444 lines
15 KiB
Rust
444 lines
15 KiB
Rust
//! Scope-aware filesystem primitive.
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//!
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//! `ScopedFs` is the write/read gate layered on top of a [`manifest::Scope`]
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//! and a Pod's working directory. The scope decides which paths are
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//! readable and writable; the pwd is carried alongside for convenience
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//! (Glob/Grep default their search base to it).
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//!
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//! `ScopedFs` is cheap to clone (`Arc` inside) and carries no per-session
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//! state — the read-before-edit policy lives separately in
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//! [`crate::Tracker`].
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use std::io::Write as _;
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use std::path::{Path, PathBuf};
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use std::sync::Arc;
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use manifest::{Scope, SharedScope};
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use crate::error::ToolsError;
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#[derive(Debug)]
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struct ScopedFsInner {
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scope: SharedScope,
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pwd: PathBuf,
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}
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/// Scope-aware filesystem handle. Clone-cheap (`Arc` inside).
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///
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/// The wrapped [`SharedScope`] is shared with every clone of this
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/// `ScopedFs` and with whoever else holds the same `SharedScope`
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/// handle (typically the owning Pod). Mutations to that `SharedScope`
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/// propagate atomically; the next permission check inside any
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/// `ScopedFs` reads the new view.
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#[derive(Debug, Clone)]
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pub struct ScopedFs {
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inner: Arc<ScopedFsInner>,
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}
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/// Outcome of a [`ScopedFs::write`] call.
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#[derive(Debug, Clone, Copy)]
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pub struct WriteOutcome {
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pub bytes_written: usize,
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pub created: bool,
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}
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impl ScopedFs {
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/// Create a new [`ScopedFs`] wrapping `scope` and `pwd` in a fresh
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/// [`SharedScope`]. Use [`ScopedFs::with_shared_scope`] when you
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/// need the resulting `ScopedFs` to share scope state with another
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/// holder of the `SharedScope` (typically the Pod).
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pub fn new(scope: Scope, pwd: PathBuf) -> Self {
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Self::with_shared_scope(SharedScope::new(scope), pwd)
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}
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/// Build a [`ScopedFs`] over an existing [`SharedScope`]. The
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/// resulting handle and any future updates the caller pushes to
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/// `scope` are observed by every clone of this `ScopedFs`.
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pub fn with_shared_scope(scope: SharedScope, pwd: PathBuf) -> Self {
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Self {
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inner: Arc::new(ScopedFsInner { scope, pwd }),
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}
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}
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/// Snapshot the current scope. Cheap; the returned `Arc<Scope>` is
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/// a coherent point-in-time view that subsequent mutations do not
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/// affect.
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pub fn scope(&self) -> Arc<Scope> {
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self.inner.scope.snapshot()
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}
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/// Shared scope handle backing this `ScopedFs`. Cloning it lets a
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/// caller (usually the Pod) hold the same view and push updates
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/// that are immediately reflected in subsequent permission checks.
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pub fn shared_scope(&self) -> &SharedScope {
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&self.inner.scope
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}
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/// The Pod's working directory. Glob/Grep default their search base
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/// to this path when callers omit an explicit `path` parameter.
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pub fn pwd(&self) -> &Path {
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&self.inner.pwd
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}
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// =========================================================================
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// Read — scope-checked against readability
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// =========================================================================
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/// Read the full contents of `path` as raw bytes.
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///
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/// Follows symlinks. Rejects directories, relative paths, paths not
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/// readable by the scope, and missing files.
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pub fn read_bytes(&self, path: &Path) -> Result<Vec<u8>, ToolsError> {
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if !path.is_absolute() {
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return Err(ToolsError::RelativePath(path.to_path_buf()));
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}
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if !self.inner.scope.load().is_readable(path) {
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return Err(ToolsError::OutOfScope(path.to_path_buf()));
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}
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let meta = std::fs::metadata(path).map_err(|e| match e.kind() {
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std::io::ErrorKind::NotFound => ToolsError::NotFound(path.to_path_buf()),
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_ => ToolsError::io(path, e),
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})?;
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if meta.is_dir() {
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return Err(ToolsError::IsDirectory(path.to_path_buf()));
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}
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std::fs::read(path).map_err(|e| ToolsError::io(path, e))
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}
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// =========================================================================
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// Write — scope-checked, atomic
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// =========================================================================
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/// Atomically write `content` to `path`, creating or overwriting it.
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///
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/// - `path` must be absolute and writable under the scope.
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/// - Paths that are readable but not writable return [`ToolsError::ReadOnly`].
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/// - Paths outside the scope entirely return [`ToolsError::OutOfScope`].
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/// - Missing parent directories are created.
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/// - The actual write uses a sibling tempfile + `persist`, so the
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/// target file transitions atomically between states.
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///
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/// This method does **not** consult any read history. Callers that
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/// want the "must read before overwrite" policy should verify with a
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/// [`Tracker`](crate::Tracker) beforehand.
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pub fn write(&self, path: &Path, content: &[u8]) -> Result<WriteOutcome, ToolsError> {
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if !path.is_absolute() {
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return Err(ToolsError::RelativePath(path.to_path_buf()));
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}
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let scope = self.inner.scope.load();
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if !scope.is_writable(path) {
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return Err(if scope.is_readable(path) {
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ToolsError::ReadOnly(path.to_path_buf())
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} else {
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ToolsError::OutOfScope(path.to_path_buf())
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});
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}
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drop(scope);
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// Reject existing directory targets.
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match std::fs::metadata(path) {
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Ok(meta) if meta.is_dir() => {
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return Err(ToolsError::IsDirectory(path.to_path_buf()));
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}
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_ => {}
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}
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let existed = path.exists();
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let parent = path.parent().ok_or_else(|| {
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ToolsError::InvalidArgument(format!("path has no parent directory: {}", path.display()))
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})?;
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if !parent.as_os_str().is_empty() && !parent.exists() {
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std::fs::create_dir_all(parent).map_err(|e| ToolsError::io(parent, e))?;
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}
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let tmp_parent: &Path = if parent.as_os_str().is_empty() {
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Path::new(".")
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} else {
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parent
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};
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let mut tmp = tempfile::NamedTempFile::new_in(tmp_parent)
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.map_err(|e| ToolsError::io(tmp_parent, e))?;
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tmp.write_all(content)
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.map_err(|e| ToolsError::io(path, e))?;
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tmp.as_file()
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.sync_all()
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.map_err(|e| ToolsError::io(path, e))?;
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tmp.persist(path)
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.map_err(|e| ToolsError::io(path, e.error))?;
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Ok(WriteOutcome {
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bytes_written: content.len(),
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created: !existed,
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})
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}
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}
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// =============================================================================
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// Tests
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// =============================================================================
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#[cfg(test)]
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mod tests {
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use super::*;
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use manifest::{Permission, ScopeConfig, ScopeRule};
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use std::fs;
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use tempfile::TempDir;
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fn make_fs(dir: &TempDir) -> ScopedFs {
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ScopedFs::new(
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Scope::writable(dir.path()).unwrap(),
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dir.path().to_path_buf(),
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)
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}
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// -------------------------------------------------------------------------
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// read_bytes
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// -------------------------------------------------------------------------
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#[test]
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fn read_bytes_returns_content() {
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let dir = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let file = dir.path().join("a.txt");
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fs::write(&file, b"abc").unwrap();
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assert_eq!(fs.read_bytes(&file).unwrap(), b"abc");
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}
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#[test]
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fn read_bytes_rejects_relative() {
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let dir = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let err = fs.read_bytes(Path::new("rel.txt")).unwrap_err();
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assert!(matches!(err, ToolsError::RelativePath(_)));
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}
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#[test]
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fn read_bytes_rejects_directory() {
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let dir = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let err = fs.read_bytes(dir.path()).unwrap_err();
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assert!(matches!(err, ToolsError::IsDirectory(_)));
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}
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#[test]
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fn read_bytes_rejects_missing() {
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let dir = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let err = fs.read_bytes(&dir.path().join("nope.txt")).unwrap_err();
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assert!(matches!(err, ToolsError::NotFound(_)));
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}
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#[test]
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fn read_bytes_rejects_paths_outside_scope() {
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let dir = TempDir::new().unwrap();
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let outside = TempDir::new().unwrap();
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let outside_file = outside.path().join("x.txt");
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fs::write(&outside_file, b"hi").unwrap();
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let scoped = make_fs(&dir);
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let err = scoped.read_bytes(&outside_file).unwrap_err();
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assert!(matches!(err, ToolsError::OutOfScope(_)));
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}
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// -------------------------------------------------------------------------
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// write
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// -------------------------------------------------------------------------
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#[test]
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fn write_creates_new_file() {
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let dir = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let file = dir.path().join("new.txt");
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let out = fs.write(&file, b"hello").unwrap();
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assert!(out.created);
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assert_eq!(out.bytes_written, 5);
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assert_eq!(fs::read(&file).unwrap(), b"hello");
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}
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#[test]
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fn write_overwrites_existing() {
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let dir = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let file = dir.path().join("a.txt");
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fs::write(&file, b"old").unwrap();
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let out = fs.write(&file, b"new").unwrap();
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assert!(!out.created);
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assert_eq!(fs::read(&file).unwrap(), b"new");
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}
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#[test]
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fn write_rejects_out_of_scope() {
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let dir = TempDir::new().unwrap();
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let outside = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let err = fs.write(&outside.path().join("x"), b"x").unwrap_err();
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assert!(matches!(err, ToolsError::OutOfScope(_)));
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}
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#[test]
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fn write_rejects_readonly_path() {
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let dir = TempDir::new().unwrap();
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let sub = dir.path().join("sub");
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fs::create_dir(&sub).unwrap();
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let cfg = ScopeConfig {
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allow: vec![ScopeRule {
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target: dir.path().to_path_buf(),
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permission: Permission::Write,
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recursive: true,
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}],
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deny: vec![ScopeRule {
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target: sub.clone(),
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permission: Permission::Write,
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recursive: true,
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}],
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};
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let scope = Scope::from_config(&cfg).unwrap();
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let scoped = ScopedFs::new(scope, dir.path().to_path_buf());
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let err = scoped.write(&sub.join("locked.txt"), b"x").unwrap_err();
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assert!(
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matches!(err, ToolsError::ReadOnly(_)),
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"expected ReadOnly, got {err:?}"
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);
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}
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#[test]
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fn write_rejects_relative_path() {
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let dir = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let err = fs.write(Path::new("rel.txt"), b"x").unwrap_err();
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assert!(matches!(err, ToolsError::RelativePath(_)));
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}
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#[test]
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fn write_creates_missing_parents_inside_scope() {
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let dir = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let nested = dir.path().join("a/b/c/deep.txt");
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fs.write(&nested, b"x").unwrap();
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assert_eq!(fs::read(&nested).unwrap(), b"x");
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}
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#[test]
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fn write_rejects_directory_target() {
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let dir = TempDir::new().unwrap();
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let fs = make_fs(&dir);
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let err = fs.write(dir.path(), b"x").unwrap_err();
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assert!(matches!(err, ToolsError::IsDirectory(_)));
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}
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// -------------------------------------------------------------------------
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// Dynamic scope: SharedScope mutations propagate into ScopedFs decisions
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// -------------------------------------------------------------------------
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#[test]
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fn add_allow_rule_through_shared_scope_grows_readable_set() {
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use manifest::SharedScope;
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let dir = TempDir::new().unwrap();
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let extra = TempDir::new().unwrap();
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let extra_file = extra.path().join("x.txt");
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fs::write(&extra_file, b"hi").unwrap();
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let shared = SharedScope::new(Scope::writable(dir.path()).unwrap());
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let fs = ScopedFs::with_shared_scope(shared.clone(), dir.path().to_path_buf());
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// Before: extra is out of scope.
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let err = fs.read_bytes(&extra_file).unwrap_err();
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assert!(matches!(err, ToolsError::OutOfScope(_)));
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// Push an allow(Read) rule.
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shared
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.update(|cur| {
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cur.with_added_allow_rules([ScopeRule {
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target: extra.path().to_path_buf(),
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permission: Permission::Read,
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recursive: true,
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}])
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})
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.unwrap();
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// After: read goes through.
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assert_eq!(fs.read_bytes(&extra_file).unwrap(), b"hi");
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// But write still fails — allow only granted Read.
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let err = fs.write(&extra.path().join("y.txt"), b"x").unwrap_err();
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assert!(
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matches!(err, ToolsError::ReadOnly(_)),
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"expected ReadOnly, got {err:?}"
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);
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}
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#[test]
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fn revoke_write_through_shared_scope_blocks_subsequent_writes() {
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use manifest::SharedScope;
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let dir = TempDir::new().unwrap();
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let sub = dir.path().join("sub");
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fs::create_dir(&sub).unwrap();
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let target = sub.join("a.txt");
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let shared = SharedScope::new(Scope::writable(dir.path()).unwrap());
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let fs = ScopedFs::with_shared_scope(shared.clone(), dir.path().to_path_buf());
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// Write succeeds initially.
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fs.write(&target, b"first").unwrap();
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// Revoke Write on `sub` (push a deny(Write) rule).
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shared
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.update(|cur| {
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cur.with_added_deny_rules([ScopeRule {
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target: sub.clone(),
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permission: Permission::Write,
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recursive: true,
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}])
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})
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.unwrap();
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// Subsequent write fails with ReadOnly — Read is preserved.
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let err = fs.write(&target, b"second").unwrap_err();
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assert!(
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matches!(err, ToolsError::ReadOnly(_)),
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"expected ReadOnly after revoke, got {err:?}"
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);
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// Read still works.
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assert_eq!(fs.read_bytes(&target).unwrap(), b"first");
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}
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#[test]
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fn shared_scope_changes_propagate_across_clones() {
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use manifest::SharedScope;
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let dir = TempDir::new().unwrap();
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let target = dir.path().join("a.txt");
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let shared = SharedScope::new(Scope::writable(dir.path()).unwrap());
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let fs1 = ScopedFs::with_shared_scope(shared.clone(), dir.path().to_path_buf());
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let fs2 = fs1.clone();
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// fs1 writes; both clones see the file.
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fs1.write(&target, b"hi").unwrap();
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assert_eq!(fs2.read_bytes(&target).unwrap(), b"hi");
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// Revoke write through the original handle.
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shared
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.update(|cur| {
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cur.with_added_deny_rules([ScopeRule {
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target: dir.path().to_path_buf(),
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permission: Permission::Write,
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recursive: true,
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}])
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})
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.unwrap();
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// Both clones reject writes now — they share the same SharedScope.
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assert!(matches!(
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fs1.write(&target, b"x").unwrap_err(),
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ToolsError::ReadOnly(_)
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));
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assert!(matches!(
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fs2.write(&target, b"x").unwrap_err(),
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ToolsError::ReadOnly(_)
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));
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}
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}
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