Bug #42334 [Com]: Error after ob_start causes buffer flush
Edit report at https://bugs.php.net/bug.php?id=42334&edit=1
ID: 42334
Comment by: mbutscher at gmx dot de
Reported by: ahaig at penguinmililtia dot net
Summary: Error after ob_start causes buffer flush
Status: Not a bug
Type: Bug
Package: Output Control
Operating System: Irrelevant
PHP Version: irrelevant
Block user comment: N
Private report: N
New Comment:
One possible way to create a fatal error (ok, only if programmer is lazy)
function foo() ...
if (<usually false>)
foop(); // spelling error
As long as the if-clause is false the error won't be noticed.
Previous Comments:
------------------------------------------------------------------------
[2016-09-24 00:43:06] yohgaki@php.net
Output buffer is flushed when PHP terminates execution. Current PHP cannot catch E_ERROR. This
prevents cleaning up buffer, but not E_USER_ERROR. e.g.
set_error_handler(function ($errno, $errstr, $errfile, $errline)
{
if (!(error_reporting() & $errno)) {
// This error code is not included in error_reporting
return;
}
switch ($errno) {
case E_USER_ERROR:
ob_clean(); //////////////// CLEAN UP BUFFER //////////////////////
echo "<b>My ERROR</b> [$errno] $errstr<br />\n";
echo " Fatal error on line $errline in file $errfile";
echo ", PHP " . PHP_VERSION . " (" . PHP_OS . ")<br
/>\n";
echo "Aborting...<br />\n";
exit(1);
break;
case E_USER_WARNING:
echo "<b>My WARNING</b> [$errno] $errstr<br />\n";
break;
case E_USER_NOTICE:
echo "<b>My NOTICE</b> [$errno] $errstr<br />\n";
break;
default:
echo "Unknown error type: [$errno] $errstr<br />\n";
break;
}
/* Don't execute PHP internal error handler */
return true;
});
ob_start();
echo 'test';
trigger_error('error', E_USER_ERROR);
$output = ob_get_contents();
ob_end_clean();
?>
We have not many problematic E_ERRORs in our code base now. Most problematic E_ERRORs are in SOAP
module.
------------------------------------------------------------------------
[2016-09-23 23:36:49] mbutscher at gmx dot de
At least if ob_start is called like e.g.
ob_start(NULL, 0, PHP_OUTPUT_HANDLER_CLEANABLE | PHP_OUTPUT_HANDLER_REMOVABLE);
it should (as far as I understand) forbid to flush the buffer contents even on error.
------------------------------------------------------------------------
[2007-08-20 07:50:58] jani@php.net
Hint: Try changing the error to E_USER_WARNING instead.
(fatal errors stop script processing and are..eh..FATAL..:)
------------------------------------------------------------------------
[2007-08-19 20:00:46] jani@php.net
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to
report
a bug at http://bugs.php.net/how-to-report.php
------------------------------------------------------------------------
[2007-08-18 01:49:23] ahaig at penguinmililtia dot net
Description:
------------
An error that occurs after ob_start() has been called causes the buffer to flush.
This makes it impossible to appropriately manage output for error handling because sometimes text
will randomly be inserted prior to the error output (which means the error output has a full
<html></html> tag set, but content gets output before it - often open tags - which
messes up tag pairing and display).
I ran into this bug using Smarty templating. Smarty uses ob_get_contents() to grab output from an
include() of a compiled template that takes place inbetween ob_start() and ob_end_clean(). Error
handling for calls inside the compiled template (which ends up being just combined php and html with
multiple <?php ?> pairs) end up with junk before their proper output.
Reproduce code:
---------------
<?php
ob_start();
echo 'test';
trigger_error('error', E_USER_ERROR);
$output = ob_get_contents();
ob_end_clean();
?>
Expected result:
----------------
I expect to see output from trigger_error() (or any other error php might throw) and nothing else.
Non-error output should be buffered and not displayed unless requested. Error output constitutes an
exception to normal processing, so should be output.
The only other logical functioning I can see (although this would not, in my mind, be the preferred
functioning) is that the code should output nothing at all, even the error output should go to the
output buffer. This would be absolutely consistent for the functions, but would make it impossible
to do any error handling inside a buffered section.
Actual result:
--------------
Echo outputs 'test' and trigger_error outputs an error.
------------------------------------------------------------------------
--
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