resolve.c revision 1.6 
1/*	$OpenBSD: resolve.c,v 1.6 2002/02/21 23:17:53 drahn Exp $ */
2
3/*
4 * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 *    must display the following acknowledgement:
16 *	This product includes software developed under OpenBSD by
17 *	Per Fogelstrom, Opsycon AB, Sweden.
18 * 4. The name of the author may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
22 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
25 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 */
34
35#define _DYN_LOADER
36
37#include <sys/types.h>
38
39#include <nlist.h>
40#include <link.h>
41#include "syscall.h"
42#include "archdep.h"
43#include "resolve.h"
44
45elf_object_t *_dl_objects;
46elf_object_t *_dl_last_object;
47
48/*
49 *	Initialize and add a new dynamic object to the object list.
50 *	Perform necessary relocations of pointers.
51 */
52
53elf_object_t *
54_dl_add_object(const char *objname, Elf_Dyn *dynp, const u_long *dl_data,
55	const int objtype, const long laddr, const long loff)
56{
57	elf_object_t *object;
58#if 0
59	_dl_printf("objname [%s], dynp %p, dl_data %p, objtype %x laddr %lx, loff %lx\n",
60		objname, dynp, dl_data, objtype, laddr, loff);
61#endif
62
63	object = _dl_malloc(sizeof(elf_object_t));
64
65	if (_dl_objects == 0) {			/* First object ? */
66		_dl_last_object = _dl_objects = object;
67	} else {
68		_dl_last_object->next = object;
69		object->prev = _dl_last_object;
70		_dl_last_object = object;
71	}
72
73	object->load_dyn = dynp;
74	while (dynp->d_tag != DT_NULL) {
75		if (dynp->d_tag < DT_NUM) {
76			object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val;
77		} else if (dynp->d_tag >= DT_LOPROC &&
78			    dynp->d_tag < DT_LOPROC + DT_NUM) {
79			object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] = dynp->
80d_un.d_val;
81		}
82		if (dynp->d_tag == DT_TEXTREL)
83			object->dyn.textrel = 1;
84		if (dynp->d_tag == DT_SYMBOLIC)
85			object->dyn.symbolic = 1;
86		if (dynp->d_tag == DT_BIND_NOW)
87			object->dyn.bind_now = 1;
88		dynp++;
89	}
90
91	/*
92	 *  Now relocate all pointer to dynamic info, but only
93	 *  the ones which has pointer values.
94	 */
95	if(object->Dyn.info[DT_PLTGOT])
96		object->Dyn.info[DT_PLTGOT] += loff;
97	if(object->Dyn.info[DT_HASH])
98		object->Dyn.info[DT_HASH] += loff;
99	if(object->Dyn.info[DT_STRTAB])
100		object->Dyn.info[DT_STRTAB] += loff;
101	if(object->Dyn.info[DT_SYMTAB])
102		object->Dyn.info[DT_SYMTAB] += loff;
103	if(object->Dyn.info[DT_RELA])
104		object->Dyn.info[DT_RELA] += loff;
105	if(object->Dyn.info[DT_SONAME])
106		object->Dyn.info[DT_SONAME] += loff;
107	if(object->Dyn.info[DT_RPATH])
108		object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB];
109	if(object->Dyn.info[DT_REL])
110		object->Dyn.info[DT_REL] += loff;
111	if(object->Dyn.info[DT_INIT])
112		object->Dyn.info[DT_INIT] += loff;
113	if(object->Dyn.info[DT_FINI])
114		object->Dyn.info[DT_FINI] += loff;
115	if(object->Dyn.info[DT_JMPREL])
116		object->Dyn.info[DT_JMPREL] += loff;
117
118	if (object->Dyn.info[DT_HASH] != 0) {
119		Elf_Word *hashtab = (Elf_Word *)object->Dyn.info[DT_HASH];
120
121		object->nbuckets = hashtab[0];
122		object->nchains  = hashtab[1];
123		object->buckets = hashtab + 2;
124		object->chains   = object->buckets + object->nbuckets;
125	}
126
127	if (dl_data) {
128		object->phdrp = (Elf_Phdr *) dl_data[AUX_phdr];
129		object->phdrc = dl_data[AUX_phnum];
130	}
131	object->obj_type = objtype;
132	object->load_addr = laddr;
133	object->load_offs = loff;
134	object->load_name = _dl_strdup(objname);
135	object->refcount = 1;
136
137	return(object);
138}
139
140
141void
142_dl_remove_object(elf_object_t *object)
143{
144	elf_object_t *depobj;
145
146	object->prev->next = object->next;
147	if(object->next) {
148		object->next->prev = object->prev;
149	}
150	if(object->load_name) {
151		_dl_free(object->load_name);
152	}
153	while((depobj = object->dep_next)) {
154		object->dep_next = object->dep_next->dep_next;
155		_dl_free(depobj);
156	}
157	_dl_free(object);
158}
159
160
161elf_object_t *
162_dl_lookup_object(const char *name)
163{
164	elf_object_t *object;
165
166	object = _dl_objects;
167	while(object) {
168		if(_dl_strcmp(name, object->load_name) == 0) {
169			return(object);
170		}
171		object = object->next;
172	}
173	return(0);
174}
175
176
177Elf_Addr
178_dl_find_symbol(const char *name, elf_object_t *startlook,
179			const Elf_Sym **ref, int myself, int warnnotfound)
180{
181	unsigned long h = 0;
182	const char *p = name;
183	elf_object_t *object;
184	const Elf_Sym *weak_sym = 0;
185	Elf_Addr weak_offs = 0;
186
187	while (*p) {
188		unsigned long g;
189		h = (h << 4) + *p++;
190		if((g = h & 0xf0000000)) {
191			h ^= g >> 24;
192		}
193		h &= ~g;
194	}
195
196	for (object = startlook; object; object = (myself ? 0 : object->next)) {
197		const Elf_Sym *symt;
198		const char	*strt;
199		long	si;
200
201		symt = object->dyn.symtab;
202		strt = object->dyn.strtab;
203
204
205		for (si = object->buckets[h % object->nbuckets];
206		    si != STN_UNDEF; si = object->chains[si]) {
207			const Elf_Sym *sym = symt + si;
208
209			if (sym->st_value == 0 ||
210			    sym->st_shndx == SHN_UNDEF) {
211				continue;
212			}
213
214			if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE &&
215			    ELF_ST_TYPE(sym->st_info) != STT_OBJECT &&
216			    ELF_ST_TYPE(sym->st_info) != STT_FUNC) {
217				continue;
218			}
219
220
221			if (sym != *ref &&
222			    _dl_strcmp(strt + sym->st_name, name)) {
223				continue;
224			}
225
226			if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) {
227				*ref = sym;
228				return(object->load_offs);
229			} else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) {
230				if (!weak_sym) {
231					weak_sym = sym;
232					weak_offs = object->load_offs;
233				}
234			}
235		}
236	}
237	if (warnnotfound) {
238		if (!weak_sym &&
239		    *ref &&
240		    ELF_ST_BIND((*ref)->st_info) != STB_WEAK) {
241			_dl_printf("%s: undefined symbol '%s'\n",
242				_dl_progname, name);
243		}
244	}
245	*ref = weak_sym;
246	return(weak_offs);
247}
248
249