Bug #72320 [NEW]: iconv_substr returns false for empty strings

From: chris at ocproducts dot com Operating system: PHP version: 7.0.7 Package: ICONV related Bug Type: Bug Bug description:iconv_substr returns false for empty strings Description: ------------ From iconv.c... _php_iconv_substr returns success if the offset is more than or equal to the character length of the input string... if ((size_t)offset >= total_len) { return PHP_ICONV_ERR_SUCCESS; } ... Then in the calling function (iconv_substr) we check the result... if (err == PHP_ICONV_ERR_SUCCESS && ZSTR_LEN(str) > 0 && retval.s != NULL) { RETURN_NEW_STR(retval.s); } smart_str_free(&retval); RETURN_FALSE; Note how this will always return false for an empty input string. Additionally it will also return false if offset==total_len, because retval.s will not have been set at the point of _php_iconv_substr returning (as indicated). The documentation says: "If str is shorter than offset characters long, FALSE will be returned." I believe the documentation describes the correct behaviour. 0 characters is not shorter than a 0 offset. mb_substr and substr are confirmed to work correctly. Likely nobody has noticed this bug until now because false and '' are similar, but it matters for us strict type users, and when interacting with persistency layers. Test script: --------------- var_dump(iconv_substr('',0,10,'utf-8')); Expected result: ---------------- string(0) "" Actual result: -------------- bool(false) -- Edit bug report at https://bugs.php.net/bug.php?id=72320&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=72320&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=72320&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=72320&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=72320&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=72320&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=72320&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=72320&r=needscript Try newer version: https://bugs.php.net/fix.php?id=72320&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=72320&r=support Expected behavior: https://bugs.php.net/fix.php?id=72320&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=72320&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=72320&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=72320&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=72320&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=72320&r=dst IIS Stability: https://bugs.php.net/fix.php?id=72320&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=72320&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=72320&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=72320&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=72320&r=mysqlcfg