Prevent resumption of generator suspended in yield from

Author: arnaud-lb

Zend/tests/gh19306.phpt

@@ -0,0 +1,40 @@
+--TEST--
+GH-19306: Generator suspended in yield from may be resumed
+--FILE--
+<?php
+
+class It implements IteratorAggregate
+{
+    public function getIterator(): Generator
+    {
+        yield "";
+        Fiber::suspend();
+    }
+}
+function g()
+{
+    yield from new It();
+}
+$a = g();
+$fiber = new Fiber(function () use ($a) {
+    echo "Fiber start\n";
+    $a->next();
+    echo "Fiber return\n";
+});
+$fiber->start();
+echo "Fiber suspended\n";
+try {
+    $a->next();
+} catch (Throwable $t) {
+    echo $t->getMessage(), "\n";
+}
+echo "Destroying fiber\n";
+$fiber = null;
+echo "Shutdown\n";
+?>
+--EXPECT--
+Fiber start
+Fiber suspended
+Cannot resume an already running generator
+Destroying fiber
+Shutdown

Zend/zend_generators.c

@@ -787,6 +787,8 @@ ZEND_API void zend_generator_resume(zend_generator *orig_generator) /* {{{ */
 		orig_generator->execute_fake.prev_execute_data = original_execute_data;
 	}
 
+	generator->flags |= ZEND_GENERATOR_CURRENTLY_RUNNING;
+
 	/* Ensure this is run after executor_data swap to have a proper stack trace */
 	if (UNEXPECTED(!Z_ISUNDEF(generator->values))) {
 		if (EXPECTED(zend_generator_get_next_delegated_value(generator) == SUCCESS)) {
@@ -795,7 +797,7 @@ ZEND_API void zend_generator_resume(zend_generator *orig_generator) /* {{{ */
 			EG(jit_trace_num) = original_jit_trace_num;
 
 			orig_generator->flags &= ~(ZEND_GENERATOR_DO_INIT | ZEND_GENERATOR_IN_FIBER);
-			generator->flags &= ~ZEND_GENERATOR_IN_FIBER;
+			generator->flags &= ~(ZEND_GENERATOR_CURRENTLY_RUNNING | ZEND_GENERATOR_IN_FIBER);
 			return;
 		}
 		if (UNEXPECTED(EG(exception))) {
@@ -817,7 +819,6 @@ ZEND_API void zend_generator_resume(zend_generator *orig_generator) /* {{{ */
 	}
 
 	/* Resume execution */
-	generator->flags |= ZEND_GENERATOR_CURRENTLY_RUNNING;
 	if (!ZEND_OBSERVER_ENABLED) {
 		zend_execute_ex(generator->execute_data);
 	} else {