repl: handle unexpected error objects #12400

cjihrig · 2017-04-13T15:58:22Z

This commit allows the repl's domain error handler to process
unexpected error formats, such as primitives.

Fixes: #12373

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
tests and/or benchmarks are included
commit message follows commit guidelines

Affected core subsystem(s)

repl

aqrln · 2017-04-13T16:29:21Z

lib/repl.js

    }
-    top.outputStream.write((e.stack || e) + '\n');
+
+    top.outputStream.write(out + '\n');


It will fail if e is a Symbol, won't it?

refack · 2017-04-13T16:01:48Z

lib/repl.js

@@ -282,17 +282,24 @@ function REPLServer(prompt,
  self._domain.on('error', function debugDomainError(e) {
    debug('domain error');
    const top = replMap.get(self);
+    var out;


We haven't moved over to let completely yet.

refack · 2017-04-13T16:18:30Z

lib/repl.js

+
+    if (!((e instanceof Error) && typeof e.stack === 'string')) {
+      out = e;
+    } else if (e instanceof SyntaxError) {


if there a chance e.stack != true || !('replace' in e.stack)?
Maybe a custom error:

function MySillyError(a, b, c) { console.log(a) } MySillyError.prototype = SyntaxError

I don't think we need to jump through hoops for extreme edge cases like this. As long as they don't crash.

Cool, just tested, no crash just TypeError: Function.prototype.toString is not generic

refack · 2017-04-13T16:30:40Z

lib/repl.js

    }
-    top.outputStream.write((e.stack || e) + '\n');
+
+    top.outputStream.write(out + '\n');


how about if delete e.toString?

refack · 2017-04-13T16:32:18Z

test/parallel/test-repl.js

+      client: client_unix,
+      send: 'var e = new Error(\'test error\'); delete e.stack; throw e;',
+      expect: /^Error: test error/
+    },


add this monstrosity:

send: 'function MySillyError() {}; MySillyError.prototype = SyntaxError; var e = new MySillyError(); throw e', expect: /^TypeError: Function.prototype.toString is not generic/

No crash, but INHO it's a good test
also @aqrln's

send: 'throw Symbol.for', expect: /^function for() { [native code] }/

refack · 2017-04-13T16:34:33Z

@cjihrig you're not a first time contributor 😁 kudos on the commitment...

I added some horrible code to try and crash your cases...

cjihrig · 2017-04-13T17:17:21Z

lib/repl.js

-    if (e instanceof SyntaxError && e.stack) {
+
+    if (!((e instanceof Error) && typeof e.stack === 'string')) {
+      out = e;


Symbols and other bad inputs are taken care of here if I move to out = util.inspect(e);. However, it causes test-repl-sigint.js and test-repl-sigint-nested-eval.js to fail. @addaleax any idea why that would be?

that’s odd… I’ll have a look

@addaleax I just pushed up the changes that include that and more tests, if you want to take a look.

@cjihrig I think this might be the missing puzzle piece. ;)

Anyway I would "de-morgan" it to:

(!(e instanceof Error) || typeof e.stack !== 'string')

then add the original ~~gourd🎃~~ guard

(typeof e === 'undefined' || !(e instanceof Error) || typeof e.stack !== 'string')

Thanks @addaleax. The special snowflake that is the REPL. I added a length check for stack, so errors with empty stacks will print with util.inspect().

refack · 2017-04-13T17:28:49Z

mo' tests less trouble?!

refack · 2017-04-13T17:31:07Z

You could add the extreme edge cases as tests

send: 'function MySillyError() {}; MySillyError.prototype = SyntaxError; var e = new MySillyError(); throw e',
expect: /^TypeError: Function.prototype.toString is not generic/

also @aqrln's

send: 'throw Symbol.for',
expect: /^function for() { [native code] }/

benjamingr

Changes LGTM and improve current status quo.

This commit allows the repl's domain error handler to process unexpected error formats, such as primitives.

refack · 2017-04-14T00:41:17Z

test/parallel/test-repl.js

+    // Throws Object with bad toString() method and prints out
+    {
+      client: client_unix,
+      send: 'var e = { toString() { throw new Error(\'test\'); } }; throw e;',


Even smarter! 👍

TimothyGu · 2017-04-14T06:35:35Z

lib/repl.js

-    if (e instanceof SyntaxError && e.stack) {
+
+    if (!((e instanceof Error) && typeof e.stack === 'string' &&
+        e.stack.length > 0)) {


Not sure how robust you want this code to be, but the typeof e.stack will crash with

function FakeError() {} FakeError.prototype = Object.create(Error.prototype, { stack: { get() { throw new Error(); } } }); var e = new FakeError();

I don't know how others feel, but I'm OK with it, at least in the context of this PR. It seems like any Node application can be crashed with a well crafted getter.

One thing that I would (personally) prefer is either using V8’s IsNativeError over instanceof Error or going full 🦆 here. Both would increase robustness in different ways :)

Just noting that whatever is done here would need to factor in compatibility with internal/errors.js

Refs: nodejs#12400 PR-URL: nodejs#12546 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

Refs: #12400 PR-URL: #12546 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

addaleax · 2017-05-26T19:29:27Z

@cjihrig Did you mean to close this?

cjihrig · 2017-06-06T17:21:17Z

Sorry @addaleax. Yes, I did. The move to internal/errors.js is going to prevent IsNativeError() from working correctly, and I didn't want to go full on duck typing.

TimothyGu · 2017-06-17T16:03:16Z

@cjihrig

The move to internal/errors.js is going to prevent IsNativeError() from working correctly

Can you elaborate? The Node.js error classes all extend from the native error classes, and generally V8's methods recognize subclasses.

cjihrig · 2017-06-19T00:15:14Z

Hm, good question. I tested this before, but maybe I did something wrong. process.binding('util').isNativeError() does appear to work with internal/errors.

nodejs-github-bot added the repl Issues and PRs related to the REPL subsystem. label Apr 13, 2017

aqrln reviewed Apr 13, 2017

View reviewed changes

refack suggested changes Apr 13, 2017

View reviewed changes

cjihrig commented Apr 13, 2017

View reviewed changes

refack approved these changes Apr 13, 2017

View reviewed changes

cjihrig force-pushed the repl branch from 6052da6 to 9828645 Compare April 13, 2017 17:23

princejwesley approved these changes Apr 13, 2017

View reviewed changes

benjamingr approved these changes Apr 13, 2017

View reviewed changes

cjihrig force-pushed the repl branch from 9828645 to 5262d6d Compare April 14, 2017 00:37

repl: handle unexpected error objects

9a8dec0

This commit allows the repl's domain error handler to process unexpected error formats, such as primitives.

cjihrig force-pushed the repl branch from 5262d6d to 9a8dec0 Compare April 14, 2017 00:39

refack reviewed Apr 14, 2017

View reviewed changes

refack approved these changes Apr 14, 2017

View reviewed changes

cjihrig added the semver-major PRs that contain breaking changes and should be released in the next major version. label Apr 14, 2017

refack force-pushed the master branch from 16073c0 to fbe946b Compare April 14, 2017 04:12

aqrln approved these changes Apr 14, 2017

View reviewed changes

TimothyGu reviewed Apr 14, 2017

View reviewed changes

cjihrig mentioned this pull request Apr 20, 2017

src: expose V8's IsNativeError() in util bindings #12546

Merged

3 tasks

cjihrig closed this May 17, 2017

bnoordhuis mentioned this pull request Jun 16, 2017

setTimeout(function(){throw null},0) crashes toplevel #12373

Closed

TimothyGu mentioned this pull request Jul 18, 2017

repl: handle null thrown #14306

Closed

3 tasks

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

repl: handle unexpected error objects #12400

repl: handle unexpected error objects #12400

cjihrig commented Apr 13, 2017

aqrln Apr 13, 2017

refack Apr 13, 2017

cjihrig Apr 13, 2017

refack Apr 13, 2017

cjihrig Apr 13, 2017

refack Apr 13, 2017

refack Apr 13, 2017

refack Apr 13, 2017 •

edited

Loading

refack Apr 13, 2017

refack commented Apr 13, 2017

cjihrig Apr 13, 2017

addaleax Apr 13, 2017

cjihrig Apr 13, 2017

addaleax Apr 13, 2017

refack Apr 13, 2017 •

edited

Loading

cjihrig Apr 14, 2017

refack commented Apr 13, 2017

refack commented Apr 13, 2017

benjamingr left a comment

refack Apr 14, 2017

TimothyGu Apr 14, 2017

cjihrig Apr 14, 2017

addaleax Apr 14, 2017

jasnell Apr 20, 2017

addaleax commented May 26, 2017

cjihrig commented Jun 6, 2017

TimothyGu commented Jun 17, 2017

cjihrig commented Jun 19, 2017

repl: handle unexpected error objects #12400

repl: handle unexpected error objects #12400

Conversation

cjihrig commented Apr 13, 2017

Checklist

Affected core subsystem(s)

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

refack Apr 13, 2017 • edited Loading

Choose a reason for hiding this comment

Choose a reason for hiding this comment

refack commented Apr 13, 2017

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

refack Apr 13, 2017 • edited Loading

Choose a reason for hiding this comment

Choose a reason for hiding this comment

refack commented Apr 13, 2017

refack commented Apr 13, 2017

benjamingr left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

addaleax commented May 26, 2017

cjihrig commented Jun 6, 2017

TimothyGu commented Jun 17, 2017

cjihrig commented Jun 19, 2017

refack Apr 13, 2017 •

edited

Loading

refack Apr 13, 2017 •

edited

Loading