C11 quick_exit() support for <stdlib.h>

Import some <stdlib.h> function declarations from latest FreeBSD and
implement them.  I am not sure if we should call the global reent
cleanup in quick_exit() similar to exit().

newlib/ChangeLog
2015-10-14  Sebastian Huber  <sebastian.huber@embedded-brains.de>

	* libc/include/stdlib.h (at_quick_exit): Declare.
	(quick_exit): Likewise.
	* libc/stdlib/Makefile.am (GENERAL_SOURCES): Add
	quick_exit.c.
	* libc/stdlib/Makefile.in: Regenerate.
	* libc/stdlib/quick_exit.c: New.

1 files changed, 81 insertions, 0 deletions

diff --git a/newlib/libc/stdlib/quick_exit.c b/newlib/libc/stdlib/quick_exit.c
new file mode 100644
index 0000000..fc43571
--- /dev/null
+++ b/newlib/libc/stdlib/quick_exit.c
@@ -0,0 +1,81 @@
+/*-
+ * Copyright (c) 2011 David Chisnall
+ * Copyright (c) 2015 embedded brains GmbH
+ * 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <stdlib.h>
+#include <sys/lock.h>
+
+/**
+ * Linked list of quick exit handlers.  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);
+};
+
+/**
+ * Lock protecting the handlers list.
+ */
+__LOCK_INIT(static, atexit_mutex);
+/**
+ * Stack of cleanup handlers.  These will be invoked in reverse order when
+ */
+static struct quick_exit_handler *handlers;
+
+int
+at_quick_exit(void (*func)(void))
+{
+	struct quick_exit_handler *h;
+
+	h = malloc(sizeof(*h));
+
+	if (NULL == h)
+		return (1);
+	h->cleanup = func;
+	__lock_acquire(atexit_mutex);
+	h->next = handlers;
+	handlers = h;
+	__lock_release(atexit_mutex);
+	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 = handlers; NULL != h; h = h->next)
+		h->cleanup();
+	_exit(status);
+}