Bug #81092 [Asn->Ver]: Calling fflush before stream_filter_remove results in corrupted stream

Edit report at https://bugs.php.net/bug.php?id=81092&edit=1 ID: 81092 Updated by: cmb@php.net Reported by: mark at klb dot jp Summary: Calling fflush before stream_filter_remove results in corrupted stream -Status: Assigned +Status: Verified Type: Bug -Package: Bzip2 Related +Package: Streams related Operating System: Linux -PHP Version: 8.0.6 +PHP Version: 7.4 Assigned To: cmb Block user comment: N Private report: N New Comment: I can confirm that the script outputs int(0), but I get the same result with PHP-7.4 either (regardless of explicitly calling fflush()). Interestingly, using a str_repeat("*", 8192) instead of random_bytes(8192) gives the expected result. If I use the zlib.deflate and gzinflate(), I get an explicit: Warning: gzinflate(): data error So apparently a general stream (compression) filter issue. Previous Comments: ------------------------------------------------------------------------ [2021-05-31 23:17:35] mark at klb dot jp A couple notes: I am not sure this is a bz2 issue, this could come from filters too. Outputting to php://output using a filter and fflush()ing before removing the filter are conditions for this bug to happen. The bz2 stream generated is cut partially, using bzcat will for example output: php bug.php output | bzcat -tvv (stdin): [1: huff+mtf file ends unexpectedly ------------------------------------------------------------------------ [2021-05-31 18:34:32] mark at klb dot jp Description: ------------ When using filters to output bzip2 compressed data, one may be tempted to call fflush() before stream_filter_remove() to ensure all data has been written. This used to work fine, however since php8, this causes the generated stream to be corrupt. Test script: --------------- <?php if ($_SERVER['argv'][1]??'' == 'output') { $stream = fopen('php://output', 'wb+'); $filter = stream_filter_append($stream, 'bzip2.compress', STREAM_FILTER_WRITE, ['blocks' => 9, 'work' => 0]); fwrite($stream, random_bytes(8192)); fflush($stream); stream_filter_remove($filter); // should call dtor exit; } $script = $_SERVER['argv'][0]; $res = shell_exec('php '.escapeshellarg($script).' output'); // should output bz encoded data $data = bzdecompress($res); var_dump(strlen($data)); Expected result: ---------------- int(8192) Actual result: -------------- int(0) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=81092&edit=1