libbe
—
library for creating, destroying and modifying ZFS boot
environments
Boot Environment Library (libbe, -lbe)
#include <be.h>
libbe_handle_t *hdl
libbe_init
(const
char *be_root);
void
libbe_close
(libbe_handle_t
*hdl);
const char *
be_active_name
(libbe_handle_t
*hdl);
const char *
be_active_path
(libbe_handle_t
*hdl);
const char *
be_nextboot_name
(libbe_handle_t
*hdl);
const char *
be_nextboot_path
(libbe_handle_t
*hdl);
const char *
be_root_path
(libbe_handle_t
*hdl);
int
be_snapshot
(libbe_handle_t
*hdl, const char
*be_name, const char
*snap_name, bool
recursive, char
*result);
bool
be_is_auto_snapshot_name
(libbe_handle_t
*hdl, const char
*snap);
int
be_create
(libbe_handle_t
*hdl, const char
*be_name);
int
be_create_depth
(libbe_handle_t
*hdl, const char
*be_name, const char
*snap, int
depth);
int
be_create_from_existing
(libbe_handle_t
*hdl, const char
*be_name, const char
*be_origin);
int
be_create_from_existing_snap
(libbe_handle_t
*hdl, const char
*be_name, const char
*snap);
int
be_rename
(libbe_handle_t
*hdl, const char
*be_old, const char
*be_new);
int
be_activate
(libbe_handle_t
*hdl, const char
*be_name, bool
temporary);
int
be_deactivate
(libbe_handle_t
*hdl, const char
*be_name, bool
temporary);
int
be_destroy
(libbe_handle_t
*hdl, const char
*be_name, int
options);
void
be_nicenum
(uint64_t
num, char *buf,
size_t bufsz);
int
be_mount
(libbe_handle_t
*hdl, const char
*be_name, const char
*mntpoint, int
flags, char
*result);
int
be_mounted_at
(libbe_handle_t
*hdl, const char
*path, nvlist_t
*details);
int
be_unmount
(libbe_handle_t
*hdl, const char
*be_name, int
flags);
int
libbe_errno
(libbe_handle_t
*hdl);
const char *
libbe_error_description
(libbe_handle_t
*hdl);
void
libbe_print_on_error
(libbe_handle_t
*hdl, bool
doprint);
int
be_root_concat
(libbe_handle_t
*hdl, const char
*be_name, char
*result);
int
be_validate_name
(libbe_handle_t
*hdl, const char
*be_name);
int
be_validate_snap
(libbe_handle_t
*hdl, const char
*snap);
int
be_exists
(libbe_handle_t
*hdl, const char
*be_name);
int
be_export
(libbe_handle_t
*hdl, const char
*be_name, int
fd);
int
be_import
(libbe_handle_t
*hdl, const char
*be_name, int
fd);
int
be_prop_list_alloc
(nvlist_t
**prop_list);
int
be_get_bootenv_props
(libbe_handle_t
*hdl, nvlist_t
*be_list);
int
be_get_dataset_props
(libbe_handle_t
*hdl, const char
*ds_name, nvlist_t
*props);
int
be_get_dataset_snapshots
(libbe_handle_t
*hdl, const char
*ds_name, nvlist_t
*snap_list);
void
be_prop_list_free
(nvlist_t
*prop_list);
libbe
interfaces with libzfs to provide a set of
functions for various operations regarding ZFS boot environments including
"deep" boot environments in which a boot environments has child
datasets.
A context structure is passed to each function, allowing for a
small amount of state to be retained, such as errors from previous
operations. libbe
may be configured to print the
corresponding error message to stderr
when an error
is encountered with libbe_print_on_error
().
All functions returning an int return 0 on
success, or a libbe
errno otherwise as described in
DIAGNOSTICS.
The libbe_init
() function takes an
optional BE root and initializes libbe
, returning a
libbe_handle_t * on success, or
NULL
on error. If a BE root is supplied,
libbe
will only operate out of that pool and BE
root. An error may occur if:
/boot and / are not on the same filesystem and device, |
libzfs fails to initialize, |
The system has not been properly booted with a ZFS boot
environment, |
libbe fails to open the zpool the active boot
environment resides on, or |
libbe fails to locate the boot environment that
is currently mounted. |
The libbe_close
() function frees all
resources previously acquired in libbe_init
(),
invalidating the handle in the process.
The be_active_name
() function returns the
name of the currently booted boot environment. This boot environment may not
belong to the same BE root as the root libbe is operating on!
The be_active_path
() function returns the
full path of the currently booted boot environment. This boot environment
may not belong to the same BE root as the root libbe is operating on!
The be_nextboot_name
() function returns
the name of the boot environment that will be active on reboot.
The be_nextboot_path
() function returns
the full path of the boot environment that will be active on reboot.
The be_root_path
() function returns the
boot environment root path.
The be_snapshot
() function creates a
snapshot of be_name named
snap_name. A NULL
snap_name may be used, indicating that
be_snaphot
() should derive the snapshot name from
the current date and time. If recursive is set, then
be_snapshot
() will recursively snapshot the dataset.
If result is not NULL
, then it
will be populated with the final
“be_name@snap_name”.
The be_is_auto_snapshot_name
() function is
used to determine if the given snapshot name matches the format that the
be_snapshot
() function will use by default if it is
not given a snapshot name to use. It returns true
if
the name matches the format, and false
if it does
not.
The be_create
() function creates a boot
environment with the given name. The new boot environment will be created
from a recursive snapshot of the currently booted boot environment.
The be_create_depth
() function creates a
boot environment with the given name from an existing snapshot. The depth
parameter specifies the depth of recursion that will be cloned from the
existing snapshot. A depth of '0' is no recursion and '-1' is unlimited
(i.e., a recursive boot environment).
The be_create_from_existing
() function
creates a boot environment with the given name from the name of an existing
boot environment. A recursive snapshot will be made of the origin boot
environment, and the new boot environment will be created from that.
The be_create_from_existing_snap
()
function creates a recursive boot environment with the given name from an
existing snapshot.
The be_rename
() function renames a boot
environment without unmounting it, as if renamed with the
-u
argument were passed to
zfs
rename
The be_activate
() function makes a boot
environment active on the next boot. If the temporary
flag is set, then it will be active for the next boot only, as done by
zfsbootcfg(8).
The be_deactivate
() function deactivates a
boot environment. If the temporary flag is set, then
it will cause removal of boot once configuration, set by
be_activate
() function or by
zfsbootcfg(8).
If the temporary flag is not set,
be_deactivate
() function will set zfs
canmount
property to
noauto
.
The be_destroy
() function will recursively
destroy the given boot environment. It will not destroy a mounted boot
environment unless the BE_DESTROY_FORCE
option is
set in options. If the
BE_DESTROY_ORIGIN
option is set in
options, the be_destroy
()
function will destroy the origin snapshot to this boot environment as
well.
The be_nicenum
() function will format
name in a traditional ZFS humanized format, similar to
humanize_number(3).
This function effectively proxies zfs_nicenum
() from
libzfs.
The be_mount
() function will mount the
given boot environment. If mountpoint is
NULL
, a mount point will be generated in
/tmp using
mkdtemp(3).
If result is not NULL
, it
should be large enough to accommodate BE_MAXPATHLEN
including the null terminator. the final mount point will be copied into it.
Setting the BE_MNT_FORCE
flag will pass
MNT_FORCE
to the underlying
mount(2)
call.
The be_mounted_at
() function will check if
there is a boot environment mounted at the given path.
If details is not NULL
, it
will be populated with a list of the mounted dataset's properties. This list
of properties matches the properties collected by
be_get_bootenv_props
().
The be_unmount
() function will unmount the
given boot environment. Setting the BE_MNT_FORCE
flag will pass MNT_FORCE
to the underlying
mount(2)
call.
The libbe_errno
() function returns the
libbe
errno.
The libbe_error_description
() function
returns a string description of the currently set
libbe
errno.
The libbe_print_on_error
() function will
change whether or not libbe
prints the description
of any encountered error to stderr
, based on
doprint.
The be_root_concat
() function will
concatenate the boot environment root and the given boot environment name
into result.
The be_validate_name
() function will
validate the given boot environment name for both length restrictions as
well as valid character restrictions. This function does not set the
internal library error state.
The be_validate_snap
() function will
validate the given snapshot name. The snapshot must have a valid name,
exist, and have a mountpoint of /. This function
does not set the internal library error state.
The be_exists
() function will check
whether the given boot environment exists and has a mountpoint of
/. This function does not set the internal library
error state, but will return the appropriate error.
The be_export
() function will export the
given boot environment to the file specified by fd. A
snapshot will be created of the boot environment prior to export.
The be_import
() function will import the
boot environment in the file specified by fd, and give
it the name be_name.
The be_prop_list_alloc
() function
allocates a property list suitable for passing to
be_get_bootenv_props
(),
be_get_dataset_props
(), or
be_get_dataset_snapshots
(). It should be freed later
by be_prop_list_free.
The be_get_bootenv_props
() function will
populate be_list with nvpair_t
of boot environment names paired with an nvlist_t of
their properties. The following properties are currently collected as
appropriate:
Returned name |
Description |
dataset |
- |
name |
Boot environment name |
mounted |
Current mount point |
mountpoint |
“mountpoint” property |
origin |
“origin” property |
creation |
“creation” property |
active |
Currently booted environment |
used |
Literal “used” property |
usedds |
Literal “usedds” property |
usedsnap |
Literal “usedrefreserv” property |
referenced |
Literal “referenced” property |
nextboot |
Active on next boot |
Only the “dataset”, “name”,
“active”, and “nextboot” returned values will
always be present. All other properties may be omitted if not available.
The be_get_dataset_props
() function will
get properties of the specified dataset. props is
populated directly with a list of the properties as returned by
be_get_bootenv_props
().
The be_get_dataset_snapshots
() function
will retrieve all snapshots of the given dataset.
snap_list will be populated with a list of
nvpair_t exactly as specified by
be_get_bootenv_props
().
The be_prop_list_free
() function will free
the property list.
Upon error, one of the following values will be returned:
- BE_ERR_SUCCESS
- BE_ERR_INVALIDNAME
- BE_ERR_EXISTS
- BE_ERR_NOENT
- BE_ERR_PERMS
- BE_ERR_DESTROYACT
- BE_ERR_DESTROYMNT
- BE_ERR_BADPATH
- BE_ERR_PATHBUSY
- BE_ERR_PATHLEN
- BE_ERR_BADMOUNT
- BE_ERR_NOORIGIN
- BE_ERR_MOUNTED
- BE_ERR_NOMOUNT
- BE_ERR_ZFSOPEN
- BE_ERR_ZFSCLONE
- BE_ERR_IO
- BE_ERR_NOPOOL
- BE_ERR_NOMEM
- BE_ERR_UNKNOWN
- BE_ERR_INVORIGIN
libbe
and its corresponding command,
bectl(8),
were written as a 2017 Google Summer of Code project with Allan Jude serving
as a mentor. Later work was done by Kyle Evans
<kevans@FreeBSD.org>.