--- /dev/null
+++ libmalloc/libmalloc-374.40.6/src/msl_lite_support.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2018 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+/*
+ * Support for stack logging lite in the malloc stack logging library. This code
+ * will go away when MSL lite no longer requires its own zone.
+ */
+#ifndef MALLOC_ENABLE_MSL_LITE_SPI
+#define MALLOC_ENABLE_MSL_LITE_SPI 1
+#endif // MALLOC_ENABLE_MSL_LITE_SPI
+
+#include "internal.h"
+
+// These definitions are here and not in a header file because all of this code
+// is intended to go away very soon.
+extern malloc_zone_t **malloc_zones;
+extern malloc_zone_t* lite_zone;
+extern void malloc_zone_register_while_locked(malloc_zone_t *zone, bool make_default);
+extern boolean_t has_default_zone0(void);
+
+static szone_t *create_and_insert_msl_lite_zone(const char *name,
+		void *mallocp, void *callocp,
+		void *vallocp, void *reallocp, void *batch_mallocp,
+		void *batch_freep, void *memalignp, void *freep,
+		void *free_definite_sizep, void *sizep);
+
+static size_t
+_calloc_get_size(size_t num_items, size_t size, size_t extra_size,
+		size_t *total_size)
+{
+	// calloc_get_size is inlined.
+	return calloc_get_size(num_items, size, extra_size, total_size);
+}
+
+static malloc_zone_t *
+szone_helper_zone(szone_t *zone)
+{
+	return &zone->helper_zone->basic_zone;
+}
+
+static malloc_zone_t *
+szone_basic_zone(szone_t *zone)
+{
+	return &zone->basic_zone;
+}
+
+static struct _malloc_msl_lite_hooks_s malloc_msl_lite_hooks = {
+	.create_and_insert_msl_lite_zone = &create_and_insert_msl_lite_zone,
+	.helper_zone = &szone_helper_zone,
+	.szone_size = &szone_size,
+	.szone_malloc = &szone_malloc,
+	.szone_malloc_should_clear = &szone_malloc_should_clear,
+	.szone_free = &szone_free,
+	.szone_realloc = &szone_realloc,
+	.szone_valloc = &szone_valloc,
+	.szone_memalign = &szone_memalign,
+	.szone_batch_malloc = &szone_batch_malloc,
+	.szone_batch_free = &szone_batch_free,
+	.has_default_zone0 = &has_default_zone0,
+	.calloc_get_size = &_calloc_get_size,
+	.basic_zone = &szone_basic_zone,
+	.szone_good_size = &szone_good_size,
+};
+
+static szone_t *
+create_and_insert_msl_lite_zone(const char *name,
+		void *mallocp, void *callocp,
+		void *vallocp, void *reallocp, void *batch_mallocp,
+		void *batch_freep, void *memalignp, void *freep,
+		void *free_definite_sizep, void *sizep)
+{
+// TODO: this has to be locked in some way....
+	szone_t* szone = create_scalable_szone(0, malloc_debug_flags);
+	malloc_zone_t *zone = &szone->basic_zone;
+	
+	// unprotect function pointers
+	mprotect(szone, sizeof(szone->basic_zone), PROT_READ | PROT_WRITE);
+	
+	// set the function pointers
+	szone->basic_zone.malloc = mallocp;
+	szone->basic_zone.calloc = callocp;
+	szone->basic_zone.valloc = vallocp;
+	szone->basic_zone.realloc = reallocp;
+	szone->basic_zone.batch_malloc = batch_mallocp;
+	szone->basic_zone.batch_free = batch_freep;
+	szone->basic_zone.memalign = memalignp;
+	szone->basic_zone.free = freep;
+	szone->basic_zone.free_definite_size = free_definite_sizep;
+	szone->basic_zone.size = sizep;
+	
+	// protect function pointers
+	mprotect(szone, sizeof(szone->basic_zone), PROT_READ);
+	
+	// set helper zone
+	szone->helper_zone = (szone_t *)malloc_zones[0];  // TODO: this is broken
+	
+	malloc_zone_register_while_locked(zone, false);
+	malloc_set_zone_name(zone, name);
+	lite_zone = zone;
+
+	return szone;
+}
+
+/*
+ * Copies the malloc library's _malloc_msl_lite_hooks_t structure to a given
+ * location. We pass the structure size to allow the structure to
+ * grow. Since this is a temporary arrangement, we don't need to worry about
+ * pointer authentication here or in the _malloc_msl_lite_hooks_t structure itself.
+ */
+MALLOC_NOEXPORT
+void
+set_msl_lite_hooks(set_msl_lite_hooks_callout_t callout)
+{
+	callout(&malloc_msl_lite_hooks, sizeof(malloc_msl_lite_hooks));
+}