This is xnu-8019. See this file in:
/*
 * Copyright (c) 2016 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_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. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * 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_OSREFERENCE_LICENSE_HEADER_END@
 */

#ifndef _SYS_SNAPSHOT_H_
#define _SYS_SNAPSHOT_H_

#ifndef KERNEL

#include <sys/cdefs.h>
#include <machine/_types.h>
#include <sys/_types/_size_t.h>
#include <_types/_uint32_t.h>
#include <sys/attr.h>
#include <Availability.h>

__BEGIN_DECLS

int fs_snapshot_create(int, const char *, uint32_t) __OSX_AVAILABLE(10.12) __IOS_AVAILABLE(10.0) __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0);

int fs_snapshot_list(int, struct attrlist  *, void *, size_t, uint32_t) __OSX_AVAILABLE(10.12) __IOS_AVAILABLE(10.0) __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0);

int fs_snapshot_delete(int, const char *, uint32_t) __OSX_AVAILABLE(10.12) __IOS_AVAILABLE(10.0) __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0);

int fs_snapshot_rename(int, const char *, const char *, uint32_t) __OSX_AVAILABLE(10.12) __IOS_AVAILABLE(10.0) __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0);

int fs_snapshot_mount(int, const char *, const char *, uint32_t) __OSX_AVAILABLE(10.12) __IOS_AVAILABLE(10.0)       __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0);

int fs_snapshot_revert(int, const char *, uint32_t) __OSX_AVAILABLE(10.12) __IOS_AVAILABLE(10.0) __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0);

#ifdef PRIVATE
int fs_snapshot_root(int, const char *, uint32_t) __OSX_AVAILABLE(10.12.4) __IOS_AVAILABLE(10.3) __TVOS_AVAILABLE(10.3) __WATCHOS_AVAILABLE(3.3);
#endif

__END_DECLS

#endif /* !KERNEL */

#ifdef PRIVATE

#define SNAPSHOT_OP_CREATE 0x01
#define SNAPSHOT_OP_DELETE 0x02
#define SNAPSHOT_OP_RENAME 0x03
#define SNAPSHOT_OP_MOUNT  0x04
#define SNAPSHOT_OP_REVERT 0x05
#define SNAPSHOT_OP_ROOT   0x06

#endif

#endif /* !_SYS_SNAPSHOT_H_ */