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/*-
* Copyright (c) 1998 John D. Polstra
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id: dlfcn.c,v 1.1 1998/02/09 06:05:24 jdp Exp $
*/
/*
* Linkage to services provided by the dynamic linker. These are
* implemented differently in ELF and a.out, because the dynamic
* linkers have different interfaces.
*/
#ifdef __ELF__
#include <dlfcn.h>
#include <stddef.h>
static const char sorry[] = "Service unavailable";
/*
* For ELF, the dynamic linker directly resolves references to its
* services to functions inside the dynamic linker itself. These
* weak-symbol stubs are necessary so that "ld" won't complain about
* undefined symbols. The stubs are executed only when the program is
* linked statically, or when a given service isn't implemented in the
* dynamic linker. They must return an error if called, and they must
* be weak symbols so that the dynamic linker can override them.
*/
#pragma weak _rtld_error
void
_rtld_error(const char *fmt, ...)
{
}
#pragma weak dladdr
int
dladdr(const void *addr, Dl_info *dlip)
{
_rtld_error(sorry);
return 0;
}
#pragma weak dlclose
int
dlclose(void *handle)
{
_rtld_error(sorry);
return -1;
}
#pragma weak dlerror
const char *
dlerror(void)
{
return sorry;
}
#pragma weak dlopen
void *
dlopen(const char *name, int mode)
{
_rtld_error(sorry);
return NULL;
}
#pragma weak dlsym
void *
dlsym(void *handle, const char *name)
{
_rtld_error(sorry);
return NULL;
}
#else /* a.out format */
#include <sys/types.h>
#include <nlist.h> /* XXX - Required by link.h */
#include <dlfcn.h>
#include <link.h>
#include <stddef.h>
/*
* For a.out, entry to the dynamic linker is via these trampolines.
* They enter the dynamic linker through the ld_entry struct that was
* passed back from the dynamic linker at startup time.
*/
/* GCC is needed because we use its __builtin_return_address construct. */
#ifndef __GNUC__
#error "GCC is needed to compile this file"
#endif
/*
* These variables are set by code in crt0.o. For compatibility with
* old executables, they must be common, not extern.
*/
struct ld_entry *__ldso_entry; /* Entry points to dynamic linker */
int __ldso_version; /* Dynamic linker version number */
int
dladdr(const void *addr, Dl_info *dlip)
{
if (__ldso_entry == NULL || __ldso_version < LDSO_VERSION_HAS_DLADDR)
return 0;
return (__ldso_entry->dladdr)(addr, dlip);
}
int
dlclose(void *handle)
{
if (__ldso_entry == NULL)
return -1;
return (__ldso_entry->dlclose)(handle);
}
const char *
dlerror(void)
{
if (__ldso_entry == NULL)
return "Service unavailable";
return (__ldso_entry->dlerror)();
}
void *
dlopen(const char *name, int mode)
{
if (__ldso_entry == NULL)
return NULL;
return (__ldso_entry->dlopen)(name, mode);
}
void *
dlsym(void *handle, const char *name)
{
if (__ldso_entry == NULL)
return NULL;
if (__ldso_version >= LDSO_VERSION_HAS_DLSYM3) {
void *retaddr = __builtin_return_address(0); /* __GNUC__ only */
return (__ldso_entry->dlsym3)(handle, name, retaddr);
} else
return (__ldso_entry->dlsym)(handle, name);
}
#endif /* __ELF__ */
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