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![Kyle Evans](/assets/img/avatar_default.png)
be_destroy is documented to recursively destroy a boot environment. In the case of snapshots, one would take this to mean that these are also recursively destroyed. However, this was previously not the case. be_destroy would descend into the be_destroy callback and attempt to zfs_iter_children on the top-level snapshot, which is bogus. Our alternative approach is to take note of the snapshot name and iterate through all of fs children of the BE to try destruction in the children. The -o option is also fixed to work properly with deep BEs. If the BE was created with `bectl create -e otherDeepBE newDeepBE`, for instance, then a recursive snapshot of otherDeepBE would have been taken for construction of newDeepBE but a subsequent destroy with BE_DESTROY_ORIGIN set would only clean up the snapshot at the root of otherDeepBE: ${BEROOT}/otherDeepBE@... The most recent iteration instead pretends not to know how these things work, verifies that the origin is another BE and then passes that back through be_destroy to DTRT when snapshots and deep BEs may be in play. MFC after: 1 week
505 lines
12 KiB
Groff
505 lines
12 KiB
Groff
.\"
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.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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.\"
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.\" Copyright (c) 2017 Kyle Kneitinger
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.\" All rights reserved.
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.\" Copyright (c) 2018 Kyle Evans <kevans@FreeBSD.org>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 12, 2019
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.Dt LIBBE 3
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.Os
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.Sh NAME
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.Nm libbe
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.Nd library for creating, destroying and modifying ZFS boot environments
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.Sh LIBRARY
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.Lb libbe
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.Sh SYNOPSIS
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.In be.h
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.Ft "libbe_handle_t *hdl" Ns
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.Fn libbe_init "const char *be_root"
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.Pp
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.Ft void
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.Fn libbe_close "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_active_name "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_active_path "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_nextboot_name "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_nextboot_path "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_root_path "libbe_handle_t *hdl"
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.Pp
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.Ft int
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.Fn be_create "libbe_handle_t *hdl" "const char *be_name"
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.Pp
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.Ft int
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.Fn be_create_from_existing "libbe_handle_t *hdl" "const char *be_name" "const char *be_origin"
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.Pp
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.Ft int
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.Fn be_create_from_existing_snap "libbe_handle_t *hdl" "const char *be_name" "const char *snap"
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.Pp
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.Ft int
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.Fn be_rename "libbe_handle_t *hdl" "const char *be_old" "const char *be_new"
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.Pp
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.Ft int
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.Fn be_activate "libbe_handle_t *hdl" "const char *be_name" "bool temporary"
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.Ft int
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.Fn be_destroy "libbe_handle_t *hdl" "const char *be_name" "int options"
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.Pp
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.Ft void
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.Fn be_nicenum "uint64_t num" "char *buf" "size_t bufsz"
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.Pp
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.\" TODO: Write up of mount options
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.\" typedef enum {
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.\" BE_MNT_FORCE = 1 << 0,
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.\" BE_MNT_DEEP = 1 << 1,
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.\" } be_mount_opt_t
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.Ft int
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.Fn be_mount "libbe_handle_t *hdl" "char *be_name" "char *mntpoint" "int flags" "char *result"
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.Pp
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.Ft int
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.Fn be_mounted_at "libbe_handle_t *hdl" "const char *path" "nvlist_t *details"
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.Pp
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.Ft int
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.Fn be_unmount "libbe_handle_t *hdl" "char *be_name" "int flags"
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.Pp
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.Ft int
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.Fn libbe_errno "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn libbe_error_description "libbe_handle_t *hdl"
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.Pp
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.Ft void
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.Fn libbe_print_on_error "libbe_handle_t *hdl" "bool doprint"
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.Pp
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.Ft int
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.Fn be_root_concat "libbe_handle_t *hdl" "const char *be_name" "char *result"
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.Pp
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.Ft int
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.Fn be_validate_name "libbe_handle_t *hdl" "const char *be_name"
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.Pp
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.Ft int
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.Fn be_validate_snap "libbe_handle_t *hdl" "const char *snap"
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.Pp
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.Ft int
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.Fn be_exists "libbe_handle_t *hdl" "char *be_name"
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.Pp
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.Ft int
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.Fn be_export "libbe_handle_t *hdl" "const char *be_name" "int fd"
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.Pp
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.Ft int
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.Fn be_import "libbe_handle_t *hdl" "const char *be_name" "int fd"
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.Pp
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.Ft int
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.Fn be_prop_list_alloc "nvlist_t **prop_list"
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.Pp
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.Ft int
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.Fn be_get_bootenv_props "libbe_handle_t *hdl" "nvlist_t *be_list"
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.Pp
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.Ft int
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.Fn be_get_dataset_props "libbe_handle_t *hdl" "const char *ds_name" "nvlist_t *props"
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.Pp
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.Ft int
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.Fn be_get_dataset_snapshots "libbe_handle_t *hdl" "const char *ds_name" "nvlist_t *snap_list"
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.Pp
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.Ft void
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.Fn be_prop_list_free "nvlist_t *prop_list"
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.Sh DESCRIPTION
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.Nm
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interfaces with libzfs to provide a set of functions for various operations
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regarding ZFS boot environments including "deep" boot environments in which
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a boot environments has child datasets.
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.Pp
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A context structure is passed to each function, allowing for a small amount
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of state to be retained, such as errors from previous operations.
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.Nm
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may be configured to print the corresponding error message to
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.Dv stderr
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when an error is encountered with
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.Fn libbe_print_on_error .
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.Pp
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All functions returning an
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.Vt int
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return 0 on success, or a
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.Nm
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errno otherwise as described in
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.Sx DIAGNOSTICS .
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.Pp
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The
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.Fn libbe_init
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function takes an optional BE root and initializes
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.Nm ,
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returning a
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.Vt "libbe_handle_t *"
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on success, or
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.Dv NULL
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on error.
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If a BE root is supplied,
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.Nm
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will only operate out of that pool and BE root.
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An error may occur if:
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.Bl -column
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.It /boot and / are not on the same filesystem and device,
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.It libzfs fails to initialize,
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.It The system has not been properly booted with a ZFS boot
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environment,
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.It Nm
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fails to open the zpool the active boot environment resides on, or
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.It Nm
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fails to locate the boot environment that is currently mounted.
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.El
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.Pp
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The
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.Fn libbe_close
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function frees all resources previously acquired in
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.Fn libbe_init ,
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invalidating the handle in the process.
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.Pp
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The
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.Fn be_active_name
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function returns the name of the currently booted boot environment.
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This boot environment may not belong to the same BE root as the root libbe
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is operating on!
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.Pp
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The
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.Fn be_active_path
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function returns the full path of the currently booted boot environment.
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This boot environment may not belong to the same BE root as the root libbe
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is operating on!
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.Pp
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The
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.Fn be_nextboot_name
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function returns the name of the boot environment that will be active on reboot.
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.Pp
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The
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.Fn be_nextboot_path
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function returns the full path of the boot environment that will be
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active on reboot.
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.Pp
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The
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.Fn be_root_path
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function returns the boot environment root path.
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.Pp
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The
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.Fn be_create
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function creates a boot environment with the given name.
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It will be created from a snapshot of the currently booted boot environment.
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.Pp
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The
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.Fn be_create_from_existing
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function creates a boot environment with the given name from the name of an
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existing boot environment.
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A snapshot will be made of the base boot environment, and the new boot
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environment will be created from that.
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.Pp
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The
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.Fn be_create_from_existing_snap
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function creates a boot environment with the given name from an existing
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snapshot.
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.Pp
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The
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.Fn be_rename
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function renames a boot environment without unmounting it, as if renamed with
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the
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.Fl u
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argument were passed to
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.Nm zfs
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.Cm rename
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.Pp
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The
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.Fn be_activate
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function makes a boot environment active on the next boot.
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If the
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.Fa temporary
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flag is set, then it will be active for the next boot only, as done by
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.Xr zfsbootcfg 8 .
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Next boot functionality is currently only available when booting in x86 BIOS
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mode.
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.Pp
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The
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.Fn be_destroy
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function will recursively destroy the given boot environment.
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It will not destroy a mounted boot environment unless the
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.Dv BE_DESTROY_FORCE
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option is set in
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.Fa options .
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If the
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.Dv BE_DESTROY_ORIGIN
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option is set in
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.Fa options ,
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the
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.Fn be_destroy
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function will destroy the origin snapshot to this boot environment as well.
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.Pp
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The
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.Fn be_nicenum
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function will format
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.Fa name
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in a traditional ZFS humanized format, similar to
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.Xr humanize_number 3 .
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This function effectively proxies
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.Fn zfs_nicenum
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from libzfs.
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.Pp
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The
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.Fn be_mount
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function will mount the given boot environment.
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If
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.Fa mountpoint
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is
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.Dv NULL ,
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a mount point will be generated in
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.Pa /tmp
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using
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.Xr mkdtemp 3 .
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If
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.Fa result
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is not
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.Dv NULL ,
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it should be large enough to accommodate
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.Dv BE_MAXPATHLEN
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including the null terminator.
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the final mount point will be copied into it.
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Setting the
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.Dv BE_MNT_FORCE
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flag will pass
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.Dv MNT_FORCE
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to the underlying
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.Xr mount 2
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call.
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.Pp
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The
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.Fn be_mounted_at
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function will check if there is a boot environment mounted at the given
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.Fa path .
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If
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.Fa details
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is not
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.Dv NULL ,
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it will be populated with a list of the mounted dataset's properties.
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This list of properties matches the properties collected by
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.Fn be_get_bootenv_props .
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.Pp
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The
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.Fn be_unmount
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function will unmount the given boot environment.
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Setting the
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.Dv BE_MNT_FORCE
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flag will pass
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.Dv MNT_FORCE
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to the underlying
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.Xr mount 2
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call.
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.Pp
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The
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.Fn libbe_errno
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function returns the
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.Nm
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errno.
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.Pp
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The
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.Fn libbe_error_description
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function returns a string description of the currently set
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.Nm
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errno.
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.Pp
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The
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.Fn libbe_print_on_error
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function will change whether or not
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.Nm
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prints the description of any encountered error to
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.Dv stderr ,
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based on
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.Fa doprint .
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.Pp
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The
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.Fn be_root_concat
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function will concatenate the boot environment root and the given boot
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environment name into
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.Fa result .
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.Pp
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The
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.Fn be_validate_name
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function will validate the given boot environment name for both length
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restrictions as well as valid character restrictions.
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This function does not set the internal library error state.
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.Pp
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The
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.Fn be_validate_snap
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function will validate the given snapshot name.
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The snapshot must have a valid name, exist, and have a mountpoint of
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.Pa / .
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This function does not set the internal library error state.
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.Pp
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The
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.Fn be_exists
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function will check whether the given boot environment exists and has a
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mountpoint of
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.Pa / .
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This function does not set the internal library error state, but will return
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the appropriate error.
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.Pp
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The
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.Fn be_export
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function will export the given boot environment to the file specified by
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.Fa fd .
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A snapshot will be created of the boot environment prior to export.
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.Pp
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The
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.Fn be_import
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function will import the boot environment in the file specified by
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.Fa fd ,
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and give it the name
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.Fa be_name .
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.Pp
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The
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.Fn be_prop_list_alloc
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function allocates a property list suitable for passing to
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.Fn be_get_bootenv_props ,
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.Fn be_get_dataset_props ,
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or
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.Fn be_get_dataset_snapshots .
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It should be freed later by
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.Fa be_prop_list_free .
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.Pp
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The
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.Fn be_get_bootenv_props
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function will populate
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.Fa be_list
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with
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.Vt nvpair_t
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of boot environment names paired with an
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.Vt nvlist_t
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of their properties.
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The following properties are currently collected as appropriate:
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.Bl -column "Returned name"
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.It Sy Returned name Ta Sy Description
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.It dataset Ta -
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.It name Ta Boot environment name
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.It mounted Ta Current mount point
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.It mountpoint Ta Do mountpoint Dc property
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.It origin Ta Do origin Dc property
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.It creation Ta Do creation Dc property
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.It active Ta Currently booted environment
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.It used Ta Literal Do used Dc property
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.It usedds Ta Literal Do usedds Dc property
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.It usedsnap Ta Literal Do usedrefreserv Dc property
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.It referenced Ta Literal Do referenced Dc property
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.It nextboot Ta Active on next boot
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.El
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.Pp
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Only the
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.Dq dataset ,
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.Dq name ,
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.Dq active ,
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and
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.Dq nextboot
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returned values will always be present.
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All other properties may be omitted if not available.
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.Pp
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The
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.Fn be_get_dataset_props
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function will get properties of the specified dataset.
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.Fa props
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is populated directly with a list of the properties as returned by
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.Fn be_get_bootenv_props .
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.Pp
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The
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.Fn be_get_dataset_snapshots
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function will retrieve all snapshots of the given dataset.
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.Fa snap_list
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will be populated with a list of
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.Vt nvpair_t
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exactly as specified by
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.Fn be_get_bootenv_props .
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.Pp
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The
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.Fn be_prop_list_free
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function will free the property list.
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.Sh DIAGNOSTICS
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Upon error, one of the following values will be returned:
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.Bl -dash -offset indent -compact
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.It
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BE_ERR_SUCCESS
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.It
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BE_ERR_INVALIDNAME
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.It
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BE_ERR_EXISTS
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.It
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BE_ERR_NOENT
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.It
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BE_ERR_PERMS
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.It
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BE_ERR_DESTROYACT
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.It
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BE_ERR_DESTROYMNT
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.It
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BE_ERR_BADPATH
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.It
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BE_ERR_PATHBUSY
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.It
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BE_ERR_PATHLEN
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.It
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BE_ERR_BADMOUNT
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.It
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BE_ERR_NOORIGIN
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.It
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BE_ERR_MOUNTED
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.It
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BE_ERR_NOMOUNT
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.It
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BE_ERR_ZFSOPEN
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.It
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BE_ERR_ZFSCLONE
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.It
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BE_ERR_IO
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.It
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BE_ERR_NOPOOL
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.It
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BE_ERR_NOMEM
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.It
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BE_ERR_UNKNOWN
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.It
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BE_ERR_INVORIGIN
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.El
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.Sh SEE ALSO
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.Xr bectl 8
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.Sh HISTORY
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.Nm
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and its corresponding command,
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.Xr bectl 8 ,
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were written as a 2017 Google Summer of Code project with Allan Jude serving
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as a mentor.
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Later work was done by
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.An Kyle Evans Aq Mt kevans@FreeBSD.org .
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