Bug #67043 [Csd]: substr_compare falsely reports equality on negative offset
Edit report at https://bugs.php.net/bug.php?id=67043&edit=1
ID: 67043
User updated by: php at kirk dot at
Reported by: php at kirk dot at
Summary: substr_compare falsely reports equality on negative
offset
Status: Closed
Type: Bug
Package: Strings related
Operating System: any
PHP Version: 5.5.11
Assigned To: datibbaw
Block user comment: N
Private report: N
New Comment:
That was fast. thanks!
Previous Comments:
------------------------------------------------------------------------
[2014-04-08 23:44:34] datibbaw@php.net
The fix for this bug has been committed.
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/.
For Windows:
http://windows.php.net/snapshots/
Thank you for the report, and for helping us make PHP better.
Noob mistake on my part. Updated the test case to also test the aspect of substr_compare() that
deals with no explicit length given.
------------------------------------------------------------------------
[2014-04-08 17:54:14] aharvey@php.net
That does appear to be the relevant commit, per a git bisect.
Tjerk, can you have a look at this, please?
------------------------------------------------------------------------
[2014-04-08 09:53:26] php at kirk dot at
Saw this bug on multiple OSes, therefore changing OS to any.
------------------------------------------------------------------------
[2014-04-08 09:40:19] php at kirk dot at
Description:
------------
Since version 5.5.11 a substr_compare with a negative 3rd parameter (=offset, thus it should start
counting from the end of the string) incorrectly reports equality.
See http://3v4l.org/8co5P
I believe the bug could have been introduced in this commit: https://github.com/datibbaw/php-src/commit/e292391b3899ed2d80a8f44dc94074d68328c6ea
What caught my eye is the introduced cast to an unsigned integer but I don't know if this
really is the source of the bug.
Workaround: specify a length (absolute value of the negative offset)
Test script:
---------------
var_dump(substr_compare("template", "_emplate", -8));
var_dump(substr_compare("template", "_emplate", -8, 8));
Expected result:
----------------
int(21)
int(21)
Actual result:
--------------
int(0)
int(21)
------------------------------------------------------------------------
--
Edit this bug report at https://bugs.php.net/bug.php?id=67043&edit=1
Thread (5 messages)