Preloading has no defined io-stream constants

[SCIF]

Description

As of https://www.php.net/manual/en/features.commandline.io-streams.php , there should be constants defined in CLI.

Added the following to preload.ini:

opcache.preload_user=www-data
opcache.preload=/path/to/preload.php

The following code wrote to preload.php:

<?php

var_dump(defined('STDIN'));
var_dump(defined('STDOUT'));
var_dump(defined('STDERR'));

Resulted in this output:

/path/to/preload.php:3:
bool(false)
/path/to/preload.php:4:
bool(false)
/path/to/preload.php:5:
bool(false)

But I expected this output instead:

/path/to/preload.php:3:
bool(true)
/path/to/preload.php:4:
bool(true)
/path/to/preload.php:5:
bool(true)

I could imagine this is the expected behavior but docs should be updated then. :) There are no restrictions defined in https://www.php.net/manual/en/opcache.preloading.php BTW, the opcache_enabled shown as false for var_dump(opcache_get_status(false));.

PHP Version

8.1.16

Operating System

Docker image: php:8.1-fpm-bullseye

[iluuu1994]

Given that echo works in CLI with preloading I think expecting these constants to be there is reasonable.

[ndossche]

I tried tackling this, but it's more complicated than I thought. The constants (and stdin/stdout/stderr stream configuration) happen in cli_register_file_handles() which is called from do_cli(). But the preloaded script gets executed before that happens, in php_module_startup() which is called from php_cli_startup(). I tried to create a fake module that calls cli_register_file_handles() that runs before opcache's startup, but that crashes because we need zend_activate() to have been called for the open files and resources lists.
So in short this means that only for the lifetime of the main script the cli_register_file_handles() function is called. This also means that the following gives strange results:

preload.php:

<?php
$f = fopen("php://stdout", "w");
fwrite($f, "hello\n");
fclose($f);

index.php:

<?php
echo "hi"; // nothing printed

Put the echo in the preload file and you get a "bad file descriptor" warning, and put the fopen-fwrite-fclose in the index file and you get "hello" and "hi".