libc/gen/dlfcn.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: stable/10/lib/libc/gen/dlfcn.c 276908 2015-01-10 09:22:17Z kib $");

/*
 * Linkage to services provided by the dynamic linker.
 */
#include <sys/mman.h>
#include <dlfcn.h>
#include <link.h>
#include <stddef.h>
#include "namespace.h"
#include <pthread.h>
#include "un-namespace.h"
#include "libc_private.h"

static 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
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);
}

static pthread_once_t dl_phdr_info_once = PTHREAD_ONCE_INIT;
static struct dl_phdr_info phdr_info;

static void
dl_init_phdr_info(void)
{
	Elf_Auxinfo *auxp;
	size_t phent;
	unsigned int i;

	phent = 0;
	for (auxp = __elf_aux_vector; auxp->a_type != AT_NULL; auxp++) {
		switch (auxp->a_type) {
		case AT_BASE:
			phdr_info.dlpi_addr = (Elf_Addr)auxp->a_un.a_ptr;
			break;
		case AT_EXECPATH:
			phdr_info.dlpi_name = (const char *)auxp->a_un.a_ptr;
			break;
		case AT_PHDR:
			phdr_info.dlpi_phdr =
			    (const Elf_Phdr *)auxp->a_un.a_ptr;
			break;
		case AT_PHENT:
			phent = auxp->a_un.a_val;
			break;
		case AT_PHNUM:
			phdr_info.dlpi_phnum = (Elf_Half)auxp->a_un.a_val;
			break;
		}
	}
	for (i = 0; i < phdr_info.dlpi_phnum; i++) {
		if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) {
			phdr_info.dlpi_tls_modid = 1;
			phdr_info.dlpi_tls_data =
			    (void*)phdr_info.dlpi_phdr[i].p_vaddr;
		}
	}
	phdr_info.dlpi_adds = 1;
}

#pragma weak dl_iterate_phdr
int
dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *),
    void *data)
{

	__init_elf_aux_vector();
	if (__elf_aux_vector == NULL)
		return (1);
	_once(&dl_phdr_info_once, dl_init_phdr_info);
	return (callback(&phdr_info, sizeof(phdr_info), data));
}

#pragma weak fdlopen
void *
fdlopen(int fd, int mode)
{

	_rtld_error(sorry);
	return NULL;
}

#pragma weak _rtld_atfork_pre
void
_rtld_atfork_pre(int *locks)
{
}

#pragma weak _rtld_atfork_post
void
_rtld_atfork_post(int *locks)
{
}

#pragma weak _rtld_addr_phdr
int
_rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
{

	return (0);
}

#pragma weak _rtld_get_stack_prot
int
_rtld_get_stack_prot(void)
{

	return (PROT_EXEC | PROT_READ | PROT_WRITE);
}

#pragma weak _rtld_is_dlopened
int
_rtld_is_dlopened(void *arg)
{

	return (0);
}