abort_async_function.diff

diff --git a/src/completion.mjs b/src/completion.mjs
index 96a909a..e56da42 100644
--- a/src/completion.mjs
+++ b/src/completion.mjs
@@ -5,6 +5,8 @@ import {
   PerformPromiseThen,
   PromiseResolve,
   SetFunctionLength,
+  ToBoolean,
+  Get,
 } from './abstract-ops/all.mjs';
 import { Value } from './value.mjs';
 import { resume } from './helpers.mjs';
@@ -112,12 +114,28 @@ export function EnsureCompletion(val) {
   return NormalCompletion(val);
 }
 
+export function CheckAborted(signal) {
+  const aborted = ToBoolean(Q(Get(signal, new Value('aborted'))));
+  if (aborted === Value.true) {
+    return surroundingAgent.Throw('Error', 'Raw', 'aborted by signal');
+  }
+  return NormalCompletion(undefined);
+}
+
 export function AwaitFulfilledFunctions([value]) {
   const F = surroundingAgent.activeFunctionObject;
   const asyncContext = F.AsyncContext;
   const prevContext = surroundingAgent.runningExecutionContext;
   // Suspend prevContext
   surroundingAgent.executionContextStack.push(asyncContext);
+  if (asyncContext.signal) {
+    const aborted = CheckAborted(asyncContext.signal);
+    if (aborted instanceof AbruptCompletion) {
+      resume(asyncContext, aborted);
+      Assert(surroundingAgent.runningExecutionContext === prevContext);
+      return Value.undefined;
+    }
+  }
   resume(asyncContext, NormalCompletion(value));
   Assert(surroundingAgent.runningExecutionContext === prevContext);
   return Value.undefined;
@@ -129,6 +147,14 @@ function AwaitRejectedFunctions([reason]) {
   const prevContext = surroundingAgent.runningExecutionContext;
   // Suspend prevContext
   surroundingAgent.executionContextStack.push(asyncContext);
+  if (asyncContext.signal) {
+    const aborted = CheckAborted(asyncContext.signal);
+    if (aborted instanceof AbruptCompletion) {
+      resume(asyncContext, aborted);
+      Assert(surroundingAgent.runningExecutionContext === prevContext);
+      return Value.undefined;
+    }
+  }
   resume(asyncContext, ThrowCompletion(reason));
   Assert(surroundingAgent.runningExecutionContext === prevContext);
   return Value.undefined;
@@ -136,6 +162,9 @@ function AwaitRejectedFunctions([reason]) {
 
 export function* Await(value) {
   const asyncContext = surroundingAgent.runningExecutionContext;
+  if (asyncContext.signal) {
+    Q(CheckAborted(asyncContext.signal));
+  }
   const promise = Q(PromiseResolve(surroundingAgent.intrinsic('%Promise%'), value));
   const stepsFulfilled = AwaitFulfilledFunctions;
   const onFulfilled = X(CreateBuiltinFunction(stepsFulfilled, ['AsyncContext']));
diff --git a/src/realm.mjs b/src/realm.mjs
index f4fad05..cd61179 100644
--- a/src/realm.mjs
+++ b/src/realm.mjs
@@ -7,9 +7,10 @@ import {
   Assert,
   DefinePropertyOrThrow,
   OrdinaryObjectCreate,
+  CreateBuiltinFunction,
 } from './abstract-ops/all.mjs';
 import { NewGlobalEnvironment } from './environment.mjs';
-import { Q, X } from './completion.mjs';
+import { Q, X, CheckAborted } from './completion.mjs';
 import { BootstrapObjectPrototype } from './intrinsics/ObjectPrototype.mjs';
 import { BootstrapObject } from './intrinsics/Object.mjs';
 import { BootstrapArrayPrototype } from './intrinsics/ArrayPrototype.mjs';
@@ -389,5 +390,16 @@ export function SetDefaultGlobalBindings(realmRec) {
     })));
   }
 
+  Q(DefinePropertyOrThrow(global, new Value('setSignal'), Descriptor({
+    Value: CreateBuiltinFunction(([signal = Value.undefined]) => {
+      Q(CheckAborted(signal));
+      surroundingAgent.executionContextStack[surroundingAgent.executionContextStack.length - 2].signal = signal;
+      return Value.undefined;
+    }, [], realmRec),
+    Writable: Value.true,
+    Enumerable: Value.false,
+    Configurable: Value.true,
+  })));
+
   return global;
 }