SplFileObject::isReadable and SplFileObject::isWriteable provide an untrustworthy interface

Description

isReadable and isWriteable only consider the file system permissions but that isn't actually reflective of the state of the object because read and write methods also consider the resource mode so if you trust them you can can run into unexpected bugs as demonstrated in the example below.

Specifically
1 . Streams don't look readable?
2. Resources that are opened write only look readable.

The following code:

<?php

function showFile(\SplFileObject $file) {
    var_dump($file->isReadable());
    if ($file->isReadable()) {
      var_dump($file->fread($file->getSize()));
    }
    echo str_repeat('=', 80) . PHP_EOL;
}

showFile(new SplFileObject(__FILE__));
$f = new SplFileObject('php://temp', 'r+');
$f->fwrite('content');
showFile($f);
showFile(new SplFileObject(__FILE__, 'a'));

Resulted in this output:

bool(true)
string(376) "<?php

function showFile(\SplFileObject $file) {
    var_dump($file->isReadable());
    if ($file->isReadable()) {
      var_dump($file->fread($file->getSize()));
    }
    echo str_repeat('=', 80) . PHP_EOL;
}

showFile(new SplFileObject(__FILE__));
$f = new SplFileObject('php://temp', 'r+');
$f->fwrite('content');
showFile($f);
showFile(new SplFileObject(__FILE__, 'a'));
"
================================================================================
bool(false)
================================================================================
bool(true)
PHP Notice:  SplFileObject::fread(): Read of 8192 bytes failed with errno=9 Bad file descriptor in /tmp/tmp.php on line 6
bool(false)
================================================================================

But I expected this output instead:

bool(true)
string(376) "<?php

function showFile(\SplFileObject $file) {
    var_dump($file->isReadable());
    if ($file->isReadable()) {
      var_dump($file->fread($file->getSize()));
    }
    echo str_repeat('=', 80) . PHP_EOL;
}

showFile(new SplFileObject(__FILE__));
$f = new SplFileObject('php://temp', 'r+');
$f->fwrite('content');
showFile($f);
showFile(new SplFileObject(__FILE__, 'a'));
"
================================================================================
bool(true)
string(7) "content"
================================================================================
bool(false)

PHP Version

all

Operating System

No response

Les points d’entrée sont SplFileObject::isReadable(), SplFileObject::isWriteable() et les méthodes de lecture/écriture présentées dans l’exemple. Commencez par suivre la manière dont ces méthodes évaluent les permissions du système de fichiers par rapport au mode de la ressource. Ajoutez une couverture de régression pour les cas r+, écriture seule et ajout, puis vérifiez les sorties rapportées et attendues.