Bug #79222 [Opn]: unread_bytes do not work

Edit report at https://bugs.php.net/bug.php?id=79222&edit=1 ID: 79222 Updated by: nikic@php.net Reported by: skullnobrains at gmail dot com Summary: unread_bytes do not work Status: Open Type: Bug Package: Sockets related Operating System: linux PHP Version: 7.2.27 Block user comment: N Private report: N New Comment: unread_bytes is the number of bytes stored in PHP's internal read buffer. It does not indicate whether data is available to read or not. That's what stream_select() is for. The documentation has this peculiar note for this value: > Note: You shouldn't use this value in a script. Previous Comments: ------------------------------------------------------------------------ [2020-02-04 13:13:06] skullnobrains at gmail dot com Description: ------------ i am directly connecting to a mysql server using stream socket functions. when there is something to read, stream_get_meta_data() reports 0 bytes to read, and 255 when there is nothing to read. i tried multiple 7.x versions and ended up with similar results : 7.2.7 , 7.3 , and a few others Test script: --------------- function my_msg_r($sock){ echo "===== READ =====\n"; var_dump(stream_get_meta_data($sock)['unread_bytes']); $header=stream_socket_recvfrom($sock, 4, STREAM_PEEK); my_od($header); if(4!==strlen($header)) return my_wrn("failed to read a complete packet header"); $len=my_str2int(substr($header,0,3)); if($len===0xffffff)return my_wrn("i do not handle packets longer than 2pow24 yet, sorry"); printf("READ LEN %s 0x%x\n",$len,$len); printf("READ SEQ %u\n",ord($header[3])); /* TODO CHECK THE SEQUENCE NUMBER : THE CALLER SHOULD PASS THE EXPECTED SEQ NUMBER AND WRITE AN OUT OF ORDER ERROR IF SOMETHING GOES WRONG */ /* TODO CHECK WE HAVE ENOUGH UNREAD BYTES OR AT LEAST WHAT LENGTH WE MANAGED TO READ */ //if($n===0xffffff)return fread($sock,$n).my_msg_r($sock); # TODO proper error handling + this is not compatible with async operations return substr(fread($sock,$len+4),4); # TODO proper error handling ! } /* i am not including my_od which merely produces the lines starting with od : one line per character with the increment, decimal ascii code, ascii character, and hex value and have no relation with the bug. this looks like an old 5.6 bug i stumbled upon many years ago and was fixed */ Actual result: -------------- ===== READ ===== int(0) od 0 7 111 od 1 0 0 od 2 0 0 od 3 2  10 READ LEN 7 0x7 READ SEQ 2 CONNECTED AND AUTHENTICATED : Resource id #2 ===== WRITE ===== od 0 15 1111 od 1 0 0 od 2 0 0 od 3 0 0 WRITE LEN=15 WRITE SEQ=0 ===== READ ===== int(0) od 0 1
1 od 1 0 0 od 2 0 0 od 3 1
1 READ LEN 1 0x1 READ SEQ 1 field count=1 ===== READ ===== int(255) ... a this point, i hit ctrl+c because there is and won't be anything to read ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=79222&edit=1