Regression: file_get_contents(php://filter/…) — filter chains return false not transformed body (ext/standard/streams.c) #13741

Category

stdlib · php-src-strict

Problem

file_get_contents() on php://filter/read=…/resource=… URIs returns false on the VM. Zend applies the registered stream filters and returns the transformed bytes.

stream_filter_append() on an open php://memory handle works; the gap is the php://filter wrapper read path used by file_get_contents().

php-src reference

• php/php-src ext/standard/streams.c — php_stream_filter brigades
• php/php-src main/php_streams.h — php://filter wrapper
• php/php-src ext/standard/file.c — file_get_contents()

Repro (verified 2026-06-29)

php test/repro/maintainer_gap_php_filter_read_chain.php
php bin/vm.php test/repro/maintainer_gap_php_filter_read_chain.php

Minimal case:

<?php
echo file_get_contents('php://filter/read=string.toupper/resource=data://text/plain,hello');

Scope (PHP-in-PHP first)

Done when (php-src-strict)

• Minimal repro prints HELLO on VM
• data:// resource target still works
• Multi-filter chains (a|b) match Zend
• stream_filter_append() behavior unchanged

Verification

php test/repro/maintainer_gap_php_filter_read_chain.php
php bin/vm.php test/repro/maintainer_gap_php_filter_read_chain.php

Links

• Stdlib: stream_filter_append() / stream_filter_prepend() / stream_filter_register() (ext/standard/streams.c parity) #3283 stream_filter_register · Regression: stream_filter_register() non-php_user_filter class — returns false, Zend returns true + E_WARNING (ext/standard/streams.c) #13733 php_user_filter classes · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492