mod file_attr;
mod inode_tracker;
mod inodes;
mod root_nodes;
#[cfg(feature = "fuse")]
pub mod fuse;
#[cfg(feature = "virtiofs")]
pub mod virtiofs;
pub use self::root_nodes::RootNodes;
use self::{
file_attr::ROOT_FILE_ATTR,
inode_tracker::InodeTracker,
inodes::{DirectoryInodeData, InodeData},
};
use crate::{
blobservice::{BlobReader, BlobService},
directoryservice::DirectoryService,
path::PathComponent,
B3Digest, Node,
};
use bstr::ByteVec;
use fuse_backend_rs::abi::fuse_abi::{stat64, OpenOptions};
use fuse_backend_rs::api::filesystem::{
Context, FileSystem, FsOptions, GetxattrReply, ListxattrReply, ROOT_ID,
};
use futures::StreamExt;
use parking_lot::RwLock;
use std::sync::Mutex;
use std::{
collections::HashMap,
io,
sync::atomic::AtomicU64,
sync::{atomic::Ordering, Arc},
time::Duration,
};
use std::{ffi::CStr, io::Cursor};
use tokio::{
io::{AsyncReadExt, AsyncSeekExt},
sync::mpsc,
};
use tracing::{debug, error, instrument, warn, Instrument as _, Span};
/// This implements a read-only FUSE filesystem for a tvix-store
/// with the passed [BlobService], [DirectoryService] and [RootNodes].
///
/// Linux uses inodes in filesystems. When implementing FUSE, most calls are
/// *for* a given inode.
///
/// This means, we need to have a stable mapping of inode numbers to the
/// corresponding store nodes.
///
/// We internally delegate all inode allocation and state keeping to the
/// inode tracker.
/// We store a mapping from currently "explored" names in the root to their
/// inode.
///
/// There's some places where inodes are allocated / data inserted into
/// the inode tracker, if not allocated before already:
/// - Processing a `lookup` request, either in the mount root, or somewhere
/// deeper.
/// - Processing a `readdir` request
///
/// Things pointing to the same contents get the same inodes, irrespective of
/// their own location.
/// This means:
/// - Symlinks with the same target will get the same inode.
/// - Regular/executable files with the same contents will get the same inode
/// - Directories with the same contents will get the same inode.
///
/// Due to the above being valid across the whole store, and considering the
/// merkle structure is a DAG, not a tree, this also means we can't do "bucketed
/// allocation", aka reserve Directory.size inodes for each directory node we
/// explore.
/// Tests for this live in the tvix-store crate.
pub struct TvixStoreFs<BS, DS, RN> {
blob_service: BS,
directory_service: DS,
root_nodes_provider: RN,
/// Whether to (try) listing elements in the root.
list_root: bool,
/// Whether to expose blob and directory digests as extended attributes.
show_xattr: bool,
/// This maps a given basename in the root to the inode we allocated for the node.
root_nodes: RwLock<HashMap<PathComponent, u64>>,
/// This keeps track of inodes and data alongside them.
inode_tracker: RwLock<InodeTracker>,
// FUTUREWORK: have a generic container type for dir/file handles and handle
// allocation.
/// Maps from the handle returned from an opendir to
/// This holds all opendir handles (for the root inode)
/// They point to the rx part of the channel producing the listing.
#[allow(clippy::type_complexity)]
dir_handles: RwLock<
HashMap<
u64,
(
Span,
Arc<Mutex<mpsc::Receiver<(usize, Result<(PathComponent, Node), crate::Error>)>>>,
),
>,
>,
next_dir_handle: AtomicU64,
/// This holds all open file handles
#[allow(clippy::type_complexity)]
file_handles: RwLock<HashMap<u64, (Span, Arc<Mutex<Box<dyn BlobReader>>>)>>,
next_file_handle: AtomicU64,
tokio_handle: tokio::runtime::Handle,
}
impl<BS, DS, RN> TvixStoreFs<BS, DS, RN>
where
BS: AsRef<dyn BlobService> + Clone + Send,
DS: AsRef<dyn DirectoryService> + Clone + Send + 'static,
RN: RootNodes + Clone + 'static,
{
pub fn new(
blob_service: BS,
directory_service: DS,
root_nodes_provider: RN,
list_root: bool,
show_xattr: bool,
) -> Self {
Self {
blob_service,
directory_service,
root_nodes_provider,
list_root,
show_xattr,
root_nodes: RwLock::new(HashMap::default()),
inode_tracker: RwLock::new(Default::default()),
dir_handles: RwLock::new(Default::default()),
next_dir_handle: AtomicU64::new(1),
file_handles: RwLock::new(Default::default()),
next_file_handle: AtomicU64::new(1),
tokio_handle: tokio::runtime::Handle::current(),
}
}
/// Retrieves the inode for a given root node basename, if present.
/// This obtains a read lock on self.root_nodes.
fn get_inode_for_root_name(&self, name: &PathComponent) -> Option<u64> {
self.root_nodes.read().get(name).cloned()
}
/// For a given inode, look up the given directory behind it (from
/// self.inode_tracker), and return its children.
/// The inode_tracker MUST know about this inode already, and it MUST point
/// to a [InodeData::Directory].
/// It is ok if it's a [DirectoryInodeData::Sparse] - in that case, a lookup
/// in self.directory_service is performed, and self.inode_tracker is updated with the
/// [DirectoryInodeData::Populated].
#[allow(clippy::type_complexity)]
#[instrument(skip(self), err)]
fn get_directory_children(
&self,
ino: u64,
) -> io::Result<(B3Digest, Vec<(u64, PathComponent, Node)>)> {
let data = self.inode_tracker.read().get(ino).unwrap();
match *data {
// if it's populated already, return children.
InodeData::Directory(DirectoryInodeData::Populated(
ref parent_digest,
ref children,
)) => Ok((parent_digest.clone(), children.clone())),
// if it's sparse, fetch data using directory_service, populate child nodes
// and update it in [self.inode_tracker].
InodeData::Directory(DirectoryInodeData::Sparse(ref parent_digest, _)) => {
let directory = self
.tokio_handle
.block_on({
let directory_service = self.directory_service.clone();
let parent_digest = parent_digest.to_owned();
async move { directory_service.as_ref().get(&parent_digest).await }
})?
.ok_or_else(|| {
warn!(directory.digest=%parent_digest, "directory not found");
// If the Directory can't be found, this is a hole, bail out.
io::Error::from_raw_os_error(libc::EIO)
})?;
// Turn the retrieved directory into a InodeData::Directory(DirectoryInodeData::Populated(..)),
// allocating inodes for the children on the way.
// FUTUREWORK: there's a bunch of cloning going on here, which we can probably avoid.
let children = {
let mut inode_tracker = self.inode_tracker.write();
let children: Vec<(u64, PathComponent, Node)> = directory
.into_nodes()
.map(|(child_name, child_node)| {
let inode_data = InodeData::from_node(&child_node);
let child_ino = inode_tracker.put(inode_data);
(child_ino, child_name, child_node)
})
.collect();
// replace.
inode_tracker.replace(
ino,
Arc::new(InodeData::Directory(DirectoryInodeData::Populated(
parent_digest.clone(),
children.clone(),
))),
);
children
};
Ok((parent_digest.clone(), children))
}
// if the parent inode was not a directory, this doesn't make sense
InodeData::Regular(..) | InodeData::Symlink(_) => {
Err(io::Error::from_raw_os_error(libc::ENOTDIR))
}
}
}
/// This will turn a lookup request for a name in the root to a ino and
/// [InodeData].
/// It will peek in [self.root_nodes], and then either look it up from
/// [self.inode_tracker],
/// or otherwise fetch from [self.root_nodes], and then insert into
/// [self.inode_tracker].
/// In the case the name can't be found, a libc::ENOENT is returned.
fn name_in_root_to_ino_and_data(
&self,
name: &PathComponent,
) -> io::Result<(u64, Arc<InodeData>)> {
// Look up the inode for that root node.
// If there's one, [self.inode_tracker] MUST also contain the data,
// which we can then return.
if let Some(inode) = self.get_inode_for_root_name(name) {
return Ok((
inode,
self.inode_tracker
.read()
.get(inode)
.expect("must exist")
.to_owned(),
));
}
// We don't have it yet, look it up in [self.root_nodes].
match self.tokio_handle.block_on({
let root_nodes_provider = self.root_nodes_provider.clone();
let name = name.clone();
async move { root_nodes_provider.get_by_basename(&name).await }
}) {
// if there was an error looking up the root node, propagate up an IO error.
Err(_e) => Err(io::Error::from_raw_os_error(libc::EIO)),
// the root node doesn't exist, so the file doesn't exist.
Ok(None) => Err(io::Error::from_raw_os_error(libc::ENOENT)),
// The root node does exist
Ok(Some(root_node)) => {
// Let's check if someone else beat us to updating the inode tracker and
// root_nodes map. This avoids locking inode_tracker for writing.
if let Some(ino) = self.root_nodes.read().get(name) {
return Ok((
*ino,
self.inode_tracker.read().get(*ino).expect("must exist"),
));
}
// Only in case it doesn't, lock [self.root_nodes] and
// [self.inode_tracker] for writing.
let mut root_nodes = self.root_nodes.write();
let mut inode_tracker = self.inode_tracker.write();
// insert the (sparse) inode data and register in
// self.root_nodes.
let inode_data = InodeData::from_node(&root_node);
let ino = inode_tracker.put(inode_data.clone());
root_nodes.insert(name.to_owned(), ino);
Ok((ino, Arc::new(inode_data)))
}
}
}
}
/// Buffer size of the channel providing nodes in the mount root
const ROOT_NODES_BUFFER_SIZE: usize = 16;
const XATTR_NAME_DIRECTORY_DIGEST: &[u8] = b"user.tvix.castore.directory.digest";
const XATTR_NAME_BLOB_DIGEST: &[u8] = b"user.tvix.castore.blob.digest";
impl<BS, DS, RN> FileSystem for TvixStoreFs<BS, DS, RN>
where
BS: AsRef<dyn BlobService> + Clone + Send + 'static,
DS: AsRef<dyn DirectoryService> + Send + Clone + 'static,
RN: RootNodes + Clone + 'static,
{
type Handle = u64;
type Inode = u64;
fn init(&self, _capable: FsOptions) -> io::Result<FsOptions> {
Ok(FsOptions::empty())
}
#[tracing::instrument(skip_all, fields(rq.inode = inode))]
fn getattr(
&self,
_ctx: &Context,
inode: Self::Inode,
_handle: Option<Self::Handle>,
) -> io::Result<(stat64, Duration)> {
if inode == ROOT_ID {
return Ok((ROOT_FILE_ATTR.into(), Duration::MAX));
}
match self.inode_tracker.read().get(inode) {
None => Err(io::Error::from_raw_os_error(libc::ENOENT)),
Some(inode_data) => {
debug!(inode_data = ?inode_data, "found node");
Ok((inode_data.as_fuse_file_attr(inode).into(), Duration::MAX))
}
}
}
#[tracing::instrument(skip_all, fields(rq.parent_inode = parent, rq.name = ?name))]
fn lookup(
&self,
_ctx: &Context,
parent: Self::Inode,
name: &std::ffi::CStr,
) -> io::Result<fuse_backend_rs::api::filesystem::Entry> {
debug!("lookup");
// convert the CStr to a PathComponent
// If it can't be converted, we definitely don't have anything here.
let name: PathComponent = name.try_into().map_err(|_| std::io::ErrorKind::NotFound)?;
// This goes from a parent inode to a node.
// - If the parent is [ROOT_ID], we need to check
// [self.root_nodes] (fetching from a [RootNode] provider if needed)
// - Otherwise, lookup the parent in [self.inode_tracker] (which must be
// a [InodeData::Directory]), and find the child with that name.
if parent == ROOT_ID {
let (ino, inode_data) = self.name_in_root_to_ino_and_data(&name)?;
debug!(inode_data=?&inode_data, ino=ino, "Some");
return Ok(inode_data.as_fuse_entry(ino));
}
// This is the "lookup for "a" inside inode 42.
// We already know that inode 42 must be a directory.
let (parent_digest, children) = self.get_directory_children(parent)?;
Span::current().record("directory.digest", parent_digest.to_string());
// Search for that name in the list of children and return the FileAttrs.
// in the children, find the one with the desired name.
if let Some((child_ino, _, _)) = children.iter().find(|(_, n, _)| n == &name) {
// lookup the child [InodeData] in [self.inode_tracker].
// We know the inodes for children have already been allocated.
let child_inode_data = self.inode_tracker.read().get(*child_ino).unwrap();
// Reply with the file attributes for the child.
// For child directories, we still have all data we need to reply.
Ok(child_inode_data.as_fuse_entry(*child_ino))
} else {
// Child not found, return ENOENT.
Err(io::Error::from_raw_os_error(libc::ENOENT))
}
}
#[tracing::instrument(skip_all, fields(rq.inode = inode))]
fn opendir(
&self,
_ctx: &Context,
inode: Self::Inode,
_flags: u32,
) -> io::Result<(Option<Self::Handle>, OpenOptions)> {
// In case opendir on the root is called, we provide the handle, as re-entering that listing is expensive.
// For all other directory inodes we just let readdir take care of it.
if inode == ROOT_ID {
if !self.list_root {
return Err(io::Error::from_raw_os_error(libc::EPERM)); // same error code as ipfs/kubo
}
let root_nodes_provider = self.root_nodes_provider.clone();
let (tx, rx) = mpsc::channel(ROOT_NODES_BUFFER_SIZE);
// This task will run in the background immediately and will exit
// after the stream ends or if we no longer want any more entries.
self.tokio_handle.spawn(
async move {
let mut stream = root_nodes_provider.list().enumerate();
while let Some(e) = stream.next().await {
if tx.send(e).await.is_err() {
// If we get a send error, it means the sync code
// doesn't want any more entries.
break;
}
}
}
// instrument the task with the current span, this is not done by default
.in_current_span(),
);
// Put the rx part into [self.dir_handles].
// TODO: this will overflow after 2**64 operations,
// which is fine for now.
// See https://cl.tvl.fyi/c/depot/+/8834/comment/a6684ce0_d72469d1
// for the discussion on alternatives.
let dh = self.next_dir_handle.fetch_add(1, Ordering::SeqCst);
self.dir_handles
.write()
.insert(dh, (Span::current(), Arc::new(Mutex::new(rx))));
return Ok((
Some(dh),
fuse_backend_rs::api::filesystem::OpenOptions::empty(), // TODO: non-seekable
));
}
Ok((None, OpenOptions::empty()))
}
#[tracing::instrument(skip_all, fields(rq.inode = inode, rq.handle = handle, rq.offset = offset), parent = self.dir_handles.read().get(&handle).and_then(|x| x.0.id()))]
fn readdir(
&self,
_ctx: &Context,
inode: Self::Inode,
handle: Self::Handle,
_size: u32,
offset: u64,
add_entry: &mut dyn FnMut(fuse_backend_rs::api::filesystem::DirEntry) -> io::Result<usize>,
) -> io::Result<()> {
debug!("readdir");
if inode == ROOT_ID {
if !self.list_root {
return Err(io::Error::from_raw_os_error(libc::EPERM)); // same error code as ipfs/kubo
}
// get the handle from [self.dir_handles]
let (_span, rx) = match self.dir_handles.read().get(&handle) {
Some(rx) => rx.clone(),
None => {
warn!("dir handle {} unknown", handle);
return Err(io::Error::from_raw_os_error(libc::EIO));
}
};
let mut rx = rx
.lock()
.map_err(|_| crate::Error::StorageError("mutex poisoned".into()))?;
while let Some((i, n)) = rx.blocking_recv() {
let (name, node) = n.map_err(|e| {
warn!("failed to retrieve root node: {}", e);
io::Error::from_raw_os_error(libc::EIO)
})?;
let inode_data = InodeData::from_node(&node);
// obtain the inode, or allocate a new one.
let ino = self.get_inode_for_root_name(&name).unwrap_or_else(|| {
// insert the (sparse) inode data and register in
// self.root_nodes.
let ino = self.inode_tracker.write().put(inode_data.clone());
self.root_nodes.write().insert(name.clone(), ino);
ino
});
let written = add_entry(fuse_backend_rs::api::filesystem::DirEntry {
ino,
offset: offset + (i as u64) + 1,
type_: inode_data.as_fuse_type(),
name: name.as_ref(),
})?;
// If the buffer is full, add_entry will return `Ok(0)`.
if written == 0 {
break;
}
}
return Ok(());
}
// Non root-node case: lookup the children, or return an error if it's not a directory.
let (parent_digest, children) = self.get_directory_children(inode)?;
Span::current().record("directory.digest", parent_digest.to_string());
for (i, (ino, child_name, child_node)) in
children.into_iter().skip(offset as usize).enumerate()
{
let inode_data = InodeData::from_node(&child_node);
// the second parameter will become the "offset" parameter on the next call.
let written = add_entry(fuse_backend_rs::api::filesystem::DirEntry {
ino,
offset: offset + (i as u64) + 1,
type_: inode_data.as_fuse_type(),
name: child_name.as_ref(),
})?;
// If the buffer is full, add_entry will return `Ok(0)`.
if written == 0 {
break;
}
}
Ok(())
}
#[tracing::instrument(skip_all, fields(rq.inode = inode, rq.handle = handle), parent = self.dir_handles.read().get(&handle).and_then(|x| x.0.id()))]
fn readdirplus(
&self,
_ctx: &Context,
inode: Self::Inode,
handle: Self::Handle,
_size: u32,
offset: u64,
add_entry: &mut dyn FnMut(
fuse_backend_rs::api::filesystem::DirEntry,
fuse_backend_rs::api::filesystem::Entry,
) -> io::Result<usize>,
) -> io::Result<()> {
debug!("readdirplus");
if inode == ROOT_ID {
if !self.list_root {
return Err(io::Error::from_raw_os_error(libc::EPERM)); // same error code as ipfs/kubo
}
// get the handle from [self.dir_handles]
let (_span, rx) = match self.dir_handles.read().get(&handle) {
Some(rx) => rx.clone(),
None => {
warn!("dir handle {} unknown", handle);
return Err(io::Error::from_raw_os_error(libc::EIO));
}
};
let mut rx = rx
.lock()
.map_err(|_| crate::Error::StorageError("mutex poisoned".into()))?;
while let Some((i, n)) = rx.blocking_recv() {
let (name, node) = n.map_err(|e| {
warn!("failed to retrieve root node: {}", e);
io::Error::from_raw_os_error(libc::EPERM)
})?;
let inode_data = InodeData::from_node(&node);
// obtain the inode, or allocate a new one.
let ino = self.get_inode_for_root_name(&name).unwrap_or_else(|| {
// insert the (sparse) inode data and register in
// self.root_nodes.
let ino = self.inode_tracker.write().put(inode_data.clone());
self.root_nodes.write().insert(name.clone(), ino);
ino
});
let written = add_entry(
fuse_backend_rs::api::filesystem::DirEntry {
ino,
offset: offset + (i as u64) + 1,
type_: inode_data.as_fuse_type(),
name: name.as_ref(),
},
inode_data.as_fuse_entry(ino),
)?;
// If the buffer is full, add_entry will return `Ok(0)`.
if written == 0 {
break;
}
}
return Ok(());
}
// Non root-node case: lookup the children, or return an error if it's not a directory.
let (parent_digest, children) = self.get_directory_children(inode)?;
Span::current().record("directory.digest", parent_digest.to_string());
for (i, (ino, name, child_node)) in children.into_iter().skip(offset as usize).enumerate() {
let inode_data = InodeData::from_node(&child_node);
// the second parameter will become the "offset" parameter on the next call.
let written = add_entry(
fuse_backend_rs::api::filesystem::DirEntry {
ino,
offset: offset + (i as u64) + 1,
type_: inode_data.as_fuse_type(),
name: name.as_ref(),
},
inode_data.as_fuse_entry(ino),
)?;
// If the buffer is full, add_entry will return `Ok(0)`.
if written == 0 {
break;
}
}
Ok(())
}
#[tracing::instrument(skip_all, fields(rq.inode = inode, rq.handle = handle), parent = self.dir_handles.read().get(&handle).and_then(|x| x.0.id()))]
fn releasedir(
&self,
_ctx: &Context,
inode: Self::Inode,
_flags: u32,
handle: Self::Handle,
) -> io::Result<()> {
if inode == ROOT_ID {
// drop the rx part of the channel.
match self.dir_handles.write().remove(&handle) {
// drop it, which will close it.
Some(rx) => drop(rx),
None => {
warn!("dir handle not found");
}
}
}
Ok(())
}
#[tracing::instrument(skip_all, fields(rq.inode = inode))]
fn open(
&self,
_ctx: &Context,
inode: Self::Inode,
_flags: u32,
_fuse_flags: u32,
) -> io::Result<(
Option<Self::Handle>,
fuse_backend_rs::api::filesystem::OpenOptions,
)> {
if inode == ROOT_ID {
return Err(io::Error::from_raw_os_error(libc::ENOSYS));
}
// lookup the inode
match *self.inode_tracker.read().get(inode).unwrap() {
// read is invalid on non-files.
InodeData::Directory(..) | InodeData::Symlink(_) => {
warn!("is directory");
Err(io::Error::from_raw_os_error(libc::EISDIR))
}
InodeData::Regular(ref blob_digest, _blob_size, _) => {
Span::current().record("blob.digest", blob_digest.to_string());
match self.tokio_handle.block_on({
let blob_service = self.blob_service.clone();
let blob_digest = blob_digest.clone();
async move { blob_service.as_ref().open_read(&blob_digest).await }
}) {
Ok(None) => {
warn!("blob not found");
Err(io::Error::from_raw_os_error(libc::EIO))
}
Err(e) => {
warn!(e=?e, "error opening blob");
Err(io::Error::from_raw_os_error(libc::EIO))
}
Ok(Some(blob_reader)) => {
// get a new file handle
// TODO: this will overflow after 2**64 operations,
// which is fine for now.
// See https://cl.tvl.fyi/c/depot/+/8834/comment/a6684ce0_d72469d1
// for the discussion on alternatives.
let fh = self.next_file_handle.fetch_add(1, Ordering::SeqCst);
self.file_handles
.write()
.insert(fh, (Span::current(), Arc::new(Mutex::new(blob_reader))));
Ok((
Some(fh),
fuse_backend_rs::api::filesystem::OpenOptions::empty(),
))
}
}
}
}
}
#[tracing::instrument(skip_all, fields(rq.inode = inode, rq.handle = handle), parent = self.file_handles.read().get(&handle).and_then(|x| x.0.id()))]
fn release(
&self,
_ctx: &Context,
inode: Self::Inode,
_flags: u32,
handle: Self::Handle,
_flush: bool,
_flock_release: bool,
_lock_owner: Option<u64>,
) -> io::Result<()> {
match self.file_handles.write().remove(&handle) {
// drop the blob reader, which will close it.
Some(blob_reader) => drop(blob_reader),
None => {
// These might already be dropped if a read error occured.
warn!("file handle not found");
}
}
Ok(())
}
#[tracing::instrument(skip_all, fields(rq.inode = inode, rq.handle = handle, rq.offset = offset, rq.size = size), parent = self.file_handles.read().get(&handle).and_then(|x| x.0.id()))]
fn read(
&self,
_ctx: &Context,
inode: Self::Inode,
handle: Self::Handle,
w: &mut dyn fuse_backend_rs::api::filesystem::ZeroCopyWriter,
size: u32,
offset: u64,
_lock_owner: Option<u64>,
_flags: u32,
) -> io::Result<usize> {
debug!("read");
// We need to take out the blob reader from self.file_handles, so we can
// interact with it in the separate task.
// On success, we pass it back out of the task, so we can put it back in self.file_handles.
let (_span, blob_reader) = self
.file_handles
.read()
.get(&handle)
.ok_or_else(|| {
warn!("file handle {} unknown", handle);
io::Error::from_raw_os_error(libc::EIO)
})
.cloned()?;
let mut blob_reader = blob_reader
.lock()
.map_err(|_| crate::Error::StorageError("mutex poisoned".into()))?;
let buf = self.tokio_handle.block_on(async move {
// seek to the offset specified, which is relative to the start of the file.
let pos = blob_reader
.seek(io::SeekFrom::Start(offset))
.await
.map_err(|e| {
warn!("failed to seek to offset {}: {}", offset, e);
io::Error::from_raw_os_error(libc::EIO)
})?;
debug_assert_eq!(offset, pos);
// As written in the fuse docs, read should send exactly the number
// of bytes requested except on EOF or error.
let mut buf: Vec<u8> = Vec::with_capacity(size as usize);
// copy things from the internal buffer into buf to fill it till up until size
tokio::io::copy(&mut blob_reader.as_mut().take(size as u64), &mut buf).await?;
Ok::<_, std::io::Error>(buf)
})?;
// We cannot use w.write() here, we're required to call write multiple
// times until we wrote the entirety of the buffer (which is `size`, except on EOF).
let buf_len = buf.len();
let bytes_written = io::copy(&mut Cursor::new(buf), w)?;
if bytes_written != buf_len as u64 {
error!(bytes_written=%bytes_written, "unable to write all of buf to kernel");
return Err(io::Error::from_raw_os_error(libc::EIO));
}
Ok(bytes_written as usize)
}
#[tracing::instrument(skip_all, fields(rq.inode = inode))]
fn readlink(&self, _ctx: &Context, inode: Self::Inode) -> io::Result<Vec<u8>> {
if inode == ROOT_ID {
return Err(io::Error::from_raw_os_error(libc::ENOSYS));
}
// lookup the inode
match *self.inode_tracker.read().get(inode).unwrap() {
InodeData::Directory(..) | InodeData::Regular(..) => {
Err(io::Error::from_raw_os_error(libc::EINVAL))
}
InodeData::Symlink(ref target) => Ok(target.to_vec()),
}
}
#[tracing::instrument(skip_all, fields(rq.inode = inode, name=?name))]
fn getxattr(
&self,
_ctx: &Context,
inode: Self::Inode,
name: &CStr,
size: u32,
) -> io::Result<GetxattrReply> {
if !self.show_xattr {
return Err(io::Error::from_raw_os_error(libc::ENOSYS));
}
// Peek at the inode requested, and construct the response.
let digest_str = match *self
.inode_tracker
.read()
.get(inode)
.ok_or_else(|| io::Error::from_raw_os_error(libc::ENODATA))?
{
InodeData::Directory(DirectoryInodeData::Sparse(ref digest, _))
| InodeData::Directory(DirectoryInodeData::Populated(ref digest, _))
if name.to_bytes() == XATTR_NAME_DIRECTORY_DIGEST =>
{
digest.to_string()
}
InodeData::Regular(ref digest, _, _) if name.to_bytes() == XATTR_NAME_BLOB_DIGEST => {
digest.to_string()
}
_ => {
return Err(io::Error::from_raw_os_error(libc::ENODATA));
}
};
if size == 0 {
Ok(GetxattrReply::Count(digest_str.len() as u32))
} else if size < digest_str.len() as u32 {
Err(io::Error::from_raw_os_error(libc::ERANGE))
} else {
Ok(GetxattrReply::Value(digest_str.into_bytes()))
}
}
#[tracing::instrument(skip_all, fields(rq.inode = inode))]
fn listxattr(
&self,
_ctx: &Context,
inode: Self::Inode,
size: u32,
) -> io::Result<ListxattrReply> {
if !self.show_xattr {
return Err(io::Error::from_raw_os_error(libc::ENOSYS));
}
// determine the (\0-terminated list) to of xattr keys present, depending on the type of the inode.
let xattrs_names = {
let mut out = Vec::new();
if let Some(inode_data) = self.inode_tracker.read().get(inode) {
match *inode_data {
InodeData::Directory(_) => {
out.extend_from_slice(XATTR_NAME_DIRECTORY_DIGEST);
out.push_byte(b'\x00');
}
InodeData::Regular(..) => {
out.extend_from_slice(XATTR_NAME_BLOB_DIGEST);
out.push_byte(b'\x00');
}
_ => {}
}
}
out
};
if size == 0 {
Ok(ListxattrReply::Count(xattrs_names.len() as u32))
} else if size < xattrs_names.len() as u32 {
Err(io::Error::from_raw_os_error(libc::ERANGE))
} else {
Ok(ListxattrReply::Names(xattrs_names.to_vec()))
}
}
}
