stop infinite recursion w/ crawling external refs

Author: cody-greene

lib/resolve-external.js

@@ -44,17 +44,20 @@ function resolveExternal (parser, options) {
  * @param {string} path - The full path of `obj`, possibly with a JSON Pointer in the hash
  * @param {$Refs} $refs
  * @param {$RefParserOptions} options
+ * @param {WeakMap} seen - Internal.
  *
  * @returns {Promise[]}
  * Returns an array of promises. There will be one promise for each JSON reference in `obj`.
  * If `obj` does not contain any JSON references, then the array will be empty.
  * If any of the JSON references point to files that contain additional JSON references,
  * then the corresponding promise will internally reference an array of promises.
  */
-function crawl (obj, path, $refs, options) {
+function crawl (obj, path, $refs, options, seen) {
+  seen = seen || new WeakMap();
   let promises = [];
 
-  if (obj && typeof obj === "object" && !ArrayBuffer.isView(obj)) {
+  if (obj && typeof obj === "object" && !ArrayBuffer.isView(obj) && !seen.has(obj)) {
+    seen.set(obj, 1); // Track previously seen objects to avoid infinite recursion
     if ($Ref.isExternal$Ref(obj)) {
       promises.push(resolve$Ref(obj, path, $refs, options));
     }
@@ -67,7 +70,7 @@ function crawl (obj, path, $refs, options) {
           promises.push(resolve$Ref(value, keyPath, $refs, options));
         }
         else {
-          promises = promises.concat(crawl(value, keyPath, $refs, options));
+          promises = promises.concat(crawl(value, keyPath, $refs, options, seen));
         }
       }
     }

test/specs/circular/circular.spec.js

@@ -36,6 +36,18 @@ describe("Schema with circular (recursive) $refs", () => {
       expect(schema.definitions.child.properties.pet).to.equal(schema.definitions.pet);
     });
 
+    it("should double dereference successfully", async () => {
+      const firstPassSchema = await $RefParser.dereference(path.rel("specs/circular/circular-self.yaml"));
+      let parser = new $RefParser();
+      const schema = await parser.dereference(firstPassSchema);
+      expect(schema).to.equal(parser.schema);
+      expect(schema).to.deep.equal(dereferencedSchema.self);
+      // The "circular" flag should be set
+      expect(parser.$refs.circular).to.equal(true);
+      // Reference equality
+      expect(schema.definitions.child.properties.pet).to.equal(schema.definitions.pet);
+    });
+
     it('should produce the same results if "options.$refs.circular" is "ignore"', async () => {
       let parser = new $RefParser();
       const schema = await parser.dereference(path.rel("specs/circular/circular-self.yaml"), { dereference: { circular: "ignore" }});
@@ -103,6 +115,19 @@ describe("Schema with circular (recursive) $refs", () => {
       expect(schema.definitions.person.properties.pet).to.equal(schema.definitions.pet);
     });
 
+    it("should double dereference successfully", async () => {
+      let parser = new $RefParser();
+      const firstPassSchema = await $RefParser.dereference(path.rel("specs/circular/circular-ancestor.yaml"));
+      const schema = await parser.dereference(firstPassSchema);
+      expect(schema).to.equal(parser.schema);
+      expect(schema).to.deep.equal(dereferencedSchema.ancestor.fullyDereferenced);
+      // The "circular" flag should be set
+      expect(parser.$refs.circular).to.equal(true);
+      // Reference equality
+      expect(schema.definitions.person.properties.spouse).to.equal(schema.definitions.person);
+      expect(schema.definitions.person.properties.pet).to.equal(schema.definitions.pet);
+    });
+
     it('should not dereference circular $refs if "options.$refs.circular" is "ignore"', async () => {
       let parser = new $RefParser();
       const schema = await parser.dereference(path.rel("specs/circular/circular-ancestor.yaml"), { dereference: { circular: "ignore" }});
@@ -174,6 +199,21 @@ describe("Schema with circular (recursive) $refs", () => {
         .to.equal(schema.definitions.parent);
     });
 
+    it("should double dereference successfully", async () => {
+      let parser = new $RefParser();
+      const firstPassSchema = await $RefParser.dereference(path.rel("specs/circular/circular-indirect.yaml"));
+      const schema = await parser.dereference(firstPassSchema);
+      expect(schema).to.equal(parser.schema);
+      expect(schema).to.deep.equal(dereferencedSchema.indirect.fullyDereferenced);
+      // The "circular" flag should be set
+      expect(parser.$refs.circular).to.equal(true);
+      // Reference equality
+      expect(schema.definitions.parent.properties.children.items)
+        .to.equal(schema.definitions.child);
+      expect(schema.definitions.child.properties.parents.items)
+        .to.equal(schema.definitions.parent);
+    });
+
     it('should not dereference circular $refs if "options.$refs.circular" is "ignore"', async () => {
       let parser = new $RefParser();
       const schema = await parser.dereference(path.rel("specs/circular/circular-indirect.yaml"), { dereference: { circular: "ignore" }});
@@ -245,6 +285,21 @@ describe("Schema with circular (recursive) $refs", () => {
         .to.equal(schema.definitions.child);
     });
 
+    it("should double dereference successfully", async () => {
+      let parser = new $RefParser();
+      const firstPassSchema = await parser.dereference(path.rel("specs/circular/circular-indirect-ancestor.yaml"));
+      const schema = await parser.dereference(firstPassSchema);
+      expect(schema).to.equal(parser.schema);
+      expect(schema).to.deep.equal(dereferencedSchema.indirectAncestor.fullyDereferenced);
+      // The "circular" flag should be set
+      expect(parser.$refs.circular).to.equal(true);
+      // Reference equality
+      expect(schema.definitions.parent.properties.child)
+        .to.equal(schema.definitions.child);
+      expect(schema.definitions.child.properties.children.items)
+        .to.equal(schema.definitions.child);
+    });
+
     it('should not dereference circular $refs if "options.$refs.circular" is "ignore"', async () => {
       let parser = new $RefParser();
       const schema = await parser.dereference(path.rel("specs/circular/circular-indirect-ancestor.yaml"), { dereference: { circular: "ignore" }});