new_value
= afct->symbind (&sym, ndx,
&match->l_audit[cnt].cookie,
&result->l_audit[cnt].cookie,
&flags, strtab + ref->st_name);
if (new_value != (uintptr_t) sym.st_value)
{
altvalue = LA_SYMB_ALTVALUE;
sym.st_value = new_value;
}
}
afct = afct->next;
}
value = (void *) sym.st_value;
}
}
#endif
return value;
}
return NULL;
}
void *
internal_function
_dl_vsym (void *handle, const char *name, const char *version, void *who)
{
struct r_found_version vers;
/* Compute hash value to the version string. */
vers.name = version;
vers.hidden = 1;
vers.hash = _dl_elf_hash (version);
/* We don't have a specific file where the symbol can be found. */
vers.filename = NULL;
return do_sym (handle, name, who, &vers, 0);
}
void *
internal_function
_dl_sym (void *handle, const char *name, void *who)
{
return do_sym (handle, name, who, NULL, DL_LOOKUP_RETURN_NEWEST);
}