From 3b27bebd5e9b4ed98e87a0b67123de9544284d25 Mon Sep 17 00:00:00 2001
From: cjihrig <cjihrig@gmail.com>
Date: Tue, 1 Dec 2015 20:34:45 -0500
Subject: [PATCH] src: don't print garbage errors

If JS throws an object whose toString() method throws, then Node
attempts to print an empty message, but actually prints garbage.
This commit checks for this case, and prints a message instead.
---
 src/node.cc                           | 6 ++++--
 test/fixtures/throws_error7.js        | 5 +++++
 test/parallel/test-error-reporting.js | 9 ++++++---
 3 files changed, 15 insertions(+), 5 deletions(-)
 create mode 100644 test/fixtures/throws_error7.js

diff --git a/src/node.cc b/src/node.cc
index 4e591ff5af6053..14ad0c9fa940c8 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -1512,8 +1512,10 @@ static void ReportException(Environment* env,
         name.IsEmpty() ||
         name->IsUndefined()) {
       // Not an error object. Just print as-is.
-      node::Utf8Value message(env->isolate(), er);
-      PrintErrorString("%s\n", *message);
+      String::Utf8Value message(er);
+
+      PrintErrorString("%s\n", *message ? *message :
+                                          "<toString() threw exception>");
     } else {
       node::Utf8Value name_string(env->isolate(), name);
       node::Utf8Value message_string(env->isolate(), message);
diff --git a/test/fixtures/throws_error7.js b/test/fixtures/throws_error7.js
new file mode 100644
index 00000000000000..f730bc6def1ba9
--- /dev/null
+++ b/test/fixtures/throws_error7.js
@@ -0,0 +1,5 @@
+throw {
+  toString: function() {
+    throw this;
+  }
+};
diff --git a/test/parallel/test-error-reporting.js b/test/parallel/test-error-reporting.js
index 88ef5d306e3e37..b5b70eeb3b2add 100644
--- a/test/parallel/test-error-reporting.js
+++ b/test/parallel/test-error-reporting.js
@@ -24,8 +24,6 @@ function errExec(script, callback) {
 
     // Count the tests
     exits++;
-
-    console.log('.');
   });
 }
 
@@ -64,6 +62,11 @@ errExec('throws_error6.js', function(err, stdout, stderr) {
   assert.ok(/SyntaxError/.test(stderr));
 });
 
+// Object that throws in toString() doesn't print garbage
+errExec('throws_error7.js', function(err, stdout, stderr) {
+  assert.ok(/<toString\(\) threw exception/.test(stderr));
+});
+
 process.on('exit', function() {
-  assert.equal(6, exits);
+  assert.equal(7, exits);
 });