[BUG]: Storage adapter getKeys method return empty array when set prefix = ''

[aa65535]

Steps to reproduce the behavior:

use Phalcon\Storage\Adapter\Libmemcached;
use Phalcon\Storage\SerializerFactory;

$factory = new SerializerFactory();
$options = [
    'servers'           => [
        [
            'host'   => '127.0.0.1',
            'port'   => 11211,
            'weight' => 1
        ]
    ],
    'defaultSerializer' => 'Php',
    'lifetime'          => 3600,
    'prefix'            => '' // set empty string
];

$adapter = new Libmemcached($factory, $options);

$adapter->getKeys(); // return empty array

If patternis an empty string, keys should be returned directly.

cphalcon/phalcon/Storage/Adapter/AbstractAdapter.zep

Lines 138 to 154 in c7a713d

	protected function getFilteredKeys(var keys, string! prefix) -> array
	{
	var key, pattern;
	array results;
	let results = [],
	pattern = this->prefix . prefix,
	keys = !keys ? [] : keys;
	for key in keys {
	if Str::startsWith(key, pattern) {
	let results[] = key;
	}
	}
	return results;
	}

Expected behavior
A clear and concise description of what you expected to happen.

When prefix is set to empty string, all keys should be returned

Details

• Phalcon version: 4.1.2
• PHP Version: 7.4.16
• Operating System: CentOS 7
• Installation type: Compiling from source
• Zephir version (if any):
• Server: Nginx

[BeMySlaveDarlin]

I suppose its related to Libmemcached adapter constructor

cphalcon/phalcon/Storage/Adapter/Libmemcached.zep

Lines 45 to 61 in c7a713d

	public function __construct(<SerializerFactory> factory, array! options = [])
	{
	if !isset options["servers"] {
	let options["servers"] = [
	0 : [
	"host" : "127.0.0.1",
	"port" : 11211,
	"weight" : 1
	]
	];
	}
	let this->prefix = "ph-memc-",
	this->options = options;
	parent::__construct(factory, options);
	}

As we can see, it sets this->prefix = "ph-memc-";, so pattern is never empty.

[aa65535]

parent::__construct(factory, options); 

If options["prefix"] = '' is set, the this->prefix will be reset in the parent class.

[niden]

@aa65535 I am not convinced that this should happen.

By using the prefix we are namespacing so to speak the keys stored in the storage (Libmemcached in this case). If there are other processes using the same server, without the prefix, you will be able to retrieve keys that do not necessarily belong to your application.

So if I use say an application that stores data in memcached, and then use my Phalcon app with this adapter, without the prefix I will be able to read all the keys in memcached, even from the other application.

Thoughts?

[aa65535]

Of course, the best practice is to set a unique prefix for each application, but you can use the constructor to set the prefix to an empty string.
The problem is that when the prefix is an empty string, getKeys() does not return the expected value.

use Phalcon\Storage\Adapter\Libmemcached;
use Phalcon\Cache\Adapter\Redis;
use Phalcon\Storage\SerializerFactory;

$factory = new SerializerFactory();
$options = [
    'prefix' => '' // set empty string
];

$mem = new Libmemcached($factory, $options);

var_dump($mem->getPrefix()); // string(0) ""
var_dump($mem->getKeys()); // array(0) {}

$redis = new Redis($factory, $options);
var_dump($redis->getPrefix()); // string(0) ""
var_dump($redis->getKeys()); // array(0) {}

[niden]

@aa65535 The example you gave is correct.

If you specify an empty prefix, Phalcon needs to internally set one in order to "namespace" the keys i.e. the keys stored only for your application. If it does not, you will be able to see all keys stored in Libmemcached or Redis or elsewhere.

This is done on purpose so as not to be able to access data that does not belong to you per se.

If you want to access all the keys in Memcached or Redis etc. you can instantiate the underlying adapter and then use the getKeys() on that object.

[niden]

I will write a couple of tests to ensure that the key can be changed if need be but never be empty. I do not recall the code right now but will check just in case.

[niden]

After discussions with @Jeckerson we decided to offer this functionality. If the user wishes to not use a prefix, they can specify an empty prefix with the passed $options array.

[niden]

Resolved in #15654