xref: /freebsd/lib/libc/gen/dlfcn.c (revision 396c556d77189a5c474d35cec6f44a762e310b7d)
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 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #if !defined(IN_LIBDL) || defined(PIC)
31 
32 /*
33  * Linkage to services provided by the dynamic linker.
34  */
35 #include <sys/mman.h>
36 #include <dlfcn.h>
37 #include <link.h>
38 #include <stddef.h>
39 #include "namespace.h"
40 #include <pthread.h>
41 #include "un-namespace.h"
42 #include "libc_private.h"
43 
44 static char sorry[] = "Service unavailable";
45 
46 void _rtld_thread_init(void *);
47 void _rtld_atfork_pre(int *);
48 void _rtld_atfork_post(int *);
49 
50 /*
51  * For ELF, the dynamic linker directly resolves references to its
52  * services to functions inside the dynamic linker itself.  These
53  * weak-symbol stubs are necessary so that "ld" won't complain about
54  * undefined symbols.  The stubs are executed only when the program is
55  * linked statically, or when a given service isn't implemented in the
56  * dynamic linker.  They must return an error if called, and they must
57  * be weak symbols so that the dynamic linker can override them.
58  */
59 
60 #pragma weak _rtld_error
61 void
62 _rtld_error(const char *fmt __unused, ...)
63 {
64 }
65 
66 #pragma weak dladdr
67 int
68 dladdr(const void *addr __unused, Dl_info *dlip __unused)
69 {
70 
71 	_rtld_error(sorry);
72 	return (0);
73 }
74 
75 #pragma weak dlclose
76 int
77 dlclose(void *handle __unused)
78 {
79 
80 	_rtld_error(sorry);
81 	return (-1);
82 }
83 
84 #pragma weak dlerror
85 char *
86 dlerror(void)
87 {
88 
89 	return (sorry);
90 }
91 
92 #pragma weak dllockinit
93 void
94 dllockinit(void *context,
95     void *(*lock_create)(void *context) __unused,
96     void (*rlock_acquire)(void *lock) __unused,
97     void (*wlock_acquire)(void *lock) __unused,
98     void (*lock_release)(void *lock) __unused,
99     void (*lock_destroy)(void *lock) __unused,
100     void (*context_destroy)(void *context) __unused)
101 {
102 
103 	if (context_destroy != NULL)
104 		context_destroy(context);
105 }
106 
107 #pragma weak dlopen
108 void *
109 dlopen(const char *name __unused, int mode __unused)
110 {
111 
112 	_rtld_error(sorry);
113 	return (NULL);
114 }
115 
116 #pragma weak dlsym
117 void *
118 dlsym(void * __restrict handle __unused, const char * __restrict name __unused)
119 {
120 
121 	_rtld_error(sorry);
122 	return (NULL);
123 }
124 
125 #pragma weak dlfunc
126 dlfunc_t
127 dlfunc(void * __restrict handle __unused, const char * __restrict name __unused)
128 {
129 
130 	_rtld_error(sorry);
131 	return (NULL);
132 }
133 
134 #pragma weak dlvsym
135 void *
136 dlvsym(void * __restrict handle __unused, const char * __restrict name __unused,
137     const char * __restrict version __unused)
138 {
139 
140 	_rtld_error(sorry);
141 	return (NULL);
142 }
143 
144 #pragma weak dlinfo
145 int
146 dlinfo(void * __restrict handle __unused, int request __unused,
147     void * __restrict p __unused)
148 {
149 
150 	_rtld_error(sorry);
151 	return (0);
152 }
153 
154 #pragma weak _rtld_thread_init
155 void
156 _rtld_thread_init(void *li __unused)
157 {
158 
159 	_rtld_error(sorry);
160 }
161 
162 #ifndef IN_LIBDL
163 static pthread_once_t dl_phdr_info_once = PTHREAD_ONCE_INIT;
164 static struct dl_phdr_info phdr_info;
165 
166 static void
167 dl_init_phdr_info(void)
168 {
169 	Elf_Auxinfo *auxp;
170 	unsigned int i;
171 
172 	for (auxp = __elf_aux_vector; auxp->a_type != AT_NULL; auxp++) {
173 		switch (auxp->a_type) {
174 		case AT_BASE:
175 			phdr_info.dlpi_addr = (Elf_Addr)auxp->a_un.a_ptr;
176 			break;
177 		case AT_EXECPATH:
178 			phdr_info.dlpi_name = (const char *)auxp->a_un.a_ptr;
179 			break;
180 		case AT_PHDR:
181 			phdr_info.dlpi_phdr =
182 			    (const Elf_Phdr *)auxp->a_un.a_ptr;
183 			break;
184 		case AT_PHNUM:
185 			phdr_info.dlpi_phnum = (Elf_Half)auxp->a_un.a_val;
186 			break;
187 		}
188 	}
189 	for (i = 0; i < phdr_info.dlpi_phnum; i++) {
190 		if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) {
191 			phdr_info.dlpi_tls_modid = 1;
192 			phdr_info.dlpi_tls_data =
193 			    (void*)phdr_info.dlpi_phdr[i].p_vaddr;
194 		}
195 	}
196 	phdr_info.dlpi_adds = 1;
197 }
198 #endif
199 
200 #pragma weak dl_iterate_phdr
201 int
202 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *) __unused,
203     void *data __unused)
204 {
205 
206 #ifndef IN_LIBDL
207 	__init_elf_aux_vector();
208 	if (__elf_aux_vector == NULL)
209 		return (1);
210 	_once(&dl_phdr_info_once, dl_init_phdr_info);
211 	return (callback(&phdr_info, sizeof(phdr_info), data));
212 #else
213 	return (0);
214 #endif
215 }
216 
217 #pragma weak fdlopen
218 void *
219 fdlopen(int fd __unused, int mode __unused)
220 {
221 
222 	_rtld_error(sorry);
223 	return (NULL);
224 }
225 
226 #pragma weak _rtld_atfork_pre
227 void
228 _rtld_atfork_pre(int *locks __unused)
229 {
230 }
231 
232 #pragma weak _rtld_atfork_post
233 void
234 _rtld_atfork_post(int *locks __unused)
235 {
236 }
237 
238 #pragma weak _rtld_addr_phdr
239 int
240 _rtld_addr_phdr(const void *addr __unused,
241     struct dl_phdr_info *phdr_info_a __unused)
242 {
243 
244 	return (0);
245 }
246 
247 #pragma weak _rtld_get_stack_prot
248 int
249 _rtld_get_stack_prot(void)
250 {
251 
252 	return (PROT_EXEC | PROT_READ | PROT_WRITE);
253 }
254 
255 #pragma weak _rtld_is_dlopened
256 int
257 _rtld_is_dlopened(void *arg __unused)
258 {
259 
260 	return (0);
261 }
262 
263 #endif /* !defined(IN_LIBDL) || defined(PIC) */
264