1 /*-
2 * Copyright (c) 1998 John D. Polstra
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: src/lib/libc/gen/dlfcn.c 217154 2011-01-08 17:13:43Z kib $
27 */
28
29 #include <sys/mman.h>
30 #include <dlfcn.h>
31 #include <link.h>
32 #include <stddef.h>
33 #include <string.h>
34 #include "libc_private.h"
35
36 struct dl_phdr_info build_phdr_info(void) __dso_hidden;
37 void _rtld_thread_childfork(void);
38 void _rtld_thread_init(void *);
39 void _rtld_thread_postfork(void);
40 void _rtld_thread_prefork(void);
41 void _rtld_setthreaded(void);
42
43 extern char **environ;
44
45 static char sorry[] = "Service unavailable";
46
47 /*
48 * For ELF, the dynamic linker directly resolves references to its
49 * services to functions inside the dynamic linker itself. These
50 * weak-symbol stubs are necessary so that "ld" won't complain about
51 * undefined symbols. The stubs are executed only when the program is
52 * linked statically, or when a given service isn't implemented in the
53 * dynamic linker. They must return an error if called, and they must
54 * be weak symbols so that the dynamic linker can override them.
55 */
56
57 #pragma weak _rtld_error
58 void
_rtld_error(const char * fmt __unused,...)59 _rtld_error(const char *fmt __unused, ...)
60 {
61 }
62
63 #pragma weak dladdr
64 int
dladdr(const void * addr __unused,Dl_info * dlip __unused)65 dladdr(const void *addr __unused, Dl_info *dlip __unused)
66 {
67 _rtld_error(sorry);
68 return 0;
69 }
70
71 #pragma weak dlclose
72 int
dlclose(void * handle __unused)73 dlclose(void *handle __unused)
74 {
75 _rtld_error(sorry);
76 return -1;
77 }
78
79 #pragma weak dlerror
80 char *
dlerror(void)81 dlerror(void)
82 {
83 return sorry;
84 }
85
86 #pragma weak dlopen
87 void *
dlopen(const char * name __unused,int mode __unused)88 dlopen(const char *name __unused, int mode __unused)
89 {
90 _rtld_error(sorry);
91 return NULL;
92 }
93
94 #pragma weak dlsym
95 void *
dlsym(void * handle __unused,const char * name __unused)96 dlsym(void *handle __unused, const char *name __unused)
97 {
98 _rtld_error(sorry);
99 return NULL;
100 }
101
102 #pragma weak dlfunc
103 dlfunc_t
dlfunc(void * handle __unused,const char * name __unused)104 dlfunc(void * handle __unused, const char * name __unused)
105 {
106 _rtld_error(sorry);
107 return NULL;
108 }
109
110 #pragma weak dlvsym
111 void *
dlvsym(void * handle __unused,const char * name __unused,const char * version __unused)112 dlvsym(void *handle __unused,const char *name __unused,
113 const char *version __unused)
114 {
115 _rtld_error(sorry);
116 return NULL;
117 }
118
119 #pragma weak _rtld_thread_init
120 void
_rtld_thread_init(void * li __unused)121 _rtld_thread_init(void * li __unused)
122 {
123 _rtld_error(sorry);
124 }
125
126 #pragma weak dlinfo
127 int
dlinfo(void * handle __unused,int request __unused,void * p __unused)128 dlinfo(void *handle __unused, int request __unused, void *p __unused)
129 {
130 _rtld_error(sorry);
131 return 0;
132 }
133
134 struct dl_phdr_info
build_phdr_info(void)135 build_phdr_info(void)
136 {
137 struct dl_phdr_info phdr_info;
138 Elf_Addr *sp;
139 Elf_Auxinfo *aux, *auxp;
140 unsigned int i;
141
142 sp = (Elf_Addr *) environ;
143 while (*sp++ != 0)
144 ;
145 aux = (Elf_Auxinfo *) sp;
146 memset (&phdr_info, 0, sizeof(phdr_info));
147 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
148 switch (auxp->a_type) {
149 case AT_BASE:
150 phdr_info.dlpi_addr = (Elf_Addr) auxp->a_un.a_ptr;
151 break;
152 case AT_EXECPATH:
153 phdr_info.dlpi_name = (const char *) auxp->a_un.a_ptr;
154 break;
155 case AT_PHDR:
156 phdr_info.dlpi_phdr = (const Elf_Phdr *) auxp->a_un.a_ptr;
157 break;
158 case AT_PHNUM:
159 phdr_info.dlpi_phnum = (Elf_Half) auxp->a_un.a_val;
160 break;
161 }
162 }
163
164 for (i = 0; i < phdr_info.dlpi_phnum; i++)
165 if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) {
166 phdr_info.dlpi_tls_modid = 1;
167 phdr_info.dlpi_tls_data =
168 (void*)phdr_info.dlpi_phdr[i].p_vaddr;
169 }
170
171 return (phdr_info);
172 }
173
174 #pragma weak dl_iterate_phdr
175 int
dl_iterate_phdr(int (* callback)(struct dl_phdr_info *,size_t,void *),void * data)176 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *),
177 void *data)
178 {
179 static int seen = 0;
180 static struct dl_phdr_info phdr_info;
181 if (!seen) {
182 seen = 1;
183 phdr_info = build_phdr_info();
184 }
185
186 return callback(&phdr_info, sizeof(phdr_info), data);
187 }
188
189 #pragma weak fdlopen
190 void *
fdlopen(int fd __unused,int mode __unused)191 fdlopen(int fd __unused, int mode __unused)
192 {
193 _rtld_error(sorry);
194 return NULL;
195 }
196
197 #pragma weak _rtld_addr_phdr
198 int
_rtld_addr_phdr(const void * addr __unused,struct dl_phdr_info * phdr_info __unused)199 _rtld_addr_phdr(const void *addr __unused,
200 struct dl_phdr_info *phdr_info __unused)
201 {
202
203 return (0);
204 }
205
206 #pragma weak _rtld_get_stack_prot
207 int
_rtld_get_stack_prot(void)208 _rtld_get_stack_prot(void)
209 {
210 return (PROT_EXEC | PROT_READ | PROT_WRITE);
211 }
212
213 #pragma weak _rtld_thread_prefork
214 void
_rtld_thread_prefork(void)215 _rtld_thread_prefork(void)
216 {
217 }
218
219 #pragma weak _rtld_thread_postfork
220 void
_rtld_thread_postfork(void)221 _rtld_thread_postfork(void)
222 {
223 }
224
225 #pragma weak _rtld_thread_childfork
226 void
_rtld_thread_childfork(void)227 _rtld_thread_childfork(void)
228 {
229 }
230
231 #pragma weak _rtld_setthreaded
232 void
_rtld_setthreaded(void)233 _rtld_setthreaded(void)
234 {
235 }
236