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repl: handle unexpected error objects #12400

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repl: handle unexpected error objects #12400

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24 changes: 16 additions & 8 deletions lib/repl.js
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Original file line number Diff line number Diff line change
Expand Up @@ -282,17 +282,25 @@ function REPLServer(prompt,
self._domain.on('error', function debugDomainError(e) {
debug('domain error');
const top = replMap.get(self);
var out;
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let?

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We haven't moved over to let completely yet.

internalUtil.decorateErrorStack(e);
if (e instanceof SyntaxError && e.stack) {

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

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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.

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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 :)

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

out = util.inspect(e);
} else if (e instanceof SyntaxError) {
// remove repl:line-number and stack trace
e.stack = e.stack
.replace(/^repl:\d+\r?\n/, '')
.replace(/^\s+at\s.*\n?/gm, '');
} else if (e.stack && self.replMode === exports.REPL_MODE_STRICT) {
e.stack = e.stack.replace(/(\s+at\s+repl:)(\d+)/,
(_, pre, line) => pre + (line - 1));
out = e.stack
.replace(/^repl:\d+\r?\n/, '')
.replace(/^\s+at\s.*\n?/gm, '');
} else if (self.replMode === exports.REPL_MODE_STRICT) {
out = e.stack.replace(/(\s+at\s+repl:)(\d+)/,
(_, pre, line) => pre + (line - 1));
} else {
out = e.stack;
}
top.outputStream.write((e.stack || e) + '\n');

top.outputStream.write(out + '\n');
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It will fail if e is a Symbol, won't it?

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how about if delete e.toString?

top.bufferedCommand = '';
top.lines.level = [];
top.displayPrompt();
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2 changes: 1 addition & 1 deletion test/parallel/test-repl-sigint.js
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Expand Up @@ -38,7 +38,7 @@ child.stdout.once('data', common.mustCall(() => {
child.on('close', function(code) {
assert.strictEqual(code, 0);
assert.ok(
stdout.includes('Script execution interrupted.\n'),
stdout.includes('Script execution interrupted.'),
`Expected stdout to contain "Script execution interrupted.", got ${stdout}`
);
assert.ok(
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21 changes: 21 additions & 0 deletions test/parallel/test-repl.js
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Expand Up @@ -134,6 +134,27 @@ function error_test() {
// Uncaught error throws and prints out
{ client: client_unix, send: 'throw new Error(\'test error\');',
expect: /^Error: test error/ },
// Throws primitive and prints out
{ client: client_unix, send: 'throw null;',
expect: 'null' },
// Throws Object without toString() method and prints out
{ client: client_unix, send: 'throw Object.create(null);',
expect: '{}' },
// Throws Object with bad toString() method and prints out
{
client: client_unix,
send: 'var e = { toString() { throw new Error(\'test\'); } }; throw e;',
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Even smarter! 👍

expect: /{ toString: \[Function: toString\] }/
},
// Throws Symbol and prints out
{ client: client_unix, send: 'throw Symbol(\'test\');',
expect: /^Symbol\(test\)/ },
// Throws Error without stack and prints out
{
client: client_unix,
send: 'var e = new Error(\'test error\'); delete e.stack; throw e;',
expect: /^\[Error: test error\]/
},
// Common syntax error is treated as multiline command
{ client: client_unix, send: 'function test_func() {',
expect: prompt_multiline },
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