fix: system ID for Apache graceful restart

Apache forks workers from a parent process. During a graceful
restart, PHP shuts down and starts up again in that same parent
process.

However, `finalized` was not reset to 0 during subsequent startups,
so all calls to `zend_add_system_entropy()` would fail. This could
cause the process state to diverge from the system ID used to
validate OPcache's file cache.

For example, `zend_get_resource_handle()` would still allocate a
handle, but its entropy would not contribute to the system ID.
Enabling, disabling, or reordering extensions or features across
graceful restarts could therefore change resource-slot assignments
without a corresponding change to the system ID.

Reset `finalized` when initializing the system ID so each startup
can register fresh entropy.

Author: morrisonlevi

Zend/zend_system_id.c

@@ -43,6 +43,7 @@ ZEND_API zend_result zend_add_system_entropy(const char *module_name, const char
 
 void zend_startup_system_id(void)
 {
+	finalized = 0;
 	PHP_MD5Init(&context);
 	PHP_MD5Update(&context, PHP_VERSION, sizeof(PHP_VERSION)-1);
 	PHP_MD5Update(&context, ZEND_EXTENSION_BUILD_ID, sizeof(ZEND_EXTENSION_BUILD_ID)-1);

ext/zend_test/test.c

@@ -36,6 +36,7 @@
 #include "test_arginfo.h"
 #include "zend_call_stack.h"
 #include "zend_exceptions.h"
+#include "zend_system_id.h"
 #include "zend_mm_custom_handlers.h"
 #include <signal.h>
 
@@ -1149,6 +1150,7 @@ static ZEND_METHOD(_ZendTestMagicCallForward, __call)
 }
 
 PHP_INI_BEGIN()
+	PHP_INI_ENTRY("zend_test.register_system_entropy", "0", PHP_INI_SYSTEM, NULL)
 	STD_PHP_INI_BOOLEAN("zend_test.replace_zend_execute_ex", "0", PHP_INI_SYSTEM, OnUpdateBool, replace_zend_execute_ex, zend_zend_test_globals, zend_test_globals)
 	STD_PHP_INI_BOOLEAN("zend_test.register_passes", "0", PHP_INI_SYSTEM, OnUpdateBool, register_passes, zend_zend_test_globals, zend_test_globals)
 	STD_PHP_INI_BOOLEAN("zend_test.print_stderr_mshutdown", "0", PHP_INI_SYSTEM, OnUpdateBool, print_stderr_mshutdown, zend_zend_test_globals, zend_test_globals)
@@ -1347,6 +1349,10 @@ PHP_MINIT_FUNCTION(zend_test)
 	// Loading via dl() not supported with the observer API
 	if (type != MODULE_TEMPORARY) {
 		REGISTER_INI_ENTRIES();
+		if (INI_BOOL("zend_test.register_system_entropy") &&
+			zend_add_system_entropy("zend_test", "test", ZEND_STRL("test entropy")) == FAILURE) {
+			php_error_docref(NULL, E_WARNING, "Failed to register system entropy");
+		}
 	} else {
 		(void)ini_entries;
 	}

ext/zend_test/tests/system_id_reinitialization.phpt

@@ -0,0 +1,40 @@
+--TEST--
+System ID reinitialization accepts extension entropy after engine restart
+--SKIPIF--
+<?php
+if (!extension_loaded('zend_test')) die('skip zend_test extension required');
+?>
+--INI--
+zend_test.register_system_entropy=1
+--PHPDBG--
+r
+clean
+r
+clean
+r
+q
+--FILE--
+<?php
+echo "Done\n";
+?>
+--EXPECTF--
+[Successful compilation of %s]
+prompt> Done
+[Script ended normally]
+prompt> Cleaning Execution Environment
+Classes    %d
+Functions  %d
+Constants  %d
+Includes   0
+[Script ended normally]
+prompt> Done
+[Script ended normally]
+prompt> Cleaning Execution Environment
+Classes    %d
+Functions  %d
+Constants  %d
+Includes   0
+[Script ended normally]
+prompt> Done
+[Script ended normally]
+prompt>