ID: 32414
Updated by: [EMAIL PROTECTED]
Reported By: d dot geels at grape dot ru
-Status: Open
+Status: Closed
Bug Type: Documentation problem
Operating System: any
PHP Version: 4.3.10, also 5
New Comment:
This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.
Thank you for the report, and for helping us make our documentation
better.
"Shutdown function is called during the script shutdown so headers are
always already sent."
Previous Comments:
------------------------------------------------------------------------
[2005-03-23 01:10:03] d dot geels at grape dot ru
The problem is that session_start() tries to send headers, but it must
not.
Try 'curl -v <url to above example>' and just call function a() at the
end, without registering shutdown function, you'll see, that
session_start() doesn't send any headers if second call to
session_cache_limiter has parameter 'none'. So, why does it complain,
when called from shutdown function? That is the bug actually.
------------------------------------------------------------------------
[2005-03-22 22:56:05] [EMAIL PROTECTED]
This is actually just documentation problem:
You can't send any headers from a register_shutdown_function() call.
Or use any functions in such function that might send headers..such as
almost any session function.
------------------------------------------------------------------------
[2005-03-22 18:46:42] d dot geels at grape dot ru
Tiny example, that always reproduces the bug.
<?
ini_set('session.use_cookies', 0);
session_id('1234');
session_cache_limiter('public');
session_start();
session_write_close();
?>
text
<?
function a(){
session_cache_limiter('none');
session_start();
session_write_close();
}
register_shutdown_function('a');
?>
If just call a() at the end -- no warnings, if a() called at shutdown
-- warning issued.
------------------------------------------------------------------------
[2005-03-22 17:38:57] d dot geels at grape dot ru
Description:
------------
The problem described already in user contributed noted in
documentation. Strange, that it is not yet fixed...
Also problem mentioned in http://bugs.php.net/bug.php?id=11213
==================================
laacz at laacz dot lv (28-Oct-2004 03:37)
If You are not using cookies to store session_id's, that does not mean,
that session_start() will not send any headers at all. It still sends
cache controlling information to user. For example:
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0,
pre-check=0
Pragma: no-cache
Even, if You set cache_limiter to none (via
ini_set('session.use_cookies', 0) or ini_set('session.cache_limiter',
'none')), session_start() still tries to send empty headers and that
causes error message "Cannot send session cache limiter - headers
already sent". So, use output buffering, if You need to output
something before session_start().
==================================
even session_cache_limiter('none') doesn't work
In my case, problem is that I call session_start(), then
session_write_close() in the beginning, then send data, then call
session_start(), then session_write_close() in the function, registered
on shutdown.
There are two reasons, why I do so:
1) there are several processes, that access same session (I use
md5($_SERVER['REMOTE_ADDR']) as session_id)
2) I can't buffer output at all. Amount of data is very large, it is a
file being downloaded. It must be sent ASAP.
Reproduce code:
---------------
if(!empty($_SERVER['HTTP_RANGE'])){
$sid = md5($_SERVER['REMOTE_ADDR']);
ini_set('session.use_cookies', 0);
session_cache_limiter('public'); // for IE "Open" bug
session_id($sid);
session_start(); //this one starts normally
//check, if this download thread is permitted or not
if(!empty($_SESSION['file_'.$file_id]) && $_SESSION['file_'.$file_id]
>= MAX_DOWNLOAD_THREADS){
header('HTTP/1.1 403 Forbidden', true, 403);
exit;
}elseif(!isset($_SESSION['file_'.$file_id]))
$_SESSION['file_'.$file_id] = 0;
$_SESSION['file_'.$file_id]++;
session_write_close();
//close session ASAP, because else other processes would be blocked
//this function will decrement threads counter...
function decrementCounter($sid, $file_id)
{
//this must help us evade "Warning: session_start(): Cannot send
session cache limiter - headers already sent"
session_cache_limiter('none');
session_id($sid);
session_start(); // this is line #45
//decrement threads counter
$_SESSION['file_'.$file_id]--;
session_write_close();
//close session ASAP
}
//... when script finished
register_shutdown_function('decrementCounter', $sid, $file_id);
}
Expected result:
----------------
No warnings in log file.
Actual result:
--------------
[Tue Mar 22 18:32:08 2005] [error] PHP Warning: session_start():
Cannot send session cache limiter - headers already sent (output
started at /home/httpd/pantech/htdocs/file.php:144) in
/home/httpd/pantech/htdocs/file.php on line 45
reproduced always, when user downloading a file
line 144 sends data to client:
echo fread( $fp, $size > READ_BLOCK_SIZE ? READ_BLOCK_SIZE : $size );
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=32414&edit=1
