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freebsd/lib/libc/gen/dlfcn.c
Konstantin Belousov c8da4f07d7 Allow the NULL, RTLD_SELF and RTLD_NEXT handles to work with dlfunc(3).
dlfunc() called dlsym() to do the work, and dlsym() determines the dso
that originating the call by the return address. Due to this, dlfunc()
operated as if the caller is always the libc.

To fix this, move the dlfunc() to rtld, where it can call the internal
implementation of dlsym, and still correctly fetch return address.
Provide usual weak stub for the symbol from libc for static binaries.
dlfunc is put to FBSD_1.0 symver namespace in the ld.so export to
override dlfunc@FBSD_1.0 weak symbol, exported by libc.

Reported, analyzed and tested by:	Tijl Coosemans <tijl ulyssis org>
PR: standards/133339
Reviewed by:	kan
2009-04-03 19:17:23 +00:00

160 lines
3.7 KiB
C

/*-
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* Linkage to services provided by the dynamic linker.
*/
#include <dlfcn.h>
#include <link.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 dllockinit
void
dllockinit(void *context,
void *(*lock_create)(void *context),
void (*rlock_acquire)(void *lock),
void (*wlock_acquire)(void *lock),
void (*lock_release)(void *lock),
void (*lock_destroy)(void *lock),
void (*context_destroy)(void *context))
{
if (context_destroy != NULL)
context_destroy(context);
}
#pragma weak dlopen
void *
dlopen(const char *name, int mode)
{
_rtld_error(sorry);
return NULL;
}
#pragma weak dlsym
void *
dlsym(void * __restrict handle, const char * __restrict name)
{
_rtld_error(sorry);
return NULL;
}
#pragma weak dlfunc
dlfunc_t
dlfunc(void * __restrict handle, const char * __restrict name)
{
_rtld_error(sorry);
return NULL;
}
#pragma weak dlvsym
void *
dlvsym(void * __restrict handle, const char * __restrict name,
const char * __restrict version)
{
_rtld_error(sorry);
return NULL;
}
#pragma weak dlinfo
int
dlinfo(void * __restrict handle, int request, void * __restrict p)
{
_rtld_error(sorry);
return 0;
}
#pragma weak _rtld_thread_init
void
_rtld_thread_init(void * li)
{
_rtld_error(sorry);
}
#pragma weak dl_iterate_phdr
int
dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *),
void *data)
{
_rtld_error(sorry);
return 0;
}
#pragma weak _rtld_atfork_pre
void
_rtld_atfork_pre(int *locks)
{
}
#pragma weak _rtld_atfork_post
void
_rtld_atfork_post(int *locks)
{
}