Custom stream wrapper dir_readdir output truncated to 255 characters in PHP 8.3

[joec4i]

Description

The following code:

class DummyWrapper
{
    public $context;
    public const TEST_FILENAME = 'ieNoquiaC6ijeiy9beejaiphoriejo2cheehooGou8uhoh7eh0gefahyuQuohd7eec9auso9eeFah2Maedohsemi1eetoo5fo5biePh5eephai7SiuguipouLeemequ2oope9aigoQu5efak2aLeri9ithaiJ9eew3dianaiHoo1aexaighiitee6geghiequ5nohhiikahwee8ohk2Soip2Aikeithohdeitiedeiku7DiTh2eep3aiyeejair4dau4osai1si9laeZaiquoopomomai5eeMoce0oecietu';

    public function dir_opendir()
    {
        return true;
    }

    public function dir_readdir()
    {
        return self::TEST_FILENAME;
    }
}


stream_wrapper_register('dummy', 'DummyWrapper');

$dh = opendir('dummy://', stream_context_create());
$file = readdir($dh);

var_dump($file);
var_dump(DummyWrapper::TEST_FILENAME);

Resulted in this output:

➜  /tmp php stream_wrapper.php
/private/tmp/stream_wrapper.php:25:
string(255) "ieNoquiaC6ijeiy9beejaiphoriejo2cheehooGou8uhoh7eh0gefahyuQuohd7eec9auso9eeFah2Maedohsemi1eetoo5fo5biePh5eephai7SiuguipouLeemequ2oope9aigoQu5efak2aLeri9ithaiJ9eew3dianaiHoo1aexaighiitee6geghiequ5nohhiikahwee8ohk2Soip2Aikeithohdeitiedeiku7DiTh2eep3aiyeejair"
/private/tmp/stream_wrapper.php:26:
string(300) "ieNoquiaC6ijeiy9beejaiphoriejo2cheehooGou8uhoh7eh0gefahyuQuohd7eec9auso9eeFah2Maedohsemi1eetoo5fo5biePh5eephai7SiuguipouLeemequ2oope9aigoQu5efak2aLeri9ithaiJ9eew3dianaiHoo1aexaighiitee6geghiequ5nohhiikahwee8ohk2Soip2Aikeithohdeitiedeiku7DiTh2eep3aiyeejair4dau4osai1si9laeZaiquoopomomai5eeMoce0oecietu"

➜  /tmp php -v
PHP 8.3.9 (cli) (built: Jul  2 2024 14:10:14) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.3.9, Copyright (c) Zend Technologies
    with Xdebug v3.3.1, Copyright (c) 2002-2023, by Derick Rethans
    with Zend OPcache v8.3.9, Copyright (c), by Zend Technologies

But I expected this output instead:

➜  /tmp /opt/homebrew/Cellar/[email protected]/8.2.21/bin/php stream_wrapper.php
/private/tmp/stream_wrapper.php:25:
string(300) "ieNoquiaC6ijeiy9beejaiphoriejo2cheehooGou8uhoh7eh0gefahyuQuohd7eec9auso9eeFah2Maedohsemi1eetoo5fo5biePh5eephai7SiuguipouLeemequ2oope9aigoQu5efak2aLeri9ithaiJ9eew3dianaiHoo1aexaighiitee6geghiequ5nohhiikahwee8ohk2Soip2Aikeithohdeitiedeiku7DiTh2eep3aiyeejair4dau4osai1si9laeZaiquoopomomai5eeMoce0oecietu"
/private/tmp/stream_wrapper.php:26:
string(300) "ieNoquiaC6ijeiy9beejaiphoriejo2cheehooGou8uhoh7eh0gefahyuQuohd7eec9auso9eeFah2Maedohsemi1eetoo5fo5biePh5eephai7SiuguipouLeemequ2oope9aigoQu5efak2aLeri9ithaiJ9eew3dianaiHoo1aexaighiitee6geghiequ5nohhiikahwee8ohk2Soip2Aikeithohdeitiedeiku7DiTh2eep3aiyeejair4dau4osai1si9laeZaiquoopomomai5eeMoce0oecietu"

➜  /tmp /opt/homebrew/Cellar/[email protected]/8.2.21/bin/php -v
PHP 8.2.21 (cli) (built: Jul  2 2024 12:51:54) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.2.21, Copyright (c) Zend Technologies
    with Xdebug v3.3.1, Copyright (c) 2002-2023, by Derick Rethans
    with Zend OPcache v8.2.21, Copyright (c), by Zend Technologies

PHP Version

PHP 8.3.9

Operating System

Reproducible on both macOS and Debian Buster / Bookworm.

[joec4i]

This was likely due to 00c1e7b . Since the change could break existing code, any chance if we can revert it or find a way to make it backward compatible? In our case, we have a legacy custom stream wrapper that returns a json string from dir_readdir(). It's a bad idea but I imagine there could be similarly weird use cases in other PHP apps that could hit this.
cc @nielsdos

[nielsdos]

I'm fine with simply reverting it. Cc @bukka
For reference, the commit was part of #11577

[bukka]

Yeah agreed, we should revert it.

[bukka]

It would be good to also add a test for this so we don't break it again in the future.

[joec4i]

Thanks @nielsdos and @bukka . Please let me know if you want me to open a new PR with the test cases.

[nielsdos]

Thanks @nielsdos and @bukka . Please let me know if you want me to open a new PR with the test cases.

Please do! :)

[bukka]

Just for the info, this got reverted from 8.3 because it was a serious ABI break that caused crashes in some extensions. It is kept only in master and will be part of PHP 8.4.