Bug #79222 [Opn]: unread_bytes do not work
Edit report at https://bugs.php.net/bug.php?id=79222&edit=1
ID: 79222
User updated by: skullnobrains at gmail dot com
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:
ok, duly noted. it did work reliably at some point though ( and strangely still does in some cases )
this explains why the number of unread bytes would be zero when data just freshly arrived into the
network buffer.
but that does not really explain why the internal buffer would contain 255 characters when it is
actually empty ... ?
not sure it is a bug. it is quite painful not to be able to determine the number of bytes that can
be read before reading them any more other than with PEEK.
thanks for your time
best regards
Previous Comments:
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[2020-02-04 13:39:01] nikic@php.net
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.
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[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
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=79222&edit=1
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