Bug #76859 [Opn->Csd]: stream_get_line skips data if used with data-generating filter

Edit report at https://bugs.php.net/bug.php?id=76859&edit=1 ID: 76859 Updated by: krakjoe@php.net Reported by: tenzzor at gmail dot com Summary: stream_get_line skips data if used with data-generating filter -Status: Open +Status: Closed Type: Bug Package: Streams related Operating System: Linux PHP Version: master-Git-2018-09-11 (Git) Block user comment: N Private report: N New Comment: Automatic comment on behalf of tenzzor@gmail.com Revision: http://git.php.net/?p=php-src.git;a=commit;h=05560b67bc87a2bcbfd5b48a48443a62f3311e7d Log: Fix #76859 stream_get_line skips data if used with data-generating filter Previous Comments: ------------------------------------------------------------------------ [2018-09-11 04:48:21] tenzzor at gmail dot com Description: ------------ This is happening with stream filters which create more data then they consume. For example, base64_encode, zlib.inflate. The issue is happening because stream_get_line internally calls php_stream_get_record function, which repeatedly calls php_stream_fill_read_buffer until enough data is "accumulated" in the buffer. Problem with that is repeated calls to populate read buffer force reset state of stream->readpos and stream->writepos in case filters exist on the stream. In other words, if on second call to get_record function, buffer holds some data, but does not have delimiter in it and length of data is less then required, then function attempts to put more data into buffer, which is in effect, resets buffer and content is lost. Test script: --------------- <?php $h = fopen('php://temp', 'r+b'); $len = floor(1.5 * 8 * 1024); // 8*1024 == stream->chunk_size. We need a bit more. $data = str_repeat('1', $len); fwrite($h, $data); rewind($h); stream_filter_append($h, 'convert.base64-encode'); $out = ''; while (!feof($h)) { $out .= stream_get_line($h, 1024); } fclose($h); echo $len, ' and ', strlen(base64_decode($out)), PHP_EOL; assert($data == base64_decode($out)); Expected result: ---------------- 12288 and 12288 Actual result: -------------- 12288 and 11520 Warning: assert(): assert($data == base64_decode($out)) failed in /usr/src/app/t3.php on line 17 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=76859&edit=1