pbs-client/src/pxar/fuse.rs

   1 //! Asynchronous fuse implementation.
   2
   3 use std::collections::BTreeMap;
   4 use std::convert::TryFrom;
   5 use std::ffi::{OsStr, OsString};
   6 use std::future::Future;
   7 use std::io;
   8 use std::mem;
   9 use std::ops::Range;
  10 use std::os::unix::ffi::OsStrExt;
  11 use std::path::Path;
  12 use std::pin::Pin;
  13 use std::sync::atomic::{AtomicUsize, Ordering};
  14 use std::sync::{Arc, RwLock};
  15 use std::task::{Context, Poll};
  16
  17 use anyhow::{format_err, Error};
  18 use futures::channel::mpsc::UnboundedSender;
  19 use futures::select;
  20 use futures::sink::SinkExt;
  21 use futures::stream::{StreamExt, TryStreamExt};
  22
  23 use proxmox_io::vec;
  24 use pxar::accessor::{self, EntryRangeInfo, ReadAt};
  25
  26 use proxmox_fuse::requests::{self, FuseRequest};
  27 use proxmox_fuse::{EntryParam, Fuse, ReplyBufState, Request, ROOT_ID};
  28 use proxmox_lang::io_format_err;
  29 use proxmox_sys::fs::xattr;
  30
  31 /// We mark inodes for regular files this way so we know how to access them.
  32 const NON_DIRECTORY_INODE: u64 = 1u64 << 63;
  33
  34 #[inline]
  35 fn is_dir_inode(inode: u64) -> bool {
  36     0 == (inode & NON_DIRECTORY_INODE)
  37 }
  38
  39 /// Our reader type instance used for accessors.
  40 pub type Reader = Arc<dyn ReadAt + Send + Sync + 'static>;
  41
  42 /// Our Accessor type instance.
  43 pub type Accessor = accessor::aio::Accessor<Reader>;
  44
  45 /// Our Directory type instance.
  46 pub type Directory = accessor::aio::Directory<Reader>;
  47
  48 /// Our FileEntry type instance.
  49 pub type FileEntry = accessor::aio::FileEntry<Reader>;
  50
  51 /// Our FileContents type instance.
  52 pub type FileContents = accessor::aio::FileContents<Reader>;
  53
  54 pub struct Session {
  55     fut: Pin<Box<dyn Future<Output = Result<(), Error>> + Send + Sync + 'static>>,
  56 }
  57
  58 impl Session {
  59     /// Create a fuse session for an archive.
  60     pub async fn mount_path(
  61         archive_path: &Path,
  62         options: &OsStr,
  63         verbose: bool,
  64         mountpoint: &Path,
  65     ) -> Result<Self, Error> {
  66         // TODO: Add a buffered/caching ReadAt layer?
  67         let file = std::fs::File::open(archive_path)?;
  68         let file_size = file.metadata()?.len();
  69         let reader: Reader = Arc::new(accessor::sync::FileReader::new(file));
  70         let accessor = Accessor::new(reader, file_size).await?;
  71         Self::mount(accessor, options, verbose, mountpoint)
  72     }
  73
  74     /// Create a new fuse session for the given pxar `Accessor`.
  75     pub fn mount(
  76         accessor: Accessor,
  77         options: &OsStr,
  78         verbose: bool,
  79         path: &Path,
  80     ) -> Result<Self, Error> {
  81         let fuse = Fuse::builder("pxar-mount")?
  82             .debug()
  83             .options_os(options)?
  84             .enable_readdirplus()
  85             .enable_read()
  86             .enable_readlink()
  87             .enable_read_xattr()
  88             .build()?
  89             .mount(path)?;
  90
  91         let session = SessionImpl::new(accessor, verbose);
  92
  93         Ok(Self {
  94             fut: Box::pin(session.main(fuse)),
  95         })
  96     }
  97 }
  98
  99 impl Future for Session {
 100     type Output = Result<(), Error>;
 101
 102     fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
 103         Pin::new(&mut self.fut).poll(cx)
 104     }
 105 }
 106
 107 /// We use this to return an errno value back to the kernel.
 108 macro_rules! io_return {
 109     ($errno:expr) => {{
 110         return Err(::std::io::Error::from_raw_os_error($errno).into());
 111     }};
 112 }
 113
 114 /// This is what we need to cache as a "lookup" entry. The kernel assumes that these are easily
 115 /// accessed.
 116 struct Lookup {
 117     refs: AtomicUsize,
 118
 119     inode: u64,
 120     parent: u64,
 121     entry_range_info: EntryRangeInfo,
 122     content_range: Option<Range<u64>>,
 123 }
 124
 125 impl Lookup {
 126     fn new(
 127         inode: u64,
 128         parent: u64,
 129         entry_range_info: EntryRangeInfo,
 130         content_range: Option<Range<u64>>,
 131     ) -> Box<Lookup> {
 132         Box::new(Self {
 133             refs: AtomicUsize::new(1),
 134             inode,
 135             parent,
 136             entry_range_info,
 137             content_range,
 138         })
 139     }
 140
 141     /// Decrease the reference count by `count`. Note that this must not include the reference held
 142     /// by `self` itself, so this must not decrease the count below 2.
 143     fn forget(&self, count: usize) -> Result<(), Error> {
 144         loop {
 145             let old = self.refs.load(Ordering::Acquire);
 146             if count >= old {
 147                 // We use this to bail out of a functionin an unexpected error case. This will cause the fuse
 148                 // request to be answered with a generic `EIO` error code. The error message contained in here
 149                 // will be printed to stdout if the verbose flag is used, otherwise silently dropped.
 150                 return Err(io_format_err!("reference count underflow").into());
 151             }
 152             let new = old - count;
 153             match self
 154                 .refs
 155                 .compare_exchange(old, new, Ordering::SeqCst, Ordering::SeqCst)
 156             {
 157                 Ok(_) => break Ok(()),
 158                 Err(_) => continue,
 159             }
 160         }
 161     }
 162
 163     fn get_ref<'a>(&self, session: &'a SessionImpl) -> LookupRef<'a> {
 164         if self.refs.fetch_add(1, Ordering::AcqRel) == 0 {
 165             panic!("atomic refcount increased from 0 to 1");
 166         }
 167
 168         LookupRef {
 169             session,
 170             lookup: self as *const Lookup,
 171         }
 172     }
 173 }
 174
 175 struct LookupRef<'a> {
 176     session: &'a SessionImpl,
 177     lookup: *const Lookup,
 178 }
 179
 180 unsafe impl<'a> Send for LookupRef<'a> {}
 181 unsafe impl<'a> Sync for LookupRef<'a> {}
 182
 183 impl<'a> Clone for LookupRef<'a> {
 184     fn clone(&self) -> Self {
 185         self.get_ref(self.session)
 186     }
 187 }
 188
 189 impl<'a> std::ops::Deref for LookupRef<'a> {
 190     type Target = Lookup;
 191
 192     fn deref(&self) -> &Self::Target {
 193         unsafe { &*self.lookup }
 194     }
 195 }
 196
 197 impl<'a> Drop for LookupRef<'a> {
 198     fn drop(&mut self) {
 199         if self.lookup.is_null() {
 200             return;
 201         }
 202
 203         if self.refs.fetch_sub(1, Ordering::AcqRel) == 1 {
 204             let inode = self.inode;
 205             drop(self.session.lookups.write().unwrap().remove(&inode));
 206         }
 207     }
 208 }
 209
 210 impl<'a> LookupRef<'a> {
 211     fn leak(mut self) -> &'a Lookup {
 212         unsafe { &*mem::replace(&mut self.lookup, std::ptr::null()) }
 213     }
 214 }
 215
 216 struct SessionImpl {
 217     accessor: Accessor,
 218     verbose: bool,
 219     lookups: RwLock<BTreeMap<u64, Box<Lookup>>>,
 220 }
 221
 222 impl SessionImpl {
 223     fn new(accessor: Accessor, verbose: bool) -> Self {
 224         let root = Lookup::new(
 225             ROOT_ID,
 226             ROOT_ID,
 227             EntryRangeInfo::toplevel(0..accessor.size()),
 228             None,
 229         );
 230
 231         let mut tree = BTreeMap::new();
 232         tree.insert(ROOT_ID, root);
 233
 234         Self {
 235             accessor,
 236             verbose,
 237             lookups: RwLock::new(tree),
 238         }
 239     }
 240
 241     /// Here's how we deal with errors:
 242     ///
 243     /// Any error will be printed if the verbose flag was set, otherwise the message will be
 244     /// silently dropped.
 245     ///
 246     /// Opaque errors will cause the fuse main loop to bail out with that error.
 247     ///
 248     /// `io::Error`s will cause the fuse request to responded to with the given `io::Error`. An
 249     /// `io::ErrorKind::Other` translates to a generic `EIO`.
 250     async fn handle_err(
 251         &self,
 252         request: impl FuseRequest,
 253         err: Error,
 254         mut sender: UnboundedSender<Error>,
 255     ) {
 256         let final_result = match err.downcast::<io::Error>() {
 257             Ok(err) => {
 258                 if err.kind() == io::ErrorKind::Other && self.verbose {
 259                     eprintln!("an IO error occurred: {}", err);
 260                 }
 261
 262                 // fail the request
 263                 request.io_fail(err).map_err(Error::from)
 264             }
 265             Err(err) => {
 266                 // `bail` (non-`io::Error`) is used for fatal errors which should actually cancel:
 267                 if self.verbose {
 268                     eprintln!("internal error: {}, bailing out", err);
 269                 }
 270                 Err(err)
 271             }
 272         };
 273         if let Err(err) = final_result {
 274             // either we failed to send the error code to fuse, or the above was not an
 275             // `io::Error`, so in this case notify the main loop:
 276             sender
 277                 .send(err)
 278                 .await
 279                 .expect("failed to propagate error to main loop");
 280         }
 281     }
 282
 283     async fn main(self, fuse: Fuse) -> Result<(), Error> {
 284         Arc::new(self).main_do(fuse).await
 285     }
 286
 287     async fn main_do(self: Arc<Self>, fuse: Fuse) -> Result<(), Error> {
 288         let (err_send, mut err_recv) = futures::channel::mpsc::unbounded::<Error>();
 289         let mut fuse = fuse.fuse(); // make this a futures::stream::FusedStream!
 290         loop {
 291             select! {
 292                 request = fuse.try_next() => match request? {
 293                     Some(request) => {
 294                         tokio::spawn(Arc::clone(&self).handle_request(request, err_send.clone()));
 295                     }
 296                     None => break,
 297                 },
 298                 err = err_recv.next() => match err {
 299                     Some(err) => if self.verbose {
 300                         eprintln!("cancelling fuse main loop due to error: {}", err);
 301                         return Err(err);
 302                     },
 303                     None => panic!("error channel was closed unexpectedly"),
 304                 },
 305             }
 306         }
 307         Ok(())
 308     }
 309
 310     async fn handle_request(
 311         self: Arc<Self>,
 312         request: Request,
 313         mut err_sender: UnboundedSender<Error>,
 314     ) {
 315         let result: Result<(), Error> = match request {
 316             Request::Lookup(request) => {
 317                 match self.lookup(request.parent, &request.file_name).await {
 318                     Ok((entry, lookup)) => match request.reply(&entry) {
 319                         Ok(()) => {
 320                             lookup.leak();
 321                             Ok(())
 322                         }
 323                         Err(err) => Err(Error::from(err)),
 324                     },
 325                     Err(err) => return self.handle_err(request, err, err_sender).await,
 326                 }
 327             }
 328             Request::Forget(request) => match self.forget(request.inode, request.count as usize) {
 329                 Ok(()) => {
 330                     request.reply();
 331                     Ok(())
 332                 }
 333                 Err(err) => return self.handle_err(request, err, err_sender).await,
 334             },
 335             Request::Getattr(request) => match self.getattr(request.inode).await {
 336                 Ok(stat) => request.reply(&stat, f64::MAX).map_err(Error::from),
 337                 Err(err) => return self.handle_err(request, err, err_sender).await,
 338             },
 339             Request::ReaddirPlus(mut request) => match self.readdirplus(&mut request).await {
 340                 Ok(lookups) => match request.reply() {
 341                     Ok(()) => {
 342                         for i in lookups {
 343                             i.leak();
 344                         }
 345                         Ok(())
 346                     }
 347                     Err(err) => Err(Error::from(err)),
 348                 },
 349                 Err(err) => return self.handle_err(request, err, err_sender).await,
 350             },
 351             Request::Read(request) => {
 352                 match self.read(request.inode, request.size, request.offset).await {
 353                     Ok(data) => request.reply(&data).map_err(Error::from),
 354                     Err(err) => return self.handle_err(request, err, err_sender).await,
 355                 }
 356             }
 357             Request::Readlink(request) => match self.readlink(request.inode).await {
 358                 Ok(data) => request.reply(&data).map_err(Error::from),
 359                 Err(err) => return self.handle_err(request, err, err_sender).await,
 360             },
 361             Request::ListXAttrSize(request) => match self.listxattrs(request.inode).await {
 362                 Ok(data) => request
 363                     .reply(
 364                         data.into_iter()
 365                             .fold(0, |sum, i| sum + i.name().to_bytes_with_nul().len()),
 366                     )
 367                     .map_err(Error::from),
 368                 Err(err) => return self.handle_err(request, err, err_sender).await,
 369             },
 370             Request::ListXAttr(mut request) => match self.listxattrs_into(&mut request).await {
 371                 Ok(ReplyBufState::Ok) => request.reply().map_err(Error::from),
 372                 Ok(ReplyBufState::Full) => request.fail_full().map_err(Error::from),
 373                 Err(err) => return self.handle_err(request, err, err_sender).await,
 374             },
 375             Request::GetXAttrSize(request) => {
 376                 match self.getxattr(request.inode, &request.attr_name).await {
 377                     Ok(xattr) => request.reply(xattr.value().len()).map_err(Error::from),
 378                     Err(err) => return self.handle_err(request, err, err_sender).await,
 379                 }
 380             }
 381             Request::GetXAttr(request) => {
 382                 match self.getxattr(request.inode, &request.attr_name).await {
 383                     Ok(xattr) => request.reply(xattr.value()).map_err(Error::from),
 384                     Err(err) => return self.handle_err(request, err, err_sender).await,
 385                 }
 386             }
 387             other => {
 388                 if self.verbose {
 389                     eprintln!("Received unexpected fuse request");
 390                 }
 391                 other.fail(libc::ENOSYS).map_err(Error::from)
 392             }
 393         };
 394
 395         if let Err(err) = result {
 396             err_sender
 397                 .send(err)
 398                 .await
 399                 .expect("failed to propagate error to main loop");
 400         }
 401     }
 402
 403     fn get_lookup(&self, inode: u64) -> Result<LookupRef, Error> {
 404         let lookups = self.lookups.read().unwrap();
 405         if let Some(lookup) = lookups.get(&inode) {
 406             return Ok(lookup.get_ref(self));
 407         }
 408         io_return!(libc::ENOENT);
 409     }
 410
 411     async fn open_dir(&self, inode: u64) -> Result<Directory, Error> {
 412         if inode == ROOT_ID {
 413             Ok(self.accessor.open_root().await?)
 414         } else if !is_dir_inode(inode) {
 415             io_return!(libc::ENOTDIR);
 416         } else {
 417             Ok(unsafe { self.accessor.open_dir_at_end(inode).await? })
 418         }
 419     }
 420
 421     async fn open_entry(&self, lookup: &LookupRef<'_>) -> io::Result<FileEntry> {
 422         unsafe {
 423             self.accessor
 424                 .open_file_at_range(&lookup.entry_range_info)
 425                 .await
 426         }
 427     }
 428
 429     fn open_content(&self, lookup: &LookupRef) -> Result<FileContents, Error> {
 430         if is_dir_inode(lookup.inode) {
 431             io_return!(libc::EISDIR);
 432         }
 433
 434         match lookup.content_range.clone() {
 435             Some(range) => Ok(unsafe { self.accessor.open_contents_at_range(range) }),
 436             None => io_return!(libc::EBADF),
 437         }
 438     }
 439
 440     fn make_lookup(&self, parent: u64, inode: u64, entry: &FileEntry) -> Result<LookupRef, Error> {
 441         let lookups = self.lookups.read().unwrap();
 442         if let Some(lookup) = lookups.get(&inode) {
 443             return Ok(lookup.get_ref(self));
 444         }
 445         drop(lookups);
 446
 447         let entry = Lookup::new(
 448             inode,
 449             parent,
 450             entry.entry_range_info().clone(),
 451             entry.content_range()?,
 452         );
 453         let reference = entry.get_ref(self);
 454         entry.refs.store(1, Ordering::Release);
 455
 456         let mut lookups = self.lookups.write().unwrap();
 457         if let Some(lookup) = lookups.get(&inode) {
 458             return Ok(lookup.get_ref(self));
 459         }
 460
 461         lookups.insert(inode, entry);
 462         drop(lookups);
 463         Ok(reference)
 464     }
 465
 466     fn forget(&self, inode: u64, count: usize) -> Result<(), Error> {
 467         let node = self.get_lookup(inode)?;
 468         node.forget(count)?;
 469         Ok(())
 470     }
 471
 472     async fn lookup(
 473         &'_ self,
 474         parent: u64,
 475         file_name: &OsStr,
 476     ) -> Result<(EntryParam, LookupRef<'_>), Error> {
 477         let dir = self.open_dir(parent).await?;
 478
 479         let entry = match { dir }.lookup(file_name).await? {
 480             Some(entry) => entry,
 481             None => io_return!(libc::ENOENT),
 482         };
 483
 484         let entry = if let pxar::EntryKind::Hardlink(_) = entry.kind() {
 485             // we don't know the file's end-offset, so we'll just allow the decoder to decode the
 486             // entire rest of the archive until we figure out something better...
 487             let entry = self.accessor.follow_hardlink(&entry).await?;
 488
 489             if let pxar::EntryKind::Hardlink(_) = entry.kind() {
 490                 // hardlinks must not point to other hardlinks...
 491                 io_return!(libc::ELOOP);
 492             }
 493
 494             entry
 495         } else {
 496             entry
 497         };
 498
 499         let response = to_entry(&entry)?;
 500         let inode = response.inode;
 501         Ok((response, self.make_lookup(parent, inode, &entry)?))
 502     }
 503
 504     async fn getattr(&self, inode: u64) -> Result<libc::stat, Error> {
 505         let entry = unsafe {
 506             self.accessor.open_file_at_range(&self.get_lookup(inode)?.entry_range_info).await?
 507         };
 508         to_stat(inode, &entry)
 509     }
 510
 511     async fn readdirplus(
 512         &'_ self,
 513         request: &mut requests::ReaddirPlus,
 514     ) -> Result<Vec<LookupRef<'_>>, Error> {
 515         let mut lookups = Vec::new();
 516         let offset = usize::try_from(request.offset)
 517             .map_err(|_| io_format_err!("directory offset out of range"))?;
 518
 519         let dir = self.open_dir(request.inode).await?;
 520         let dir_lookup = self.get_lookup(request.inode)?;
 521
 522         let entry_count = dir.read_dir().count() as isize;
 523
 524         let mut next = offset as isize;
 525         let mut iter = dir.read_dir().skip(offset);
 526         while let Some(file) = iter.next().await {
 527             next += 1;
 528             let file = file?.decode_entry().await?;
 529             let stat = to_stat(to_inode(&file), &file)?;
 530             let name = file.file_name();
 531             match request.add_entry(name, &stat, next, 1, f64::MAX, f64::MAX)? {
 532                 ReplyBufState::Ok => (),
 533                 ReplyBufState::Full => return Ok(lookups),
 534             }
 535             lookups.push(self.make_lookup(request.inode, stat.st_ino, &file)?);
 536         }
 537
 538         if next == entry_count {
 539             next += 1;
 540             let file = dir.lookup_self().await?;
 541             let stat = to_stat(to_inode(&file), &file)?;
 542             let name = OsStr::new(".");
 543             match request.add_entry(name, &stat, next, 1, f64::MAX, f64::MAX)? {
 544                 ReplyBufState::Ok => (),
 545                 ReplyBufState::Full => return Ok(lookups),
 546             }
 547             lookups.push(LookupRef::clone(&dir_lookup));
 548         }
 549
 550         if next == entry_count + 1 {
 551             next += 1;
 552             let lookup = self.get_lookup(dir_lookup.parent)?;
 553             let parent_dir = self.open_dir(lookup.inode).await?;
 554             let file = parent_dir.lookup_self().await?;
 555             let stat = to_stat(to_inode(&file), &file)?;
 556             let name = OsStr::new("..");
 557             match request.add_entry(name, &stat, next, 1, f64::MAX, f64::MAX)? {
 558                 ReplyBufState::Ok => (),
 559                 ReplyBufState::Full => return Ok(lookups),
 560             }
 561             lookups.push(lookup);
 562         }
 563
 564         Ok(lookups)
 565     }
 566
 567     async fn read(&self, inode: u64, len: usize, offset: u64) -> Result<Vec<u8>, Error> {
 568         let file = self.get_lookup(inode)?;
 569         let content = self.open_content(&file)?;
 570         let mut buf = vec::undefined(len);
 571         let got = content.read_at(&mut buf, offset).await?;
 572         buf.truncate(got);
 573         Ok(buf)
 574     }
 575
 576     async fn readlink(&self, inode: u64) -> Result<OsString, Error> {
 577         let lookup = self.get_lookup(inode)?;
 578         let file = self.open_entry(&lookup).await?;
 579         match file.get_symlink() {
 580             None => io_return!(libc::EINVAL),
 581             Some(link) => Ok(link.to_owned()),
 582         }
 583     }
 584
 585     async fn listxattrs(&self, inode: u64) -> Result<Vec<pxar::format::XAttr>, Error> {
 586         let lookup = self.get_lookup(inode)?;
 587         let metadata = self
 588             .open_entry(&lookup)
 589             .await?
 590             .into_entry()
 591             .into_metadata();
 592
 593         let mut xattrs = metadata.xattrs;
 594
 595         use pxar::format::XAttr;
 596
 597         if let Some(fcaps) = metadata.fcaps {
 598             xattrs.push(XAttr::new(xattr::xattr_name_fcaps().to_bytes(), fcaps.data));
 599         }
 600
 601         // TODO: Special cases:
 602         //     b"system.posix_acl_access
 603         //     b"system.posix_acl_default
 604         //
 605         // For these we need to be able to create posix acl format entries, at that point we could
 606         // just ditch libacl as well...
 607
 608         Ok(xattrs)
 609     }
 610
 611     async fn listxattrs_into(
 612         &self,
 613         request: &mut requests::ListXAttr,
 614     ) -> Result<ReplyBufState, Error> {
 615         let xattrs = self.listxattrs(request.inode).await?;
 616
 617         for entry in xattrs {
 618             match request.add_c_string(entry.name()) {
 619                 ReplyBufState::Ok => (),
 620                 ReplyBufState::Full => return Ok(ReplyBufState::Full),
 621             }
 622         }
 623
 624         Ok(ReplyBufState::Ok)
 625     }
 626
 627     async fn getxattr(&self, inode: u64, xattr: &OsStr) -> Result<pxar::format::XAttr, Error> {
 628         // TODO: pxar::Accessor could probably get a more optimized method to fetch a specific
 629         // xattr for an entry...
 630         let xattrs = self.listxattrs(inode).await?;
 631         for entry in xattrs {
 632             if entry.name().to_bytes() == xattr.as_bytes() {
 633                 return Ok(entry);
 634             }
 635         }
 636         io_return!(libc::ENODATA);
 637     }
 638 }
 639
 640 #[inline]
 641 fn to_entry(entry: &FileEntry) -> Result<EntryParam, Error> {
 642     to_entry_param(to_inode(entry), entry)
 643 }
 644
 645 #[inline]
 646 fn to_inode(entry: &FileEntry) -> u64 {
 647     if entry.is_dir() {
 648         entry.entry_range_info().entry_range.end
 649     } else {
 650         entry.entry_range_info().entry_range.start | NON_DIRECTORY_INODE
 651     }
 652 }
 653
 654 fn to_entry_param(inode: u64, entry: &pxar::Entry) -> Result<EntryParam, Error> {
 655     Ok(EntryParam::simple(inode, to_stat(inode, entry)?))
 656 }
 657
 658 fn to_stat(inode: u64, entry: &pxar::Entry) -> Result<libc::stat, Error> {
 659     let nlink = if entry.is_dir() { 2 } else { 1 };
 660
 661     let metadata = entry.metadata();
 662
 663     let mut stat: libc::stat = unsafe { mem::zeroed() };
 664     stat.st_ino = inode;
 665     stat.st_nlink = nlink;
 666     stat.st_mode = u32::try_from(metadata.stat.mode)
 667         .map_err(|err| format_err!("mode does not fit into st_mode field: {}", err))?;
 668     stat.st_size = i64::try_from(entry.file_size().unwrap_or(0))
 669         .map_err(|err| format_err!("size does not fit into st_size field: {}", err))?;
 670     stat.st_uid = metadata.stat.uid;
 671     stat.st_gid = metadata.stat.gid;
 672     stat.st_atime = metadata.stat.mtime.secs;
 673     stat.st_atime_nsec = metadata.stat.mtime.nanos as _;
 674     stat.st_mtime = metadata.stat.mtime.secs;
 675     stat.st_mtime_nsec = metadata.stat.mtime.nanos as _;
 676     stat.st_ctime = metadata.stat.mtime.secs;
 677     stat.st_ctime_nsec = metadata.stat.mtime.nanos as _;
 678     Ok(stat)
 679 }