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[glibc.git] / elf / dl-deps.c
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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. */
20 #include <dlfcn.h>
21 #include <errno.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <elf/ldsodefs.h>
26 #include <assert.h>
28 /* Whether an shared object references one or more auxiliary objects
29 is signaled by the AUXTAG entry in l_info. */
30 #define AUXTAG (DT_NUM + DT_PROCNUM + DT_VERSIONTAGNUM \
31 + DT_EXTRATAGIDX (DT_AUXILIARY))
32 /* Whether an shared object references one or more auxiliary objects
33 is signaled by the AUXTAG entry in l_info. */
34 #define FILTERTAG (DT_NUM + DT_PROCNUM + DT_VERSIONTAGNUM \
35 + DT_EXTRATAGIDX (DT_FILTER))
38 /* When loading auxiliary objects we must ignore errors. It's ok if
39 an object is missing. */
40 struct openaux_args
42 /* The arguments to openaux. */
43 struct link_map *map;
44 int trace_mode;
45 const char *strtab;
46 const ElfW(Dyn) *d;
48 /* The return value of openaux. */
49 struct link_map *aux;
52 static void
53 openaux (void *a)
55 struct openaux_args *args = (struct openaux_args *) a;
57 args->aux = _dl_map_object (args->map, args->strtab + args->d->d_un.d_val, 0,
58 (args->map->l_type == lt_executable
59 ? lt_library : args->map->l_type),
60 args->trace_mode);
65 /* We use a very special kind of list to track the two kinds paths
66 through the list of loaded shared objects. We have to
68 - produce a flat list with unique members of all involved objects
70 - produce a flat list of all shared objects.
72 struct list
74 int done; /* Nonzero if this map was processed. */
75 struct link_map *map; /* The data. */
77 struct list *unique; /* Elements for normal list. */
78 struct list *dup; /* Elements in complete list. */
82 void
83 internal_function
84 _dl_map_object_deps (struct link_map *map,
85 struct link_map **preloads, unsigned int npreloads,
86 int trace_mode)
88 struct list known[1 + npreloads + 1];
89 struct list *runp, *utail, *dtail;
90 unsigned int nlist, nduplist, i;
92 inline void preload (struct link_map *map)
94 known[nlist].done = 0;
95 known[nlist].map = map;
97 known[nlist].unique = &known[nlist + 1];
98 known[nlist].dup = &known[nlist + 1];
100 ++nlist;
101 /* We use `l_reserved' as a mark bit to detect objects we have
102 already put in the search list and avoid adding duplicate
103 elements later in the list. */
104 map->l_reserved = 1;
107 /* No loaded object so far. */
108 nlist = 0;
110 /* First load MAP itself. */
111 preload (map);
113 /* Add the preloaded items after MAP but before any of its dependencies. */
114 for (i = 0; i < npreloads; ++i)
115 preload (preloads[i]);
117 /* Terminate the lists. */
118 known[nlist - 1].unique = NULL;
119 known[nlist - 1].dup = NULL;
121 /* Pointer to last unique object. */
122 utail = &known[nlist - 1];
123 /* Pointer to last loaded object. */
124 dtail = &known[nlist - 1];
126 /* Until now we have the same number of libraries in the normal and
127 the list with duplicates. */
128 nduplist = nlist;
130 /* Process each element of the search list, loading each of its
131 auxiliary objects and immediate dependencies. Auxiliary objects
132 will be added in the list before the object itself and
133 dependencies will be appended to the list as we step through it.
134 This produces a flat, ordered list that represents a
135 breadth-first search of the dependency tree.
137 The whole process is complicated by the fact that we better
138 should use alloca for the temporary list elements. But using
139 alloca means we cannot use recursive function calls. */
140 for (runp = known; runp; )
142 struct link_map *l = runp->map;
144 if (l->l_info[DT_NEEDED] || l->l_info[AUXTAG] || l->l_info[FILTERTAG])
146 const char *strtab = ((void *) l->l_addr
147 + l->l_info[DT_STRTAB]->d_un.d_ptr);
148 struct openaux_args args;
149 struct list *orig;
150 const ElfW(Dyn) *d;
152 /* Mark map as processed. */
153 runp->done = 1;
155 args.strtab = strtab;
156 args.map = l;
157 args.trace_mode = trace_mode;
158 orig = runp;
160 for (d = l->l_ld; d->d_tag != DT_NULL; ++d)
161 if (d->d_tag == DT_NEEDED)
163 /* Map in the needed object. */
164 struct link_map *dep
165 = _dl_map_object (l, strtab + d->d_un.d_val, 0,
166 l->l_type == lt_executable ? lt_library :
167 l->l_type, trace_mode);
168 /* Allocate new entry. */
169 struct list *newp = alloca (sizeof (struct list));
171 /* Add it in any case to the duplicate list. */
172 newp->map = dep;
173 newp->dup = NULL;
174 dtail->dup = newp;
175 dtail = newp;
176 ++nduplist;
178 if (dep->l_reserved)
179 /* This object is already in the search list we are
180 building. Don't add a duplicate pointer.
181 Release the reference just added by
182 _dl_map_object. */
183 --dep->l_opencount;
184 else
186 /* Append DEP to the unique list. */
187 newp->done = 0;
188 newp->unique = NULL;
189 utail->unique = newp;
190 utail = newp;
191 ++nlist;
192 /* Set the mark bit that says it's already in the list. */
193 dep->l_reserved = 1;
196 else if (d->d_tag == DT_AUXILIARY || d->d_tag == DT_FILTER)
198 char *errstring;
199 struct list *newp;
201 if (d->d_tag == DT_AUXILIARY)
203 /* Store the tag in the argument structure. */
204 args.d = d;
206 /* Say that we are about to load an auxiliary library. */
207 if (_dl_debug_libs)
208 _dl_debug_message (1, "load auxiliary object=",
209 strtab + d->d_un.d_val,
210 " requested by file=",
211 l->l_name[0]
212 ? l->l_name : _dl_argv[0],
213 "\n", NULL);
215 /* We must be prepared that the addressed shared
216 object is not available. */
217 if (_dl_catch_error (&errstring, openaux, &args))
219 /* We are not interested in the error message. */
220 assert (errstring != NULL);
221 free (errstring);
223 /* Simply ignore this error and continue the work. */
224 continue;
227 else
229 /* Say that we are about to load an auxiliary library. */
230 if (_dl_debug_libs)
231 _dl_debug_message (1, "load filtered object=",
232 strtab + d->d_un.d_val,
233 " requested by file=",
234 l->l_name[0]
235 ? l->l_name : _dl_argv[0],
236 "\n", NULL);
238 /* For filter objects the dependency must be available. */
239 args.aux = _dl_map_object (l, strtab + d->d_un.d_val, 0,
240 (l->l_type == lt_executable
241 ? lt_library : l->l_type),
242 trace_mode);
245 /* The auxiliary object is actually available.
246 Incorporate the map in all the lists. */
248 /* Allocate new entry. This always has to be done. */
249 newp = alloca (sizeof (struct list));
251 /* Copy the content of the current entry over. */
252 orig->dup = memcpy (newp, orig, sizeof (*newp));
254 /* Initialize new entry. */
255 orig->done = 0;
256 orig->map = args.aux;
258 /* We must handle two situations here: the map is new,
259 so we must add it in all three lists. If the map
260 is already known, we have two further possibilities:
261 - if the object is before the current map in the
262 search list, we do nothing. It is already found
263 early
264 - if the object is after the current one, we must
265 move it just before the current map to make sure
266 the symbols are found early enough
268 if (args.aux->l_reserved)
270 /* The object is already somewhere in the list.
271 Locate it first. */
272 struct list *late;
274 /* This object is already in the search list we
275 are building. Don't add a duplicate pointer.
276 Release the reference just added by
277 _dl_map_object. */
278 --args.aux->l_opencount;
280 for (late = orig; late->unique; late = late->unique)
281 if (late->unique->map == args.aux)
282 break;
284 if (late->unique)
286 /* The object is somewhere behind the current
287 position in the search path. We have to
288 move it to this earlier position. */
289 orig->unique = newp;
291 /* Now remove the later entry from the unique list. */
292 late->unique = late->unique->unique;
294 /* We must move the earlier in the chain. */
295 if (args.aux->l_prev)
296 args.aux->l_prev->l_next = args.aux->l_next;
297 if (args.aux->l_next)
298 args.aux->l_next->l_prev = args.aux->l_prev;
300 args.aux->l_prev = newp->map->l_prev;
301 newp->map->l_prev = args.aux;
302 if (args.aux->l_prev != NULL)
303 args.aux->l_prev->l_next = args.aux;
304 args.aux->l_next = newp->map;
306 else
308 /* The object must be somewhere earlier in the
309 list. That's good, we only have to insert
310 an entry for the duplicate list. */
311 orig->unique = NULL; /* Never used. */
313 /* Now we have a problem. The element
314 pointing to ORIG in the unique list must
315 point to NEWP now. This is the only place
316 where we need this backreference and this
317 situation is really not that frequent. So
318 we don't use a double-linked list but
319 instead search for the preceding element. */
320 late = known;
321 while (late->unique != orig)
322 late = late->unique;
323 late->unique = newp;
326 else
328 /* This is easy. We just add the symbol right here. */
329 orig->unique = newp;
330 ++nlist;
331 /* Set the mark bit that says it's already in the list. */
332 args.aux->l_reserved = 1;
334 /* The only problem is that in the double linked
335 list of all objects we don't have this new
336 object at the correct place. Correct this here. */
337 if (args.aux->l_prev)
338 args.aux->l_prev->l_next = args.aux->l_next;
339 if (args.aux->l_next)
340 args.aux->l_next->l_prev = args.aux->l_prev;
342 args.aux->l_prev = newp->map->l_prev;
343 newp->map->l_prev = args.aux;
344 if (args.aux->l_prev != NULL)
345 args.aux->l_prev->l_next = args.aux;
346 args.aux->l_next = newp->map;
349 /* Move the tail pointers if necessary. */
350 if (orig == utail)
351 utail = newp;
352 if (orig == dtail)
353 dtail = newp;
355 /* Move on the insert point. */
356 orig = newp;
358 /* We always add an entry to the duplicate list. */
359 ++nduplist;
362 else
363 /* Mark as processed. */
364 runp->done = 1;
366 /* If we have no auxiliary objects just go on to the next map. */
367 if (runp->done)
369 runp = runp->unique;
370 while (runp != NULL && runp->done);
373 /* Store the search list we built in the object. It will be used for
374 searches in the scope of this object. */
375 map->l_searchlist = malloc (nlist * sizeof (struct link_map *));
376 if (map->l_searchlist == NULL)
377 _dl_signal_error (ENOMEM, map->l_name,
378 "cannot allocate symbol search list");
379 map->l_nsearchlist = nlist;
381 for (nlist = 0, runp = known; runp; runp = runp->unique)
383 map->l_searchlist[nlist++] = runp->map;
385 /* Now clear all the mark bits we set in the objects on the search list
386 to avoid duplicates, so the next call starts fresh. */
387 runp->map->l_reserved = 0;
390 map->l_ndupsearchlist = nduplist;
391 if (nlist == nduplist)
392 map->l_dupsearchlist = map->l_searchlist;
393 else
395 map->l_dupsearchlist = malloc (nduplist * sizeof (struct link_map *));
396 if (map->l_dupsearchlist == NULL)
397 _dl_signal_error (ENOMEM, map->l_name,
398 "cannot allocate symbol search list");
400 for (nlist = 0, runp = known; runp; runp = runp->dup)
401 map->l_dupsearchlist[nlist++] = runp->map;