Add a path to Module (and expose it in Referrer) (#3783)

* Add an integration test for relative imports on SimpleModuleLoader

* Add a path to Module (and expose it in Referrer)

This allows SimpleModuleLoader to resolve relative to the current
file (which this commit also does).

Fixes #3782

* cargo clippy and fmt

* prettier

core/engine/src/module/loader.rs

@@ -24,6 +24,18 @@ pub enum Referrer {
     Script(Script),
 }
 
+impl Referrer {
+    /// Gets the path of the referrer, if it has one.
+    #[must_use]
+    pub fn path(&self) -> Option<&Path> {
+        match self {
+            Self::Module(module) => module.path(),
+            Self::Realm(_) => None,
+            Self::Script(_script) => None,
+        }
+    }
+}
+
 impl From<ActiveRunnable> for Referrer {
     fn from(value: ActiveRunnable) -> Self {
         match value {
@@ -176,17 +188,40 @@ impl SimpleModuleLoader {
 impl ModuleLoader for SimpleModuleLoader {
     fn load_imported_module(
         &self,
-        _referrer: Referrer,
+        referrer: Referrer,
         specifier: JsString,
         finish_load: Box<dyn FnOnce(JsResult<Module>, &mut Context)>,
         context: &mut Context,
     ) {
         let result = (|| {
+            // If the referrer has a path, we use it as the base for the specifier.
             let path = specifier
                 .to_std_string()
                 .map_err(|err| JsNativeError::typ().with_message(err.to_string()))?;
+
             let short_path = Path::new(&path);
-            let path = self.root.join(short_path);
+
+            let path = if let Some(p) = referrer.path().and_then(|p| p.parent()) {
+                let root = if p.is_absolute() {
+                    p.to_path_buf()
+                } else {
+                    self.root.join(p)
+                };
+                root.join(short_path)
+            } else {
+                self.root.join(short_path)
+            };
+
+            // Make sure we don't exit the root.
+            if !path.starts_with(&self.root) {
+                return Err(JsNativeError::typ()
+                    .with_message(format!(
+                        "path `{}` is outside the module root",
+                        path.display()
+                    ))
+                    .into());
+            }
+
             let path = path.canonicalize().map_err(|err| {
                 JsNativeError::typ()
                     .with_message(format!(

core/engine/src/module/mod.rs

@@ -21,27 +21,23 @@
 //! [spec]: https://tc39.es/ecma262/#sec-modules
 //! [module]: https://tc39.es/ecma262/#sec-abstract-module-records
 
-mod loader;
-mod namespace;
-mod source;
-mod synthetic;
-use boa_parser::source::ReadChar;
-pub use loader::*;
-pub use namespace::ModuleNamespace;
-use source::SourceTextModule;
-pub use synthetic::{SyntheticModule, SyntheticModuleInitializer};
-
 use std::cell::{Cell, RefCell};
 use std::collections::HashSet;
 use std::hash::Hash;
+use std::path::{Path, PathBuf};
 use std::rc::Rc;
 
 use rustc_hash::FxHashSet;
 
 use boa_gc::{Finalize, Gc, GcRefCell, Trace};
 use boa_interner::Interner;
+use boa_parser::source::ReadChar;
 use boa_parser::{Parser, Source};
 use boa_profiler::Profiler;
+pub use loader::*;
+pub use namespace::ModuleNamespace;
+use source::SourceTextModule;
+pub use synthetic::{SyntheticModule, SyntheticModuleInitializer};
 
 use crate::{
     builtins::promise::{PromiseCapability, PromiseState},
@@ -51,6 +47,11 @@ use crate::{
     Context, HostDefined, JsError, JsResult, JsString, JsValue, NativeFunction,
 };
 
+mod loader;
+mod namespace;
+mod source;
+mod synthetic;
+
 /// ECMAScript's [**Abstract module record**][spec].
 ///
 /// [spec]: https://tc39.es/ecma262/#sec-abstract-module-records
@@ -75,6 +76,7 @@ struct ModuleRepr {
     namespace: GcRefCell<Option<JsObject>>,
     kind: ModuleKind,
     host_defined: HostDefined,
+    path: Option<PathBuf>,
 }
 
 /// The kind of a [`Module`].
@@ -155,6 +157,7 @@ impl Module {
         context: &mut Context,
     ) -> JsResult<Self> {
         let _timer = Profiler::global().start_event("Module parsing", "Main");
+        let path = src.path().map(std::path::Path::to_path_buf);
         let mut parser = Parser::new(src);
         parser.set_identifier(context.next_parser_identifier());
         let module = parser.parse_module(context.interner_mut())?;
@@ -167,6 +170,7 @@ impl Module {
                 namespace: GcRefCell::default(),
                 kind: ModuleKind::SourceText(src),
                 host_defined: HostDefined::default(),
+                path,
             }),
         })
     }
@@ -181,6 +185,7 @@ impl Module {
     pub fn synthetic(
         export_names: &[JsString],
         evaluation_steps: SyntheticModuleInitializer,
+        path: Option<PathBuf>,
         realm: Option<Realm>,
         context: &mut Context,
     ) -> Self {
@@ -194,6 +199,7 @@ impl Module {
                 namespace: GcRefCell::default(),
                 kind: ModuleKind::Synthetic(synth),
                 host_defined: HostDefined::default(),
+                path,
             }),
         }
     }
@@ -564,6 +570,12 @@ impl Module {
             })
             .clone()
     }
+
+    /// Returns the path of the module, if it was created from a file or assigned.
+    #[must_use]
+    pub fn path(&self) -> Option<&Path> {
+        self.inner.path.as_deref()
+    }
 }
 
 impl PartialEq for Module {

core/engine/tests/assets/dir1/file1_1.js

@@ -0,0 +1,5 @@
+import { file1_2 } from "./file1_2.js";
+
+export function file1_1() {
+  return "file1_1" + "." + file1_2();
+}

core/engine/tests/assets/dir1/file1_2.js

@@ -0,0 +1,3 @@
+export function file1_2() {
+  return "file1_2";
+}

core/engine/tests/assets/file1.js

@@ -0,0 +1,5 @@
+import { file1_1 } from "./dir1/file1_1.js";
+
+export function file1() {
+  return "file1" + ".." + file1_1();
+}

core/engine/tests/imports.rs

@@ -0,0 +1,50 @@
+#![allow(unused_crate_dependencies, missing_docs)]
+
+use std::path::PathBuf;
+use std::rc::Rc;
+
+use boa_engine::builtins::promise::PromiseState;
+use boa_engine::module::SimpleModuleLoader;
+use boa_engine::{js_string, Context, JsValue, Source};
+
+/// Test that relative imports work with the simple module loader.
+#[test]
+fn subdirectories() {
+    let assets_dir =
+        PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap()).join("tests/assets");
+
+    let loader = Rc::new(SimpleModuleLoader::new(assets_dir).unwrap());
+    let mut context = Context::builder()
+        .module_loader(loader.clone())
+        .build()
+        .unwrap();
+
+    let source = Source::from_bytes(b"export { file1 } from './file1.js';");
+    let module = boa_engine::Module::parse(source, None, &mut context).unwrap();
+    let result = module.load_link_evaluate(&mut context);
+
+    context.run_jobs();
+    match result.state() {
+        PromiseState::Pending => {}
+        PromiseState::Fulfilled(v) => {
+            assert!(v.is_undefined());
+
+            let foo_value = module
+                .namespace(&mut context)
+                .get(js_string!("file1"), &mut context)
+                .unwrap()
+                .as_callable()
+                .unwrap()
+                .call(&JsValue::undefined(), &[], &mut context)
+                .unwrap();
+
+            assert_eq!(
+                foo_value,
+                JsValue::String(js_string!("file1..file1_1.file1_2"))
+            );
+        }
+        PromiseState::Rejected(reason) => {
+            panic!("Module failed to load: {}", reason.display());
+        }
+    }
+}

core/parser/src/source/mod.rs

@@ -1,8 +1,5 @@
 //! Boa parser input source types.
 
-mod utf16;
-mod utf8;
-
 use std::{
     fs::File,
     io::{self, BufReader, Read},
@@ -12,6 +9,9 @@ use std::{
 pub use utf16::UTF16Input;
 pub use utf8::UTF8Input;
 
+mod utf16;
+mod utf8;
+
 /// A source of ECMAScript code.
 ///
 /// [`Source`]s can be created from plain [`str`]s, file [`Path`]s or more generally, any [`Read`]
@@ -119,6 +119,13 @@ impl<'path, R: Read> Source<'path, UTF8Input<R>> {
     }
 }
 
+impl<'path, R> Source<'path, R> {
+    /// Returns the path (if any) of this source file.
+    pub fn path(&self) -> Option<&'path Path> {
+        self.path
+    }
+}
+
 /// This trait is used to abstract over the different types of input readers.
 pub trait ReadChar {
     /// Retrieves the next unicode code point. Returns `None` if the end of the input is reached.
@@ -131,9 +138,10 @@ pub trait ReadChar {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use std::io::Cursor;
 
+    use super::*;
+
     #[test]
     fn from_bytes() {
         let mut source = Source::from_bytes("'Hello' + 'World';");

examples/src/bin/synthetic.rs

@@ -175,6 +175,7 @@ fn create_operations_module(context: &mut Context) -> Module {
             (sum, sub, mult, div, sqrt),
         ),
         None,
+        None,
         context,
     )
 }