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sourceware.org Git - glibc.git/blob - elf/dl-deps.c
c069fab0c8a85d08fb0f766bdb9dcb47cc04ba8d
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
[AUXTAG
] || l
->l_info
[FILTERTAG
] || l
->l_info
[DT_NEEDED
])
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 memcpy (newp
, orig
, sizeof (*newp
));
233 /* Initialize new entry. */
235 orig
->map
= args
.aux
;
238 /* We must handle two situations here: the map is new,
239 so we must add it in all three lists. If the map
240 is already known, we have two further possibilities:
241 - if the object is before the current map in the
242 search list, we do nothing. It is already found
244 - if the object is after the current one, we must
245 move it just before the current map to make sure
246 the symbols are found early enough
248 if (args
.aux
->l_reserved
)
250 /* The object is already somewhere in the list.
254 /* This object is already in the search list we
255 are building. Don't add a duplicate pointer.
256 Release the reference just added by
258 --args
.aux
->l_opencount
;
260 for (late
= orig
; late
->unique
; late
= late
->unique
)
261 if (late
->unique
->map
== args
.aux
)
266 /* The object is somewhere behind the current
267 position in the search path. We have to
268 move it to this earlier position. */
271 /* Now remove the later entry from the unique list. */
272 late
->unique
= late
->unique
->unique
;
274 /* We must move the earlier in the chain. */
275 if (args
.aux
->l_prev
)
276 args
.aux
->l_prev
->l_next
= args
.aux
->l_next
;
277 if (args
.aux
->l_next
)
278 args
.aux
->l_next
->l_prev
= args
.aux
->l_prev
;
280 args
.aux
->l_prev
= newp
->map
->l_prev
;
281 newp
->map
->l_prev
= args
.aux
;
282 if (args
.aux
->l_prev
!= NULL
)
283 args
.aux
->l_prev
->l_next
= args
.aux
;
284 args
.aux
->l_next
= newp
->map
;
288 /* The object must be somewhere earlier in the
289 list. That's good, we only have to insert
290 an entry for the duplicate list. */
291 orig
->unique
= NULL
; /* Never used. */
293 /* Now we have a problem. The element
294 pointing to ORIG in the unique list must
295 point to NEWP now. This is the only place
296 where we need this backreference and this
297 situation is really not that frequent. So
298 we don't use a double-linked list but
299 instead search for the preceding element. */
301 while (late
->unique
!= orig
)
308 /* This is easy. We just add the symbol right here. */
311 /* Set the mark bit that says it's already in the list. */
312 args
.aux
->l_reserved
= 1;
314 /* The only problem is that in the double linked
315 list of all objects we don't have this new
316 object at the correct place. Correct this here. */
317 if (args
.aux
->l_prev
)
318 args
.aux
->l_prev
->l_next
= args
.aux
->l_next
;
319 if (args
.aux
->l_next
)
320 args
.aux
->l_next
->l_prev
= args
.aux
->l_prev
;
322 args
.aux
->l_prev
= newp
->map
->l_prev
;
323 newp
->map
->l_prev
= args
.aux
;
324 if (args
.aux
->l_prev
!= NULL
)
325 args
.aux
->l_prev
->l_next
= args
.aux
;
326 args
.aux
->l_next
= newp
->map
;
329 /* Move the tail pointers if necessary. */
335 /* Move on the insert point. */
338 /* We always add an entry to the duplicate list. */
343 /* Mark as processed. */
346 /* If we have no auxiliary objects just go on to the next map. */
350 while (runp
&& runp
->done
);
353 /* Store the search list we built in the object. It will be used for
354 searches in the scope of this object. */
355 map
->l_searchlist
= malloc (nlist
* sizeof (struct link_map
*));
356 if (map
->l_searchlist
== NULL
)
357 _dl_signal_error (ENOMEM
, map
->l_name
,
358 "cannot allocate symbol search list");
359 map
->l_nsearchlist
= nlist
;
361 for (nlist
= 0, runp
= known
; runp
; runp
= runp
->unique
)
363 map
->l_searchlist
[nlist
++] = runp
->map
;
365 /* Now clear all the mark bits we set in the objects on the search list
366 to avoid duplicates, so the next call starts fresh. */
367 runp
->map
->l_reserved
= 0;
370 map
->l_ndupsearchlist
= nduplist
;
371 if (nlist
== nduplist
)
372 map
->l_dupsearchlist
= map
->l_searchlist
;
375 map
->l_dupsearchlist
= malloc (nduplist
* sizeof (struct link_map
*));
376 if (map
->l_dupsearchlist
== NULL
)
377 _dl_signal_error (ENOMEM
, map
->l_name
,
378 "cannot allocate symbol search list");
380 for (nlist
= 0, runp
= known
; runp
; runp
= runp
->dup
)
381 map
->l_dupsearchlist
[nlist
++] = runp
->map
;
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