127 lines
4.2 KiB
Rust
127 lines
4.2 KiB
Rust
//! Resolves virtual paths before routing them to mounted layers.
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use crate::*;
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use std::{collections::BTreeMap, io::ErrorKind as E};
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struct Mount {
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layer: Arc<dyn Layer>,
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readonly: bool,
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}
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/// A per-process mount namespace. Mount the root before use.
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pub struct Mounts {
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mounts: BTreeMap<String, Mount>,
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observer: observe::Observer,
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}
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impl Default for Mounts {
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fn default() -> Self {
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Self {
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mounts: BTreeMap::new(),
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observer: observe::Observer::new(|_| {}),
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}
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}
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}
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impl Mounts {
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/// Add or replace a mount. Read-only mounts reject every mutation.
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pub fn mount(&mut self, path: &str, layer: Arc<dyn Layer>, readonly: bool) {
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let path = resolve("/", path);
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let layer = self.observer.layer(layer, &path, Process::default());
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self.mounts.insert(path, Mount { layer, readonly });
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}
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pub(crate) async fn metadata_file(&self, path: &str, follow: bool) -> Result<Arc<dyn File>> {
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let (m, p) = self.route(path, true)?;
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m.layer
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.open(
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&p,
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Open {
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follow,
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..Open::default()
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},
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)
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.await
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}
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fn route(&self, path: &str, write: bool) -> Result<(&Mount, String)> {
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let path = resolve("/", path);
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let (base, m) = self
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.mounts
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.iter()
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.filter(|(p, _)| p.as_str() == "/" || path == **p || path.starts_with(&format!("{p}/")))
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.max_by_key(|(p, _)| p.len())
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.ok_or_else(|| error(E::NotFound))?;
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if write && m.readonly {
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return Err(error(E::ReadOnlyFilesystem));
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}
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let rest = if base == "/" {
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path
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} else {
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path[base.len()..].into()
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};
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Ok((m, if rest.is_empty() { "/".into() } else { rest }))
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}
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}
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#[async_trait]
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impl Layer for Mounts {
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fn observer(&self) -> Option<observe::Observer> {
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Some(self.observer.clone())
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}
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async fn stat(&self, path: &str, follow: bool) -> Result<Stat> {
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let (m, p) = self.route(path, false)?;
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m.layer.stat(&p, follow).await
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}
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async fn readlink(&self, path: &str) -> Result<String> {
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let (m, p) = self.route(path, false)?;
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m.layer.readlink(&p).await
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}
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async fn list(&self, path: &str) -> Result<Vec<Entry>> {
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let path = resolve("/", path);
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let (m, p) = self.route(&path, false)?;
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let mut entries = m.layer.list(&p).await?;
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let prefix = if path == "/" {
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"/".into()
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} else {
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format!("{path}/")
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};
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for mount in self.mounts.keys() {
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if let Some(rest) = mount.strip_prefix(&prefix)
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&& !rest.is_empty()
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{
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let name = rest.split('/').next().unwrap();
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entries.retain(|e| e.name != name);
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entries.push(Entry {
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name: name.into(),
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directory: true,
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symlink: false,
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});
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}
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}
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entries.sort_by(|a, b| a.name.cmp(&b.name));
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Ok(entries)
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}
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async fn open(&self, path: &str, options: Open) -> Result<Arc<dyn File>> {
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let (m, p) = self.route(path, options.write || options.create || options.truncate)?;
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let file = m.layer.open(&p, options).await?;
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if m.readonly {
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Ok(Arc::new(crate::readonly::Readonly(file)))
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} else {
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Ok(file)
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}
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}
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async fn mkdir(&self, path: &str) -> Result<()> {
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let (m, p) = self.route(path, true)?;
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m.layer.mkdir(&p).await
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}
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async fn remove_file(&self, path: &str) -> Result<()> {
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let (m, p) = self.route(path, true)?;
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m.layer.remove_file(&p).await
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}
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async fn remove_dir(&self, path: &str) -> Result<()> {
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let (m, p) = self.route(path, true)?;
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m.layer.remove_dir(&p).await
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}
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async fn rename(&self, from: &str, to: &str) -> Result<()> {
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let (a, p) = self.route(from, true)?;
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let (b, q) = self.route(to, true)?;
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if !std::ptr::eq(a, b) {
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return Err(error(E::CrossesDevices));
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}
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a.layer.rename(&p, &q).await
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}
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}
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