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LibJS: No longer assume there is a cycle root when module failed before

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This issue could be triggered by evaluating a module twice. If it failed
during evaluation the cycle root was never set but that status is
evaluated. This failed in step 3 of Evaluate which assumes it has a
cycle root. This is a spec issue see:
https://github.com/tc39/ecma262/issues/2823

To fix this we check if the module itself has a top level capability
first before going to the cycle root.

Co-authored-by: Jamie Mansfield <jmansfield@cadixdev.org>
This commit is contained in:
davidot 2022-11-26 13:37:06 +01:00 committed by Linus Groh
parent d87676de8a
commit 1dc9769f7d
Notes: sideshowbarker 2024-07-17 04:00:45 +09:00 
Author: https://github.com/davidot
Commit: https://github.com/SerenityOS/serenity/commit/1dc9769f7d
Pull-request: https://github.com/SerenityOS/serenity/pull/16217
Reviewed-by: https://github.com/linusg
1 changed files with 10 additions and 1 deletions
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11
Userland/Libraries/LibJS/CyclicModule.cpp
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@ -191,10 +191,19 @@ ThrowCompletionOr<Promise*> CyclicModule::evaluate(VM& vm)
// 2. Assert: module.[[Status]] is linked, evaluating-async, or evaluated.
VERIFY(m_status == ModuleStatus::Linked || m_status == ModuleStatus::EvaluatingAsync || m_status == ModuleStatus::Evaluated);
// NOTE: The spec does not catch the case where evaluate is called twice on a script which failed
// during evaluation. This means the script is evaluated but does not have a cycle root.
// In that case we first check if this module itself has a top level capability.
// See also: https://github.com/tc39/ecma262/issues/2823 .
if (m_top_level_capability != nullptr)
return verify_cast<Promise>(m_top_level_capability->promise().ptr());
// 3. If module.[[Status]] is evaluating-async or evaluated, set module to module.[[CycleRoot]].
if (m_status == ModuleStatus::EvaluatingAsync || m_status == ModuleStatus::Evaluated) {
// Note: This will continue this function with module.[[CycleRoot]]
VERIFY(m_cycle_root && m_cycle_root->m_status == ModuleStatus::Linked && this != m_cycle_root);
VERIFY(m_cycle_root);
VERIFY(this != m_cycle_root);
VERIFY(m_cycle_root->m_status == ModuleStatus::Linked);
dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] evaluate[{}](vm) deferring to cycle root at {}", this, m_cycle_root);
return m_cycle_root->evaluate(vm);
}