1 files changed, 77 insertions, 0 deletions
diff --git a/lib/libc/stdlib/quick_exit.c b/lib/libc/stdlib/quick_exit.c
new file mode 100644
index 000000000000..4dee7b20bd2b
--- /dev/null
+++ b/lib/libc/stdlib/quick_exit.c
@@ -0,0 +1,77 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2011 David Chisnall
+ * Copyright (c) 2023 Klara, Inc.
+ * 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.
+ */
+
+#include <sys/types.h>
+
+#include <stdatomic.h>
+#include <stdlib.h>
+
+/**
+ * Linked list of quick exit handlers.  These will be invoked in reverse
+ * order of insertion when quick_exit() is called.  This is simpler than
+ * the atexit() version, because it is not required to support C++
+ * destructors or DSO-specific cleanups.
+ */
+struct quick_exit_handler {
+	struct quick_exit_handler *next;
+	void (*cleanup)(void);
+};
+
+static _Atomic(struct quick_exit_handler *) handlers;
+
+int
+at_quick_exit(void (*func)(void))
+{
+	struct quick_exit_handler *h;
+
+	if ((h = calloc(1, sizeof(*h))) == NULL) {
+		return (-1);
+	}
+	h->cleanup = func;
+	while (!atomic_compare_exchange_strong(&handlers, &h->next, h)) {
+		/* nothing */ ;
+	}
+	return (0);
+}
+
+void
+quick_exit(int status)
+{
+	struct quick_exit_handler *h;
+
+	/*
+	 * XXX: The C++ spec requires us to call std::terminate if there is an
+	 * exception here.
+	 */
+	for (h = atomic_load_explicit(&handlers, memory_order_acquire);
+	     h != NULL; h = h->next) {
+		h->cleanup();
+	}
+	_Exit(status);
+}