resolve.c revision 1.4 
1/*	$OpenBSD: resolve.c,v 1.4 2001/06/08 06:46:59 art 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, const u_long *dl_data,
57	const int objtype, const long laddr, const long loff)
58{
59	elf_object_t *object;
60#if 0
61	_dl_printf("objname [%s], dynp %p, dl_data %p, objtype %x laddr %lx, loff %lx\n",
62		objname, dynp, dl_data, objtype, laddr, loff);
63#endif
64
65	object = _dl_malloc(sizeof(elf_object_t));
66
67	if (_dl_objects == 0) {			/* First object ? */
68		_dl_last_object = _dl_objects = object;
69	} else {
70		_dl_last_object->next = object;
71		object->prev = _dl_last_object;
72		_dl_last_object = object;
73	}
74
75	object->load_dyn = dynp;
76	while (dynp->d_tag != DT_NULL) {
77		if (dynp->d_tag < DT_NUM) {
78			object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val;
79		} else if (dynp->d_tag >= DT_LOPROC &&
80			    dynp->d_tag < DT_LOPROC + DT_NUM) {
81			object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] = dynp->
82d_un.d_val;
83		}
84		if (dynp->d_tag == DT_TEXTREL)
85			object->dyn.textrel = 1;
86		if (dynp->d_tag == DT_SYMBOLIC)
87			object->dyn.symbolic = 1;
88		if (dynp->d_tag == DT_BIND_NOW)
89			object->dyn.bind_now = 1;
90		dynp++;
91	}
92
93	/*
94	 *  Now relocate all pointer to dynamic info, but only
95	 *  the ones which has pointer values.
96	 */
97	if(object->Dyn.info[DT_PLTGOT])
98		object->Dyn.info[DT_PLTGOT] += loff;
99	if(object->Dyn.info[DT_HASH])
100		object->Dyn.info[DT_HASH] += loff;
101	if(object->Dyn.info[DT_STRTAB])
102		object->Dyn.info[DT_STRTAB] += loff;
103	if(object->Dyn.info[DT_SYMTAB])
104		object->Dyn.info[DT_SYMTAB] += loff;
105	if(object->Dyn.info[DT_RELA])
106		object->Dyn.info[DT_RELA] += loff;
107	if(object->Dyn.info[DT_SONAME])
108		object->Dyn.info[DT_SONAME] += loff;
109	if(object->Dyn.info[DT_RPATH])
110		object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB];
111	if(object->Dyn.info[DT_REL])
112		object->Dyn.info[DT_REL] += loff;
113	if(object->Dyn.info[DT_INIT])
114		object->Dyn.info[DT_INIT] += loff;
115	if(object->Dyn.info[DT_FINI])
116		object->Dyn.info[DT_FINI] += loff;
117	if(object->Dyn.info[DT_JMPREL])
118		object->Dyn.info[DT_JMPREL] += loff;
119
120	object->buckets = object->dyn.hash;
121	if(object->buckets != 0) {
122		object->nbuckets = *object->buckets++;
123		object->nchains  = *object->buckets++;
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 = (char *)_dl_malloc(_dl_strlen(objname) + 1);
135	_dl_strcpy(object->load_name, 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(object->load_name) {
152		_dl_free(object->load_name);
153	}
154	while((depobj = object->dep_next)) {
155		object->dep_next = object->dep_next->dep_next;
156		_dl_free(depobj);
157	}
158	_dl_free(object);
159}
160
161
162elf_object_t *
163_dl_lookup_object(const char *name)
164{
165	elf_object_t *object;
166
167	object = _dl_objects;
168	while(object) {
169		if(_dl_strcmp(name, object->load_name) == 0) {
170			return(object);
171		}
172		object = object->next;
173	}
174	return(0);
175}
176
177
178Elf_Addr
179_dl_find_symbol(const char *name, elf_object_t *startlook,
180			const Elf_Sym **ref, int myself, int warnnotfound)
181{
182	unsigned long h = 0;
183	const char *p = name;
184	elf_object_t *object;
185	const Elf_Sym *weak_sym = 0;
186	Elf_Addr weak_offs = 0;
187
188	while(*p) {
189		unsigned long g;
190		h = (h << 4) + *p++;
191		if((g = h & 0xf0000000)) {
192			h ^= g >> 24;
193		}
194		h &= ~g;
195	}
196
197	for(object = startlook; object; object = (myself ? 0 : object->next)) {
198		const Elf_Sym *symt;
199		const char	*strt;
200		u_int32_t	si;
201
202		symt = object->dyn.symtab;
203		strt = object->dyn.strtab;
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			if(sym != *ref && _dl_strcmp(strt+sym->st_name, name)) {
221				continue;
222			}
223
224			if(ELF_ST_BIND(sym->st_info) == STB_GLOBAL) {
225				*ref = sym;
226				return(object->load_offs);
227			}
228			else if(ELF_ST_BIND(sym->st_info) == STB_WEAK) {
229				if(!weak_sym) {
230					weak_sym = sym;
231					weak_offs = object->load_offs;
232				}
233			}
234		}
235	}
236	if (warnnotfound) {
237		if(!weak_sym &&
238			*ref && ELF_ST_BIND((*ref)->st_info) != STB_WEAK)
239		{
240			_dl_printf("%s: undefined symbol '%s'\n",
241				_dl_progname, name);
242		}
243	}
244	*ref = weak_sym;
245	return(weak_offs);
246}
247
248