resolve.c revision 1.2 
1/*	$OpenBSD: resolve.c,v 1.2 2001/04/02 23:11:21 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
48void * _dl_malloc(int);
49
50/*
51 *	Initialize and add a new dynamic object to the object list.
52 *	Perform necessary relocations of pointers.
53 */
54
55elf_object_t *
56_dl_add_object(const char *objname, Elf_Dyn *dynp,
57			     const u_long *dl_data, const int objtype,
58			     const long laddr, const long loff)
59{
60	elf_object_t *object;
61#if 0
62	_dl_printf("objname [%s], dynp %p, dl_data %p, objtype %x laddr %lx, loff %lx\n",
63		objname, dynp, dl_data, objtype, laddr, loff);
64#endif
65
66	object = (elf_object_t *)_dl_malloc(sizeof(elf_object_t));
67
68	if(_dl_objects == 0) {	/* First object ? */
69		_dl_last_object = _dl_objects = object;
70	}
71	else {
72		_dl_last_object->next = object;
73		object->prev = _dl_last_object;
74		_dl_last_object = object;
75	}
76
77	object->load_dyn = dynp;
78	while(dynp->d_tag != DT_NULL) {
79		if(dynp->d_tag < DT_NUM) {
80			object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val;
81		}
82		else if(dynp->d_tag >= DT_LOPROC && dynp->d_tag < DT_LOPROC + DT_NUM) {
83			object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] = dynp->
84d_un.d_val;
85		}
86		if(dynp->d_tag == DT_TEXTREL)
87			object->dyn.textrel = 1;
88		if(dynp->d_tag == DT_SYMBOLIC)
89			object->dyn.symbolic = 1;
90		if(dynp->d_tag == DT_BIND_NOW)
91			object->dyn.bind_now = 1;
92		dynp++;
93	}
94
95	/*
96	 *  Now relocate all pointer to dynamic info, but only
97	 *  the ones which has pointer values.
98	 */
99	if(object->Dyn.info[DT_PLTGOT])
100		object->Dyn.info[DT_PLTGOT] += loff;
101	if(object->Dyn.info[DT_HASH])
102		object->Dyn.info[DT_HASH] += loff;
103	if(object->Dyn.info[DT_STRTAB])
104		object->Dyn.info[DT_STRTAB] += loff;
105	if(object->Dyn.info[DT_SYMTAB])
106		object->Dyn.info[DT_SYMTAB] += loff;
107	if(object->Dyn.info[DT_RELA])
108		object->Dyn.info[DT_RELA] += loff;
109	if(object->Dyn.info[DT_SONAME])
110		object->Dyn.info[DT_SONAME] += loff;
111	if(object->Dyn.info[DT_RPATH])
112		object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB];
113	if(object->Dyn.info[DT_REL])
114		object->Dyn.info[DT_REL] += loff;
115	if(object->Dyn.info[DT_INIT])
116		object->Dyn.info[DT_INIT] += loff;
117	if(object->Dyn.info[DT_FINI])
118		object->Dyn.info[DT_FINI] += loff;
119	if(object->Dyn.info[DT_JMPREL])
120		object->Dyn.info[DT_JMPREL] += loff;
121
122	object->buckets = object->dyn.hash;
123	if(object->buckets != 0) {
124		object->nbuckets = *object->buckets++;
125		object->nchains  = *object->buckets++;
126		object->chains   = object->buckets + object->nbuckets;
127	}
128
129	if(dl_data) {
130		object->phdrp = (Elf_Phdr *) dl_data[AUX_phdr];
131		object->phdrc = dl_data[AUX_phnum];
132	}
133	object->obj_type = objtype;
134	object->load_addr = laddr;
135	object->load_offs = loff;
136	object->load_name = (char *)_dl_malloc(_dl_strlen(objname) + 1);
137	_dl_strcpy(object->load_name, objname);
138	object->refcount = 1;
139
140	return(object);
141}
142
143
144void
145_dl_remove_object(elf_object_t *object)
146{
147	elf_object_t *depobj;
148
149	object->prev->next = object->next;
150	if(object->next) {
151		object->next->prev = object->prev;
152	}
153	if(object->load_name) {
154		_dl_free(object->load_name);
155	}
156	while((depobj = object->dep_next)) {
157		object->dep_next = object->dep_next->dep_next;
158		_dl_free(depobj);
159	}
160	_dl_free(object);
161}
162
163
164elf_object_t *
165_dl_lookup_object(const char *name)
166{
167	elf_object_t *object;
168
169	object = _dl_objects;
170	while(object) {
171		if(_dl_strcmp(name, object->load_name) == 0) {
172			return(object);
173		}
174		object = object->next;
175	}
176	return(0);
177}
178
179
180Elf_Addr
181_dl_find_symbol(const char *name, elf_object_t *startlook,
182			const Elf_Sym **ref, int myself, int warnnotfound)
183{
184	u_int32_t h = 0;
185	const char *p = name;
186	elf_object_t *object;
187	const Elf_Sym *weak_sym = 0;
188	Elf_Addr weak_offs = 0;
189
190	while(*p) {
191		u_int32_t g;
192		h = (h << 4) + *p++;
193		if((g = h & 0xf0000000)) {
194			h ^= g >> 24;
195		}
196		h &= ~g;
197	}
198
199	for(object = startlook; object; object = (myself ? 0 : object->next)) {
200		const Elf_Sym *symt;
201		const char	*strt;
202		u_int32_t	si;
203
204		symt = object->dyn.symtab;
205		strt = object->dyn.strtab;
206
207		for(si = object->buckets[h % object->nbuckets];
208			si != STN_UNDEF; si = object->chains[si]) {
209			const Elf_Sym *sym = symt + si;
210
211			if(sym->st_value == 0 ||
212			   sym->st_shndx == SHN_UNDEF) {
213				continue;
214			}
215
216			if(ELF_ST_TYPE(sym->st_info) != STT_NOTYPE &&
217			   ELF_ST_TYPE(sym->st_info) != STT_OBJECT &&
218			   ELF_ST_TYPE(sym->st_info) != STT_FUNC) {
219				continue;
220			}
221
222			if(sym != *ref && _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			}
230			else if(ELF_ST_BIND(sym->st_info) == STB_WEAK) {
231				if(!weak_sym) {
232					weak_sym = sym;
233					weak_offs = object->load_offs;
234				}
235			}
236		}
237	}
238	if (warnnotfound) {
239		if(!weak_sym &&
240			*ref && ELF_ST_BIND((*ref)->st_info) != STB_WEAK)
241		{
242			_dl_printf("%s: undefined symbol '%s'\n",
243				_dl_progname, name);
244		}
245	}
246	*ref = weak_sym;
247	return(weak_offs);
248}
249
250