Description:
------------
set post_max_size  in php.ini to something relatively small (for easy testing)
  say 2M or 3M
  upload_max_filesize setting does not matter...
       though for practical reasons it should be smaller than post_max_size

if posted data exceeds post_max_size... output seems to be limited to under 24500 - 33000 bytes  (a modest amount of html)     as soon as that unknown amount is exceeded, the script "hangs"?

*  next statement after the triggering echo (or print or file passthru, etc) is not executed.
*  headers not received by browser,
*  max_execution_time not reached
*  no errors generated (other than Warning "POST Content-Length of xxxx bytes exceeds the limit of xxxx bytes in Unknown on line 0,")

firefox just sits spinning "Sending request to localhost..."
IE says waiting for....


Test script:
---------------
<?php

/**
 * set post_max_size  in php.ini to something relatively small (for easy testing)
 *   say 2M or 3M
 *   upload_max_filesize setting does not matter...
 *       though for practical reasons it should be smaller than post_max_size
 *
 *   now using this script, upload a file that's over that limit.
 */

if ( $_SERVER['REQUEST_METHOD'] == 'POST' )
{
	/**
	 * change $output_length to trigger the bug
	 *   on one system I tested, the magic number is 24506.. crashes at 24507
	 *   on another the number is 32742.. crashes at 32743
	 *   what limit am I encountering?
	 *   this number appears to be arbitrary... varying by system and
	 *     I think the scripts memory usage also affects how much may be returned
	 *     the number seems to remain static to that system..
	 *     but if I change this script, the number may change
	 *       (ie, changing the length of $repeat_str below)
	 */
	$output_length = 24593;		// increase/decrease to trigger/not-trigger the bug
	//
	$repeat_str = 'Too much arbitrary output and this script will hang.  Why so?'."\n";
	// even changing the length of $repeat_str seems to affect the total amount that can be output
	//     perhaps due to change in memory usage?
	header('Content-Length: '.$output_length);	// adding/removing headers does not have any effect
	$strlen_repeat_str = strlen($repeat_str);
	// output $repeat_str until out $strlen_output = $output_length
	$strlen_output = 0;	// including closing div;
	while ( $strlen_output < $output_length )
	{
		$diff = $output_length - $strlen_output;
		if ( $diff >= $strlen_repeat_str )
		{
			$strlen_output += $strlen_repeat_str;
			echo $repeat_str;
		}
		else
		{
			$strlen_output += $diff;
			echo substr($repeat_str,0,$diff);
		}
	}
	// when we go over $output_length,  script seems to hang on echo statement...
	//   headers not received by browser,
	//   max_execution_time not reached
	//   no errors generated (other than "PHP Warning	localhost	POST Content-Length of xxxx bytes exceeds the limit of xxxx bytes in Unknown on line 0,")
	//  firefox just sits spinning "Sending request to localhost..."
	//  IE says waiting for....
}
else
{
	echo 'uploading a file with a size over '.ini_get('post_max_size').' = potential crash';
	?>
	<form enctype="multipart/form-data" action="" method="post" >
		<input type="file" name="file" />
		<input type="submit" value="submit me!" />
	</form>
	<?php
}

?>

Expected result:
----------------
initial file-upload form...

after submitting the response should be the string 
"Too much arbitrary output and this script will hang.  Why so?"  repeated 400+times

Actual result:
--------------
script hangs -> nothing returned