Bug #67043 [NEW]: substr_compare falsely reports equality on negative offset

From: php at kirk dot at Operating system: OS X PHP version: 5.5.11 Package: Strings related Bug Type: Bug Bug description:substr_compare falsely reports equality on negative offset 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 bug report at https://bugs.php.net/bug.php?id=67043&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=67043&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=67043&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=67043&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=67043&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=67043&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=67043&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=67043&r=needscript Try newer version: https://bugs.php.net/fix.php?id=67043&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=67043&r=support Expected behavior: https://bugs.php.net/fix.php?id=67043&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=67043&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=67043&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=67043&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=67043&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=67043&r=dst IIS Stability: https://bugs.php.net/fix.php?id=67043&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=67043&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=67043&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=67043&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=67043&r=mysqlcfg