/*
 * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
 * Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org>
 * 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. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * 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.
 */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
 * 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.
 * 3. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL 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/syscall.h>
#include "namespace.h"
#include <errno.h>
#include <link.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <spinlock.h>
#include "un-namespace.h"

#include "libc_private.h"
#include "rtld_lock.h"
#include "thr_private.h"

__weak_reference(_thr_atfork, _pthread_atfork);
__weak_reference(_thr_atfork, pthread_atfork);

bool _thr_after_fork = false;

int
_thr_atfork(void (*prepare)(void), void (*parent)(void),
    void (*child)(void))
{
        struct pthread *curthread;
        struct pthread_atfork *af;

        if ((af = malloc(sizeof(struct pthread_atfork))) == NULL)
                return (ENOMEM);

        af->prepare = prepare;
        af->parent = parent;
        af->child = child;

        if (_thr_initial != NULL) {
                curthread = _get_curthread();
                THR_CRITICAL_ENTER(curthread);
                _thr_rwl_wrlock(&_thr_atfork_lock);
                TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe);
                _thr_rwl_unlock(&_thr_atfork_lock);
                THR_CRITICAL_LEAVE(curthread);
        } else {
                TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe);
        }

        return (0);
}

void
__pthread_cxa_finalize(struct dl_phdr_info *phdr_info)
{
        atfork_head    temp_list = TAILQ_HEAD_INITIALIZER(temp_list);
        struct pthread *curthread;
        struct pthread_atfork *af, *af1;

        _thr_check_init();

        curthread = _get_curthread();
        THR_CRITICAL_ENTER(curthread);
        _thr_rwl_wrlock(&_thr_atfork_lock);
        TAILQ_FOREACH_SAFE(af, &_thr_atfork_list, qe, af1) {
                if (__elf_phdr_match_addr(phdr_info, af->prepare) ||
                    __elf_phdr_match_addr(phdr_info, af->parent) ||
                    __elf_phdr_match_addr(phdr_info, af->child)) {
                        TAILQ_REMOVE(&_thr_atfork_list, af, qe);
                        TAILQ_INSERT_TAIL(&temp_list, af, qe);
                }
        }
        _thr_rwl_unlock(&_thr_atfork_lock);
        THR_CRITICAL_LEAVE(curthread);
        while ((af = TAILQ_FIRST(&temp_list)) != NULL) {
                TAILQ_REMOVE(&temp_list, af, qe);
                free(af);
        }
        _thr_tsd_unload(phdr_info);
        _thr_sigact_unload(phdr_info);
}

enum thr_fork_mode {
        MODE_FORK,
        MODE_PDFORK,
};

struct thr_fork_args {
        enum thr_fork_mode mode;
        void *fdp;
        int flags;
};

static pid_t
thr_fork_impl(const struct thr_fork_args *a)
{
        struct pthread *curthread;
        struct pthread_atfork *af;
        pid_t ret;
        int errsave, cancelsave;
        int was_threaded;
        int rtld_locks[MAX_RTLD_LOCKS];

        if (!_thr_is_inited()) {
                switch (a->mode) {
                case MODE_FORK:
                        return (__sys_fork());
                case MODE_PDFORK:
                        return (__sys_pdfork(a->fdp, a->flags));
                default:
                        errno = EDOOFUS;
                        return (-1);
                }
        }

        curthread = _get_curthread();
        cancelsave = curthread->no_cancel;
        curthread->no_cancel = 1;
        _thr_rwl_rdlock(&_thr_atfork_lock);

        /* Run down atfork prepare handlers. */
        TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) {
                if (af->prepare != NULL)
                        af->prepare();
        }

        /*
         * Block all signals until we reach a safe point.
         */
        _thr_signal_block(curthread);
        _thr_signal_prefork();

        /*
         * All bets are off as to what should happen soon if the parent
         * process was not so kindly as to set up pthread fork hooks to
         * relinquish all running threads.
         */
        if (_thr_isthreaded() != 0) {
                was_threaded = 1;
                __thr_malloc_prefork(curthread);
                _malloc_prefork();
                __thr_pshared_atfork_pre();
                _rtld_atfork_pre(rtld_locks);
        } else {
                was_threaded = 0;
        }

        /*
         * Fork a new process.
         * There is no easy way to pre-resolve the __sys_fork symbol
         * without performing the fork.  Use the syscall(2)
         * indirection, the syscall symbol is resolved in
         * _thr_rtld_init() with side-effect free call.
         */
        switch (a->mode) {
        case MODE_FORK:
                ret = syscall(SYS_fork);
                break;
        case MODE_PDFORK:
                ret = syscall(SYS_pdfork, a->fdp, a->flags);
                break;
        default:
                ret = -1;
                errno = EDOOFUS;
                break;
        }

        if (ret == 0) {
                /* Child process */
                errsave = errno;
                curthread->cancel_pending = 0;
                curthread->flags &= ~(THR_FLAGS_NEED_SUSPEND|THR_FLAGS_DETACHED);

                /*
                 * Thread list will be reinitialized, and later we call
                 * _libpthread_init(), it will add us back to list.
                 */
                curthread->tlflags &= ~TLFLAGS_IN_TDLIST;

                /* before thr_self() */
                if (was_threaded)
                        __thr_malloc_postfork(curthread);

                /* child is a new kernel thread. */
                thr_self(&curthread->tid);

                /* clear other threads locked us. */
                _thr_umutex_init(&curthread->lock);
                _mutex_fork(curthread);

                _thr_signal_postfork_child();

                if (was_threaded) {
                        _thr_after_fork = true;
                        _rtld_atfork_post(rtld_locks);
                        _thr_after_fork = false;
                        __thr_pshared_atfork_post();
                }
                _thr_setthreaded(0);

                /* reinitalize library. */
                _libpthread_init(curthread);

                /* atfork is reinitialized by _libpthread_init()! */
                _thr_rwl_rdlock(&_thr_atfork_lock);

                if (was_threaded) {
                        _thr_setthreaded(1);
                        _malloc_postfork();
                        _thr_setthreaded(0);
                }

                /* Ready to continue, unblock signals. */ 
                _thr_signal_unblock(curthread);

                /* Run down atfork child handlers. */
                TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
                        if (af->child != NULL)
                                af->child();
                }
                _thr_rwlock_unlock(&_thr_atfork_lock);
                curthread->no_cancel = cancelsave;
        } else {
                /* Parent process */
                errsave = errno;

                _thr_signal_postfork();

                if (was_threaded) {
                        __thr_malloc_postfork(curthread);
                        _rtld_atfork_post(rtld_locks);
                        __thr_pshared_atfork_post();
                        _malloc_postfork();
                }

                /* Ready to continue, unblock signals. */ 
                _thr_signal_unblock(curthread);

                /* Run down atfork parent handlers. */
                TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
                        if (af->parent != NULL)
                                af->parent();
                }

                _thr_rwlock_unlock(&_thr_atfork_lock);
                curthread->no_cancel = cancelsave;
                /* test async cancel */
                if (curthread->cancel_async)
                        _thr_testcancel(curthread);
        }
        errno = errsave;

        return (ret);
}

__weak_reference(__thr_fork, _fork);

pid_t
__thr_fork(void)
{
        struct thr_fork_args a;

        a.mode = MODE_FORK;
        return (thr_fork_impl(&a));
}

pid_t
__thr_pdfork(int *fdp, int flags)
{
        struct thr_fork_args a;

        a.mode = MODE_PDFORK;
        a.fdp = fdp;
        a.flags = flags;
        return (thr_fork_impl(&a));
}