2 * Copyright (c) 1998 John D. Polstra
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
26 * $FreeBSD: src/lib/libc/gen/dlfcn.c,v 1.6.2.1 2003/02/20 20:42:45 kan Exp $
30 * Linkage to services provided by the dynamic linker. These are
31 * implemented differently in ELF and a.out, because the dynamic
32 * linkers have different interfaces.
40 static const char sorry[] = "Service unavailable";
43 * For ELF, the dynamic linker directly resolves references to its
44 * services to functions inside the dynamic linker itself. These
45 * weak-symbol stubs are necessary so that "ld" won't complain about
46 * undefined symbols. The stubs are executed only when the program is
47 * linked statically, or when a given service isn't implemented in the
48 * dynamic linker. They must return an error if called, and they must
49 * be weak symbols so that the dynamic linker can override them.
52 #pragma weak _rtld_error
54 _rtld_error(const char *fmt, ...)
60 dladdr(const void *addr, Dl_info *dlip)
81 #pragma weak dllockinit
83 dllockinit(void *context,
84 void *(*lock_create)(void *context),
85 void (*rlock_acquire)(void *lock),
86 void (*wlock_acquire)(void *lock),
87 void (*lock_release)(void *lock),
88 void (*lock_destroy)(void *lock),
89 void (*context_destroy)(void *context))
91 if (context_destroy != NULL)
92 context_destroy(context);
97 dlopen(const char *name, int mode)
105 dlsym(void *handle, const char *name)
113 dlinfo(void *handle, int request, void *p)
119 #else /* a.out format */
121 #include <sys/types.h>
122 #include <nlist.h> /* XXX - Required by link.h */
128 * For a.out, entry to the dynamic linker is via these trampolines.
129 * They enter the dynamic linker through the ld_entry struct that was
130 * passed back from the dynamic linker at startup time.
133 /* GCC is needed because we use its __builtin_return_address construct. */
136 #error "GCC is needed to compile this file"
140 * These variables are set by code in crt0.o. For compatibility with
141 * old executables, they must be common, not extern.
143 struct ld_entry *__ldso_entry; /* Entry points to dynamic linker */
144 int __ldso_version; /* Dynamic linker version number */
147 dladdr(const void *addr, Dl_info *dlip)
149 if (__ldso_entry == NULL || __ldso_version < LDSO_VERSION_HAS_DLADDR)
151 return (__ldso_entry->dladdr)(addr, dlip);
155 dlclose(void *handle)
157 if (__ldso_entry == NULL)
159 return (__ldso_entry->dlclose)(handle);
165 if (__ldso_entry == NULL)
166 return "Service unavailable";
167 return (__ldso_entry->dlerror)();
171 dlopen(const char *name, int mode)
173 if (__ldso_entry == NULL)
175 return (__ldso_entry->dlopen)(name, mode);
179 dlsym(void *handle, const char *name)
181 if (__ldso_entry == NULL)
183 if (__ldso_version >= LDSO_VERSION_HAS_DLSYM3) {
184 void *retaddr = __builtin_return_address(0); /* __GNUC__ only */
185 return (__ldso_entry->dlsym3)(handle, name, retaddr);
187 return (__ldso_entry->dlsym)(handle, name);