diff --git a/lib/libcmdutils/libcmdutils.h b/lib/libcmdutils/libcmdutils.h
new file mode 100644
index 000000000000..5f9957b861ff
--- /dev/null
+++ b/lib/libcmdutils/libcmdutils.h
@@ -0,0 +1,231 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+/*
+ * Copyright (c) 2013 RackTop Systems.
+ */
+/*
+ * Copyright 2017 Joyent, Inc.
+ */
+
+/*
+ * Declarations for the functions in libcmdutils.
+ */
+
+#ifndef	_LIBCMDUTILS_H
+#define	_LIBCMDUTILS_H
+
+#if !defined(_LP64) && \
+	!((_FILE_OFFSET_BITS == 64) || defined(_LARGEFILE64_SOURCE))
+#error "libcmdutils.h can only be used in a largefile compilation environment"
+#endif
+
+/*
+ * This is a private header file.  Applications should not directly include
+ * this file.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <libintl.h>
+#include <string.h>
+#include <dirent.h>
+#include <attr.h>
+#include <sys/avl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <libnvpair.h>
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+/* extended system attribute support */
+#define	_NOT_SATTR	0
+#define	_RO_SATTR	1
+#define	_RW_SATTR	2
+
+#define	MAXMAPSIZE	(1024*1024*8)	/* map at most 8MB */
+#define	SMALLFILESIZE	(32*1024)	/* don't use mmap on little file */
+
+/* Type used for a node containing a device id and inode number */
+
+#if defined(_LP64) || (_FILE_OFFSET_BITS == 64)
+typedef struct tree_node {
+	dev_t		node_dev;
+	ino_t		node_ino;
+	avl_node_t	avl_link;
+} tree_node_t;
+#else
+typedef struct tree_node {
+	dev_t		node_dev;
+	ino64_t		node_ino;
+	avl_node_t	avl_link;
+} tree_node_t;
+#endif
+
+		/* extended system attribute support */
+
+/* Determine if a file is the name of an extended system attribute file */
+extern int sysattr_type(char *);
+
+/* Determine if the underlying file system supports system attributes */
+extern int sysattr_support(char *, int);
+
+/* Copies the content of the source file to the target file */
+#if defined(_LP64) || (_FILE_OFFSET_BITS == 64)
+extern int writefile(int, int, char *, char *, char *, char *,
+	struct stat *, struct stat *);
+#else
+extern int writefile(int, int, char *, char *, char *, char *,
+	struct stat64 *, struct stat64 *);
+#endif
+
+/* Gets file descriptors of the source and target attribute files */
+extern int get_attrdirs(int, int, char *, int *, int *);
+
+/* Move extended attribute and extended system attribute */
+extern int mv_xattrs(char *, char *, char *, int, int);
+
+/* Returns non default extended system attribute list */
+extern nvlist_t *sysattr_list(char *, int, char *);
+
+
+
+		/* avltree */
+
+/*
+ * Used to compare two nodes.  We are attempting to match the 1st
+ * argument (node) against the 2nd argument (a node which
+ * is already in the search tree).
+ */
+
+extern int tnode_compare(const void *, const void *);
+
+/*
+ * Used to add a single node (containing the input device id and
+ * inode number) to the specified search tree.  The calling
+ * application must set the tree pointer to NULL before calling
+ * add_tnode() for the first time.
+ */
+#if defined(_LP64) || (_FILE_OFFSET_BITS == 64)
+extern int add_tnode(avl_tree_t **, dev_t, ino_t);
+#else
+extern int add_tnode(avl_tree_t **, dev_t, ino64_t);
+#endif
+
+/*
+ * Used to destroy a whole tree (all nodes) without rebalancing.
+ * The calling application is responsible for setting the tree
+ * pointer to NULL upon return.
+ */
+extern void destroy_tree(avl_tree_t *);
+
+
+
+		/* user/group id helpers */
+
+/*
+ * Used to get the next available user id in given range.
+ */
+extern int findnextuid(uid_t, uid_t, uid_t *);
+
+/*
+ * Used to get the next available group id in given range.
+ */
+extern int findnextgid(gid_t, gid_t, gid_t *);
+
+
+
+		/* dynamic string utilities */
+
+typedef struct custr custr_t;
+
+/*
+ * Allocate and free a "custr_t" dynamic string object.  Returns 0 on success
+ * and -1 otherwise.
+ */
+extern int custr_alloc(custr_t **);
+extern void custr_free(custr_t *);
+
+/*
+ * Allocate a "custr_t" dynamic string object that operates on a fixed external
+ * buffer.
+ */
+extern int custr_alloc_buf(custr_t **, void *, size_t);
+
+/*
+ * Append a single character, or a NUL-terminated string of characters, to a
+ * dynamic string.  Returns 0 on success and -1 otherwise.  The dynamic string
+ * will be unmodified if the function returns -1.
+ */
+extern int custr_appendc(custr_t *, char);
+extern int custr_append(custr_t *, const char *);
+
+/*
+ * Append a format string and arguments as though the contents were being parsed
+ * through snprintf. Returns 0 on success and -1 otherwise.  The dynamic string
+ * will be unmodified if the function returns -1.
+ */
+extern int custr_append_printf(custr_t *, const char *, ...);
+extern int custr_append_vprintf(custr_t *, const char *, va_list);
+
+/*
+ * Determine the length in bytes, not including the NUL terminator, of the
+ * dynamic string.
+ */
+extern size_t custr_len(custr_t *);
+
+/*
+ * Clear the contents of a dynamic string.  Does not free the underlying
+ * memory.
+ */
+extern void custr_reset(custr_t *);
+
+/*
+ * Retrieve a const pointer to a NUL-terminated string version of the contents
+ * of the dynamic string.  Storage for this string should not be freed, and
+ * the pointer will be invalidated by any mutations to the dynamic string.
+ */
+extern const char *custr_cstr(custr_t *str);
+
+#define	NN_DIVISOR_1000		(1U << 0)
+
+/* Minimum size for the output of nicenum, including NULL */
+#define	NN_NUMBUF_SZ		(6)
+
+void nicenum(uint64_t, char *, size_t);
+void nicenum_scale(uint64_t, size_t, char *, size_t, uint32_t);
+
+#ifdef	__cplusplus
+}
+#endif
+
+#endif /* _LIBCMDUTILS_H */