Doc #71951 [Com]: stream_socket_shutdown(..., STREAM_SHUT_RD) will not shutdown read on Linux

Edit report at https://bugs.php.net/bug.php?id=71951&edit=1 ID: 71951 Comment by: grzegorz129 at gmail dot com Reported by: grzegorz129 at gmail dot com Summary: stream_socket_shutdown(..., STREAM_SHUT_RD) will not shutdown read on Linux Status: Closed Type: Documentation Problem Package: Streams related Operating System: Linux PHP Version: 7.0.5 Assigned To: krakjoe Block user comment: N Private report: N New Comment: After digging in old Linux list archives I found the suspect - in fact it's how Linux handles (or actually not handles at all) shutdown(sock, SHUT_RD): http://oss.sgi.com/archives/netdev/2003-07/msg00692.html - it's a pretty interesting discussion about this particular issue. Maybe, since PHP is trying to be platform-independent, interpreter can unify this behavior and discard data on recv() when socket/stream was closed for reading? Previous Comments: ------------------------------------------------------------------------ [2016-04-08 02:22:33] grzegorz129 at gmail dot com This documentation not is quite nice, maybe not 100% clear for beginners but anyway - it's somewhat weird how it's actually working. Let's take a look at this code: <?php $server = stream_socket_server('tcp://127.0.0.1:9999'); $clientOnClient = stream_socket_client('tcp://127.0.0.1:9999'); $clientOnServer = stream_socket_accept($server, 0.5); var_dump(stream_set_chunk_size($clientOnServer, 1)); var_dump(stream_set_read_buffer($clientOnServer, 1)); fwrite($clientOnClient, 'ping'); //This now works as defined in documentation var_dump(fread($clientOnServer, 2)); stream_socket_shutdown($clientOnServer, STREAM_SHUT_RD); var_dump(fread($clientOnServer, 3)); //This should not work since buffer is empty at call stream_socket_shutdown($clientOnServer, STREAM_SHUT_RD); fwrite($clientOnClient, 'still-broken'); var_dump(fread($clientOnServer, 12)); //...and iterestingly it works as expected if you use RDWR or WR stream_socket_shutdown($clientOnServer, STREAM_SHUT_WR); fwrite($clientOnClient, 'or-is-it'); var_dump(fread($clientOnServer, 8)); Since buffer is closed and in fact event emptied why it's still receiving data on Linux? ;) To be entirely sure I've also tested it using PHP server on the one side and telnet at the other - stream still receives data. This behavior is also present while using sockets. <?php $server = stream_socket_server('tcp://127.0.0.1:9999'); $clientOnServer = stream_socket_accept($server, 10); stream_socket_shutdown($clientOnServer, STREAM_SHUT_RD); while(1) { sleep(1); var_dump(fread($clientOnServer, 1)); } ------------------------------------------------------------------------ [2016-04-04 08:59:15] krakjoe@php.net The fix for this bug has been committed. Snapshots of the sources are packaged every three hours; this change will be in the next snapshot. You can grab the snapshot at http://snaps.php.net/. For Windows: http://windows.php.net/snapshots/ Thank you for the report, and for helping us make PHP better. ------------------------------------------------------------------------ [2016-04-04 08:58:45] krakjoe@php.net Automatic comment from SVN on behalf of krakjoe Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=338908 Log: Fix #71951: shutdown behaviour note ------------------------------------------------------------------------ [2016-04-04 07:53:58] krakjoe@php.net On OSX (BSD) the kernel space read buffer is emptied when the socket is shutdown. On Linux, it only rejects further packets (so the other side cannot write). A note in the documentation would be nice. ------------------------------------------------------------------------ [2016-04-04 03:34:18] grzegorz129 at gmail dot com Edit: "Expected result" was accidentally switched with "Actual result". ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=71951 -- Edit this bug report at https://bugs.php.net/bug.php?id=71951&edit=1