From 4abab5ad6c8465a7528ccdd5f49367da05f78bbd Mon Sep 17 00:00:00 2001
From: Vladimir Azarov <avm@intermediate-node.net>
Date: Tue, 1 Oct 2024 15:47:05 +0200
Subject: Initial version

---
 src/process/fork.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 src/process/fork.c

(limited to 'src/process/fork.c')

diff --git a/src/process/fork.c b/src/process/fork.c
new file mode 100644
index 0000000..56f1931
--- /dev/null
+++ b/src/process/fork.c
@@ -0,0 +1,90 @@
+#include <unistd.h>
+#include <errno.h>
+#include "libc.h"
+#include "lock.h"
+#include "pthread_impl.h"
+#include "fork_impl.h"
+
+static volatile int *const dummy_lockptr = 0;
+
+weak_alias(dummy_lockptr, __at_quick_exit_lockptr);
+weak_alias(dummy_lockptr, __atexit_lockptr);
+weak_alias(dummy_lockptr, __gettext_lockptr);
+weak_alias(dummy_lockptr, __locale_lockptr);
+weak_alias(dummy_lockptr, __random_lockptr);
+weak_alias(dummy_lockptr, __sem_open_lockptr);
+weak_alias(dummy_lockptr, __stdio_ofl_lockptr);
+weak_alias(dummy_lockptr, __syslog_lockptr);
+weak_alias(dummy_lockptr, __timezone_lockptr);
+weak_alias(dummy_lockptr, __bump_lockptr);
+
+weak_alias(dummy_lockptr, __vmlock_lockptr);
+
+static volatile int *const *const atfork_locks[] = {
+	&__at_quick_exit_lockptr,
+	&__atexit_lockptr,
+	&__gettext_lockptr,
+	&__locale_lockptr,
+	&__random_lockptr,
+	&__sem_open_lockptr,
+	&__stdio_ofl_lockptr,
+	&__syslog_lockptr,
+	&__timezone_lockptr,
+	&__bump_lockptr,
+};
+
+static void dummy(int x) { }
+weak_alias(dummy, __fork_handler);
+weak_alias(dummy, __malloc_atfork);
+weak_alias(dummy, __aio_atfork);
+weak_alias(dummy, __pthread_key_atfork);
+weak_alias(dummy, __ldso_atfork);
+
+static void dummy_0(void) { }
+weak_alias(dummy_0, __tl_lock);
+weak_alias(dummy_0, __tl_unlock);
+
+pid_t fork(void)
+{
+	sigset_t set;
+	__fork_handler(-1);
+	__block_app_sigs(&set);
+	int need_locks = libc.need_locks > 0;
+	if (need_locks) {
+		__ldso_atfork(-1);
+		__pthread_key_atfork(-1);
+		__aio_atfork(-1);
+		__inhibit_ptc();
+		for (int i=0; i<sizeof atfork_locks/sizeof *atfork_locks; i++)
+			if (*atfork_locks[i]) LOCK(*atfork_locks[i]);
+		__malloc_atfork(-1);
+		__tl_lock();
+	}
+	pthread_t self=__pthread_self(), next=self->next;
+	pid_t ret = _Fork();
+	int errno_save = errno;
+	if (need_locks) {
+		if (!ret) {
+			for (pthread_t td=next; td!=self; td=td->next)
+				td->tid = -1;
+			if (__vmlock_lockptr) {
+				__vmlock_lockptr[0] = 0;
+				__vmlock_lockptr[1] = 0;
+			}
+		}
+		__tl_unlock();
+		__malloc_atfork(!ret);
+		for (int i=0; i<sizeof atfork_locks/sizeof *atfork_locks; i++)
+			if (*atfork_locks[i])
+				if (ret) UNLOCK(*atfork_locks[i]);
+				else **atfork_locks[i] = 0;
+		__release_ptc();
+		if (ret) __aio_atfork(0);
+		__pthread_key_atfork(!ret);
+		__ldso_atfork(!ret);
+	}
+	__restore_sigs(&set);
+	__fork_handler(!ret);
+	if (ret<0) errno = errno_save;
+	return ret;
+}
-- 
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