src/backup/datastore.rs

   1 use std::collections::{HashSet, HashMap};
   2 use std::io::{self, Write};
   3 use std::path::{Path, PathBuf};
   4 use std::sync::{Arc, Mutex};
   5 use std::convert::TryFrom;
   6 use std::time::Duration;
   7 use std::fs::File;
   8
   9 use anyhow::{bail, format_err, Error};
  10 use lazy_static::lazy_static;
  11
  12 use proxmox::tools::fs::{replace_file, CreateOptions, open_file_locked};
  13
  14 use super::backup_info::{BackupGroup, BackupDir};
  15 use super::chunk_store::ChunkStore;
  16 use super::dynamic_index::{DynamicIndexReader, DynamicIndexWriter};
  17 use super::fixed_index::{FixedIndexReader, FixedIndexWriter};
  18 use super::manifest::{MANIFEST_BLOB_NAME, MANIFEST_LOCK_NAME, CLIENT_LOG_BLOB_NAME, BackupManifest};
  19 use super::index::*;
  20 use super::{DataBlob, ArchiveType, archive_type};
  21 use crate::config::datastore::{self, DataStoreConfig};
  22 use crate::task::TaskState;
  23 use crate::tools;
  24 use crate::tools::format::HumanByte;
  25 use crate::tools::fs::{lock_dir_noblock, DirLockGuard};
  26 use crate::api2::types::{GarbageCollectionStatus, Userid};
  27 use crate::server::UPID;
  28
  29 lazy_static! {
  30     static ref DATASTORE_MAP: Mutex<HashMap<String, Arc<DataStore>>> = Mutex::new(HashMap::new());
  31 }
  32
  33 /// Datastore Management
  34 ///
  35 /// A Datastore can store severals backups, and provides the
  36 /// management interface for backup.
  37 pub struct DataStore {
  38     chunk_store: Arc<ChunkStore>,
  39     gc_mutex: Mutex<bool>,
  40     last_gc_status: Mutex<GarbageCollectionStatus>,
  41     verify_new: bool,
  42 }
  43
  44 impl DataStore {
  45
  46     pub fn lookup_datastore(name: &str) -> Result<Arc<DataStore>, Error> {
  47
  48         let (config, _digest) = datastore::config()?;
  49         let config: datastore::DataStoreConfig = config.lookup("datastore", name)?;
  50         let path = PathBuf::from(&config.path);
  51
  52         let mut map = DATASTORE_MAP.lock().unwrap();
  53
  54         if let Some(datastore) = map.get(name) {
  55             // Compare Config - if changed, create new Datastore object!
  56             if datastore.chunk_store.base == path &&
  57                 datastore.verify_new == config.verify_new.unwrap_or(false)
  58             {
  59                 return Ok(datastore.clone());
  60             }
  61         }
  62
  63         let datastore = DataStore::open_with_path(name, &path, config)?;
  64
  65         let datastore = Arc::new(datastore);
  66         map.insert(name.to_string(), datastore.clone());
  67
  68         Ok(datastore)
  69     }
  70
  71     fn open_with_path(store_name: &str, path: &Path, config: DataStoreConfig) -> Result<Self, Error> {
  72         let chunk_store = ChunkStore::open(store_name, path)?;
  73
  74         let gc_status = GarbageCollectionStatus::default();
  75
  76         Ok(Self {
  77             chunk_store: Arc::new(chunk_store),
  78             gc_mutex: Mutex::new(false),
  79             last_gc_status: Mutex::new(gc_status),
  80             verify_new: config.verify_new.unwrap_or(false),
  81         })
  82     }
  83
  84     pub fn get_chunk_iterator(
  85         &self,
  86     ) -> Result<
  87         impl Iterator<Item = (Result<tools::fs::ReadDirEntry, Error>, usize, bool)>,
  88         Error
  89     > {
  90         self.chunk_store.get_chunk_iterator()
  91     }
  92
  93     pub fn create_fixed_writer<P: AsRef<Path>>(&self, filename: P, size: usize, chunk_size: usize) -> Result<FixedIndexWriter, Error> {
  94
  95         let index = FixedIndexWriter::create(self.chunk_store.clone(), filename.as_ref(), size, chunk_size)?;
  96
  97         Ok(index)
  98     }
  99
 100     pub fn open_fixed_reader<P: AsRef<Path>>(&self, filename: P) -> Result<FixedIndexReader, Error> {
 101
 102         let full_path =  self.chunk_store.relative_path(filename.as_ref());
 103
 104         let index = FixedIndexReader::open(&full_path)?;
 105
 106         Ok(index)
 107     }
 108
 109     pub fn create_dynamic_writer<P: AsRef<Path>>(
 110         &self, filename: P,
 111     ) -> Result<DynamicIndexWriter, Error> {
 112
 113         let index = DynamicIndexWriter::create(
 114             self.chunk_store.clone(), filename.as_ref())?;
 115
 116         Ok(index)
 117     }
 118
 119     pub fn open_dynamic_reader<P: AsRef<Path>>(&self, filename: P) -> Result<DynamicIndexReader, Error> {
 120
 121         let full_path =  self.chunk_store.relative_path(filename.as_ref());
 122
 123         let index = DynamicIndexReader::open(&full_path)?;
 124
 125         Ok(index)
 126     }
 127
 128     pub fn open_index<P>(&self, filename: P) -> Result<Box<dyn IndexFile + Send>, Error>
 129     where
 130         P: AsRef<Path>,
 131     {
 132         let filename = filename.as_ref();
 133         let out: Box<dyn IndexFile + Send> =
 134             match archive_type(filename)? {
 135                 ArchiveType::DynamicIndex => Box::new(self.open_dynamic_reader(filename)?),
 136                 ArchiveType::FixedIndex => Box::new(self.open_fixed_reader(filename)?),
 137                 _ => bail!("cannot open index file of unknown type: {:?}", filename),
 138             };
 139         Ok(out)
 140     }
 141
 142     pub fn name(&self) -> &str {
 143         self.chunk_store.name()
 144     }
 145
 146     pub fn base_path(&self) -> PathBuf {
 147         self.chunk_store.base_path()
 148     }
 149
 150     /// Cleanup a backup directory
 151     ///
 152     /// Removes all files not mentioned in the manifest.
 153     pub fn cleanup_backup_dir(&self, backup_dir: &BackupDir, manifest: &BackupManifest
 154     ) ->  Result<(), Error> {
 155
 156         let mut full_path = self.base_path();
 157         full_path.push(backup_dir.relative_path());
 158
 159         let mut wanted_files = HashSet::new();
 160         wanted_files.insert(MANIFEST_BLOB_NAME.to_string());
 161         wanted_files.insert(CLIENT_LOG_BLOB_NAME.to_string());
 162         manifest.files().iter().for_each(|item| { wanted_files.insert(item.filename.clone()); });
 163
 164         for item in tools::fs::read_subdir(libc::AT_FDCWD, &full_path)? {
 165             if let Ok(item) = item {
 166                 if let Some(file_type) = item.file_type() {
 167                     if file_type != nix::dir::Type::File { continue; }
 168                 }
 169                 let file_name = item.file_name().to_bytes();
 170                 if file_name == b"." || file_name == b".." { continue; };
 171
 172                 if let Ok(name) = std::str::from_utf8(file_name) {
 173                     if wanted_files.contains(name) { continue; }
 174                 }
 175                 println!("remove unused file {:?}", item.file_name());
 176                 let dirfd = item.parent_fd();
 177                 let _res = unsafe { libc::unlinkat(dirfd, item.file_name().as_ptr(), 0) };
 178             }
 179         }
 180
 181         Ok(())
 182     }
 183
 184     /// Returns the absolute path for a backup_group
 185     pub fn group_path(&self, backup_group: &BackupGroup) -> PathBuf {
 186         let mut full_path = self.base_path();
 187         full_path.push(backup_group.group_path());
 188         full_path
 189     }
 190
 191     /// Returns the absolute path for backup_dir
 192     pub fn snapshot_path(&self, backup_dir: &BackupDir) -> PathBuf {
 193         let mut full_path = self.base_path();
 194         full_path.push(backup_dir.relative_path());
 195         full_path
 196     }
 197
 198     /// Remove a complete backup group including all snapshots
 199     pub fn remove_backup_group(&self, backup_group: &BackupGroup) ->  Result<(), Error> {
 200
 201         let full_path = self.group_path(backup_group);
 202
 203         let _guard = tools::fs::lock_dir_noblock(&full_path, "backup group", "possible running backup")?;
 204
 205         log::info!("removing backup group {:?}", full_path);
 206
 207         // remove all individual backup dirs first to ensure nothing is using them
 208         for snap in backup_group.list_backups(&self.base_path())? {
 209             self.remove_backup_dir(&snap.backup_dir, false)?;
 210         }
 211
 212         // no snapshots left, we can now safely remove the empty folder
 213         std::fs::remove_dir_all(&full_path)
 214             .map_err(|err| {
 215                 format_err!(
 216                     "removing backup group directory {:?} failed - {}",
 217                     full_path,
 218                     err,
 219                 )
 220             })?;
 221
 222         Ok(())
 223     }
 224
 225     /// Remove a backup directory including all content
 226     pub fn remove_backup_dir(&self, backup_dir: &BackupDir, force: bool) ->  Result<(), Error> {
 227
 228         let full_path = self.snapshot_path(backup_dir);
 229
 230         let (_guard, _manifest_guard);
 231         if !force {
 232             _guard = lock_dir_noblock(&full_path, "snapshot", "possibly running or in use")?;
 233             _manifest_guard = self.lock_manifest(backup_dir);
 234         }
 235
 236         log::info!("removing backup snapshot {:?}", full_path);
 237         std::fs::remove_dir_all(&full_path)
 238             .map_err(|err| {
 239                 format_err!(
 240                     "removing backup snapshot {:?} failed - {}",
 241                     full_path,
 242                     err,
 243                 )
 244             })?;
 245
 246         Ok(())
 247     }
 248
 249     /// Returns the time of the last successful backup
 250     ///
 251     /// Or None if there is no backup in the group (or the group dir does not exist).
 252     pub fn last_successful_backup(&self, backup_group: &BackupGroup) -> Result<Option<i64>, Error> {
 253         let base_path = self.base_path();
 254         let mut group_path = base_path.clone();
 255         group_path.push(backup_group.group_path());
 256
 257         if group_path.exists() {
 258             backup_group.last_successful_backup(&base_path)
 259         } else {
 260             Ok(None)
 261         }
 262     }
 263
 264     /// Returns the backup owner.
 265     ///
 266     /// The backup owner is the user who first created the backup group.
 267     pub fn get_owner(&self, backup_group: &BackupGroup) -> Result<Userid, Error> {
 268         let mut full_path = self.base_path();
 269         full_path.push(backup_group.group_path());
 270         full_path.push("owner");
 271         let owner = proxmox::tools::fs::file_read_firstline(full_path)?;
 272         Ok(owner.trim_end().parse()?) // remove trailing newline
 273     }
 274
 275     /// Set the backup owner.
 276     pub fn set_owner(
 277         &self,
 278         backup_group: &BackupGroup,
 279         userid: &Userid,
 280         force: bool,
 281     ) -> Result<(), Error> {
 282         let mut path = self.base_path();
 283         path.push(backup_group.group_path());
 284         path.push("owner");
 285
 286         let mut open_options = std::fs::OpenOptions::new();
 287         open_options.write(true);
 288         open_options.truncate(true);
 289
 290         if force {
 291             open_options.create(true);
 292         } else {
 293             open_options.create_new(true);
 294         }
 295
 296         let mut file = open_options.open(&path)
 297             .map_err(|err| format_err!("unable to create owner file {:?} - {}", path, err))?;
 298
 299         writeln!(file, "{}", userid)
 300             .map_err(|err| format_err!("unable to write owner file  {:?} - {}", path, err))?;
 301
 302         Ok(())
 303     }
 304
 305     /// Create (if it does not already exists) and lock a backup group
 306     ///
 307     /// And set the owner to 'userid'. If the group already exists, it returns the
 308     /// current owner (instead of setting the owner).
 309     ///
 310     /// This also acquires an exclusive lock on the directory and returns the lock guard.
 311     pub fn create_locked_backup_group(
 312         &self,
 313         backup_group: &BackupGroup,
 314         userid: &Userid,
 315     ) -> Result<(Userid, DirLockGuard), Error> {
 316         // create intermediate path first:
 317         let base_path = self.base_path();
 318
 319         let mut full_path = base_path.clone();
 320         full_path.push(backup_group.backup_type());
 321         std::fs::create_dir_all(&full_path)?;
 322
 323         full_path.push(backup_group.backup_id());
 324
 325         // create the last component now
 326         match std::fs::create_dir(&full_path) {
 327             Ok(_) => {
 328                 let guard = lock_dir_noblock(&full_path, "backup group", "another backup is already running")?;
 329                 self.set_owner(backup_group, userid, false)?;
 330                 let owner = self.get_owner(backup_group)?; // just to be sure
 331                 Ok((owner, guard))
 332             }
 333             Err(ref err) if err.kind() == io::ErrorKind::AlreadyExists => {
 334                 let guard = lock_dir_noblock(&full_path, "backup group", "another backup is already running")?;
 335                 let owner = self.get_owner(backup_group)?; // just to be sure
 336                 Ok((owner, guard))
 337             }
 338             Err(err) => bail!("unable to create backup group {:?} - {}", full_path, err),
 339         }
 340     }
 341
 342     /// Creates a new backup snapshot inside a BackupGroup
 343     ///
 344     /// The BackupGroup directory needs to exist.
 345     pub fn create_locked_backup_dir(&self, backup_dir: &BackupDir)
 346         -> Result<(PathBuf, bool, DirLockGuard), Error>
 347     {
 348         let relative_path = backup_dir.relative_path();
 349         let mut full_path = self.base_path();
 350         full_path.push(&relative_path);
 351
 352         let lock = ||
 353             lock_dir_noblock(&full_path, "snapshot", "internal error - tried creating snapshot that's already in use");
 354
 355         match std::fs::create_dir(&full_path) {
 356             Ok(_) => Ok((relative_path, true, lock()?)),
 357             Err(ref e) if e.kind() == io::ErrorKind::AlreadyExists => Ok((relative_path, false, lock()?)),
 358             Err(e) => Err(e.into())
 359         }
 360     }
 361
 362     pub fn list_images(&self) -> Result<Vec<PathBuf>, Error> {
 363         let base = self.base_path();
 364
 365         let mut list = vec![];
 366
 367         use walkdir::WalkDir;
 368
 369         let walker = WalkDir::new(&base).same_file_system(true).into_iter();
 370
 371         // make sure we skip .chunks (and other hidden files to keep it simple)
 372         fn is_hidden(entry: &walkdir::DirEntry) -> bool {
 373             entry.file_name()
 374                 .to_str()
 375                 .map(|s| s.starts_with("."))
 376                 .unwrap_or(false)
 377         }
 378         let handle_entry_err = |err: walkdir::Error| {
 379             if let Some(inner) = err.io_error() {
 380                 let path = err.path().unwrap_or(Path::new(""));
 381                 match inner.kind() {
 382                     io::ErrorKind::PermissionDenied => {
 383                         // only allow to skip ext4 fsck directory, avoid GC if, for example,
 384                         // a user got file permissions wrong on datastore rsync to new server
 385                         if err.depth() > 1 || !path.ends_with("lost+found") {
 386                             bail!("cannot continue garbage-collection safely, permission denied on: {}", path.display())
 387                         }
 388                     },
 389                     _ => bail!("unexpected error on datastore traversal: {} - {}", inner, path.display()),
 390                 }
 391             }
 392             Ok(())
 393         };
 394         for entry in walker.filter_entry(|e| !is_hidden(e)) {
 395             let path = match entry {
 396                 Ok(entry) => entry.into_path(),
 397                 Err(err) => {
 398                     handle_entry_err(err)?;
 399                     continue
 400                 },
 401             };
 402             if let Ok(archive_type) = archive_type(&path) {
 403                 if archive_type == ArchiveType::FixedIndex || archive_type == ArchiveType::DynamicIndex {
 404                     list.push(path);
 405                 }
 406             }
 407         }
 408
 409         Ok(list)
 410     }
 411
 412     // mark chunks  used by ``index`` as used
 413     fn index_mark_used_chunks<I: IndexFile>(
 414         &self,
 415         index: I,
 416         file_name: &Path, // only used for error reporting
 417         status: &mut GarbageCollectionStatus,
 418         worker: &dyn TaskState,
 419     ) -> Result<(), Error> {
 420
 421         status.index_file_count += 1;
 422         status.index_data_bytes += index.index_bytes();
 423
 424         for pos in 0..index.index_count() {
 425             worker.check_abort()?;
 426             tools::fail_on_shutdown()?;
 427             let digest = index.index_digest(pos).unwrap();
 428             if let Err(err) = self.chunk_store.touch_chunk(digest) {
 429                 crate::task_warn!(
 430                     worker,
 431                     "warning: unable to access chunk {}, required by {:?} - {}",
 432                     proxmox::tools::digest_to_hex(digest),
 433                     file_name,
 434                     err,
 435                 );
 436             }
 437         }
 438         Ok(())
 439     }
 440
 441     fn mark_used_chunks(
 442         &self,
 443         status: &mut GarbageCollectionStatus,
 444         worker: &dyn TaskState,
 445     ) -> Result<(), Error> {
 446
 447         let image_list = self.list_images()?;
 448
 449         let image_count = image_list.len();
 450
 451         let mut done = 0;
 452
 453         let mut last_percentage: usize = 0;
 454
 455         for path in image_list {
 456
 457             worker.check_abort()?;
 458             tools::fail_on_shutdown()?;
 459
 460             let full_path = self.chunk_store.relative_path(&path);
 461             match std::fs::File::open(&full_path) {
 462                 Ok(file) => {
 463                     if let Ok(archive_type) = archive_type(&path) {
 464                         if archive_type == ArchiveType::FixedIndex {
 465                             let index = FixedIndexReader::new(file)?;
 466                             self.index_mark_used_chunks(index, &path, status, worker)?;
 467                         } else if archive_type == ArchiveType::DynamicIndex {
 468                             let index = DynamicIndexReader::new(file)?;
 469                             self.index_mark_used_chunks(index, &path, status, worker)?;
 470                         }
 471                     }
 472                 }
 473                 Err(err) => {
 474                     if err.kind() == std::io::ErrorKind::NotFound {
 475                         // simply ignore vanished files
 476                     } else {
 477                         return Err(err.into());
 478                     }
 479                 }
 480             }
 481             done += 1;
 482
 483             let percentage = done*100/image_count;
 484             if percentage > last_percentage {
 485                 crate::task_log!(
 486                     worker,
 487                     "percentage done: phase1 {}% ({} of {} index files)",
 488                     percentage,
 489                     done,
 490                     image_count,
 491                 );
 492                 last_percentage = percentage;
 493             }
 494         }
 495
 496         Ok(())
 497     }
 498
 499     pub fn last_gc_status(&self) -> GarbageCollectionStatus {
 500         self.last_gc_status.lock().unwrap().clone()
 501     }
 502
 503     pub fn garbage_collection_running(&self) -> bool {
 504         if let Ok(_) = self.gc_mutex.try_lock() { false } else { true }
 505     }
 506
 507     pub fn garbage_collection(&self, worker: &dyn TaskState, upid: &UPID) -> Result<(), Error> {
 508
 509         if let Ok(ref mut _mutex) = self.gc_mutex.try_lock() {
 510
 511             // avoids that we run GC if an old daemon process has still a
 512             // running backup writer, which is not save as we have no "oldest
 513             // writer" information and thus no safe atime cutoff
 514             let _exclusive_lock =  self.chunk_store.try_exclusive_lock()?;
 515
 516             let phase1_start_time = proxmox::tools::time::epoch_i64();
 517             let oldest_writer = self.chunk_store.oldest_writer().unwrap_or(phase1_start_time);
 518
 519             let mut gc_status = GarbageCollectionStatus::default();
 520             gc_status.upid = Some(upid.to_string());
 521
 522             crate::task_log!(worker, "Start GC phase1 (mark used chunks)");
 523
 524             self.mark_used_chunks(&mut gc_status, worker)?;
 525
 526             crate::task_log!(worker, "Start GC phase2 (sweep unused chunks)");
 527             self.chunk_store.sweep_unused_chunks(
 528                 oldest_writer,
 529                 phase1_start_time,
 530                 &mut gc_status,
 531                 worker,
 532             )?;
 533
 534             crate::task_log!(
 535                 worker,
 536                 "Removed garbage: {}",
 537                 HumanByte::from(gc_status.removed_bytes),
 538             );
 539             crate::task_log!(worker, "Removed chunks: {}", gc_status.removed_chunks);
 540             if gc_status.pending_bytes > 0 {
 541                 crate::task_log!(
 542                     worker,
 543                     "Pending removals: {} (in {} chunks)",
 544                     HumanByte::from(gc_status.pending_bytes),
 545                     gc_status.pending_chunks,
 546                 );
 547             }
 548             if gc_status.removed_bad > 0 {
 549                 crate::task_log!(worker, "Removed bad files: {}", gc_status.removed_bad);
 550             }
 551
 552             crate::task_log!(
 553                 worker,
 554                 "Original data usage: {}",
 555                 HumanByte::from(gc_status.index_data_bytes),
 556             );
 557
 558             if gc_status.index_data_bytes > 0 {
 559                 let comp_per = (gc_status.disk_bytes as f64 * 100.)/gc_status.index_data_bytes as f64;
 560                 crate::task_log!(
 561                     worker,
 562                     "On-Disk usage: {} ({:.2}%)",
 563                     HumanByte::from(gc_status.disk_bytes),
 564                     comp_per,
 565                 );
 566             }
 567
 568             crate::task_log!(worker, "On-Disk chunks: {}", gc_status.disk_chunks);
 569
 570             if gc_status.disk_chunks > 0 {
 571                 let avg_chunk = gc_status.disk_bytes/(gc_status.disk_chunks as u64);
 572                 crate::task_log!(worker, "Average chunk size: {}", HumanByte::from(avg_chunk));
 573             }
 574
 575             *self.last_gc_status.lock().unwrap() = gc_status;
 576
 577         } else {
 578             bail!("Start GC failed - (already running/locked)");
 579         }
 580
 581         Ok(())
 582     }
 583
 584     pub fn try_shared_chunk_store_lock(&self) -> Result<tools::ProcessLockSharedGuard, Error> {
 585         self.chunk_store.try_shared_lock()
 586     }
 587
 588     pub fn chunk_path(&self, digest:&[u8; 32]) -> (PathBuf, String) {
 589         self.chunk_store.chunk_path(digest)
 590     }
 591
 592     pub fn cond_touch_chunk(&self, digest: &[u8; 32], fail_if_not_exist: bool) -> Result<bool, Error> {
 593         self.chunk_store.cond_touch_chunk(digest, fail_if_not_exist)
 594     }
 595
 596     pub fn insert_chunk(
 597         &self,
 598         chunk: &DataBlob,
 599         digest: &[u8; 32],
 600     ) -> Result<(bool, u64), Error> {
 601         self.chunk_store.insert_chunk(chunk, digest)
 602     }
 603
 604     pub fn load_blob(&self, backup_dir: &BackupDir, filename: &str) -> Result<DataBlob, Error> {
 605         let mut path = self.base_path();
 606         path.push(backup_dir.relative_path());
 607         path.push(filename);
 608
 609         proxmox::try_block!({
 610             let mut file = std::fs::File::open(&path)?;
 611             DataBlob::load_from_reader(&mut file)
 612         }).map_err(|err| format_err!("unable to load blob '{:?}' - {}", path, err))
 613     }
 614
 615
 616     pub fn load_chunk(&self, digest: &[u8; 32]) -> Result<DataBlob, Error> {
 617
 618         let (chunk_path, digest_str) = self.chunk_store.chunk_path(digest);
 619
 620         proxmox::try_block!({
 621             let mut file = std::fs::File::open(&chunk_path)?;
 622             DataBlob::load_from_reader(&mut file)
 623         }).map_err(|err| format_err!(
 624             "store '{}', unable to load chunk '{}' - {}",
 625             self.name(),
 626             digest_str,
 627             err,
 628         ))
 629     }
 630
 631     fn lock_manifest(
 632         &self,
 633         backup_dir: &BackupDir,
 634     ) -> Result<File, Error> {
 635         let mut path = self.base_path();
 636         path.push(backup_dir.relative_path());
 637         path.push(&MANIFEST_LOCK_NAME);
 638
 639         // update_manifest should never take a long time, so if someone else has
 640         // the lock we can simply block a bit and should get it soon
 641         open_file_locked(&path, Duration::from_secs(5), true)
 642             .map_err(|err| {
 643                 format_err!(
 644                     "unable to acquire manifest lock {:?} - {}", &path, err
 645                 )
 646             })
 647     }
 648
 649     /// Load the manifest without a lock. Must not be written back.
 650     pub fn load_manifest(
 651         &self,
 652         backup_dir: &BackupDir,
 653     ) -> Result<(BackupManifest, u64), Error> {
 654         let blob = self.load_blob(backup_dir, MANIFEST_BLOB_NAME)?;
 655         let raw_size = blob.raw_size();
 656         let manifest = BackupManifest::try_from(blob)?;
 657         Ok((manifest, raw_size))
 658     }
 659
 660     /// Update the manifest of the specified snapshot. Never write a manifest directly,
 661     /// only use this method - anything else may break locking guarantees.
 662     pub fn update_manifest(
 663         &self,
 664         backup_dir: &BackupDir,
 665         update_fn: impl FnOnce(&mut BackupManifest),
 666     ) -> Result<(), Error> {
 667
 668         let _guard = self.lock_manifest(backup_dir)?;
 669         let (mut manifest, _) = self.load_manifest(&backup_dir)?;
 670
 671         update_fn(&mut manifest);
 672
 673         let manifest = serde_json::to_value(manifest)?;
 674         let manifest = serde_json::to_string_pretty(&manifest)?;
 675         let blob = DataBlob::encode(manifest.as_bytes(), None, true)?;
 676         let raw_data = blob.raw_data();
 677
 678         let mut path = self.base_path();
 679         path.push(backup_dir.relative_path());
 680         path.push(MANIFEST_BLOB_NAME);
 681
 682         // atomic replace invalidates flock - no other writes past this point!
 683         replace_file(&path, raw_data, CreateOptions::new())?;
 684
 685         Ok(())
 686     }
 687
 688     pub fn verify_new(&self) -> bool {
 689         self.verify_new
 690     }
 691 }