Make regexp execution loop interruptible #1189

Uses Thread.currentThread.isInterrupted() so that the interruption flag remains set to true,
we only terminate the RegExp evaluation loop, but other (potentially third-party calling)
code may still have to check for the interrupted flag to stop its execution as well.

I also added a test with a long-running regexp that fails without the interrupt check.

src/org/mozilla/javascript/regexp/NativeRegExp.java

@@ -1878,6 +1878,9 @@ private static boolean executeREBytecode(REGlobalData gData, String input, int e
 
         for (; ; ) {
 
+            if (Thread.currentThread().isInterrupted()) {
+                throw new RuntimeException("Received interrupt while executing regexp");
+            }
             if (reopIsSimple(op)) {
                 int match = simpleMatch(gData, input, op, program, pc, end, true);
                 result = match >= 0;

testsrc/org/mozilla/javascript/tests/NativeRegExpTest.java

@@ -5,12 +5,21 @@
 package org.mozilla.javascript.tests;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.assertTrue;
 
 import org.junit.Test;
 import org.mozilla.javascript.Context;
 import org.mozilla.javascript.Scriptable;
 import org.mozilla.javascript.ScriptableObject;
 
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
 public class NativeRegExpTest {
 
     @Test
@@ -49,6 +58,21 @@ public void ignoreCase() throws Exception {
         testEvaluate("i-false-true-false-false", "/foo/i;");
     }
 
+    /** @throws Exception if an error occurs */
+    @Test
+    public void interruptLongRunningRegExpEvaluation() throws Exception {
+        ExecutorService executorService = Executors.newSingleThreadExecutor();
+        try {
+            Future<?> future = executorService.submit(() -> test("false", "/(.*){1,32000}[bc]/.test(\"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\");"));
+            assertThrows(TimeoutException.class, () -> future.get(1, TimeUnit.SECONDS));
+            executorService.shutdownNow();
+            assertTrue(executorService.awaitTermination(30, TimeUnit.SECONDS));
+        }
+        finally {
+            executorService.shutdown();
+        }
+    }
+
     /** @throws Exception if an error occurs */
     @Test
     public void multilineCtor() throws Exception {