opcache: Improve error messages when “temporarily enabling OPcache” (#19619)

* opcache: Do not emit “temporary enabling” message when OPcache is already active

An easy way to accidentally enable OPcache “temporarily” is by using
`php_admin_value[opcache.enable]=1` within a FPM pool’s configuration, since
the `php_admin_value` settings mostly behave like settings in php.ini, with
many OPcache INI settings being a notable exception.

As long as OPcache is already enabled within php.ini (or simply by default),
emitting a warning for `php_admin_value[opcache.enable]=1` or similar is going
to be confusing, since is not actually temporarily enabling anything.

A follow-up commit will also try to detect this kind of incorrect configuration
and try to provide better advice for cases where OPcache is actually not yet
enabled.

* opcache: Improve error message when OPcache is enabled dynamically

The error message will now advice on the `php_admin_value[opcache.enable]=1`
mistake. It will also send the message to OPcache’s logging facility instead of
the regular error handling logic during startup so that it will not be made
available to `error_get_last()`, since it is related to a specific request and
thus not actionable by a script either.

php/php-src#19146 made a related change to `opcache.memory_consumption`.

* opcache: Fix typo in warning message

* opcache: Use more formal language in warning message

ext/opcache/tests/opcache_enable_noop_001.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Dynamically setting opcache.enable does not warn when noop
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+--EXTENSIONS--
+opcache
+--FILE--
+<?php
+
+echo "Should not warn:", PHP_EOL;
+ini_set('opcache.enable', 1);
+echo "Disabling:", PHP_EOL;
+ini_set('opcache.enable', 0);
+echo "Should warn:", PHP_EOL;
+ini_set('opcache.enable', 1);
+
+?>
+--EXPECTF--
+Should not warn:
+Disabling:
+Should warn:
+
+Warning: Zend OPcache can't be temporarily enabled (it may be only disabled until the end of request) in %s on line %d

ext/opcache/tests/opcache_enable_noop_002.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Dynamically setting opcache.enable warns when not a noop
+--INI--
+opcache.enable=0
+opcache.enable_cli=1
+--EXTENSIONS--
+opcache
+--FILE--
+<?php
+
+echo "Should warn, since the INI was initialized to 0:", PHP_EOL;
+ini_set('opcache.enable', 1);
+
+?>
+--EXPECTF--
+Should warn, since the INI was initialized to 0:
+
+Warning: Zend OPcache can't be temporarily enabled (it may be only disabled until the end of request) in %s on line %d

ext/opcache/zend_accelerator_module.c

@@ -159,10 +159,23 @@ static ZEND_INI_MH(OnEnable)
 	    stage == ZEND_INI_STAGE_DEACTIVATE) {
 		return OnUpdateBool(entry, new_value, mh_arg1, mh_arg2, mh_arg3, stage);
 	} else {
-		/* It may be only temporary disabled */
+		/* It may be only temporarily disabled */
 		bool *p = (bool *) ZEND_INI_GET_ADDR();
 		if (zend_ini_parse_bool(new_value)) {
-			zend_error(E_WARNING, ACCELERATOR_PRODUCT_NAME " can't be temporary enabled (it may be only disabled till the end of request)");
+			if (*p) {
+				/* Do not warn if OPcache is enabled, as the update would be a noop anyways. */
+				return SUCCESS;
+			}
+
+			if (stage == ZEND_INI_STAGE_ACTIVATE) {
+				if (strcmp(sapi_module.name, "fpm-fcgi") == 0) {
+					zend_accel_error(ACCEL_LOG_WARNING, ACCELERATOR_PRODUCT_NAME " can't be temporarily enabled. Are you using php_admin_value[opcache.enable]=1 in an individual pool's configuration?");
+				} else {
+					zend_accel_error(ACCEL_LOG_WARNING, ACCELERATOR_PRODUCT_NAME " can't be temporarily enabled (it may be only disabled until the end of request)");
+				}
+			} else {
+				zend_error(E_WARNING, ACCELERATOR_PRODUCT_NAME " can't be temporarily enabled (it may be only disabled until the end of request)");
+			}
 			return FAILURE;
 		} else {
 			*p = 0;

sapi/fpm/tests/opcache_enable_admin_value.phpt

@@ -0,0 +1,49 @@
+--TEST--
+Setting opcache.enable via php_admin_value fails gracefully
+--SKIPIF--
+<?php include "skipif.inc"; ?>
+--FILE--
+<?php
+
+require_once "tester.inc";
+
+$cfg = <<<EOT
+[global]
+error_log = {{FILE:LOG}}
+[unconfined]
+listen = {{ADDR}}
+pm = static
+pm.max_children = 1
+catch_workers_output = yes
+php_admin_value[opcache.enable] = On
+php_admin_flag[display_errors] = On
+php_admin_flag[display_startup_errors] = On
+php_admin_flag[log_errors] = On
+EOT;
+
+$code = <<<EOT
+<?php
+var_dump(error_get_last());
+EOT;
+
+$tester = new FPM\Tester($cfg, $code);
+$tester->start(iniEntries: [
+    'opcache.enable' => '0',
+    'opcache.log_verbosity_level' => '2',
+]);
+$tester->expectLogStartNotices();
+$tester->expectLogPattern("/Zend OPcache can't be temporarily enabled. Are you using php_admin_value\\[opcache.enable\\]=1 in an individual pool's configuration?/");
+echo $tester
+    ->request()
+    ->getBody();
+$tester->terminate();
+$tester->close();
+
+?>
+--EXPECT--
+NULL
+--CLEAN--
+<?php
+require_once "tester.inc";
+FPM\Tester::clean();
+?>