resolve.c revision 1.7 
1/*	$OpenBSD: resolve.c,v 1.7 2002/03/17 04:46:53 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	object->next = NULL;
66	if (_dl_objects == 0) {			/* First object ? */
67		_dl_last_object = _dl_objects = object;
68	} else {
69		_dl_last_object->next = object;
70		object->prev = _dl_last_object;
71		_dl_last_object = object;
72	}
73
74	object->load_dyn = dynp;
75	while (dynp->d_tag != DT_NULL) {
76		if (dynp->d_tag < DT_NUM) {
77			object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val;
78		} else if (dynp->d_tag >= DT_LOPROC &&
79			    dynp->d_tag < DT_LOPROC + DT_NUM) {
80			object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] = dynp->
81d_un.d_val;
82		}
83		if (dynp->d_tag == DT_TEXTREL)
84			object->dyn.textrel = 1;
85		if (dynp->d_tag == DT_SYMBOLIC)
86			object->dyn.symbolic = 1;
87		if (dynp->d_tag == DT_BIND_NOW)
88			object->dyn.bind_now = 1;
89		dynp++;
90	}
91
92	/*
93	 *  Now relocate all pointer to dynamic info, but only
94	 *  the ones which has pointer values.
95	 */
96	if(object->Dyn.info[DT_PLTGOT])
97		object->Dyn.info[DT_PLTGOT] += loff;
98	if(object->Dyn.info[DT_HASH])
99		object->Dyn.info[DT_HASH] += loff;
100	if(object->Dyn.info[DT_STRTAB])
101		object->Dyn.info[DT_STRTAB] += loff;
102	if(object->Dyn.info[DT_SYMTAB])
103		object->Dyn.info[DT_SYMTAB] += loff;
104	if(object->Dyn.info[DT_RELA])
105		object->Dyn.info[DT_RELA] += loff;
106	if(object->Dyn.info[DT_SONAME])
107		object->Dyn.info[DT_SONAME] += loff;
108	if(object->Dyn.info[DT_RPATH])
109		object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB];
110	if(object->Dyn.info[DT_REL])
111		object->Dyn.info[DT_REL] += loff;
112	if(object->Dyn.info[DT_INIT])
113		object->Dyn.info[DT_INIT] += loff;
114	if(object->Dyn.info[DT_FINI])
115		object->Dyn.info[DT_FINI] += loff;
116	if(object->Dyn.info[DT_JMPREL])
117		object->Dyn.info[DT_JMPREL] += loff;
118
119	if (object->Dyn.info[DT_HASH] != 0) {
120		Elf_Word *hashtab = (Elf_Word *)object->Dyn.info[DT_HASH];
121
122		object->nbuckets = hashtab[0];
123		object->nchains  = hashtab[1];
124		object->buckets = hashtab + 2;
125		object->chains   = object->buckets + object->nbuckets;
126	}
127
128	if (dl_data) {
129		object->phdrp = (Elf_Phdr *) dl_data[AUX_phdr];
130		object->phdrc = dl_data[AUX_phnum];
131	}
132	object->obj_type = objtype;
133	object->load_addr = laddr;
134	object->load_offs = loff;
135	object->load_name = _dl_strdup(objname);
136	object->refcount = 1;
137
138	return(object);
139}
140
141
142void
143_dl_remove_object(elf_object_t *object)
144{
145	elf_object_t *depobj;
146
147	object->prev->next = object->next;
148	if(object->next) {
149		object->next->prev = object->prev;
150	}
151	if (_dl_last_object == object) {
152		_dl_last_object = object->prev;
153	}
154	if(object->load_name) {
155		_dl_free(object->load_name);
156	}
157	while((depobj = object->dep_next)) {
158		object->dep_next = object->dep_next->dep_next;
159		_dl_free(depobj);
160	}
161	_dl_free(object);
162}
163
164
165elf_object_t *
166_dl_lookup_object(const char *name)
167{
168	elf_object_t *object;
169
170	object = _dl_objects;
171	while(object) {
172		if(_dl_strcmp(name, object->load_name) == 0) {
173			return(object);
174		}
175		object = object->next;
176	}
177	return(0);
178}
179
180
181Elf_Addr
182_dl_find_symbol(const char *name, elf_object_t *startlook,
183			const Elf_Sym **ref, int myself, int warnnotfound)
184{
185	unsigned long h = 0;
186	const char *p = name;
187	elf_object_t *object;
188	const Elf_Sym *weak_sym = 0;
189	Elf_Addr weak_offs = 0;
190
191	while (*p) {
192		unsigned long g;
193		h = (h << 4) + *p++;
194		if((g = h & 0xf0000000)) {
195			h ^= g >> 24;
196		}
197		h &= ~g;
198	}
199
200	for (object = startlook; object; object = (myself ? 0 : object->next)) {
201		const Elf_Sym *symt;
202		const char	*strt;
203		long	si;
204
205		symt = object->dyn.symtab;
206		strt = object->dyn.strtab;
207
208
209		for (si = object->buckets[h % object->nbuckets];
210		    si != STN_UNDEF; si = object->chains[si]) {
211			const Elf_Sym *sym = symt + si;
212
213			if (sym->st_value == 0 ||
214			    sym->st_shndx == SHN_UNDEF) {
215				continue;
216			}
217
218			if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE &&
219			    ELF_ST_TYPE(sym->st_info) != STT_OBJECT &&
220			    ELF_ST_TYPE(sym->st_info) != STT_FUNC) {
221				continue;
222			}
223
224
225			if (sym != *ref &&
226			    _dl_strcmp(strt + sym->st_name, name)) {
227				continue;
228			}
229
230			if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) {
231				*ref = sym;
232				return(object->load_offs);
233			} else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) {
234				if (!weak_sym) {
235					weak_sym = sym;
236					weak_offs = object->load_offs;
237				}
238			}
239		}
240	}
241	if (warnnotfound) {
242		if (!weak_sym &&
243		    *ref &&
244		    ELF_ST_BIND((*ref)->st_info) != STB_WEAK) {
245			_dl_printf("%s: undefined symbol '%s'\n",
246				_dl_progname, name);
247		}
248	}
249	*ref = weak_sym;
250	return(weak_offs);
251}
252
253