Fix segfault caused by weak references to FFI objects (php#12488)

Thank you!

Author: sj-i

ext/ffi/ffi.c

@@ -24,6 +24,7 @@
 #include "php_scandir.h"
 #include "zend_exceptions.h"
 #include "zend_closures.h"
+#include "zend_weakrefs.h"
 #include "main/SAPI.h"
 #include "ffi_arginfo.h"
 
@@ -2143,6 +2144,10 @@ static void zend_ffi_ctype_free_obj(zend_object *object) /* {{{ */
 	zend_ffi_ctype *ctype = (zend_ffi_ctype*)object;
 
 	zend_ffi_type_dtor(ctype->type);
+
+    if (UNEXPECTED(GC_FLAGS(object) & IS_OBJ_WEAKLY_REFERENCED)) {
+        zend_weakrefs_notify(object);
+    }
 }
 /* }}} */
 
@@ -2369,6 +2374,10 @@ static void zend_ffi_free_obj(zend_object *object) /* {{{ */
 		zend_hash_destroy(ffi->tags);
 		efree(ffi->tags);
 	}
+
+    if (UNEXPECTED(GC_FLAGS(object) & IS_OBJ_WEAKLY_REFERENCED)) {
+        zend_weakrefs_notify(object);
+    }
 }
 /* }}} */
 
@@ -2377,6 +2386,10 @@ static void zend_ffi_cdata_free_obj(zend_object *object) /* {{{ */
 	zend_ffi_cdata *cdata = (zend_ffi_cdata*)object;
 
 	zend_ffi_cdata_dtor(cdata);
+
+    if (UNEXPECTED(GC_FLAGS(object) & IS_OBJ_WEAKLY_REFERENCED)) {
+        zend_weakrefs_notify(object);
+    }
 }
 /* }}} */
 

ext/ffi/tests/weak_reference_001.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Weak reference to \FFI
+--EXTENSIONS--
+ffi
+--INI--
+ffi.enable=1
+--FILE--
+<?php
+$ffi = \FFI::cdef('');
+$ref = \WeakReference::create($ffi);
+var_dump($ref->get() === $ffi);
+unset($ffi);
+var_dump($ref->get() === null);
+?>
+--EXPECTF--
+bool(true)
+bool(true)

ext/ffi/tests/weak_reference_002.phpt

@@ -0,0 +1,36 @@
+--TEST--
+Weak reference to \FFI\CData
+--EXTENSIONS--
+ffi
+--INI--
+ffi.enable=1
+--FILE--
+<?php
+$cdata_value = \FFI::new('int');
+$cdata_array = \FFI::new('int[1]');
+$cdata_free = \FFI::new('int[1]', false);
+\FFI::free($cdata_free);
+
+$ref_value = \WeakReference::create($cdata_value);
+$ref_array = \WeakReference::create($cdata_array);
+$ref_free = \WeakReference::create($cdata_free);
+
+var_dump($ref_value->get() === $cdata_value);
+var_dump($ref_array->get() === $cdata_array);
+var_dump($ref_free->get() === $cdata_free);
+
+unset($cdata_value);
+unset($cdata_array);
+unset($cdata_free);
+
+var_dump($ref_value->get() === null);
+var_dump($ref_array->get() === null);
+var_dump($ref_free->get() === null);
+?>
+--EXPECTF--
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(true)

ext/ffi/tests/weak_reference_003.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Weak reference to \FFI\CType
+--EXTENSIONS--
+ffi
+--INI--
+ffi.enable=1
+--FILE--
+<?php
+$ctype = \FFI::type('int');
+$ref = \WeakReference::create($ctype);
+var_dump($ref->get() === $ctype);
+unset($ctype);
+var_dump($ref->get() === null);
+?>
+--EXPECTF--
+bool(true)
+bool(true)

ext/ffi/tests/weak_reference_004.phpt

@@ -0,0 +1,36 @@
+--TEST--
+Using FFI Types for keys of a WeakMap
+--EXTENSIONS--
+ffi
+--INI--
+ffi.enable=1
+--FILE--
+<?php
+$map = new WeakMap();
+
+$ffi = \FFI::cdef('');
+$cdata_value = \FFI::new('int');
+$cdata_array = \FFI::new('int[1]');
+$cdata_free = \FFI::new('int[1]', false);
+\FFI::free($cdata_free);
+$ctype = \FFI::type('int');
+
+$map[$ffi] = 'ffi';
+$map[$cdata_value] = 'cdata_value';
+$map[$cdata_array] = 'cdata_array';
+$map[$cdata_free] = 'cdata_free';
+$map[$ctype] = 'ctype';
+
+var_dump(count($map) === 5);
+
+unset($ffi);
+unset($cdata_value);
+unset($cdata_array);
+unset($cdata_free);
+unset($ctype);
+
+var_dump(count($map) === 0);
+?>
+--EXPECTF--
+bool(true)
+bool(true)