bug2043268-copied-trap.js

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// A Wasm trap that is copied across compartments by the Debugger's

// ErrorCopier (js::CopyErrorObject) must retain its trap flag, so it stays

// uncatchable by Wasm exception handling (catch_all).

// Exports a function that traps via `unreachable`.

const trapBytes = wasmTextToBinary(`(module

  (func (export "trap") unreachable))`);

// Imports "m.f" and wraps its call in a catch_all, returning 1 if the call

// threw something that was caught, 0 otherwise.

const catching = wasmEvalText(`(module

  (import "m" "f" (func $f))

  (func (export "run") (result i32)

    try (result i32)

      (call $f)

      (i32.const 0)

    catch_all

      (i32.const 1)

    end))`, {

  m: { f: copiedTrapThroughDebugger() },

});

// The copied trap must not be caught by catch_all; running it should propagate

// the trap as an uncatchable RuntimeError.

assertErrorMessage(() => catching.exports.run(),

                   WebAssembly.RuntimeError, /unreachable executed/);

function copiedTrapThroughDebugger() {

  const g = newGlobal({ newCompartment: true });

  g.trapBytes = trapBytes;

  g.eval(`

    var trap = new WebAssembly.Instance(

      new WebAssembly.Module(trapBytes)

    ).exports.trap;

    var proxy = new Proxy({}, { ownKeys() { trap(); } });

`);

  const dbg = new Debugger();

  const gw = dbg.addDebuggee(g);

  const proxy = gw.getOwnPropertyDescriptor("proxy").value;

  // Calling getOwnPropertyNames() triggers the proxy's ownKeys trap across the

  // compartment boundary, routing the resulting RuntimeError through the

  // Debugger's ErrorCopier.

  return function triggerCopiedTrap() {

    proxy.getOwnPropertyNames();

};