Enable semver-compatible matching of import/export lookups in target validation

Signed-off-by: Brian Hardock <brian.hardock@fermyon.com>

Author: fibonacci1729

crates/wac-types/src/lib.rs

@@ -6,12 +6,14 @@ mod aggregator;
 mod checker;
 mod component;
 mod core;
+mod names;
 mod package;
 mod targets;
 
 pub use aggregator::*;
 pub use checker::*;
 pub use component::*;
 pub use core::*;
+pub use names::*;
 pub use package::*;
 pub use targets::*;

crates/wac-types/src/names.rs

@@ -0,0 +1,276 @@
+// Adapted from https://github.com/bytecodealliance/wasmtime/blob/main/crates/environ/src/component/names.rs
+
+use anyhow::{bail, Result};
+use core::hash::Hash;
+use indexmap::IndexMap;
+use semver::Version;
+
+/// A semver-aware map for imports/exports of a component.
+///
+/// This data structure is used when looking up the names of imports/exports of
+/// a component to enable semver-compatible matching of lookups. This will
+/// enable lookups of `a:b/c@0.2.0` to match entries defined as `a:b/c@0.2.1`
+/// which is currently considered a key feature of WASI's compatibility story.
+///
+/// On the outside this looks like a map of `K` to `V`.
+#[derive(Clone, Debug)]
+pub struct NameMap<K: Clone + Hash + Eq + Ord, V> {
+    /// A map of keys to the value that they define.
+    ///
+    /// Note that this map is "exact" where the name here is the exact name that
+    /// was specified when the `insert` was called. This doesn't have any
+    /// semver-mangling or anything like that.
+    ///
+    /// This map is always consulted first during lookups.
+    definitions: IndexMap<K, V>,
+
+    /// An auxiliary map tracking semver-compatible names. This is a map from
+    /// "semver compatible alternate name" to a name present in `definitions`
+    /// and the semver version it was registered at.
+    ///
+    /// An example map would be:
+    ///
+    /// ```text
+    /// {
+    ///     "a:b/c@0.2": ("a:b/c@0.2.1", 0.2.1),
+    ///     "a:b/c@2": ("a:b/c@2.0.0+abc", 2.0.0+abc),
+    /// }
+    /// ```
+    ///
+    /// As names are inserted into `definitions` each name may have up to one
+    /// semver-compatible name with extra numbers/info chopped off which is
+    /// inserted into this map. This map is the lookup table from `@0.2` to
+    /// `@0.2.x` where `x` is what was inserted manually.
+    ///
+    /// The `Version` here is tracked to ensure that when multiple versions on
+    /// one track are defined that only the maximal version here is retained.
+    alternate_lookups: IndexMap<K, (K, Version)>,
+}
+
+impl<K, V> NameMap<K, V>
+where
+    K: Clone + Hash + Eq + Ord,
+{
+    /// Inserts the `name` specified into this map.
+    ///
+    /// The name is intern'd through the `cx` argument and shadowing is
+    /// controlled by the `allow_shadowing` variable.
+    ///
+    /// This function will automatically insert an entry in
+    /// `self.alternate_lookups` if `name` is a semver-looking name.
+    ///
+    /// Returns an error if `allow_shadowing` is `false` and the `name` is
+    /// already present in this map (by exact match). Otherwise returns the
+    /// intern'd version of `name`.
+    pub fn insert<I>(&mut self, name: &str, cx: &mut I, allow_shadowing: bool, item: V) -> Result<K>
+    where
+        I: NameMapIntern<Key = K>,
+    {
+        // Always insert `name` and `item` as an exact definition.
+        let key = cx.intern(name);
+        if let Some(prev) = self.definitions.insert(key.clone(), item) {
+            if !allow_shadowing {
+                self.definitions.insert(key, prev);
+                bail!("map entry `{name}` defined twice")
+            }
+        }
+
+        // If `name` is a semver-looking thing, like `a:b/c@1.0.0`, then also
+        // insert an entry in the semver-compatible map under a key such as
+        // `a:b/c@1`.
+        //
+        // This key is used during `get` later on.
+        if let Some((alternate_key, version)) = alternate_lookup_key(name) {
+            let alternate_key = cx.intern(alternate_key);
+            if let Some((prev_key, prev_version)) = self
+                .alternate_lookups
+                .insert(alternate_key.clone(), (key.clone(), version.clone()))
+            {
+                // Prefer the latest version, so only do this if we're
+                // greater than the prior version.
+                if version < prev_version {
+                    self.alternate_lookups
+                        .insert(alternate_key, (prev_key, prev_version));
+                }
+            }
+        }
+        Ok(key)
+    }
+
+    /// Looks up `name` within this map, using the interning specified by
+    /// `cx`.
+    ///
+    /// This may return a definition even if `name` wasn't exactly defined in
+    /// this map, such as looking up `a:b/c@0.2.0` when the map only has
+    /// `a:b/c@0.2.1` defined.
+    pub fn get<I>(&self, name: &str, cx: &I) -> Option<&V>
+    where
+        I: NameMapIntern<Key = K>,
+    {
+        // First look up an exact match and if that's found return that. This
+        // enables defining multiple versions in the map and the requested
+        // version is returned if it matches exactly.
+        let candidate = cx.lookup(name).and_then(|k| self.definitions.get(&k));
+        if let Some(def) = candidate {
+            return Some(def);
+        }
+
+        // Failing that, then try to look for a semver-compatible alternative.
+        // This looks up the key based on `name`, if any, and then looks to see
+        // if that was intern'd in `strings`. Given all that look to see if it
+        // was defined in `alternate_lookups` and finally at the end that exact
+        // key is then used to look up again in `self.definitions`.
+        let (alternate_name, _version) = alternate_lookup_key(name)?;
+        let alternate_key = cx.lookup(alternate_name)?;
+        let (exact_key, _version) = self.alternate_lookups.get(&alternate_key)?;
+        self.definitions.get(exact_key)
+    }
+
+    /// Returns an iterator over inserted values in this map.
+    ///
+    /// Note that the iterator return yields intern'd keys and additionally does
+    /// not do anything special with semver names and such, it only literally
+    /// yields what's been inserted with [`NameMap::insert`].
+    pub fn raw_iter(&self) -> impl Iterator<Item = (&K, &V)> {
+        self.definitions.iter()
+    }
+
+    /// TODO
+    pub fn raw_get_mut(&mut self, key: &K) -> Option<&mut V> {
+        self.definitions.get_mut(key)
+    }
+}
+
+impl<K, V> Default for NameMap<K, V>
+where
+    K: Clone + Hash + Eq + Ord,
+{
+    fn default() -> NameMap<K, V> {
+        NameMap {
+            definitions: Default::default(),
+            alternate_lookups: Default::default(),
+        }
+    }
+}
+
+/// A helper trait used in conjunction with [`NameMap`] to optionally intern
+/// keys to non-strings.
+pub trait NameMapIntern {
+    /// The key that this interning context generates.
+    type Key;
+
+    /// Inserts `s` into `self` and returns the intern'd key `Self::Key`.
+    fn intern(&mut self, s: &str) -> Self::Key;
+
+    /// Looks up `s` in `self` returning `Some` if it was found or `None` if
+    /// it's not present.
+    fn lookup(&self, s: &str) -> Option<Self::Key>;
+}
+
+/// For use with [`NameMap`] when no interning should happen and instead string
+/// keys are copied as-is.
+pub struct NameMapNoIntern;
+
+impl NameMapIntern for NameMapNoIntern {
+    type Key = String;
+
+    fn intern(&mut self, s: &str) -> String {
+        s.to_string()
+    }
+
+    fn lookup(&self, s: &str) -> Option<String> {
+        Some(s.to_string())
+    }
+}
+
+/// Determines a version-based "alternate lookup key" for the `name` specified.
+///
+/// Some examples are:
+///
+/// * `foo` => `None`
+/// * `foo:bar/baz` => `None`
+/// * `foo:bar/baz@1.1.2` => `Some(foo:bar/baz@1)`
+/// * `foo:bar/baz@0.1.0` => `Some(foo:bar/baz@0.1)`
+/// * `foo:bar/baz@0.0.1` => `None`
+/// * `foo:bar/baz@0.1.0-rc.2` => `None`
+///
+/// This alternate lookup key is intended to serve the purpose where a
+/// semver-compatible definition can be located, if one is defined, at perhaps
+/// either a newer or an older version.
+fn alternate_lookup_key(name: &str) -> Option<(&str, Version)> {
+    let at = name.find('@')?;
+    let version_string = &name[at + 1..];
+    let version = Version::parse(version_string).ok()?;
+    if !version.pre.is_empty() {
+        // If there's a prerelease then don't consider that compatible with any
+        // other version number.
+        None
+    } else if version.major != 0 {
+        // If the major number is nonzero then compatibility is up to the major
+        // version number, so return up to the first decimal.
+        let first_dot = version_string.find('.')? + at + 1;
+        Some((&name[..first_dot], version))
+    } else if version.minor != 0 {
+        // Like the major version if the minor is nonzero then patch releases
+        // are all considered to be on a "compatible track".
+        let first_dot = version_string.find('.')? + at + 1;
+        let second_dot = name[first_dot + 1..].find('.')? + first_dot + 1;
+        Some((&name[..second_dot], version))
+    } else {
+        // If the patch number is the first nonzero entry then nothing can be
+        // compatible with this patch, e.g. 0.0.1 isn't' compatible with
+        // any other version inherently.
+        None
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{NameMap, NameMapNoIntern};
+
+    #[test]
+    fn alternate_lookup_key() {
+        fn alt(s: &str) -> Option<&str> {
+            super::alternate_lookup_key(s).map(|(s, _)| s)
+        }
+
+        assert_eq!(alt("x"), None);
+        assert_eq!(alt("x:y/z"), None);
+        assert_eq!(alt("x:y/z@1.0.0"), Some("x:y/z@1"));
+        assert_eq!(alt("x:y/z@1.1.0"), Some("x:y/z@1"));
+        assert_eq!(alt("x:y/z@1.1.2"), Some("x:y/z@1"));
+        assert_eq!(alt("x:y/z@2.1.2"), Some("x:y/z@2"));
+        assert_eq!(alt("x:y/z@2.1.2+abc"), Some("x:y/z@2"));
+        assert_eq!(alt("x:y/z@0.1.2"), Some("x:y/z@0.1"));
+        assert_eq!(alt("x:y/z@0.1.3"), Some("x:y/z@0.1"));
+        assert_eq!(alt("x:y/z@0.2.3"), Some("x:y/z@0.2"));
+        assert_eq!(alt("x:y/z@0.2.3+abc"), Some("x:y/z@0.2"));
+        assert_eq!(alt("x:y/z@0.0.1"), None);
+        assert_eq!(alt("x:y/z@0.0.1-pre"), None);
+        assert_eq!(alt("x:y/z@0.1.0-pre"), None);
+        assert_eq!(alt("x:y/z@1.0.0-pre"), None);
+    }
+
+    #[test]
+    fn name_map_smoke() {
+        let mut map = NameMap::default();
+        let mut intern = NameMapNoIntern;
+
+        map.insert("a", &mut intern, false, 0).unwrap();
+        map.insert("b", &mut intern, false, 1).unwrap();
+
+        assert!(map.insert("a", &mut intern, false, 0).is_err());
+        assert!(map.insert("a", &mut intern, true, 0).is_ok());
+
+        assert_eq!(map.get("a", &intern), Some(&0));
+        assert_eq!(map.get("b", &intern), Some(&1));
+        assert_eq!(map.get("c", &intern), None);
+
+        map.insert("a:b/c@1.0.0", &mut intern, false, 2).unwrap();
+        map.insert("a:b/c@1.0.1", &mut intern, false, 3).unwrap();
+        assert_eq!(map.get("a:b/c@1.0.0", &intern), Some(&2));
+        assert_eq!(map.get("a:b/c@1.0.1", &intern), Some(&3));
+        assert_eq!(map.get("a:b/c@1.0.2", &intern), Some(&3));
+        assert_eq!(map.get("a:b/c@1.1.0", &intern), Some(&3));
+    }
+}

crates/wac-types/src/targets.rs

@@ -1,4 +1,6 @@
-use crate::{ExternKind, ItemKind, SubtypeChecker, Types, WorldId};
+use crate::{
+    ExternKind, ItemKind, NameMap, NameMapNoIntern, SubtypeChecker, Types, World, WorldId,
+};
 use std::collections::{BTreeMap, BTreeSet};
 use std::fmt;
 
@@ -113,20 +115,17 @@ pub fn validate_target(
 ) -> TargetValidationResult {
     let component_world = &types[component_world_id];
     let wit_world = &types[wit_world_id];
-    // The interfaces imported implicitly through uses.
-    let implicit_imported_interfaces = wit_world.implicit_imported_interfaces(types);
     let mut cache = Default::default();
     let mut checker = SubtypeChecker::new(&mut cache);
-
     let mut report = TargetValidationReport::default();
 
     // The output is allowed to import a subset of the world's imports
     checker.invert();
+
+    let world_imports = wit_world.all_imports(types);
+
     for (import, item_kind) in component_world.imports.iter() {
-        let Some(expected) = implicit_imported_interfaces
-            .get(import.as_str())
-            .or_else(|| wit_world.imports.get(import))
-        else {
+        let Some(expected) = world_imports.get(import.as_str(), &NameMapNoIntern) else {
             report.imports_not_in_target.insert(import.to_owned());
             continue;
         };
@@ -140,9 +139,19 @@ pub fn validate_target(
 
     checker.revert();
 
+    let component_exports =
+        component_world
+            .exports
+            .iter()
+            .fold(NameMap::default(), |mut map, (name, item)| {
+                // The unwrap here is safe because we allow shaddowing
+                map.insert(name, &mut NameMapNoIntern, true, *item).unwrap();
+                map
+            });
+
     // The output must export every export in the world
     for (name, expected) in &wit_world.exports {
-        let Some(export) = component_world.exports.get(name).copied() else {
+        let Some(export) = component_exports.get(name, &NameMapNoIntern).copied() else {
             report.missing_exports.insert(name.to_owned(), *expected);
             continue;
         };
@@ -156,3 +165,24 @@ pub fn validate_target(
 
     report.into()
 }
+
+impl World {
+    /// This returns all implicit and explicit imports of the world as a mapping
+    /// of names to item kinds. The `NameMap` here is used to enable
+    /// semver-compatible matching of lookups
+    fn all_imports(&self, types: &Types) -> NameMap<String, ItemKind> {
+        let mut map = NameMap::default();
+        let mut intern = NameMapNoIntern;
+        // Add implicit imports from the world
+        for (name, kind) in self.implicit_imported_interfaces(types) {
+            // The unwrap here is safe because we allow shaddowing
+            map.insert(name, &mut intern, true, kind).unwrap();
+        }
+        // Add explicit imports from the world
+        for (name, item) in &self.imports {
+            // The unwrap here is safe because we allow shaddowing.
+            map.insert(name, &mut intern, true, *item).unwrap();
+        }
+        map
+    }
+}

crates/wac-types/tests/README.md

@@ -0,0 +1,6 @@
+The `dummy_wasi_http@*.wasm`'s here were generated via the follow:
+```console
+$ wkg get wasi:http@* --format wasm 
+$ wasm-tools component wit wit/wasi_http@*.wasm -o wasi_http@*.wit 
+$ wasm-tools component embed --dummy wasi_http@*.wit | wasm-tools component new - -o dummy_wasi_http@*.wasm
+```