QuickJS: bound the JS stack to the thread's real stack; Chakra: define globalThis

[matthargett]

Two small engine-backend fixes surfaced by running the Fetch/Streams polyfill PRs (#208–#212) through the full CI matrix on the fork.

QuickJS (Android crash). RunEnvironmentTier never calls JS_SetMaxStackSize, so QuickJS guards recursion against stack_top - JS_DEFAULT_STACK_SIZE — 1 MiB in quickjs-ng, which is also the default size of a non-main thread on Android and Windows. On those threads the check sits below the real guard page: deep recursion faults (SIGSEGV, one frame repeated 150+ deep in the tombstone) before QuickJS can raise InternalError: stack overflow. The 8 MiB-stacked desktop QuickJS jobs were unaffected. The limit is now derived from the running thread (pthread_getattr_np / pthread_get_stacksize_np / GetCurrentThreadStackLimits) minus a margin for native frames.

Chakra (globalThis). The Windows 10 Chakra predates ES2020 and has no globalThis; scripts written against browsers reference it (ReferenceError: 'globalThis' is not defined). It's now defined on the global object at env attach as a plain writable, configurable property, per spec.

Fork CI twin with the full 24-job matrix: rebeckerspecialties/JsRuntimeHost (linked below).

[matthargett]

Fork CI twin (full 24-job matrix): rebeckerspecialties#21.

[Copilot]

🟡 Changes recommended

Unresolved critical build/linkage issues and correctness issues remain.

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Pull request overview

This PR improves QuickJS stack safety and adds Chakra globalThis compatibility.

Changes:

• Derives QuickJS stack limits from the current thread.
• Defines Chakra’s globalThis property during environment setup.

File summaries

File	Changes	Review findings
Core/Node-API/Source/env_chakra.cc	Initializes Chakra’s globalThis.	Moderate (3 votes): The property is enumerable; it should use a non-enumerable descriptor via JsDefineProperty.
Core/AppRuntime/Source/AppRuntime_QuickJS.cpp	Configures platform-specific, thread-aware QuickJS stack limits.	Critical (2 votes): pthread_getattr_np requires GNU feature declarations on glibc. Moderate (1 vote): Known small stacks can receive an unsafe 512 KiB limit. Critical (1 vote): Android API 21 lacks pthread_getattr_np, causing linkage failure.

Review details

Suppressed comments (1)

Core/AppRuntime/Source/AppRuntime_QuickJS.cpp:73

• When the stack query succeeds for a thread whose real stack is at most Margin (for example, a host-created 128/256 KiB thread), this branch returns a 512 KiB limit. QuickJS then permits recursion beyond that thread's guard page, which is the crash this change is intended to prevent. Distinguish an unknown size (threadStack == 0) from a known small stack and use a conservative limit derived from the latter (for example, half of threadStack).

            if (threadStack <= Margin)
            {
                return Fallback;
            }
            return std::min(threadStack - Margin, static_cast<size_t>(JS_DEFAULT_STACK_SIZE) * 8);

• Files reviewed: 2/2 changed files
• Comments generated: 3
• Review effort level: Lite

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