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/*
* Copyright (c) 2021, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Atomic.h>
#include <AK/NeverDestroyed.h>
#include <AK/Vector.h>
#include <bits/pthread_integration.h>
#include <errno.h>
#include <sched.h>
#include <unistd.h>
namespace {
// Most programs don't need this, no need to incur an extra mutex lock/unlock on them
static Atomic<bool> g_did_touch_atfork { false };
static pthread_mutex_t g_atfork_list_mutex __PTHREAD_MUTEX_INITIALIZER;
static NeverDestroyed<Vector<void (*)(void), 4>> g_atfork_prepare_list;
static NeverDestroyed<Vector<void (*)(void), 4>> g_atfork_child_list;
static NeverDestroyed<Vector<void (*)(void), 4>> g_atfork_parent_list;
}
extern "C" {
void __pthread_fork_prepare(void)
{
if (!g_did_touch_atfork.load())
return;
__pthread_mutex_lock(&g_atfork_list_mutex);
for (auto entry : g_atfork_prepare_list.get())
entry();
__pthread_mutex_unlock(&g_atfork_list_mutex);
}
void __pthread_fork_child(void)
{
if (!g_did_touch_atfork.load())
return;
__pthread_mutex_lock(&g_atfork_list_mutex);
for (auto entry : g_atfork_child_list.get())
entry();
__pthread_mutex_unlock(&g_atfork_list_mutex);
}
void __pthread_fork_parent(void)
{
if (!g_did_touch_atfork.load())
return;
__pthread_mutex_lock(&g_atfork_list_mutex);
for (auto entry : g_atfork_parent_list.get())
entry();
__pthread_mutex_unlock(&g_atfork_list_mutex);
}
void __pthread_fork_atfork_register_prepare(void (*func)(void))
{
g_did_touch_atfork.store(true);
__pthread_mutex_lock(&g_atfork_list_mutex);
g_atfork_prepare_list->append(func);
__pthread_mutex_unlock(&g_atfork_list_mutex);
}
void __pthread_fork_atfork_register_parent(void (*func)(void))
{
g_did_touch_atfork.store(true);
__pthread_mutex_lock(&g_atfork_list_mutex);
g_atfork_parent_list->append(func);
__pthread_mutex_unlock(&g_atfork_list_mutex);
}
void __pthread_fork_atfork_register_child(void (*func)(void))
{
g_did_touch_atfork.store(true);
__pthread_mutex_lock(&g_atfork_list_mutex);
g_atfork_child_list->append(func);
__pthread_mutex_unlock(&g_atfork_list_mutex);
}
int __pthread_self()
{
return gettid();
}
int pthread_self() __attribute__((weak, alias("__pthread_self")));
int __pthread_mutex_lock(pthread_mutex_t* mutex)
{
pthread_t this_thread = __pthread_self();
for (;;) {
u32 expected = 0;
if (!AK::atomic_compare_exchange_strong(&mutex->lock, expected, 1u, AK::memory_order_acquire)) {
if (mutex->type == __PTHREAD_MUTEX_RECURSIVE && mutex->owner == this_thread) {
mutex->level++;
return 0;
}
sched_yield();
continue;
}
mutex->owner = this_thread;
mutex->level = 0;
return 0;
}
}
int pthread_mutex_lock(pthread_mutex_t*) __attribute__((weak, alias("__pthread_mutex_lock")));
int __pthread_mutex_unlock(pthread_mutex_t* mutex)
{
if (mutex->type == __PTHREAD_MUTEX_RECURSIVE && mutex->level > 0) {
mutex->level--;
return 0;
}
mutex->owner = 0;
AK::atomic_store(&mutex->lock, 0u, AK::memory_order_release);
return 0;
}
int pthread_mutex_unlock(pthread_mutex_t*) __attribute__((weak, alias("__pthread_mutex_unlock")));
int __pthread_mutex_trylock(pthread_mutex_t* mutex)
{
u32 expected = 0;
if (!AK::atomic_compare_exchange_strong(&mutex->lock, expected, 1u, AK::memory_order_acquire)) {
if (mutex->type == __PTHREAD_MUTEX_RECURSIVE && mutex->owner == pthread_self()) {
mutex->level++;
return 0;
}
return EBUSY;
}
mutex->owner = pthread_self();
mutex->level = 0;
return 0;
}
int pthread_mutex_trylock(pthread_mutex_t* mutex) __attribute__((weak, alias("__pthread_mutex_trylock")));
int __pthread_mutex_init(pthread_mutex_t* mutex, const pthread_mutexattr_t* attributes)
{
mutex->lock = 0;
mutex->owner = 0;
mutex->level = 0;
mutex->type = attributes ? attributes->type : __PTHREAD_MUTEX_NORMAL;
return 0;
}
int pthread_mutex_init(pthread_mutex_t*, const pthread_mutexattr_t*) __attribute__((weak, alias("__pthread_mutex_init")));
}
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