PHP 8.6.0RC3: fclose returns FALSE instead of TRUE with stream wrappers

Description

The following code:

<?php

class Buffer {
  public function __construct(public string $bytes= '') { }

  public function uri(): string { return Buffers::uri($this); }
}

class Buffers {
  private static $buffers= [];
  private $id;
  public $context;

  public static function uri(Buffer $buffer): string {
    static $id= 0;
    self::$buffers[$id++]= $buffer;
    return "buffers://{$id}";
  }

  public function stream_open($path, $mode, $options, &$opened) {
    $this->id= (int)parse_url($path, PHP_URL_PATH);
    if (!isset(self::$buffers[$this->id])) {
      throw new Exception("Cannot open buffer {$this->id}");
    }

    $opened= $path;
    return true;
  }

  public function stream_write($bytes) {
    self::$buffers[$this->id]->bytes.= $bytes;
    return strlen($bytes);
  }

  public function stream_close() {
    unset(self::$buffers[$this->id]);
    return true;
  }
}

stream_wrapper_register('buffers', Buffers::class);

$buffer= new Buffer();

$fd= fopen($buffer->uri(), 'rb');
echo 'fd: '; var_dump($fd);
echo 'fwrite: '; var_dump(fwrite($fd, 'Test'));
echo 'fclose: '; var_dump(fclose($fd));

var_dump($buffer);

Resulted in this output:

fd: resource(6) of type (stream)
fwrite: int(4)
fclose: bool(false)
object(Buffer)#1 (1) {
  ["bytes"]=>
  string(4) "Test"
}

But I expected this output instead:

fd: resource(6) of type (stream)
fwrite: int(4)
fclose: bool(true)
object(Buffer)#1 (1) {
  ["bytes"]=>
  string(4) "Test"
}

...or easier to read as a diff:

--- 8.6beta     2026-10-11 11:15:44.899534100 +0200
+++ 8.6rc3      2026-10-11 11:15:31.824666000 +0200
@@ -1,6 +1,6 @@
 fd: resource(6) of type (stream)
 fwrite: int(4)
-fclose: bool(true)
+fclose: bool(false)
 object(Buffer)#1 (1) {
   ["bytes"]=>
   string(4) "Test"

PHP Version

PHP 8.6.0RC3 (cli) (built: Oct  6 2026 17:21:26) (NTS Visual C++ 2026 x64)
Copyright © The PHP Group and Contributors
Built by The PHP Group
Zend Engine v4.6.0RC3, Copyright © Zend by Perforce
    with Zend OPcache v8.6.0RC3, Copyright ©, by Zend by Perforce

Operating System

Windows 11

Looking at the implementation of fclose(), it returns FALSE when:

The stream has the PHP_STREAM_FLAG_NO_FCLOSE bit set (including raising an E_WARNING)
php_stream_free() returns non-zero

As no errors or warnings are raised, it might be the last branch we're running into here.

Digging deeper shows php_stream_free() returns -1, which is the result of php_stream_flush_ex() when closing succeeds. This function is implemented as follows:

static int php_stream_flush_ex(php_stream *stream, bool closing)
{
	int ret = 0;

	if (stream->writefilters.head && stream->ops->write) {
		php_stream_write_filtered(stream, NULL, 0, closing ? PSFS_FLAG_FLUSH_CLOSE : PSFS_FLAG_FLUSH_INC );
	}

	stream->flags &= ~PHP_STREAM_FLAG_WAS_WRITTEN;

	if (stream->ops->flush) {
		ret = stream->ops->flush(stream);
	}

	return ret;
}

...so I would expect it to return 0, as the above stream wrapper has no flush implementation.

By adding the following to the Buffers class:

  public function stream_flush() {
    return true;
  }

...everything works as expected.

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PHP 8.6.0RC3: fclose returns FALSE instead of TRUE with stream wrappers #24256

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PHP 8.6.0RC3: fclose returns FALSE instead of TRUE with stream wrappers #24256

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thekid commented on Oct 11, 2026

thekid commented on Oct 11, 2026

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