1 /* Load a shared object at runtime, relocate it, and run its initializer.
2 Copyright (C) 1996-2007, 2009 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
28 #include <sys/mman.h> /* Check whether MAP_COPY is defined. */
29 #include <sys/param.h>
30 #include <bits/libc-lock.h>
34 #include <sysdep-cancel.h>
40 extern ElfW(Addr
) _dl_sysdep_start (void **start_argptr
,
41 void (*dl_main
) (const ElfW(Phdr
) *phdr
,
43 ElfW(Addr
) *user_entry
));
44 weak_extern (BP_SYM (_dl_sysdep_start
))
46 extern int __libc_multiple_libcs
; /* Defined in init-first.c. */
48 /* Undefine the following for debugging. */
49 /* #define SCOPE_DEBUG 1 */
51 static void show_scope (struct link_map
*new);
54 /* We must be carefull not to leave us in an inconsistent state. Thus we
55 catch any error and re-raise it after cleaning up. */
61 /* This is the caller of the dlopen() function. */
62 const void *caller_dlopen
;
63 /* This is the caller if _dl_open(). */
64 const void *caller_dl_open
;
68 /* Original parameters to the program and the current environment. */
76 add_to_global (struct link_map
*new)
78 struct link_map
**new_global
;
79 unsigned int to_add
= 0;
82 /* Count the objects we have to put in the global scope. */
83 for (cnt
= 0; cnt
< new->l_searchlist
.r_nlist
; ++cnt
)
84 if (new->l_searchlist
.r_list
[cnt
]->l_global
== 0)
87 /* The symbols of the new objects and its dependencies are to be
88 introduced into the global scope that will be used to resolve
89 references from other dynamically-loaded objects.
91 The global scope is the searchlist in the main link map. We
92 extend this list if necessary. There is one problem though:
93 since this structure was allocated very early (before the libc
94 is loaded) the memory it uses is allocated by the malloc()-stub
95 in the ld.so. When we come here these functions are not used
96 anymore. Instead the malloc() implementation of the libc is
97 used. But this means the block from the main map cannot be used
98 in an realloc() call. Therefore we allocate a completely new
99 array the first time we have to add something to the locale scope. */
101 struct link_namespaces
*ns
= &GL(dl_ns
)[new->l_ns
];
102 if (ns
->_ns_global_scope_alloc
== 0)
104 /* This is the first dynamic object given global scope. */
105 ns
->_ns_global_scope_alloc
106 = ns
->_ns_main_searchlist
->r_nlist
+ to_add
+ 8;
107 new_global
= (struct link_map
**)
108 malloc (ns
->_ns_global_scope_alloc
* sizeof (struct link_map
*));
109 if (new_global
== NULL
)
111 ns
->_ns_global_scope_alloc
= 0;
113 _dl_signal_error (ENOMEM
, new->l_libname
->name
, NULL
,
114 N_("cannot extend global scope"));
118 /* Copy over the old entries. */
119 ns
->_ns_main_searchlist
->r_list
120 = memcpy (new_global
, ns
->_ns_main_searchlist
->r_list
,
121 (ns
->_ns_main_searchlist
->r_nlist
122 * sizeof (struct link_map
*)));
124 else if (ns
->_ns_main_searchlist
->r_nlist
+ to_add
125 > ns
->_ns_global_scope_alloc
)
127 /* We have to extend the existing array of link maps in the
129 struct link_map
**old_global
130 = GL(dl_ns
)[new->l_ns
]._ns_main_searchlist
->r_list
;
131 size_t new_nalloc
= ((ns
->_ns_global_scope_alloc
+ to_add
) * 2);
133 new_global
= (struct link_map
**)
134 malloc (new_nalloc
* sizeof (struct link_map
*));
135 if (new_global
== NULL
)
138 memcpy (new_global
, old_global
,
139 ns
->_ns_global_scope_alloc
* sizeof (struct link_map
*));
141 ns
->_ns_global_scope_alloc
= new_nalloc
;
142 ns
->_ns_main_searchlist
->r_list
= new_global
;
144 if (!RTLD_SINGLE_THREAD_P
)
145 THREAD_GSCOPE_WAIT ();
150 /* Now add the new entries. */
151 unsigned int new_nlist
= ns
->_ns_main_searchlist
->r_nlist
;
152 for (cnt
= 0; cnt
< new->l_searchlist
.r_nlist
; ++cnt
)
154 struct link_map
*map
= new->l_searchlist
.r_list
[cnt
];
156 if (map
->l_global
== 0)
159 ns
->_ns_main_searchlist
->r_list
[new_nlist
++] = map
;
162 atomic_write_barrier ();
163 ns
->_ns_main_searchlist
->r_nlist
= new_nlist
;
169 _dl_scope_free (void *old
)
171 struct dl_scope_free_list
*fsl
;
172 #define DL_SCOPE_FREE_LIST_SIZE (sizeof (fsl->list) / sizeof (fsl->list[0]))
174 if (RTLD_SINGLE_THREAD_P
)
176 else if ((fsl
= GL(dl_scope_free_list
)) == NULL
)
178 GL(dl_scope_free_list
) = fsl
= malloc (sizeof (*fsl
));
181 THREAD_GSCOPE_WAIT ();
191 else if (fsl
->count
< DL_SCOPE_FREE_LIST_SIZE
)
192 fsl
->list
[fsl
->count
++] = old
;
195 THREAD_GSCOPE_WAIT ();
196 while (fsl
->count
> 0)
197 free (fsl
->list
[--fsl
->count
]);
204 dl_open_worker (void *a
)
206 struct dl_open_args
*args
= a
;
207 const char *file
= args
->file
;
208 int mode
= args
->mode
;
209 struct link_map
*new;
211 bool any_tls
= false;
212 struct link_map
*call_map
= NULL
;
214 /* Check whether _dl_open() has been called from a valid DSO. */
215 if (__check_caller (args
->caller_dl_open
,
216 allow_libc
|allow_libdl
|allow_ldso
) != 0)
217 _dl_signal_error (0, "dlopen", NULL
, N_("invalid caller"));
219 /* Determine the caller's map if necessary. This is needed in case
220 we have a DST, when we don't know the namespace ID we have to put
221 the new object in, or when the file name has no path in which
222 case we need to look along the RUNPATH/RPATH of the caller. */
223 const char *dst
= strchr (file
, '$');
224 if (dst
!= NULL
|| args
->nsid
== __LM_ID_CALLER
225 || strchr (file
, '/') == NULL
)
227 const void *caller_dlopen
= args
->caller_dlopen
;
229 /* We have to find out from which object the caller is calling.
230 By default we assume this is the main application. */
231 call_map
= GL(dl_ns
)[LM_ID_BASE
]._ns_loaded
;
234 for (Lmid_t ns
= 0; ns
< DL_NNS
; ++ns
)
235 for (l
= GL(dl_ns
)[ns
]._ns_loaded
; l
!= NULL
; l
= l
->l_next
)
236 if (caller_dlopen
>= (const void *) l
->l_map_start
237 && caller_dlopen
< (const void *) l
->l_map_end
239 || _dl_addr_inside_object (l
, (ElfW(Addr
)) caller_dlopen
)))
241 assert (ns
== l
->l_ns
);
247 if (args
->nsid
== __LM_ID_CALLER
)
250 /* In statically linked apps there might be no loaded object. */
251 if (call_map
== NULL
)
252 args
->nsid
= LM_ID_BASE
;
255 args
->nsid
= call_map
->l_ns
;
259 assert (_dl_debug_initialize (0, args
->nsid
)->r_state
== RT_CONSISTENT
);
261 /* Maybe we have to expand a DST. */
262 if (__builtin_expect (dst
!= NULL
, 0))
264 size_t len
= strlen (file
);
268 /* Determine how much space we need. We have to allocate the
270 required
= DL_DST_REQUIRED (call_map
, file
, len
, _dl_dst_count (dst
, 0));
272 /* Get space for the new file name. */
273 new_file
= (char *) alloca (required
+ 1);
275 /* Generate the new file name. */
276 _dl_dst_substitute (call_map
, file
, new_file
, 0);
278 /* If the substitution failed don't try to load. */
279 if (*new_file
== '\0')
280 _dl_signal_error (0, "dlopen", NULL
,
281 N_("empty dynamic string token substitution"));
283 /* Now we have a new file name. */
286 /* It does not matter whether call_map is set even if we
287 computed it only because of the DST. Since the path contains
288 a slash the value is not used. See dl-load.c. */
291 /* Load the named object. */
292 args
->map
= new = _dl_map_object (call_map
, file
, 0, lt_loaded
, 0,
293 mode
| __RTLD_CALLMAP
, args
->nsid
);
295 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
296 set and the object is not already loaded. */
299 assert (mode
& RTLD_NOLOAD
);
303 if (__builtin_expect (mode
& __RTLD_SPROF
, 0))
304 /* This happens only if we load a DSO for 'sprof'. */
307 /* This object is directly loaded. */
308 ++new->l_direct_opencount
;
310 /* It was already open. */
311 if (__builtin_expect (new->l_searchlist
.r_list
!= NULL
, 0))
313 /* Let the user know about the opencount. */
314 if (__builtin_expect (GLRO(dl_debug_mask
) & DL_DEBUG_FILES
, 0))
315 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
316 new->l_name
, new->l_ns
, new->l_direct_opencount
);
318 /* If the user requested the object to be in the global namespace
319 but it is not so far, add it now. */
320 if ((mode
& RTLD_GLOBAL
) && new->l_global
== 0)
321 (void) add_to_global (new);
323 assert (_dl_debug_initialize (0, args
->nsid
)->r_state
== RT_CONSISTENT
);
328 /* Load that object's dependencies. */
329 _dl_map_object_deps (new, NULL
, 0, 0,
330 mode
& (__RTLD_DLOPEN
| RTLD_DEEPBIND
| __RTLD_AUDIT
));
332 /* So far, so good. Now check the versions. */
333 for (i
= 0; i
< new->l_searchlist
.r_nlist
; ++i
)
334 if (new->l_searchlist
.r_list
[i
]->l_real
->l_versions
== NULL
)
335 (void) _dl_check_map_versions (new->l_searchlist
.r_list
[i
]->l_real
,
343 /* Auditing checkpoint: we have added all objects. */
344 if (__builtin_expect (GLRO(dl_naudit
) > 0, 0))
346 struct link_map
*head
= GL(dl_ns
)[new->l_ns
]._ns_loaded
;
347 /* Do not call the functions for any auditing object. */
348 if (head
->l_auditing
== 0)
350 struct audit_ifaces
*afct
= GLRO(dl_audit
);
351 for (unsigned int cnt
= 0; cnt
< GLRO(dl_naudit
); ++cnt
)
353 if (afct
->activity
!= NULL
)
354 afct
->activity (&head
->l_audit
[cnt
].cookie
, LA_ACT_CONSISTENT
);
362 /* Notify the debugger all new objects are now ready to go. */
363 struct r_debug
*r
= _dl_debug_initialize (0, args
->nsid
);
364 r
->r_state
= RT_CONSISTENT
;
367 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
368 int reloc_mode
= mode
& __RTLD_AUDIT
;
370 reloc_mode
|= mode
& RTLD_LAZY
;
372 /* Relocate the objects loaded. We do this in reverse order so that copy
373 relocs of earlier objects overwrite the data written by later objects. */
375 struct link_map
*l
= new;
380 if (! l
->l_real
->l_relocated
)
383 if (__builtin_expect (GLRO(dl_profile
) != NULL
, 0))
385 /* If this here is the shared object which we want to profile
386 make sure the profile is started. We can find out whether
387 this is necessary or not by observing the `_dl_profile_map'
388 variable. If was NULL but is not NULL afterwars we must
389 start the profiling. */
390 struct link_map
*old_profile_map
= GL(dl_profile_map
);
392 _dl_relocate_object (l
, l
->l_scope
, reloc_mode
| RTLD_LAZY
, 1);
394 if (old_profile_map
== NULL
&& GL(dl_profile_map
) != NULL
)
396 /* We must prepare the profiling. */
397 _dl_start_profile ();
399 /* Prevent unloading the object. */
400 GL(dl_profile_map
)->l_flags_1
|= DF_1_NODELETE
;
405 _dl_relocate_object (l
, l
->l_scope
, reloc_mode
, 0);
413 /* If the file is not loaded now as a dependency, add the search
414 list of the newly loaded object to the scope. */
415 for (i
= 0; i
< new->l_searchlist
.r_nlist
; ++i
)
417 struct link_map
*imap
= new->l_searchlist
.r_list
[i
];
419 /* If the initializer has been called already, the object has
420 not been loaded here and now. */
421 if (imap
->l_init_called
&& imap
->l_type
== lt_loaded
)
423 struct r_scope_elem
**runp
= imap
->l_scope
;
426 while (*runp
!= NULL
)
428 if (*runp
== &new->l_searchlist
)
435 /* Avoid duplicates. */
438 if (__builtin_expect (cnt
+ 1 >= imap
->l_scope_max
, 0))
440 /* The 'r_scope' array is too small. Allocate a new one
443 struct r_scope_elem
**newp
;
445 #define SCOPE_ELEMS(imap) \
446 (sizeof (imap->l_scope_mem) / sizeof (imap->l_scope_mem[0]))
448 if (imap
->l_scope
!= imap
->l_scope_mem
449 && imap
->l_scope_max
< SCOPE_ELEMS (imap
))
451 new_size
= SCOPE_ELEMS (imap
);
452 newp
= imap
->l_scope_mem
;
456 new_size
= imap
->l_scope_max
* 2;
457 newp
= (struct r_scope_elem
**)
458 malloc (new_size
* sizeof (struct r_scope_elem
*));
460 _dl_signal_error (ENOMEM
, "dlopen", NULL
,
461 N_("cannot create scope list"));
464 memcpy (newp
, imap
->l_scope
, cnt
* sizeof (imap
->l_scope
[0]));
465 struct r_scope_elem
**old
= imap
->l_scope
;
467 imap
->l_scope
= newp
;
469 if (old
!= imap
->l_scope_mem
)
470 _dl_scope_free (old
);
472 imap
->l_scope_max
= new_size
;
475 /* First terminate the extended list. Otherwise a thread
476 might use the new last element and then use the garbage
478 imap
->l_scope
[cnt
+ 1] = NULL
;
479 atomic_write_barrier ();
480 imap
->l_scope
[cnt
] = &new->l_searchlist
;
482 /* Only add TLS memory if this object is loaded now and
483 therefore is not yet initialized. */
484 else if (! imap
->l_init_called
485 /* Only if the module defines thread local data. */
486 && __builtin_expect (imap
->l_tls_blocksize
> 0, 0))
488 /* Now that we know the object is loaded successfully add
489 modules containing TLS data to the slot info table. We
490 might have to increase its size. */
491 _dl_add_to_slotinfo (imap
);
493 if (imap
->l_need_tls_init
)
495 imap
->l_need_tls_init
= 0;
497 /* Update the slot information data for at least the
498 generation of the DSO we are allocating data for. */
499 _dl_update_slotinfo (imap
->l_tls_modid
);
502 GL(dl_init_static_tls
) (imap
);
503 assert (imap
->l_need_tls_init
== 0);
506 /* We have to bump the generation counter. */
511 /* Bump the generation number if necessary. */
512 if (any_tls
&& __builtin_expect (++GL(dl_tls_generation
) == 0, 0))
513 _dl_fatal_printf (N_("\
514 TLS generation counter wrapped! Please report this."));
516 /* Run the initializer functions of new objects. */
517 _dl_init (new, args
->argc
, args
->argv
, args
->env
);
519 /* Now we can make the new map available in the global scope. */
520 if (mode
& RTLD_GLOBAL
)
521 /* Move the object in the global namespace. */
522 if (add_to_global (new) != 0)
526 /* Mark the object as not deletable if the RTLD_NODELETE flags was
528 if (__builtin_expect (mode
& RTLD_NODELETE
, 0))
529 new->l_flags_1
|= DF_1_NODELETE
;
532 /* We must be the static _dl_open in libc.a. A static program that
533 has loaded a dynamic object now has competition. */
534 __libc_multiple_libcs
= 1;
537 /* Let the user know about the opencount. */
538 if (__builtin_expect (GLRO(dl_debug_mask
) & DL_DEBUG_FILES
, 0))
539 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
540 new->l_name
, new->l_ns
, new->l_direct_opencount
);
545 _dl_open (const char *file
, int mode
, const void *caller_dlopen
, Lmid_t nsid
,
546 int argc
, char *argv
[], char *env
[])
548 if ((mode
& RTLD_BINDING_MASK
) == 0)
549 /* One of the flags must be set. */
550 _dl_signal_error (EINVAL
, file
, NULL
, N_("invalid mode for dlopen()"));
552 /* Make sure we are alone. */
553 __rtld_lock_lock_recursive (GL(dl_load_lock
));
555 if (nsid
== LM_ID_NEWLM
)
557 /* Find a new namespace. */
558 for (nsid
= 1; nsid
< DL_NNS
; ++nsid
)
559 if (GL(dl_ns
)[nsid
]._ns_loaded
== NULL
)
564 /* No more namespace available. */
565 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
567 _dl_signal_error (EINVAL
, file
, NULL
, N_("\
568 no more namespaces available for dlmopen()"));
571 _dl_debug_initialize (0, nsid
)->r_state
= RT_CONSISTENT
;
573 /* Never allow loading a DSO in a namespace which is empty. Such
574 direct placements is only causing problems. Also don't allow
575 loading into a namespace used for auditing. */
576 else if (nsid
!= LM_ID_BASE
&& nsid
!= __LM_ID_CALLER
577 && (GL(dl_ns
)[nsid
]._ns_nloaded
== 0
578 || GL(dl_ns
)[nsid
]._ns_loaded
->l_auditing
))
579 _dl_signal_error (EINVAL
, file
, NULL
,
580 N_("invalid target namespace in dlmopen()"));
582 struct dl_open_args args
;
585 args
.caller_dlopen
= caller_dlopen
;
586 args
.caller_dl_open
= RETURN_ADDRESS (0);
594 const char *errstring
;
596 int errcode
= _dl_catch_error (&objname
, &errstring
, &malloced
,
597 dl_open_worker
, &args
);
600 /* We must munmap() the cache file. */
604 /* See if an error occurred during loading. */
605 if (__builtin_expect (errstring
!= NULL
, 0))
607 /* Remove the object from memory. It may be in an inconsistent
608 state if relocation failed, for example. */
611 /* Maybe some of the modules which were loaded use TLS.
612 Since it will be removed in the following _dl_close call
613 we have to mark the dtv array as having gaps to fill the
614 holes. This is a pessimistic assumption which won't hurt
615 if not true. There is no need to do this when we are
616 loading the auditing DSOs since TLS has not yet been set
618 if ((mode
& __RTLD_AUDIT
) == 0)
619 GL(dl_tls_dtv_gaps
) = true;
621 _dl_close_worker (args
.map
);
624 assert (_dl_debug_initialize (0, args
.nsid
)->r_state
== RT_CONSISTENT
);
626 /* Release the lock. */
627 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
629 /* Make a local copy of the error string so that we can release the
630 memory allocated for it. */
631 size_t len_errstring
= strlen (errstring
) + 1;
632 char *local_errstring
;
633 if (objname
== errstring
+ len_errstring
)
635 size_t total_len
= len_errstring
+ strlen (objname
) + 1;
636 local_errstring
= alloca (total_len
);
637 memcpy (local_errstring
, errstring
, total_len
);
638 objname
= local_errstring
+ len_errstring
;
642 local_errstring
= alloca (len_errstring
);
643 memcpy (local_errstring
, errstring
, len_errstring
);
647 free ((char *) errstring
);
649 /* Reraise the error. */
650 _dl_signal_error (errcode
, objname
, NULL
, local_errstring
);
653 assert (_dl_debug_initialize (0, args
.nsid
)->r_state
== RT_CONSISTENT
);
655 /* Release the lock. */
656 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
659 DL_STATIC_INIT (args
.map
);
670 show_scope (struct link_map
*new)
674 for (scope_cnt
= 0; new->l_scope
[scope_cnt
] != NULL
; ++scope_cnt
)
679 numbuf
[0] = '0' + scope_cnt
;
681 _dl_printf ("scope %s:", numbuf
);
683 for (cnt
= 0; cnt
< new->l_scope
[scope_cnt
]->r_nlist
; ++cnt
)
684 if (*new->l_scope
[scope_cnt
]->r_list
[cnt
]->l_name
)
685 _dl_printf (" %s", new->l_scope
[scope_cnt
]->r_list
[cnt
]->l_name
);
687 _dl_printf (" <main>");
695 /* Return non-zero if ADDR lies within one of L's segments. */
698 _dl_addr_inside_object (struct link_map
*l
, const ElfW(Addr
) addr
)
701 const ElfW(Addr
) reladdr
= addr
- l
->l_addr
;
704 if (l
->l_phdr
[n
].p_type
== PT_LOAD
705 && reladdr
- l
->l_phdr
[n
].p_vaddr
>= 0
706 && reladdr
- l
->l_phdr
[n
].p_vaddr
< l
->l_phdr
[n
].p_memsz
)