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fix(skills): normalize manifest URI keys and skip unreadable entries #1452

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fix(skills): normalize manifest URI keys and skip unreadable entries #1452

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184 changes: 111 additions & 73 deletions crates/rmcp/src/handler/server/skill_catalog.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -125,9 +125,9 @@ const MARKDOWN_MIME_TYPE: &str = "text/markdown";
/// [`reload`](Self::reload) to pick up changes.
///
/// File and directory paths are opened beneath the root without following
/// symlinks. If an entry disappears or changes to an unsupported type when
/// it is opened, the catalog skips the skills that include it and refreshes
/// the others. A hard link inside the root is an ordinary file entry and can
/// symlinks. If an entry below the root cannot be read, disappears, or
/// changes to an unsupported type when it is opened, the catalog skips the
/// skills that include it and refreshes the others. A hard link inside the root is an ordinary file entry and can
/// share its contents with a name outside the root.
/// Entries whose name starts with `.` are ignored, and a skill over
/// [`SKILL_FILE_LIMIT`] files or [`SKILL_BYTE_LIMIT`] bytes is skipped. Skipped
Expand Down Expand Up @@ -293,11 +293,14 @@ impl Snapshot {
source,
}
})?;
let tree = walk(root, &handle)?;
Self::from_walk(root, &handle, &tree)
let tree = walk(&handle).map_err(|source| SkillCatalogError::Io {
path: root.to_path_buf(),
source,
})?;
Ok(Self::from_walk(&handle, &tree))
}

fn from_walk(root: &Path, handle: &Dir, tree: &[Entry]) -> Result<Self, SkillCatalogError> {
fn from_walk(handle: &Dir, tree: &[Entry]) -> Self {
let skill_dirs: BTreeSet<&str> = tree
.iter()
.filter(|entry| is_manifest(entry))
Expand Down Expand Up @@ -337,10 +340,10 @@ impl Snapshot {
let mut cache = FileCache::default();
let mut within_limit: Vec<(&str, &[&Entry])> = Vec::new();
for (dir, entries) in kept {
match read_within_limit(handle, root, entries, &mut cache)? {
match read_within_limit(handle, entries, &mut cache) {
SkillRead::Ready => within_limit.push((dir, entries)),
SkillRead::Changed(path) => tracing::warn!(
skill = %dir, %path, "skipping skill: entry changed after the walk"
SkillRead::Unreadable(path) => tracing::warn!(
skill = %dir, %path, "skipping skill: entry changed or unreadable after the walk"
),
SkillRead::OverLimit => tracing::warn!(
skill = %dir,
Expand Down Expand Up @@ -397,7 +400,7 @@ impl Snapshot {
.collect();
snapshot.directories.insert(uri_of(dir), listing);
}
Ok(snapshot)
snapshot
}
}

Expand Down Expand Up @@ -441,44 +444,40 @@ fn check_walked(entries: &[&Entry]) -> Result<(), String> {
#[derive(Default)]
struct FileCache<'a> {
bytes: HashMap<&'a str, Arc<[u8]>>,
/// All enclosing skills must agree when the same walked file became unavailable.
changed: HashSet<&'a str>,
/// All enclosing skills must agree when the same walked file became unreadable.
unreadable: HashSet<&'a str>,
}

#[derive(Debug, PartialEq, Eq)]
enum SkillRead<'a> {
Ready,
OverLimit,
Changed(&'a str),
Unreadable(&'a str),
}

/// Share complete file reads between nested skills, charging each skill its own byte budget.
fn read_within_limit<'a>(
handle: &Dir,
root: &Path,
entries: &[&'a Entry],
cache: &mut FileCache<'a>,
) -> Result<SkillRead<'a>, SkillCatalogError> {
) -> SkillRead<'a> {
let mut budget = SKILL_BYTE_LIMIT + 1;
for entry in entries.iter().filter(|entry| entry.kind == Kind::File) {
let path = entry.path.as_str();
if cache.changed.contains(path) {
return Ok(SkillRead::Changed(path));
if cache.unreadable.contains(path) {
return SkillRead::Unreadable(path);
}
let len = match cache.bytes.get(path) {
Some(bytes) => bytes.len() as u64,
None => {
let bytes = match read_regular_file(handle, path, budget) {
Ok(bytes) => bytes,
Err(error) if entry_changed(&error) => {
cache.changed.insert(path);
return Ok(SkillRead::Changed(path));
}
Err(source) => {
return Err(SkillCatalogError::Io {
path: root.join(path),
source,
});
Err(error) => {
if !entry_changed(&error) {
tracing::warn!(%path, %error, "cannot read a walked file");
}
cache.unreadable.insert(path);
return SkillRead::Unreadable(path);
}
};
let len = bytes.len() as u64;
Expand All @@ -490,10 +489,10 @@ fn read_within_limit<'a>(
};
budget = budget.saturating_sub(len);
if budget == 0 {
return Ok(SkillRead::OverLimit);
return SkillRead::OverLimit;
}
}
Ok(SkillRead::Ready)
SkillRead::Ready
}

/// Errors a no-follow open can report when a walked component disappears or changes type.
Expand Down Expand Up @@ -623,23 +622,13 @@ fn parse_frontmatter(bytes: &[u8]) -> Result<SkillFrontmatter, String> {
Err("SKILL.md frontmatter has no closing ---".into())
}

/// Every entry below `root` except hidden ones, depth first, by name.
fn walk(root: &Path, handle: &Dir) -> Result<Vec<Entry>, SkillCatalogError> {
fn visit(
root: &Path,
handle: &Dir,
dir: &str,
tree: &mut Vec<Entry>,
) -> Result<(), SkillCatalogError> {
let io_error = |source| SkillCatalogError::Io {
path: root.join(dir),
source,
};
let mut entries = handle
.entries()
.map_err(io_error)?
.collect::<Result<Vec<_>, _>>()
.map_err(io_error)?;
/// Every entry below the root except hidden ones, depth first, by name.
///
/// Only a failure to list the root itself is an error. Anything unreadable
/// below it becomes [`Kind::Unsupported`], which skips the enclosing skills.
fn walk(root: &Dir) -> io::Result<Vec<Entry>> {
fn visit(handle: &Dir, dir: &str, tree: &mut Vec<Entry>) -> io::Result<()> {
let mut entries = handle.entries()?.collect::<Result<Vec<_>, _>>()?;
entries.sort_by_key(|entry| entry.file_name());
for entry in entries {
let name = entry.file_name();
Expand All @@ -660,12 +649,11 @@ fn walk(root: &Path, handle: &Dir) -> Result<Vec<Entry>, SkillCatalogError> {
Ok(m) if utf8 && m.is_file() => (Kind::File, m.len()),
Ok(m) if utf8 && m.is_dir() => (Kind::Directory, 0),
Ok(_) => (Kind::Unsupported, 0),
Err(error) if entry_changed(&error) => (Kind::Unsupported, 0),
Err(source) => {
return Err(SkillCatalogError::Io {
path: root.join(&path),
source,
});
Err(error) => {
if !entry_changed(&error) {
tracing::warn!(%path, %error, "cannot inspect a walked entry");
}
(Kind::Unsupported, 0)
}
};
if kind == Kind::Directory {
Expand All @@ -677,18 +665,14 @@ fn walk(root: &Path, handle: &Dir) -> Result<Vec<Entry>, SkillCatalogError> {
});
let result = handle
.open_dir_nofollow(entry.file_name())
.map_err(|source| SkillCatalogError::Io {
path: root.join(&path),
source,
})
.and_then(|child| visit(root, &child, &path, tree));
match result {
Err(SkillCatalogError::Io { source, .. }) if entry_changed(&source) => {
// An incomplete subtree invalidates every enclosing skill.
tree.truncate(index + 1);
tree[index].kind = Kind::Unsupported;
.and_then(|child| visit(&child, &path, tree));
if let Err(error) = result {
if !entry_changed(&error) {
tracing::warn!(%path, %error, "cannot read a walked directory");
}
other => other?,
// An incomplete subtree invalidates every enclosing skill.
tree.truncate(index + 1);
tree[index].kind = Kind::Unsupported;
}
} else {
tree.push(Entry { path, kind, size });
Expand All @@ -698,7 +682,7 @@ fn walk(root: &Path, handle: &Dir) -> Result<Vec<Entry>, SkillCatalogError> {
}

let mut tree = Vec::new();
visit(root, handle, "", &mut tree)?;
visit(root, "", &mut tree)?;
Ok(tree)
}

Expand Down Expand Up @@ -798,7 +782,7 @@ mod tests {
let handle = Dir::open_ambient_dir(dir.path(), ambient_authority()).unwrap();
let mut cache = FileCache::default();

let outcome = read_within_limit(&handle, dir.path(), &[&a, &b], &mut cache).unwrap();
let outcome = read_within_limit(&handle, &[&a, &b], &mut cache);

assert_eq!(outcome, SkillRead::OverLimit);
assert_eq!(cache.bytes.keys().collect::<Vec<_>>(), vec![&"a"]);
Expand All @@ -819,7 +803,7 @@ mod tests {
fs::write(public.join("assets/notes.txt"), "public").unwrap();

let handle = Dir::open_ambient_dir(root.path(), ambient_authority()).unwrap();
let tree = walk(root.path(), &handle).unwrap();
let tree = walk(&handle).unwrap();
fs::remove_file(public.join("notes.txt")).unwrap();
symlink("../.private/notes.txt", public.join("notes.txt")).unwrap();
fs::rename(public.join("assets"), public.join("old-assets")).unwrap();
Expand All @@ -830,8 +814,8 @@ mod tests {
assert_eq!(entry.kind, Kind::File);
let mut cache = FileCache::default();
assert_eq!(
read_within_limit(&handle, root.path(), &[entry], &mut cache).unwrap(),
SkillRead::Changed(path),
read_within_limit(&handle, &[entry], &mut cache),
SkillRead::Unreadable(path),
);
assert!(cache.bytes.is_empty());
}
Expand Down Expand Up @@ -861,12 +845,12 @@ mod tests {
assert_eq!(before.skills.len(), 3);

let handle = Dir::open_ambient_dir(root.path(), ambient_authority()).unwrap();
let tree = walk(root.path(), &handle).unwrap();
let tree = walk(&handle).unwrap();
fs::write(outside.path().join("asset.txt"), "outside").unwrap();
fs::remove_file(&asset).unwrap();
symlink(outside.path().join("asset.txt"), &asset).unwrap();
fs::write(sibling, "updated news").unwrap();
let after = Snapshot::from_walk(root.path(), &handle, &tree).unwrap();
let after = Snapshot::from_walk(&handle, &tree);

assert_eq!(
after.skills.iter().map(Skill::name).collect::<Vec<_>>(),
Expand All @@ -888,7 +872,7 @@ mod tests {
let path = root.path().join("asset.txt");
fs::write(&path, "original").unwrap();
let handle = Dir::open_ambient_dir(root.path(), ambient_authority()).unwrap();
let tree = walk(root.path(), &handle).unwrap();
let tree = walk(&handle).unwrap();
assert_eq!(tree[0].kind, Kind::File);
fs::remove_file(&path).unwrap();
assert!(Command::new("mkfifo").arg(path).status().unwrap().success());
Expand Down Expand Up @@ -916,13 +900,67 @@ mod tests {
size: 1,
};
let mut cache = FileCache::default();
let mut read = || read_within_limit(&handle, root.path(), &[&file], &mut cache).unwrap();
assert_eq!(read(), SkillRead::Changed("shared.txt"));
let mut read = || read_within_limit(&handle, &[&file], &mut cache);
assert_eq!(read(), SkillRead::Unreadable("shared.txt"));
std::fs::write(root.path().join(&file.path), "restored").unwrap();
assert_eq!(read(), SkillRead::Changed("shared.txt"));
assert_eq!(read(), SkillRead::Unreadable("shared.txt"));
assert!(cache.bytes.is_empty());
}

#[test]
fn read_within_limit_should_skip_a_file_it_cannot_read() {
let root = tempfile::tempdir().unwrap();
let handle = Dir::open_ambient_dir(root.path(), ambient_authority()).unwrap();
let file = Entry {
path: "sub/../file".into(),
kind: Kind::File,
size: 1,
};
let mut cache = FileCache::default();

let outcome = read_within_limit(&handle, &[&file], &mut cache);

assert_eq!(outcome, SkillRead::Unreadable("sub/../file"));
}

#[cfg(unix)]
#[test]
fn load_skips_a_skill_with_an_unreadable_directory_and_keeps_the_others() {
use std::{fs, os::unix::fs::PermissionsExt};

let root = tempfile::tempdir().unwrap();
for dir in ["locked", "healthy"] {
let path = root.path().join(dir);
fs::create_dir(&path).unwrap();
fs::write(
path.join(SKILL_MD),
format!("---\nname: {dir}\ndescription: Example\n---\n"),
)
.unwrap();
}
let refs = root.path().join("locked/refs");
fs::create_dir(&refs).unwrap();
fs::set_permissions(&refs, fs::Permissions::from_mode(0o000)).unwrap();
// Privileged users read through the permission bits.
let readable = fs::read_dir(&refs).is_ok();

let snapshot = Snapshot::load(root.path());

fs::set_permissions(&refs, fs::Permissions::from_mode(0o755)).unwrap();
if readable {
return;
}
assert_eq!(
snapshot
.unwrap()
.skills
.iter()
.map(Skill::name)
.collect::<Vec<_>>(),
["healthy"]
);
}

#[test]
fn rejects_malformed_walked_paths() {
let root = tempfile::tempdir().unwrap();
Expand Down
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