cosmopolitan/libc/thread/pthread_atfork.c
Justine Tunney 7e0a09feec
Mint APE Loader v1.5
This change ports APE Loader to Linux AARCH64, so that Raspberry Pi
users can run programs like redbean, without the executable needing
to modify itself. Progress has also slipped into this change on the
issue of making progress better conforming to user expectations and
industry standards regarding which symbols we're allowed to declare
2023-07-26 13:54:49 -07:00

121 lines
4.5 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/state.internal.h"
#include "libc/errno.h"
#include "libc/intrin/atomic.h"
#include "libc/intrin/dll.h"
#include "libc/intrin/kmalloc.h"
#include "libc/mem/mem.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/str/str.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/thread.h"
#include "libc/thread/tls.h"
static struct AtForks {
pthread_spinlock_t lock;
struct AtFork {
struct AtFork *p[2];
atfork_f f[3];
} * list;
} _atforks;
static void _pthread_purge(void) {
struct Dll *e;
while ((e = dll_first(_pthread_list))) {
dll_remove(&_pthread_list, e);
_pthread_free(POSIXTHREAD_CONTAINER(e));
}
}
static void _pthread_onfork(int i) {
struct AtFork *a;
struct PosixThread *pt;
unassert(0 <= i && i <= 2);
if (!i) pthread_spin_lock(&_atforks.lock);
for (a = _atforks.list; a; a = a->p[!i]) {
if (a->f[i]) a->f[i]();
_atforks.list = a;
}
if (i) pthread_spin_unlock(&_atforks.lock);
}
void _pthread_onfork_prepare(void) {
_pthread_onfork(0);
pthread_spin_lock(&_pthread_lock);
__fds_lock();
__mmi_lock();
__kmalloc_lock();
}
void _pthread_onfork_parent(void) {
__kmalloc_unlock();
__mmi_unlock();
__fds_unlock();
pthread_spin_unlock(&_pthread_lock);
_pthread_onfork(1);
}
void _pthread_onfork_child(void) {
struct CosmoTib *tib;
struct PosixThread *pt;
pthread_mutexattr_t attr;
extern pthread_mutex_t __mmi_lock_obj;
tib = __get_tls();
pt = (struct PosixThread *)tib->tib_pthread;
// let's choose to let the new process live.
// even though it's unclear what to do with this kind of race.
atomic_store_explicit(&pt->cancelled, false, memory_order_relaxed);
// wipe core runtime locks
__kmalloc_unlock();
pthread_mutexattr_init(&attr);
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
pthread_mutex_init(&__mmi_lock_obj, &attr);
pthread_mutex_init(&__fds_lock_obj, &attr);
pthread_spin_init(&_pthread_lock, 0);
// call user-supplied forked child callbacks
_pthread_onfork(2);
// delete other threads that existed before forking
// this must come after onfork, since it calls free
dll_remove(&_pthread_list, &pt->list);
_pthread_purge();
dll_make_first(&_pthread_list, &pt->list);
}
int _pthread_atfork(atfork_f prepare, atfork_f parent, atfork_f child) {
int rc;
struct AtFork *a;
if (!(a = kmalloc(sizeof(struct AtFork)))) return ENOMEM;
a->f[0] = prepare;
a->f[1] = parent;
a->f[2] = child;
pthread_spin_lock(&_atforks.lock);
a->p[0] = 0;
a->p[1] = _atforks.list;
if (_atforks.list) _atforks.list->p[0] = a;
_atforks.list = a;
pthread_spin_unlock(&_atforks.lock);
rc = 0;
return rc;
}