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Bug #77069 stream filter loses final block of data
Submitted: 2018-10-26 18:45 UTC Modified: 2020-08-18 11:31 UTC
Avg. Score:4.2 ± 0.8
Reproduced:4 of 4 (100.0%)
Same Version:2 (50.0%)
Same OS:2 (50.0%)
From: fisharebest at gmail dot com Assigned: cmb (profile)
Status: Closed Package: Streams related
PHP Version: 7.2.11 OS: *
Private report: No CVE-ID: None
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From: fisharebest at gmail dot com
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 [2018-10-26 18:45 UTC] fisharebest at gmail dot com
I'm using a stream filter to process data.

The test case below (also available at shows a stream filter that reverses the text on each line.

Since PHP 7.2, the final block of data is not included in the output.

My initial debugging suggests an issue with the $closing parameter.  It should be set to true when processing the final block of data.  Since PHP 7.2, it is always false.

It worked for PHP 5.5.21 -> 7.1.
It fails for PHP 7.2 and 7.3.
It fails for PHP <= 5.5.20

Test script:
class MyFilter extends php_user_filter {
    private $data = '';

    public function filter($in, $out, &$consumed, $closing) {
        $return = PSFS_FEED_ME;

        // While input data is available, continue to read it.
        while ($bucket_in = stream_bucket_make_writeable($in)) {
            $this->data .= $bucket_in->data;
            $consumed   += $bucket_in->datalen;

            // Process whole lines.
            while (preg_match('/(.*?)[\r\n]+(.*)/s', $this->data, $match) === 1) {
                list(, $data, $this->data) = $match;
                // Send this record output.
                $data       = strrev($data) . PHP_EOL;
                $bucket_out = stream_bucket_new($this->stream, $data);
                $return     = PSFS_PASS_ON;
                stream_bucket_append($out, $bucket_out);

        // Process the final line.
        if ($closing && $this->data !== '') {
            $data       = strrev($this->data) . PHP_EOL;
            $bucket_out = stream_bucket_new($this->stream, $data);
            $return     = PSFS_PASS_ON;
            stream_bucket_append($out, $bucket_out);

        return $return;

stream_filter_register('my-filter', 'MyFilter');

$input = "Line one\nLine two\nLine three";

$stream = fopen('data://text/plain,' . $input, 'r');
stream_filter_append($stream, 'my-filter');

$output = '';
while (!feof($stream)) {
    $output .= fread($stream, 16);

echo $output;

Expected result:
eno eniL
owt eniL
eerht eniL

Actual result:
eno eniL
owt eniL


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 [2018-10-27 13:43 UTC]
FWIW: this behavioral change has been introduced with commit
0a45e8f[1] which fixed bug #75515.

[1] <;a=commit;h=0a45e8f096a04464bda6277c6f3d0b5461737a27>
 [2020-08-17 15:04 UTC]
The following pull request has been associated:

Patch Name: Fix #77069: stream filter loses final block of data
On GitHub:
 [2020-08-17 15:07 UTC]
-Assigned To: +Assigned To: cmb
 [2020-08-18 11:31 UTC]
-Status: Assigned +Status: Verified -Operating System: Linux and OSX +Operating System: *
 [2020-12-08 10:50 UTC]
Automatic comment on behalf of
Log: Fix #77069: stream filter loses final block of data
 [2020-12-08 10:50 UTC]
-Status: Verified +Status: Closed
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