1.\" 2.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3.\" 4.\" Copyright (c) 2017 Kyle Kneitinger 5.\" All rights reserved. 6.\" Copyright (c) 2018 Kyle Evans <kevans@FreeBSD.org> 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd November 21, 2018 32.Dt LIBBE 3 33.Os 34.Sh NAME 35.Nm libbe 36.Nd library for creating, destroying and modifying ZFS boot environments 37.Sh LIBRARY 38.Lb libbe 39.Sh SYNOPSIS 40.In be.h 41.Ft "libbe_handle_t *hdl" Ns 42.Fn libbe_init "const char *be_root" 43.Pp 44.Ft void 45.Fn libbe_close "libbe_handle_t *hdl" 46.Pp 47.Ft const char * Ns 48.Fn be_active_name "libbe_handle_t *hdl" 49.Pp 50.Ft const char * Ns 51.Fn be_active_path "libbe_handle_t *hdl" 52.Pp 53.Ft const char * Ns 54.Fn be_nextboot_name "libbe_handle_t *hdl" 55.Pp 56.Ft const char * Ns 57.Fn be_nextboot_path "libbe_handle_t *hdl" 58.Pp 59.Ft const char * Ns 60.Fn be_root_path "libbe_handle_t *hdl" 61.Pp 62.Ft int 63.Fn be_create "libbe_handle_t *hdl" "const char *be_name" 64.Pp 65.Ft int 66.Fn be_create_from_existing "libbe_handle_t *hdl" "const char *be_name" "const char *be_origin" 67.Pp 68.Ft int 69.Fn be_create_from_existing_snap "libbe_handle_t *hdl" "const char *be_name" "const char *snap" 70.Pp 71.Ft int 72.Fn be_rename "libbe_handle_t *hdl" "const char *be_old" "const char *be_new" 73.Pp 74.Ft int 75.Fn be_activate "libbe_handle_t *hdl" "const char *be_name" "bool temporary" 76.Ft int 77.Fn be_destroy "libbe_handle_t *hdl" "const char *be_name" "int options" 78.Pp 79.Ft void 80.Fn be_nicenum "uint64_t num" "char *buf" "size_t bufsz" 81.Pp 82.\" TODO: Write up of mount options 83.\" typedef enum { 84.\" BE_MNT_FORCE = 1 << 0, 85.\" BE_MNT_DEEP = 1 << 1, 86.\" } be_mount_opt_t 87.Ft int 88.Fn be_mount "libbe_handle_t *hdl" "char *be_name" "char *mntpoint" "int flags" "char *result" 89.Pp 90.Ft int 91.Fn be_mounted_at "libbe_handle_t *hdl" "const char *path" "nvlist_t *details" 92.Pp 93.Ft int 94.Fn be_unmount "libbe_handle_t *hdl" "char *be_name" "int flags" 95.Pp 96.Ft int 97.Fn libbe_errno "libbe_handle_t *hdl" 98.Pp 99.Ft const char * Ns 100.Fn libbe_error_description "libbe_handle_t *hdl" 101.Pp 102.Ft void 103.Fn libbe_print_on_error "libbe_handle_t *hdl" "bool doprint" 104.Pp 105.Ft int 106.Fn be_root_concat "libbe_handle_t *hdl" "const char *be_name" "char *result" 107.Pp 108.Ft int 109.Fn be_validate_name "libbe_handle_t *hdl" "const char *be_name" 110.Pp 111.Ft int 112.Fn be_validate_snap "libbe_handle_t *hdl" "const char *snap" 113.Pp 114.Ft int 115.Fn be_exists "libbe_handle_t *hdl" "char *be_name" 116.Pp 117.Ft int 118.Fn be_export "libbe_handle_t *hdl" "const char *be_name" "int fd" 119.Pp 120.Ft int 121.Fn be_import "libbe_handle_t *hdl" "const char *be_name" "int fd" 122.Pp 123.Ft int 124.Fn be_prop_list_alloc "nvlist_t **prop_list" 125.Pp 126.Ft int 127.Fn be_get_bootenv_props "libbe_handle_t *hdl" "nvlist_t *be_list" 128.Pp 129.Ft int 130.Fn be_get_dataset_props "libbe_handle_t *hdl" "const char *ds_name" "nvlist_t *props" 131.Pp 132.Ft int 133.Fn be_get_dataset_snapshots "libbe_handle_t *hdl" "const char *ds_name" "nvlist_t *snap_list" 134.Pp 135.Ft void 136.Fn be_prop_list_free "nvlist_t *prop_list" 137.Sh DESCRIPTION 138.Nm 139interfaces with libzfs to provide a set of functions for various operations 140regarding ZFS boot environments including "deep" boot environments in which 141a boot environments has child datasets. 142.Pp 143A context structure is passed to each function, allowing for a small amount 144of state to be retained, such as errors from previous operations. 145.Nm 146may be configured to print the corresponding error message to 147.Dv stderr 148when an error is encountered with 149.Fn libbe_print_on_error . 150.Pp 151All functions returning an 152.Vt int 153return 0 on success, or a 154.Nm 155errno otherwise as described in 156.Sx DIAGNOSTICS . 157.Pp 158The 159.Fn libbe_init 160function takes an optional BE root and initializes 161.Nm , 162returning a 163.Vt "libbe_handle_t *" 164on success, or 165.Dv NULL 166on error. 167If a BE root is supplied, 168.Nm 169will only operate out of that pool and BE root. 170An error may occur if: 171.Bl -column 172.It /boot and / are not on the same filesystem and device, 173.It libzfs fails to initialize, 174.It The system has not been properly booted with a ZFS boot 175environment, 176.It Nm 177fails to open the zpool the active boot environment resides on, or 178.It Nm 179fails to locate the boot environment that is currently mounted. 180.El 181.Pp 182The 183.Fn libbe_close 184function frees all resources previously acquired in 185.Fn libbe_init , 186invalidating the handle in the process. 187.Pp 188The 189.Fn be_active_name 190function returns the name of the currently booted boot environment. 191This boot environment may not belong to the same BE root as the root libbe 192is operating on! 193.Pp 194The 195.Fn be_active_path 196function returns the full path of the currently booted boot environment. 197This boot environment may not belong to the same BE root as the root libbe 198is operating on! 199.Pp 200The 201.Fn be_nextboot_name 202function returns the name of the boot environment that will be active on reboot. 203.Pp 204The 205.Fn be_nextboot_path 206function returns the full path of the boot environment that will be 207active on reboot. 208.Pp 209The 210.Fn be_root_path 211function returns the boot environment root path. 212.Pp 213The 214.Fn be_create 215function creates a boot environment with the given name. 216It will be created from a snapshot of the currently booted boot environment. 217.Pp 218The 219.Fn be_create_from_existing 220function creates a boot environment with the given name from the name of an 221existing boot environment. 222A snapshot will be made of the base boot environment, and the new boot 223environment will be created from that. 224.Pp 225The 226.Fn be_create_from_existing_snap 227function creates a boot environment with the given name from an existing 228snapshot. 229.Pp 230The 231.Fn be_rename 232function renames a boot environment without unmounting it, as if renamed with 233the 234.Fl u 235argument were passed to 236.Nm zfs 237.Cm rename 238.Pp 239The 240.Fn be_activate 241function makes a boot environment active on the next boot. 242If the 243.Fa temporary 244flag is set, then it will be active for the next boot only, as done by 245.Xr zfsbootcfg 8 . 246Next boot functionality is currently only available when booting in x86 BIOS 247mode. 248.Pp 249The 250.Fn be_destroy 251function will recursively destroy the given boot environment. 252It will not destroy a mounted boot environment unless the 253.Dv BE_DESTROY_FORCE 254option is set in 255.Fa options . 256.Pp 257The 258.Fn be_nicenum 259function will format 260.Fa name 261in a traditional ZFS humanized format, similar to 262.Xr humanize_number 3 . 263This function effectively proxies 264.Fn zfs_nicenum 265from libzfs. 266.Pp 267The 268.Fn be_mount 269function will mount the given boot environment. 270If 271.Fa mountpoint 272is 273.Dv NULL , 274a mount point will be generated in 275.Pa /tmp 276using 277.Xr mkdtemp 3 . 278If 279.Fa result 280is not 281.Dv NULL , 282it should be large enough to accommodate 283.Dv BE_MAXPATHLEN 284including the null terminator. 285the final mount point will be copied into it. 286Setting the 287.Dv BE_MNT_FORCE 288flag will pass 289.Dv MNT_FORCE 290to the underlying 291.Xr mount 2 292call. 293.Pp 294The 295.Fn be_mounted_at 296function will check if there is a boot environment mounted at the given 297.Fa path . 298If 299.Fa details 300is not 301.Dv NULL , 302it will be populated with a list of the mounted dataset's properties. 303This list of properties matches the properties collected by 304.Fn be_get_bootenv_props . 305.Pp 306The 307.Fn be_unmount 308function will unmount the given boot environment. 309Setting the 310.Dv BE_MNT_FORCE 311flag will pass 312.Dv MNT_FORCE 313to the underlying 314.Xr mount 2 315call. 316.Pp 317The 318.Fn libbe_errno 319function returns the 320.Nm 321errno. 322.Pp 323The 324.Fn libbe_error_description 325function returns a string description of the currently set 326.Nm 327errno. 328.Pp 329The 330.Fn libbe_print_on_error 331function will change whether or not 332.Nm 333prints the description of any encountered error to 334.Dv stderr , 335based on 336.Fa doprint . 337.Pp 338The 339.Fn be_root_concat 340function will concatenate the boot environment root and the given boot 341environment name into 342.Fa result . 343.Pp 344The 345.Fn be_validate_name 346function will validate the given boot environment name for both length 347restrictions as well as valid character restrictions. 348This function does not set the internal library error state. 349.Pp 350The 351.Fn be_validate_snap 352function will validate the given snapshot name. 353The snapshot must have a valid name, exist, and have a mountpoint of 354.Pa / . 355This function does not set the internal library error state. 356.Pp 357The 358.Fn be_exists 359function will check whether the given boot environment exists and has a 360mountpoint of 361.Pa / . 362This function does not set the internal library error state, but will return 363the appropriate error. 364.Pp 365The 366.Fn be_export 367function will export the given boot environment to the file specified by 368.Fa fd . 369A snapshot will be created of the boot environment prior to export. 370.Pp 371The 372.Fn be_import 373function will import the boot environment in the file specified by 374.Fa fd , 375and give it the name 376.Fa be_name . 377.Pp 378The 379.Fn be_prop_list_alloc 380function allocates a property list suitable for passing to 381.Fn be_get_bootenv_props , 382.Fn be_get_dataset_props , 383or 384.Fn be_get_dataset_snapshots . 385It should be freed later by 386.Fa be_prop_list_free . 387.Pp 388The 389.Fn be_get_bootenv_props 390function will populate 391.Fa be_list 392with 393.Vt nvpair_t 394of boot environment names paired with an 395.Vt nvlist_t 396of their properties. 397The following properties are currently collected as appropriate: 398.Bl -column "Returned name" 399.It Sy Returned name Ta Sy Description 400.It dataset Ta - 401.It name Ta Boot environment name 402.It mounted Ta Current mount point 403.It mountpoint Ta Do mountpoint Dc property 404.It origin Ta Do origin Dc property 405.It creation Ta Do creation Dc property 406.It active Ta Currently booted environment 407.It used Ta Literal Do used Dc property 408.It usedds Ta Literal Do usedds Dc property 409.It usedsnap Ta Literal Do usedrefreserv Dc property 410.It referenced Ta Literal Do referenced Dc property 411.It nextboot Ta Active on next boot 412.El 413.Pp 414Only the 415.Dq dataset , 416.Dq name , 417.Dq active , 418and 419.Dq nextboot 420returned values will always be present. 421All other properties may be omitted if not available. 422.Pp 423The 424.Fn be_get_dataset_props 425function will get properties of the specified dataset. 426.Fa props 427is populated directly with a list of the properties as returned by 428.Fn be_get_bootenv_props . 429.Pp 430The 431.Fn be_get_dataset_snapshots 432function will retrieve all snapshots of the given dataset. 433.Fa snap_list 434will be populated with a list of 435.Vt nvpair_t 436exactly as specified by 437.Fn be_get_bootenv_props . 438.Pp 439The 440.Fn be_prop_list_free 441function will free the property list. 442.Sh DIAGNOSTICS 443Upon error, one of the following values will be returned: 444.Bl -dash -offset indent -compact 445.It 446BE_ERR_SUCCESS 447.It 448BE_ERR_INVALIDNAME 449.It 450BE_ERR_EXISTS 451.It 452BE_ERR_NOENT 453.It 454BE_ERR_PERMS 455.It 456BE_ERR_DESTROYACT 457.It 458BE_ERR_DESTROYMNT 459.It 460BE_ERR_BADPATH 461.It 462BE_ERR_PATHBUSY 463.It 464BE_ERR_PATHLEN 465.It 466BE_ERR_BADMOUNT 467.It 468BE_ERR_NOORIGIN 469.It 470BE_ERR_MOUNTED 471.It 472BE_ERR_NOMOUNT 473.It 474BE_ERR_ZFSOPEN 475.It 476BE_ERR_ZFSCLONE 477.It 478BE_ERR_IO 479.It 480BE_ERR_NOPOOL 481.It 482BE_ERR_NOMEM 483.It 484BE_ERR_UNKNOWN 485.El 486.Sh SEE ALSO 487.Xr bectl 8 488.Sh HISTORY 489.Nm 490and its corresponding command, 491.Xr bectl 8 , 492were written as a 2017 Google Summer of Code project with Allan Jude serving 493as a mentor. 494Later work was done by 495.An Kyle Evans Aq Mt kevans@FreeBSD.org . 496