gzfile and readgzfile no longer identify corrupted gzip data

Description

Using this (invalid) gzip file: corrupt.txt.gz for testing below.

Just for completion: this is what happens using zcat/gzip - it can't decode it and thinks it's encrypted. It's not, it's just garbage.

$ zcat corrupt.txt.gz
gzip: corrupt.txt.gz is encrypted -- not supported

The following code:

<?php
var_dump(gzfile("corrupt.txt.gz"));

Resulted in this output:

array(2) {
  [0]=>
  string(8) "x��	U"
  [1]=>
  string(6) "I-.��"
}

But I expected this output instead:

array(0) {
}

Running the same code with PHP < 8.5.3 (including 8.5.2) will result in the expected empty array.

The same issue exists when using readgzfile(): all older versions will return -1 while 8.5.3 returns binary data.

PHP Version

PHP 8.5.3 (cli) (built: Feb 12 2026 16:29:14) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.5.3, Copyright (c) Zend Technologies
    with Xdebug v3.5.1, Copyright (c) 2002-2026, by Derick Rethans
    with Zend OPcache v8.5.3, Copyright (c), by Zend Technologies

Operating System

ArchLinux

Comienza reproduciendo el caso proporcionado corrupt.txt.gz con gzfile() y readgzfile() en PHP 8.5.2 y 8.5.3. Traza el manejo de gzip utilizado por estas funciones y compara el resultado de los datos corruptos con el array vacío esperado y los valores de retorno -1; se considera terminado cuando ambas funciones rechazan el flujo no válido como antes.