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sourceware.org Git - glibc.git/blob - elf/dl-deps.c
1 /* Load the dependencies of a mapped object.
2 Copyright (C) 1996, 1997, 1998 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 Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 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 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
27 /* Whether an shared object references one or more auxiliary objects
28 is signaled by the AUXTAG entry in l_info. */
29 #define AUXTAG (DT_NUM + DT_PROCNUM + DT_VERSIONTAGNUM \
30 + DT_EXTRATAGIDX (DT_AUXILIARY))
31 /* Whether an shared object references one or more auxiliary objects
32 is signaled by the AUXTAG entry in l_info. */
33 #define FILTERTAG (DT_NUM + DT_PROCNUM + DT_VERSIONTAGNUM \
34 + DT_EXTRATAGIDX (DT_FILTER))
37 /* When loading auxiliary objects we must ignore errors. It's ok if
38 an object is missing. */
41 /* The arguments to openaux. */
47 /* The return value of openaux. */
54 struct openaux_args
*args
= (struct openaux_args
*) a
;
56 args
->aux
= _dl_map_object (args
->map
, args
->strtab
+ args
->d
->d_un
.d_val
, 0,
57 (args
->map
->l_type
== lt_executable
58 ? lt_library
: args
->map
->l_type
),
64 /* We use a very special kind of list to track the two kinds paths
65 through the list of loaded shared objects. We have to
67 - produce a flat list with unique members of all involved objects
69 - produce a flat list of all shared objects.
73 int done
; /* Nonzero if this map was processed. */
74 struct link_map
*map
; /* The data. */
76 struct list
*unique
; /* Elements for normal list. */
77 struct list
*dup
; /* Elements in complete list. */
82 _dl_map_object_deps (struct link_map
*map
,
83 struct link_map
**preloads
, unsigned int npreloads
,
86 struct list known
[1 + npreloads
+ 1];
87 struct list
*runp
, *utail
, *dtail
;
88 unsigned int nlist
, nduplist
, i
;
90 inline void preload (struct link_map
*map
)
92 known
[nlist
].done
= 0;
93 known
[nlist
].map
= map
;
95 known
[nlist
].unique
= &known
[nlist
+ 1];
96 known
[nlist
].dup
= &known
[nlist
+ 1];
99 /* We use `l_reserved' as a mark bit to detect objects we have
100 already put in the search list and avoid adding duplicate
101 elements later in the list. */
105 /* No loaded object so far. */
108 /* First load MAP itself. */
111 /* Add the preloaded items after MAP but before any of its dependencies. */
112 for (i
= 0; i
< npreloads
; ++i
)
113 preload (preloads
[i
]);
115 /* Terminate the lists. */
116 known
[nlist
- 1].unique
= NULL
;
117 known
[nlist
- 1].dup
= NULL
;
119 /* Pointer to last unique object. */
120 utail
= &known
[nlist
- 1];
121 /* Pointer to last loaded object. */
122 dtail
= &known
[nlist
- 1];
124 /* Until now we have the same number of libraries in the normal and
125 the list with duplicates. */
128 /* Process each element of the search list, loading each of its
129 auxiliary objects and immediate dependencies. Auxiliary objects
130 will be added in the list before the object itself and
131 dependencies will be appended to the list as we step through it.
132 This produces a flat, ordered list that represents a
133 breadth-first search of the dependency tree.
135 The whole process is complicated by the fact that we better
136 should use alloca for the temporary list elements. But using
137 alloca means we cannot use recursive function calls. */
138 for (runp
= known
; runp
; )
140 struct link_map
*l
= runp
->map
;
142 if (l
->l_info
[DT_NEEDED
] || l
->l_info
[AUXTAG
] || l
->l_info
[FILTERTAG
])
144 const char *strtab
= ((void *) l
->l_addr
145 + l
->l_info
[DT_STRTAB
]->d_un
.d_ptr
);
146 struct openaux_args args
;
150 /* Mark map as processed. */
153 args
.strtab
= strtab
;
155 args
.trace_mode
= trace_mode
;
158 for (d
= l
->l_ld
; d
->d_tag
!= DT_NULL
; ++d
)
159 if (d
->d_tag
== DT_NEEDED
)
161 /* Map in the needed object. */
163 = _dl_map_object (l
, strtab
+ d
->d_un
.d_val
, 0,
164 l
->l_type
== lt_executable
? lt_library
:
165 l
->l_type
, trace_mode
);
166 /* Allocate new entry. */
167 struct list
*newp
= alloca (sizeof (struct list
));
169 /* Add it in any case to the duplicate list. */
177 /* This object is already in the search list we are
178 building. Don't add a duplicate pointer.
179 Release the reference just added by
184 /* Append DEP to the unique list. */
187 utail
->unique
= newp
;
190 /* Set the mark bit that says it's already in the list. */
194 else if (d
->d_tag
== DT_AUXILIARY
|| d
->d_tag
== DT_FILTER
)
200 if (d
->d_tag
== DT_AUXILIARY
)
202 /* Store the tag in the argument structure. */
205 /* We must be prepared that the addressed shared
206 object is not available. */
207 if (_dl_catch_error (&errstring
, &objname
, openaux
, &args
))
209 /* We are not interested in the error message. */
210 assert (errstring
!= NULL
);
213 /* Simply ignore this error and continue the work. */
218 /* For filter objects the dependency must be available. */
219 args
.aux
= _dl_map_object (l
, strtab
+ d
->d_un
.d_val
, 0,
220 (l
->l_type
== lt_executable
221 ? lt_library
: l
->l_type
),
224 /* The auxiliary object is actually available.
225 Incorporate the map in all the lists. */
227 /* Allocate new entry. This always has to be done. */
228 newp
= alloca (sizeof (struct list
));
230 /* Copy the content of the current entry over. */
231 orig
->dup
= memcpy (newp
, orig
, sizeof (*newp
));
233 /* Initialize new entry. */
235 orig
->map
= args
.aux
;
237 /* We must handle two situations here: the map is new,
238 so we must add it in all three lists. If the map
239 is already known, we have two further possibilities:
240 - if the object is before the current map in the
241 search list, we do nothing. It is already found
243 - if the object is after the current one, we must
244 move it just before the current map to make sure
245 the symbols are found early enough
247 if (args
.aux
->l_reserved
)
249 /* The object is already somewhere in the list.
253 /* This object is already in the search list we
254 are building. Don't add a duplicate pointer.
255 Release the reference just added by
257 --args
.aux
->l_opencount
;
259 for (late
= orig
; late
->unique
; late
= late
->unique
)
260 if (late
->unique
->map
== args
.aux
)
265 /* The object is somewhere behind the current
266 position in the search path. We have to
267 move it to this earlier position. */
270 /* Now remove the later entry from the unique list. */
271 late
->unique
= late
->unique
->unique
;
273 /* We must move the earlier in the chain. */
274 if (args
.aux
->l_prev
)
275 args
.aux
->l_prev
->l_next
= args
.aux
->l_next
;
276 if (args
.aux
->l_next
)
277 args
.aux
->l_next
->l_prev
= args
.aux
->l_prev
;
279 args
.aux
->l_prev
= newp
->map
->l_prev
;
280 newp
->map
->l_prev
= args
.aux
;
281 if (args
.aux
->l_prev
!= NULL
)
282 args
.aux
->l_prev
->l_next
= args
.aux
;
283 args
.aux
->l_next
= newp
->map
;
287 /* The object must be somewhere earlier in the
288 list. That's good, we only have to insert
289 an entry for the duplicate list. */
290 orig
->unique
= NULL
; /* Never used. */
292 /* Now we have a problem. The element
293 pointing to ORIG in the unique list must
294 point to NEWP now. This is the only place
295 where we need this backreference and this
296 situation is really not that frequent. So
297 we don't use a double-linked list but
298 instead search for the preceding element. */
300 while (late
->unique
!= orig
)
307 /* This is easy. We just add the symbol right here. */
310 /* Set the mark bit that says it's already in the list. */
311 args
.aux
->l_reserved
= 1;
313 /* The only problem is that in the double linked
314 list of all objects we don't have this new
315 object at the correct place. Correct this here. */
316 if (args
.aux
->l_prev
)
317 args
.aux
->l_prev
->l_next
= args
.aux
->l_next
;
318 if (args
.aux
->l_next
)
319 args
.aux
->l_next
->l_prev
= args
.aux
->l_prev
;
321 args
.aux
->l_prev
= newp
->map
->l_prev
;
322 newp
->map
->l_prev
= args
.aux
;
323 if (args
.aux
->l_prev
!= NULL
)
324 args
.aux
->l_prev
->l_next
= args
.aux
;
325 args
.aux
->l_next
= newp
->map
;
328 /* Move the tail pointers if necessary. */
334 /* Move on the insert point. */
337 /* We always add an entry to the duplicate list. */
342 /* Mark as processed. */
345 /* If we have no auxiliary objects just go on to the next map. */
349 while (runp
!= NULL
&& runp
->done
);
352 /* Store the search list we built in the object. It will be used for
353 searches in the scope of this object. */
354 map
->l_searchlist
= malloc (nlist
* sizeof (struct link_map
*));
355 if (map
->l_searchlist
== NULL
)
356 _dl_signal_error (ENOMEM
, map
->l_name
,
357 "cannot allocate symbol search list");
358 map
->l_nsearchlist
= nlist
;
360 for (nlist
= 0, runp
= known
; runp
; runp
= runp
->unique
)
362 map
->l_searchlist
[nlist
++] = runp
->map
;
364 /* Now clear all the mark bits we set in the objects on the search list
365 to avoid duplicates, so the next call starts fresh. */
366 runp
->map
->l_reserved
= 0;
369 map
->l_ndupsearchlist
= nduplist
;
370 if (nlist
== nduplist
)
371 map
->l_dupsearchlist
= map
->l_searchlist
;
374 map
->l_dupsearchlist
= malloc (nduplist
* sizeof (struct link_map
*));
375 if (map
->l_dupsearchlist
== NULL
)
376 _dl_signal_error (ENOMEM
, map
->l_name
,
377 "cannot allocate symbol search list");
379 for (nlist
= 0, runp
= known
; runp
; runp
= runp
->dup
)
380 map
->l_dupsearchlist
[nlist
++] = runp
->map
;
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