Env vars with non-ASCII values are mangled when read from $_SERVER on Windows

[Seldaek]

Description

The following code:

<?php
var_dump(
    $_SERVER['FOO'] ?? 'unset', 
    $_ENV['FOO'] ?? 'unset', 
    getenv('FOO')
);

When run with variables_order = "EGPCS" and FOO=GüИter传 set in the environment variables in Windows (or using $env:FOO = 'GüИter传' in PowerShell before executing the test file above).

Resulted in this output:

string(7) "G?ter?"
string(7) "G?ter?"
string(11) "GüИter传"

But I expected this output instead:

string(11) "GüИter传"
string(11) "GüИter传"
string(11) "GüИter传"

Doing the same in WSL/Ubuntu seems to yield the correct result, so I assume it's Windows specific.

Regarding PHP version, it appears all versions <7.2 fail completely, with even getenv() returning string(7) "G?ter?" or string(7) "Gⁿ?ter?" for 5.x. From PHP 7.2 onwards I get the behavior described above.

PHP Version

8.0.13

Operating System

Windows 10

[cmb69]

From PHP 7.2 onwards I get the behavior described above.

This is likely due to fixing https://bugs.php.net/75574, so should be fixed as of PHP 7.1.13 and 7.2.1, respectively. That fix only affected getenv(), though, but not _php_import_environment_variables (and possibly other places).

[Seldaek]

Thanks, do you see any way to mitigate/detect this in userland?

I see that doing this when starting up to ensure $_SERVER is in a good state appears to work.. not sure if there's a better way:

foreach ($_SERVER as $var => $val) {
    if (($val = getenv($var)) !== false) {
        $_SERVER[$var] = $val;
    }
}

Once fixed in a release I'll at least be able to exclude this hackery from newer PHP versions.

[cmb69]

Nope, no better idea per se, but note that this wouldn't help with env var names containing non-ASCII characters (e.g. FÖÖ=bar). If that's important, you could traverse getenv() instead (that's likely a bit faster anyway).

[Seldaek]

Ok yes using getenv() once makes more sense, although we're really only interested in ascii vars in the context of Composer.

[Seldaek]

@cmb69 it's been brought to my attention that calling getenv() also still suffers from the same issue and mangles unicode values. Only getenv('FOO') appears to work correctly.

So here's a working workaround: https://github.com/composer/composer/blob/d9619985dbabb58255fb27cf78fe702345d31793/bin/composer#L68-L76

[cmb69]

Argh! getenv() without parameter also calls php_import_environment_variables(), and I tested with an already patched version.

[Seldaek]

Thanks @cmb69 !