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