/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * 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.
 */

#if !defined(IN_LIBDL) || defined(PIC)

/*
 * Linkage to services provided by the dynamic linker.
 */
#include <sys/types.h>
#include <sys/mman.h>
#include <machine/atomic.h>
#include <dlfcn.h>
#include <errno.h>
#include <link.h>
#include <stddef.h>
#include <string.h>
#include "namespace.h"
#include <pthread.h>
#include "un-namespace.h"
#include "rtld.h"
#include "libc_private.h"
#include "reentrant.h"

static const char sorry[] = "Service unavailable";

void _rtld_thread_init(void *);
void _rtld_atfork_pre(int *);
void _rtld_atfork_post(int *);

/*
 * 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 __unused, ...)
{
}

#pragma weak dladdr
int
dladdr(const void *addr __unused, Dl_info *dlip __unused)
{

        _rtld_error(sorry);
        return (0);
}

#pragma weak dlclose
int
dlclose(void *handle __unused)
{

        _rtld_error(sorry);
        return (-1);
}

#pragma weak dlerror
char *
dlerror(void)
{

        return (__DECONST(char *, sorry));
}

#pragma weak dllockinit
void
dllockinit(void *context,
    void *(*lock_create)(void *context) __unused,
    void (*rlock_acquire)(void *lock) __unused,
    void (*wlock_acquire)(void *lock) __unused,
    void (*lock_release)(void *lock) __unused,
    void (*lock_destroy)(void *lock) __unused,
    void (*context_destroy)(void *context) __unused)
{

        if (context_destroy != NULL)
                context_destroy(context);
}

#pragma weak dlopen
void *
dlopen(const char *name __unused, int mode __unused)
{

        _rtld_error(sorry);
        return (NULL);
}

#pragma weak dlsym
void *
dlsym(void * __restrict handle __unused, const char * __restrict name __unused)
{

        _rtld_error(sorry);
        return (NULL);
}

#pragma weak dlfunc
dlfunc_t
dlfunc(void * __restrict handle __unused, const char * __restrict name __unused)
{

        _rtld_error(sorry);
        return (NULL);
}

#pragma weak dlvsym
void *
dlvsym(void * __restrict handle __unused, const char * __restrict name __unused,
    const char * __restrict version __unused)
{

        _rtld_error(sorry);
        return (NULL);
}

#pragma weak dlinfo
int
dlinfo(void * __restrict handle __unused, int request __unused,
    void * __restrict p __unused)
{

        _rtld_error(sorry);
        return (0);
}

#pragma weak _rtld_thread_init
void
_rtld_thread_init(void *li __unused)
{

        _rtld_error(sorry);
}

#ifndef IN_LIBDL
static pthread_once_t dl_phdr_info_once = PTHREAD_ONCE_INIT;
static struct dl_phdr_info phdr_info;
#ifndef PIC
static mutex_t dl_phdr_info_lock = MUTEX_INITIALIZER;
#endif

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

        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_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_adds = 1;
}
#endif

#pragma weak _dl_iterate_phdr_locked
int _dl_iterate_phdr_locked(int (*callback)(struct dl_phdr_info *,
    size_t, void *), void *data);
int
_dl_iterate_phdr_locked(
    int (*callback)(struct dl_phdr_info *, size_t, void *) __unused,
    void *data __unused)
{
#if defined IN_LIBDL
        return (0);
#elif defined PIC
        int (*r)(int (*)(struct dl_phdr_info *, size_t, void *), void *);

        r = dlsym(RTLD_DEFAULT, "dl_iterate_phdr");
        if (r == NULL)
                return (0);
        return (r(callback, data));
#else
        tls_index ti;
        int ret;

        __init_elf_aux_vector();
        if (__elf_aux_vector == NULL)
                return (1);
        _once(&dl_phdr_info_once, dl_init_phdr_info);
        ti.ti_module = 1;
        ti.ti_offset = -TLS_DTV_OFFSET;
        phdr_info.dlpi_tls_data = __tls_get_addr(&ti);
        ret = callback(&phdr_info, sizeof(phdr_info), data);
        return (ret);
#endif
}

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

#if !defined(IN_LIBDL) && !defined(PIC)
        mutex_lock(&dl_phdr_info_lock);
#endif
        error = _dl_iterate_phdr_locked(callback, data);
#if !defined(IN_LIBDL) && !defined(PIC)
        mutex_unlock(&dl_phdr_info_lock);
#endif
        return (error);
}

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

        _rtld_error(sorry);
        return (NULL);
}

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

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

#ifndef IN_LIBDL
struct _rtld_addr_phdr_cb_data {
        const void *addr;
        struct dl_phdr_info *dli;
};

static int
_rtld_addr_phdr_cb(struct dl_phdr_info *dli, size_t sz, void *arg)
{
        struct _rtld_addr_phdr_cb_data *rd;
        const Elf_Phdr *ph;
        unsigned i;

        rd = arg;
        for (i = 0; i < dli->dlpi_phnum; i++) {
                ph = &dli->dlpi_phdr[i];
                if (ph->p_type == PT_LOAD &&
                    dli->dlpi_addr + ph->p_vaddr <= (uintptr_t)rd->addr &&
                    (uintptr_t)rd->addr < dli->dlpi_addr + ph->p_vaddr +
                    ph->p_memsz) {
                        memcpy(rd->dli, dli, sz);
                        return (1);
                }
        }
        return (0);
}
#endif

#pragma weak _rtld_addr_phdr
int
_rtld_addr_phdr(const void *addr __unused,
    struct dl_phdr_info *phdr_info_a __unused)
{
#ifndef IN_LIBDL
        struct _rtld_addr_phdr_cb_data rd;

        rd.addr = addr;
        rd.dli = phdr_info_a;
        return (dl_iterate_phdr(_rtld_addr_phdr_cb, &rd));
#else
        return (0);
#endif
}

#pragma weak _rtld_get_stack_prot
int
_rtld_get_stack_prot(void)
{
#ifndef IN_LIBDL
        unsigned i;
        int r;
        static int ret;

        r = atomic_load_int(&ret);
        if (r != 0)
                return (r);

        _once(&dl_phdr_info_once, dl_init_phdr_info);
        r = PROT_EXEC | PROT_READ | PROT_WRITE;
        for (i = 0; i < phdr_info.dlpi_phnum; i++) {
                if (phdr_info.dlpi_phdr[i].p_type != PT_GNU_STACK)
                        continue;
                r = PROT_READ | PROT_WRITE;
                if ((phdr_info.dlpi_phdr[i].p_flags & PF_X) != 0)
                        r |= PROT_EXEC;
                break;
        }
        atomic_store_int(&ret, r);
        return (r);
#else
        return (0);
#endif
}

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

        return (0);
}

#pragma weak rtld_get_var
const char *
rtld_get_var(const char *name __unused)
{
        _rtld_error(sorry);
        return (NULL);
}

#pragma weak rtld_set_var
int
rtld_set_var(const char *name __unused, const char *val __unused)
{
        _rtld_error(sorry);
        return (EINVAL);
}

#endif /* !defined(IN_LIBDL) || defined(PIC) */