ID:               22713
 Updated by:       [EMAIL PROTECTED]
 Reported By:      public at asd-group dot com
-Status:           Open
+Status:           Feedback
 Bug Type:         Output Control
 Operating System: Windows XP
 PHP Version:      4.3.2-RC
 New Comment:

Please try using this CVS snapshot:

  http://snaps.php.net/php4-STABLE-latest.tar.gz
 
For Windows:
 
  http://snaps.php.net/win32/php4-win32-STABLE-latest.zip

And update the version if it still happens with the snapshot.



Previous Comments:
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[2003-04-28 12:33:09] [EMAIL PROTECTED]

Related to #21637, assuming that you are using ISAPI.

------------------------------------------------------------------------

[2003-03-22 11:22:27] public at asd-group dot com

Anyone looking at this problem - there is no workaround to this, so a
fix is needed?

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[2003-03-17 20:46:48] public at asd-group dot com

I'm not sure how this just became a documentation problem.

Sure, the recent manuals are incomplete/wrong with respect to ob_start,
and that should be corrected.

And regarding the chunk size parameter, I can tell you from actual
testing and feedback from someone who knows the PHP source code (see
http://www.zend.com/phorum/read.php?num=3&id=23814&loc=0&thread=23814)
that it *DOES* cause the output callback to be called *ONCE* for each
output statement, whether it is just one character (echo "1") or many
(echo "A very,very,.....very,very long string"). 

That doesnt sound like setting a chunk size of 2 to me (assuming that
means that the output buffer is flushed in chunks of 2 characters -
without the correct info in the manual its hard to know).

However, in any event, if the output callback instructs PHP to ignore
the output text (by returning "") then headers should not be flushed
and headers_sent() should continue to return FALSE.

In a much larger application (too large to post), where I first saw
this, there's an an additional curiosity. With output being captured
and 'thrown away' by the output callback in this manner, the first
'echo' statement causes headers_sent() to return true, yet the code
later does header() calls to set cookies, and these do not fail with a
'headers already sent' type of message (and the cookies get sent).

I hoped to reproduce this within the little code snippet above, but
that does fail with the expeced message if a call to header() is made
after the first echo statement.

Please could you recategorise this to a code issue.

------------------------------------------------------------------------

[2003-03-17 20:08:32] [EMAIL PROTECTED]

Here's the proto for ob_start():

proto bool ob_start([ string|array user_function [, int chunk_size [,
bool erase]]])

The 2nd parameter determines the chunk size..not how many times the
callback is called.


------------------------------------------------------------------------

[2003-03-17 13:58:03] public at asd-group dot com

Hmm I did read and follow the notes, and the following sample script is
easily extacted from my description. 4.3.2 made no difference.

<?php

   $Html = Array();

   // Output buffering callback - just buffers text and returns "" to
PHP (telling it to ignore output)
   function PhpOutputCb ($txt)
   {
      global $Html;
      if ($txt != "")
         {$Html[] = $txt;}
      return "";
   }

   // Install output buffering callback, called on each output
statement (due to second parameter)
   // ISSUE: Second parameter should be documented
   ob_start('PhpOutputCb', 2);

   $t = "<pre>Before first output statement, headers_sent() = " . (int)
headers_sent() . " </pre>\n";

   echo "<html>\n".
        "<head>\n".
        "<meta http-equiv=\"Content-Type\" content=\"text/html;
charset=windows-1252\">\n".
        "<meta http-equiv=\"Content-Language\" content=\"en-us\">\n".
        "<title>Bug1</title>\n".
        "</head>\n".
        "<body>\n".
        $t . "\n";

   // ISSUE: Why does headers_sent() now return true, even though
headers should not have been sent (as no output actually sent)
   echo "<pre>After first output statement, headers_sent() = " .  (int)
 headers_sent() . " </pre>\n";

   echo "</body>\n".
        "</html>\n";

   // QUESTION: If commented-in, this exit() call causes PhpOutputCb to
be called with "" text - why ??
   //exit();

   // Turn off output buffering and physically output text which our
callback buffered
   ob_end_clean();
   foreach ($Html as $key => $val)
    { echo $val; }
?>

------------------------------------------------------------------------

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the rest of the comments, please view the bug report online at
    http://bugs.php.net/22713

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