src: don't print garbage errors

cjihrig · rvagg · commit da3137d0c5d5 · 2015-12-08T11:27:37.000+11:00
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. Fixes: #4079 PR-URL: #4112 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Minwoo Jung <jmwsoft@gmail.com>
diff --git a/src/node.cc b/src/node.cc
@@ -1511,8 +1511,10 @@ 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
@@ -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
@@ -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);
 });

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +throw {
 +  toString: function() {
 +    throw this;
 +  }
 +};