Test and fix memcache session redundancy php8 (#87)

* Use zend_bool for ini bool settings

I think that these might have uninitialized bytes
when a data type larger than zend_bool is used for the ini setting,
if the module globals are set from malloc?
(Not 100% sure if the entire structure isn't set to 0 before being used)

Related to #56

* add a redundancy test file

add a redundancy test file checking multiple memcached restarts
install pcntl in docker container so tests are running
add also a Vagrantfile for easier dev env setup

* fix the redundancy failover by having dataresult as null initially instead of empty string

Co-authored-by: Tyson Andre <tysonandre775@hotmail.com>
Co-authored-by: Tomas Srnka <tomassrnka@users.noreply.github.com>

Dockerfile

@@ -1,10 +1,13 @@
 ARG PHP_IMAGE=php:8.0
 FROM $PHP_IMAGE
 
+RUN docker-php-ext-configure pcntl --enable-pcntl \
+    && docker-php-ext-install -j$(nproc) pcntl
+
 RUN apt-get update && apt-get install -y \ 
 	git \
 	zlib1g-dev \
-	memcached ; 
+	memcached ;
 
 COPY docker/host.conf /etc/host.conf
 

Vagrantfile

@@ -0,0 +1,17 @@
+# -*- mode: ruby -*-
+# vi: set ft=ruby :
+
+VAGRANTFILE_API_VERSION = '2'
+
+Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
+    config.vm.box = 'ubuntu/bionic64'
+
+    config.vm.provider :virtualbox do |vb|
+        vb.name = 'ext-memcache-dev'
+        vb.memory = 1024
+        vb.cpus = 2
+    end
+
+    config.vm.provision 'docker'
+
+end

src/memcache_session.c

@@ -319,7 +319,7 @@ PS_READ_FUNC(memcache)
 			ZVAL_NULL(&addresult);
 
 			/* third request fetches the data, data is only valid if either of the lock requests succeeded */
-			ZVAL_EMPTY_STRING(&dataresult);
+			ZVAL_NULL(&dataresult);
 
 			/* create requests */
 			if (php_mmc_session_read_request(pool, &zkey, lockparam, &addresult, dataparam, &lockrequest, &addrequest, &datarequest) != MMC_OK) {

tests/redundancy_test.phpt

@@ -0,0 +1,75 @@
+--TEST--
+redundancy test
+--SKIPIF--
+<?php include 'connect.inc'; if (!MEMCACHE_HAVE_SESSION) print 'skip not compiled with session support'; else if (!function_exists('pcntl_fork')) print 'skip not compiled with pcntl_fork() support'; ?>
+--FILE--
+<?php
+
+include 'connect.inc';
+
+$sid = md5(rand());
+
+ini_set('session.save_handler', 'memcache');
+ini_set('memcache.session_save_path', "tcp://$host:$port,tcp://$host2:$port2");
+ini_set('memcache.session_redundancy', 3);
+
+$memcache1 = test_connect1();
+$memcache2 = test_connect2();
+
+$pid = pcntl_fork();
+if (!$pid) {
+    // In child process
+    session_id($sid);
+    session_start();
+    if (!isset($_SESSION['counter']))
+        $_SESSION['counter'] = 0;
+    $_SESSION['counter'] += 1;
+    session_write_close();
+
+    exit(0);
+}
+pcntl_waitpid($pid, $status);
+
+$memcache1->flush();
+
+$pid = pcntl_fork();
+if (!$pid) {
+    // In child process
+    session_id($sid);
+    session_start();
+    if (!isset($_SESSION['counter']))
+        $_SESSION['counter'] = 0;
+    $_SESSION['counter'] += 1;
+    session_write_close();
+
+    exit(0);
+}
+pcntl_waitpid($pid, $status);
+
+$memcache2->flush();
+
+$pid = pcntl_fork();
+if (!$pid) {
+    // In child process
+    session_id($sid);
+    session_start();
+    if (!isset($_SESSION['counter']))
+        $_SESSION['counter'] = 0;
+    $_SESSION['counter'] += 1;
+    session_write_close();
+
+    exit(0);
+}
+pcntl_waitpid($pid, $status);
+
+
+session_id($sid);
+session_start();
+var_dump($_SESSION);
+
+?>
+--EXPECT--
+array(1) {
+  ["counter"]=>
+  int(3)
+}