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glibc/elf/dl-deps.c

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/* Load the dependencies of a mapped object.
Copyright (C) 1996, 1997, 1998, 1999, 2000 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 <assert.h>
#include <dlfcn.h>
#include <errno.h>
#include <libintl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/param.h>
#include <ldsodefs.h>
#include <dl-dst.h>
/* Whether an shared object references one or more auxiliary objects
is signaled by the AUXTAG entry in l_info. */
#define AUXTAG (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \
+ DT_EXTRATAGIDX (DT_AUXILIARY))
/* Whether an shared object references one or more auxiliary objects
is signaled by the AUXTAG entry in l_info. */
#define FILTERTAG (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \
+ DT_EXTRATAGIDX (DT_FILTER))
/* This is zero at program start to signal that the global scope map is
allocated by rtld. Later it keeps the size of the map. It might be
reset if in _dl_close if the last global object is removed. */
size_t _dl_global_scope_alloc;
extern size_t _dl_platformlen;
/* When loading auxiliary objects we must ignore errors. It's ok if
an object is missing. */
struct openaux_args
{
/* The arguments to openaux. */
struct link_map *map;
int trace_mode;
const char *strtab;
const char *name;
/* The return value of openaux. */
struct link_map *aux;
};
static void
openaux (void *a)
{
struct openaux_args *args = (struct openaux_args *) a;
args->aux = _dl_map_object (args->map, args->name, 0,
(args->map->l_type == lt_executable
? lt_library : args->map->l_type),
args->trace_mode, 0);
}
/* We use a very special kind of list to track the two kinds paths
through the list of loaded shared objects. We have to
- produce a flat list with unique members of all involved objects
- produce a flat list of all shared objects.
*/
struct list
{
int done; /* Nonzero if this map was processed. */
struct link_map *map; /* The data. */
struct list *unique; /* Elements for normal list. */
struct list *dup; /* Elements in complete list. */
};
/* Macro to expand DST. It is an macro since we use `alloca'. */
#define expand_dst(l, str, fatal) \
({ \
const char *__str = (str); \
const char *__result = __str; \
size_t __cnt = DL_DST_COUNT(__str, 0); \
\
if (__cnt != 0) \
{ \
char *__newp; \
\
/* DST must not appear in SUID/SGID programs. */ \
if (__libc_enable_secure) \
_dl_signal_error (0, __str, \
N_("DST not allowed in SUID/SGID programs")); \
\
__newp = (char *) alloca (DL_DST_REQUIRED (l, __str, strlen (__str), \
__cnt)); \
\
__result = DL_DST_SUBSTITUTE (l, __str, __newp, 0); \
\
if (*__result == '\0') \
{ \
/* The replacement for the DST is not known. We can't \
processed. */ \
if (fatal) \
_dl_signal_error (0, __str, N_("\
empty dynamics string token substitution")); \
else \
{ \
/* This is for DT_AUXILIARY. */ \
if (__builtin_expect (_dl_debug_libs, 0)) \
_dl_debug_message (1, "cannot load auxiliary `", __str, \
"' because of empty dynamic string" \
" token substitution\n", NULL); \
continue; \
} \
} \
} \
\
__result; })
void
internal_function
_dl_map_object_deps (struct link_map *map,
struct link_map **preloads, unsigned int npreloads,
int trace_mode)
{
struct list known[1 + npreloads + 1];
struct list *runp, *utail, *dtail;
unsigned int nlist, nduplist, i;
inline void preload (struct link_map *map)
{
known[nlist].done = 0;
known[nlist].map = map;
known[nlist].unique = &known[nlist + 1];
known[nlist].dup = &known[nlist + 1];
++nlist;
/* We use `l_reserved' as a mark bit to detect objects we have
already put in the search list and avoid adding duplicate
elements later in the list. */
map->l_reserved = 1;
}
/* No loaded object so far. */
nlist = 0;
/* First load MAP itself. */
preload (map);
/* Add the preloaded items after MAP but before any of its dependencies. */
for (i = 0; i < npreloads; ++i)
preload (preloads[i]);
/* Terminate the lists. */
known[nlist - 1].unique = NULL;
known[nlist - 1].dup = NULL;
/* Pointer to last unique object. */
utail = &known[nlist - 1];
/* Pointer to last loaded object. */
dtail = &known[nlist - 1];
/* Until now we have the same number of libraries in the normal and
the list with duplicates. */
nduplist = nlist;
/* Process each element of the search list, loading each of its
auxiliary objects and immediate dependencies. Auxiliary objects
will be added in the list before the object itself and
dependencies will be appended to the list as we step through it.
This produces a flat, ordered list that represents a
breadth-first search of the dependency tree.
The whole process is complicated by the fact that we better
should use alloca for the temporary list elements. But using
alloca means we cannot use recursive function calls. */
for (runp = known; runp; )
{
struct link_map *l = runp->map;
struct link_map **needed = NULL;
unsigned int nneeded = 0;
/* Unless otherwise stated, this object is handled. */
runp->done = 1;
/* Allocate a temporary record to contain the references to the
dependencies of this object. */
if (l->l_searchlist.r_list == NULL && l->l_initfini == NULL
&& l != map && l->l_ldnum > 0)
needed = (struct link_map **) alloca (l->l_ldnum
* sizeof (struct link_map *));
if (l->l_info[DT_NEEDED] || l->l_info[AUXTAG] || l->l_info[FILTERTAG])
{
const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
struct openaux_args args;
struct list *orig;
const ElfW(Dyn) *d;
args.strtab = strtab;
args.map = l;
args.trace_mode = trace_mode;
orig = runp;
for (d = l->l_ld; d->d_tag != DT_NULL; ++d)
if (__builtin_expect (d->d_tag, DT_NEEDED) == DT_NEEDED)
{
/* Map in the needed object. */
struct link_map *dep;
/* Allocate new entry. */
struct list *newp;
/* Object name. */
const char *name;
/* Recognize DSTs. */
name = expand_dst (l, strtab + d->d_un.d_val, 0);
dep = _dl_map_object (l, name, 0,
l->l_type == lt_executable ? lt_library :
l->l_type, trace_mode, 0);
/* Add it in any case to the duplicate list. */
newp = alloca (sizeof (struct list));
newp->map = dep;
newp->dup = NULL;
dtail->dup = newp;
dtail = newp;
++nduplist;
if (dep->l_reserved)
/* This object is already in the search list we are
building. Don't add a duplicate pointer.
Release the reference just added by
_dl_map_object. */
--dep->l_opencount;
else
{
/* Append DEP to the unique list. */
newp->done = 0;
newp->unique = NULL;
utail->unique = newp;
utail = newp;
++nlist;
/* Set the mark bit that says it's already in the list. */
dep->l_reserved = 1;
}
/* Remember this dependency. */
if (needed != NULL)
needed[nneeded++] = dep;
}
else if (d->d_tag == DT_AUXILIARY || d->d_tag == DT_FILTER)
{
const char *objname;
const char *errstring;
struct list *newp;
/* Object name. */
const char *name;
/* Recognize DSTs. */
name = expand_dst (l, strtab + d->d_un.d_val,
d->d_tag == DT_AUXILIARY);
if (d->d_tag == DT_AUXILIARY)
{
/* Store the tag in the argument structure. */
args.name = name;
/* Say that we are about to load an auxiliary library. */
if (__builtin_expect (_dl_debug_libs, 0))
_dl_debug_message (1, "load auxiliary object=",
name, " requested by file=",
l->l_name[0]
? l->l_name : _dl_argv[0],
"\n", NULL);
/* We must be prepared that the addressed shared
object is not available. */
if (_dl_catch_error (&objname, &errstring, openaux, &args))
{
/* We are not interested in the error message. */
assert (errstring != NULL);
if (errstring != _dl_out_of_memory)
free ((char *) errstring);
/* Simply ignore this error and continue the work. */
continue;
}
}
else
{
/* Say that we are about to load an auxiliary library. */
if (__builtin_expect (_dl_debug_libs, 0))
_dl_debug_message (1, "load filtered object=", name,
" requested by file=",
l->l_name[0]
? l->l_name : _dl_argv[0],
"\n", NULL);
/* For filter objects the dependency must be available. */
args.aux = _dl_map_object (l, name, 0,
(l->l_type == lt_executable
? lt_library : l->l_type),
trace_mode, 0);
}
/* The auxiliary object is actually available.
Incorporate the map in all the lists. */
/* Allocate new entry. This always has to be done. */
newp = alloca (sizeof (struct list));
/* We want to insert the new map before the current one,
but we have no back links. So we copy the contents of
the current entry over. Note that ORIG and NEWP now
have switched their meanings. */
orig->dup = memcpy (newp, orig, sizeof (*newp));
/* Initialize new entry. */
orig->done = 0;
orig->map = args.aux;
/* Remember this dependency. */
if (needed != NULL)
needed[nneeded++] = args.aux;
/* We must handle two situations here: the map is new,
so we must add it in all three lists. If the map
is already known, we have two further possibilities:
- if the object is before the current map in the
search list, we do nothing. It is already found
early
- if the object is after the current one, we must
move it just before the current map to make sure
the symbols are found early enough
*/
if (args.aux->l_reserved)
{
/* The object is already somewhere in the list.
Locate it first. */
struct list *late;
/* This object is already in the search list we
are building. Don't add a duplicate pointer.
Release the reference just added by
_dl_map_object. */
--args.aux->l_opencount;
for (late = newp; late->unique; late = late->unique)
if (late->unique->map == args.aux)
break;
if (late->unique)
{
/* The object is somewhere behind the current
position in the search path. We have to
move it to this earlier position. */
orig->unique = newp;
/* Now remove the later entry from the unique list
and adjust the tail pointer. */
if (utail == late->unique)
utail = late;
late->unique = late->unique->unique;
/* We must move the object earlier in the chain. */
if (args.aux->l_prev)
args.aux->l_prev->l_next = args.aux->l_next;
if (args.aux->l_next)
args.aux->l_next->l_prev = args.aux->l_prev;
args.aux->l_prev = newp->map->l_prev;
newp->map->l_prev = args.aux;
if (args.aux->l_prev != NULL)
args.aux->l_prev->l_next = args.aux;
args.aux->l_next = newp->map;
}
else
{
/* The object must be somewhere earlier in the
list. That's good, we only have to insert
an entry for the duplicate list. */
orig->unique = NULL; /* Never used. */
/* Now we have a problem. The element
pointing to ORIG in the unique list must
point to NEWP now. This is the only place
where we need this backreference and this
situation is really not that frequent. So
we don't use a double-linked list but
instead search for the preceding element. */
late = known;
while (late->unique != orig)
late = late->unique;
late->unique = newp;
}
}
else
{
/* This is easy. We just add the symbol right here. */
orig->unique = newp;
++nlist;
/* Set the mark bit that says it's already in the list. */
args.aux->l_reserved = 1;
/* The only problem is that in the double linked
list of all objects we don't have this new
object at the correct place. Correct this here. */
if (args.aux->l_prev)
args.aux->l_prev->l_next = args.aux->l_next;
if (args.aux->l_next)
args.aux->l_next->l_prev = args.aux->l_prev;
args.aux->l_prev = newp->map->l_prev;
newp->map->l_prev = args.aux;
if (args.aux->l_prev != NULL)
args.aux->l_prev->l_next = args.aux;
args.aux->l_next = newp->map;
}
/* Move the tail pointers if necessary. */
if (orig == utail)
utail = newp;
if (orig == dtail)
dtail = newp;
/* Move on the insert point. */
orig = newp;
/* We always add an entry to the duplicate list. */
++nduplist;
}
}
/* Terminate the list of dependencies and store the array address. */
if (needed != NULL)
{
needed[nneeded++] = NULL;
l->l_initfini = malloc (nneeded * sizeof needed[0]);
if (l->l_initfini == NULL)
_dl_signal_error (ENOMEM, map->l_name,
N_("cannot allocate dependency list"));
memcpy (l->l_initfini, needed, nneeded * sizeof needed[0]);
}
/* If we have no auxiliary objects just go on to the next map. */
if (runp->done)
do
runp = runp->unique;
while (runp != NULL && runp->done);
}
/* Store the search list we built in the object. It will be used for
searches in the scope of this object. */
map->l_searchlist.r_list = malloc ((2 * nlist + 1
+ (nlist == nduplist ? 0 : nduplist))
* sizeof (struct link_map *));
if (map->l_searchlist.r_list == NULL)
_dl_signal_error (ENOMEM, map->l_name,
N_("cannot allocate symbol search list"));
map->l_searchlist.r_nlist = nlist;
for (nlist = 0, runp = known; runp; runp = runp->unique)
{
if (trace_mode && runp->map->l_opencount == 0)
/* This can happen when we trace the loading. */
--map->l_searchlist.r_nlist;
else
map->l_searchlist.r_list[nlist++] = runp->map;
/* Now clear all the mark bits we set in the objects on the search list
to avoid duplicates, so the next call starts fresh. */
runp->map->l_reserved = 0;
}
map->l_searchlist.r_nduplist = nduplist;
if (nlist == nduplist)
map->l_searchlist.r_duplist = map->l_searchlist.r_list;
else
{
unsigned int cnt;
map->l_searchlist.r_duplist = map->l_searchlist.r_list + nlist;
for (cnt = 0, runp = known; runp; runp = runp->dup)
if (trace_mode && runp->map->l_opencount == 0)
/* This can happen when we trace the loading. */
--map->l_searchlist.r_nduplist;
else
map->l_searchlist.r_duplist[cnt++] = runp->map;
}
/* Now determine the order in which the initialization has to happen. */
map->l_initfini =
(struct link_map **) memcpy (map->l_searchlist.r_duplist + nduplist,
map->l_searchlist.r_list,
nlist * sizeof (struct link_map *));
/* We can skip looking for the binary itself which is at the front
of the search list. Look through the list backward so that circular
dependencies are not changing the order. */
for (i = 1; i < nlist; ++i)
{
struct link_map *l = map->l_searchlist.r_list[i];
unsigned int j;
unsigned int k;
/* Find the place in the initfini list where the map is currently
located. */
for (j = 1; map->l_initfini[j] != l; ++j)
;
/* Find all object for which the current one is a dependency and
move the found object (if necessary) in front. */
for (k = j + 1; k < nlist; ++k)
{
struct link_map **runp;
runp = map->l_initfini[k]->l_initfini;
if (runp != NULL)
{
while (*runp != NULL)
if (*runp == l)
{
struct link_map *here = map->l_initfini[k];
/* Move it now. */
memmove (&map->l_initfini[j] + 1,
&map->l_initfini[j],
(k - j) * sizeof (struct link_map *));
map->l_initfini[j] = here;
break;
}
else
++runp;
}
}
}
/* Terminate the list of dependencies. */
map->l_initfini[nlist] = NULL;
}
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