php.net |  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login
Bug #53297 gettimeofday implementation in php/win32/time.c can return 1mil usecs.
Submitted: 2010-11-12 11:31 UTC Modified: 2010-11-12 19:37 UTC
From: ped at 7gods dot org Assigned: cataphract
Status: Closed Package: Unknown/Other Function
PHP Version: 5.3.3 OS: Win32
Private report: No CVE-ID:
 [2010-11-12 11:31 UTC] ped at 7gods dot org
Description:
------------
in source file php/win32/time.c in function
PHPAPI int gettimeofday(struct timeval *time_Info, struct timezone *timezone_Info)
toward end (L108 in 5.3.3 sources) there is this block of code:
                    if (time_Info->tv_usec > 1000000) {
                        time_Info->tv_usec -= 1000000;
                        ++time_Info->tv_sec;
                    }

Doing >= would be more correct, like this:
                    if (time_Info->tv_usec >= 1000000) {
                        time_Info->tv_usec -= 1000000;
                        ++time_Info->tv_sec;
                    }

(for most of the gettimeofday usage this is very minor bug, but while profiling with xdebug extension on windows platform this does expose the xdebug bug http://bugs.xdebug.org/view.php?id=357 which together leads to garbage profiling results)

Attached script does expose the problem also trough PHP (it fails at my machine quite regularly, shouldn't take more then 2-3 runs to catch it).

Test script:
---------------
<?php
$safety_counter = 0;
do {
	$t = gettimeofday();
} while( $t['usec'] < 1000000 && $safety_counter++ < 1000000 );
if ( $t['usec'] == 1000000 ) {
	echo '<pre>', print_r( $t, TRUE ), '</pre>';
	die('Returned gettimeofday array contains 1mil+ of microseconds (which is 1second)!');
}
echo 'The gettimeofday didn\'t produce wrong value (tried it 1mil times). Try again!';
?>

Expected result:
----------------
The returned $t['usec'] should never contain value >= 1000000, so the script should always end with final echo.

Actual result:
--------------
$t['usec'] == 1000000 occasionally (on my machine at least once per 5 runs of script).

Patches

Add a Patch

Pull Requests

Add a Pull Request

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2010-11-12 19:37 UTC] cataphract@php.net
Automatic comment from SVN on behalf of cataphract
Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=305298
Log: - Fixed bug #53297 (gettimeofday implementation in php/win32/time.c can return
  1 million microsecs). (ped at 7gods dot org)
- Moved line out of order in NEWS.
 [2010-11-12 19:38 UTC] cataphract@php.net
-Status: Open +Status: Closed -Assigned To: +Assigned To: cataphract
 [2010-11-12 19:38 UTC] cataphract@php.net
This bug has been fixed in SVN.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
Thank you for the report, and for helping us make PHP better.


 
PHP Copyright © 2001-2014 The PHP Group
All rights reserved.
Last updated: Sat Apr 19 09:02:28 2014 UTC