From 455e6f1dd88dc43b9e6d95fadb24c2cad3798ac7 Mon Sep 17 00:00:00 2001
From: Timothy Gu <timothygu99@gmail.com>
Date: Sun, 5 Mar 2017 21:57:02 -0800
Subject: [PATCH] util: throw toJSON errors when formatting %j
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Previously all errors resulting from JSON.stringify were treated as a
proof for circularity of the object structure. That is not the case if
the `toJSON` method of the object throws an error. Explicitly check for
the exact error message when determining the object structure's
cyclicity.

PR-URL: https://github.com/nodejs/node/pull/11708
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
---
 lib/util.js                       |  8 ++++++--
 test/parallel/test-util-format.js | 10 ++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/util.js b/lib/util.js
index 8048caecba00ed..31761f0dd35545 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -38,13 +38,17 @@ const inspectDefaultOptions = Object.seal({
   breakLength: 60
 });
 
+const CIRCULAR_ERROR_MESSAGE = 'Converting circular structure to JSON';
+
 var Debug;
 
 function tryStringify(arg) {
   try {
     return JSON.stringify(arg);
-  } catch (_) {
-    return '[Circular]';
+  } catch (err) {
+    if (err.name === 'TypeError' && err.message === CIRCULAR_ERROR_MESSAGE)
+      return '[Circular]';
+    throw err;
   }
 }
 
diff --git a/test/parallel/test-util-format.js b/test/parallel/test-util-format.js
index 49b234e2e2bbf7..a57a8094ac05ba 100644
--- a/test/parallel/test-util-format.js
+++ b/test/parallel/test-util-format.js
@@ -86,6 +86,16 @@ assert.strictEqual(util.format('o: %j, a: %j'), 'o: %j, a: %j');
   assert.strictEqual(util.format('%j', o), '[Circular]');
 }
 
+{
+  const o = {
+    toJSON() {
+      throw new Error('Not a circular object but still not serializable');
+    }
+  };
+  assert.throws(() => util.format('%j', o),
+                /^Error: Not a circular object but still not serializable$/);
+}
+
 // Errors
 const err = new Error('foo');
 assert.strictEqual(util.format(err), err.stack);