opcache: Disallow changing opcache.memory_consumption when SHM is set up (#19146)

* opcache: Reset `accel_startup_ok` after shutting down

This is necessary for phpdbg, which runs multiple startup/shutdown cycles in
the same process.

* opcache: Disallow changing `opcache.memory_consumption` when SHM is set up

Normally changing the INI value is not possible after SHM is set up, since it
is `PHP_INI_SYSTEM`. FPM is a notable exception: SHM is set up in the master
process, but when spawning the individual pools, the `php_admin_value` config
option can be used to change `PHP_INI_SYSTEM` INIs on a per-pool basis. This
does not work for this option, since it will only be read on early start,
leading to misleading PHPInfo output, since the INI value appears to be
successfully set and since some of the calculated values are derived from the
INI value rather than the actual value.

NEWS

@@ -11,6 +11,10 @@ PHP                                                                        NEWS
   . Add support for CURLINFO_CONN_ID in curl_getinfo() (thecaliskan)
   . Add support for CURLINFO_QUEUE_TIME_T in curl_getinfo() (thecaliskan)
 
+- OPcache:
+  . Disallow changing opcache.memory_consumption when SHM is already set up.
+    (timwolla)
+
 - OpenSSL:
   . Add $digest_algo parameter to openssl_public_encrypt() and
     openssl_private_decrypt() functions. (Jakub Zelenka)

UPGRADING

@@ -607,6 +607,9 @@ PHP 8.5 UPGRADE NOTES
   . The default value of opcache.jit_hot_loop is now 61 (a prime) to prevent it
     from being a multiple of loop iteration counts.
     It is recommended that this parameter is set to a prime number.
+  . Changing opcache.memory_consumption when OPcache SHM is already set up
+    will now correctly report a failure instead of silently doing nothing and
+    showing misleading values in PHPInfo.
 
 - OpenSSL:
   Added openssl.libctx to select the OpenSSL library context type. Either

ext/opcache/ZendAccelerator.c

@@ -3509,6 +3509,8 @@ void accel_shutdown(void)
 	if ((ini_entry = zend_hash_str_find_ptr(EG(ini_directives), "include_path", sizeof("include_path")-1)) != NULL) {
 		ini_entry->on_modify = orig_include_path_on_modify;
 	}
+
+	accel_startup_ok = false;
 }
 
 void zend_accel_schedule_restart(zend_accel_restart_reason reason)

ext/opcache/zend_accelerator_module.c

@@ -77,6 +77,15 @@ static int validate_api_restriction(void)
 
 static ZEND_INI_MH(OnUpdateMemoryConsumption)
 {
+	if (accel_startup_ok) {
+		if (strcmp(sapi_module.name, "fpm-fcgi") == 0) {
+			zend_accel_error(ACCEL_LOG_WARNING, "opcache.memory_consumption cannot be changed when OPcache is already set up. Are you using php_admin_value[opcache.memory_consumption] in an individual pool's configuration?\n");
+		} else {
+			zend_accel_error(ACCEL_LOG_WARNING, "opcache.memory_consumption cannot be changed when OPcache is already set up.\n");
+		}
+		return FAILURE;
+	}
+
 	zend_long *p = (zend_long *) ZEND_INI_GET_ADDR();
 	zend_long memsize = atoi(ZSTR_VAL(new_value));
 	/* sanity check we must use at least 8 MB */