vm: never abort on caught syntax error #17394

addaleax · 2017-11-29T20:21:19Z

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)

vm

addaleax · 2017-11-29T20:22:06Z

lib/vm.js

+  constructor(code, options) {
+    // Calling `ReThrow()` on a native TryCatch does not generate a new
+    // abort-on-uncaught-exception check. A dummy try/catch in JS land
+    // protects against that.


@nodejs/v8 Is this a bug in V8?

Yeah a ReThrow is not actually a new throw. It just "re-activates" the exception.

@hashseed Does that mean one could get the right behavior by exiting the TryCatch scope, then using isolate->ThrowException()?

Yeah. Though the message you get with this kind of "rethrow" will show the stack trace of the new throw location.

addaleax · 2017-11-29T20:35:28Z

Hm – looks like message tests fail, because the throw in JS makes us drop the filename from the output… going to need to look into this a bit more I guess

addaleax · 2017-11-29T23:07:18Z

Okay, I think I fixed it with some … cleverness.

I’d appreciate it if @bnoordhuis could take a look?

addaleax · 2017-11-29T23:07:58Z

lib/vm.js

+    try {
+      super(code, options);
+    } catch (e) {
+      throw e; /* node-do-not-add-exception-line */


Any idea for how to avoid this? Or: Is this even actually a bad thing?

Why would it be a bad thing?

I am not sure - it seems like something that people might find out, start to use, and be unhappy when they find out we changed/removed/etc. it

I'm not sure what "it" refers to. The line in the (decorated) stack trace? What info could they glean from that?

No, sorry, I should have been clearer - I was talking about the node-do-not-add-exception-line magic string and its effect of not appending the filename + arrow string in that case

Hah, okay. I read your question as "is it a bad thing for the throw to show up." I wouldn't say so, and yes, I'd say it's only a matter of time before people find out about the magic comment. :-)

If you want to exclude stack frames, you can filter based on the script id. Probably overkill for this, though.

addaleax · 2017-11-29T23:13:09Z

CI: https://ci.nodejs.org/job/node-test-commit/14468/

This is unnecessary since we only run `AppendExceptionLine()` once per exception at this point anyway.

Keep track of C++ `TryCatch` state to avoid aborting when an exception is thrown inside one, and re-throw in JS to make sure the exception is being picked up a second time by a second uncaught exception handler, if necessary. Add a bit of a hack to `AppendExceptionLine` to avoid overriding the line responsible for re-throwing the exception. Fixes: nodejs#13258

addaleax · 2017-12-05T22:50:05Z

Landed in aeddc36, b73e66e

This is unnecessary since we only run `AppendExceptionLine()` once per exception at this point anyway. PR-URL: #17394 Reviewed-By: James M Snell <jasnell@gmail.com>

Keep track of C++ `TryCatch` state to avoid aborting when an exception is thrown inside one, and re-throw in JS to make sure the exception is being picked up a second time by a second uncaught exception handler, if necessary. Add a bit of a hack to `AppendExceptionLine` to avoid overriding the line responsible for re-throwing the exception. PR-URL: #17394 Fixes: #13258 Reviewed-By: James M Snell <jasnell@gmail.com>

Currently the following warning is show when building: ../src/node_contextify.cc:642:10: warning: unused variable 'display_errors' [-Wunused-variable] bool display_errors = maybe_display_errors.ToChecked(); This commit removes the unused variable which became unused in commit aeddc36 ("src: remove tracking for exception arrow data"). Refs: nodejs#17394

Currently the following warning is show when building: ../src/node_contextify.cc:642:10: warning: unused variable 'display_errors' [-Wunused-variable] bool display_errors = maybe_display_errors.ToChecked(); This commit removes the unused variable which became unused in commit aeddc36 ("src: remove tracking for exception arrow data"). PR-URL: #17491 Refs: #17394 Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net>

MylesBorins · 2017-12-12T07:13:13Z

Should this be backported to v9.x-staging? If yes please follow the guide and raise a backport PR, if not let me know or add the dont-land-on label.

Currently the following warning is show when building: ../src/node_contextify.cc:642:10: warning: unused variable 'display_errors' [-Wunused-variable] bool display_errors = maybe_display_errors.ToChecked(); This commit removes the unused variable which became unused in commit aeddc36 ("src: remove tracking for exception arrow data"). PR-URL: #17491 Refs: #17394 Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net>

MylesBorins · 2017-12-21T19:44:53Z

Got it to land !!!

This is unnecessary since we only run `AppendExceptionLine()` once per exception at this point anyway. PR-URL: #17394 Reviewed-By: James M Snell <jasnell@gmail.com>

Keep track of C++ `TryCatch` state to avoid aborting when an exception is thrown inside one, and re-throw in JS to make sure the exception is being picked up a second time by a second uncaught exception handler, if necessary. Add a bit of a hack to `AppendExceptionLine` to avoid overriding the line responsible for re-throwing the exception. PR-URL: #17394 Fixes: #13258 Reviewed-By: James M Snell <jasnell@gmail.com>

Currently the following warning is show when building: ../src/node_contextify.cc:642:10: warning: unused variable 'display_errors' [-Wunused-variable] bool display_errors = maybe_display_errors.ToChecked(); This commit removes the unused variable which became unused in commit aeddc36 ("src: remove tracking for exception arrow data"). PR-URL: #17491 Refs: #17394 Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net>

MylesBorins · 2018-01-22T08:36:56Z

does this make sense for lts?

edit: if backported it should come with #17491

MylesBorins · 2018-02-27T03:04:14Z

ping re: backport

MylesBorins · 2018-05-22T15:56:17Z

one more backport ping

should come with #17491

addaleax requested a review from cjihrig November 29, 2017 20:21

nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. lib / src Issues and PRs related to general changes in the lib or src directory. labels Nov 29, 2017

addaleax commented Nov 29, 2017

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addaleax force-pushed the vm-no-abort branch from 4e7ba98 to 250ab47 Compare November 29, 2017 20:23

addaleax added vm Issues and PRs related to the vm subsystem. and removed lib / src Issues and PRs related to general changes in the lib or src directory. labels Nov 29, 2017

addaleax force-pushed the vm-no-abort branch from 250ab47 to 62233c9 Compare November 29, 2017 23:07

addaleax commented Nov 29, 2017

View reviewed changes

addaleax requested a review from bnoordhuis November 29, 2017 23:08

addaleax added 2 commits December 1, 2017 22:47

src: remove tracking for exception arrow data

ac1fea0

This is unnecessary since we only run `AppendExceptionLine()` once per exception at this point anyway.

addaleax force-pushed the vm-no-abort branch from 62233c9 to 2dbb612 Compare December 1, 2017 21:47

jasnell approved these changes Dec 5, 2017

View reviewed changes

addaleax closed this Dec 5, 2017

addaleax deleted the vm-no-abort branch December 5, 2017 22:50

addaleax added a commit that referenced this pull request Dec 5, 2017

src: remove tracking for exception arrow data

aeddc36

This is unnecessary since we only run `AppendExceptionLine()` once per exception at this point anyway. PR-URL: #17394 Reviewed-By: James M Snell <jasnell@gmail.com>

bnoordhuis mentioned this pull request Dec 6, 2017

src: remove unused variable in node_contextify #17491

Closed

2 tasks

MylesBorins added the backport-requested-v9.x label Dec 12, 2017

MylesBorins removed the backport-requested-v9.x label Dec 21, 2017

MylesBorins pushed a commit that referenced this pull request Dec 21, 2017

src: remove tracking for exception arrow data

df6acf9

This is unnecessary since we only run `AppendExceptionLine()` once per exception at this point anyway. PR-URL: #17394 Reviewed-By: James M Snell <jasnell@gmail.com>

MylesBorins mentioned this pull request Jan 10, 2018

v9.4.0 proposal #18069

Merged

MylesBorins added lts-watch-v6.x labels Jan 22, 2018

MylesBorins added the backport-requested-v8.x label May 22, 2018

BethGriggs removed the lts-watch-v8.x label Sep 19, 2019

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vm: never abort on caught syntax error #17394

vm: never abort on caught syntax error #17394

addaleax commented Nov 29, 2017 •

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vm: never abort on caught syntax error #17394

vm: never abort on caught syntax error #17394

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