Bug #70700 [Com]: LOB read loop ends early for multibyte strings

Edit report at https://bugs.php.net/bug.php?id=70700&edit=1 ID: 70700 Comment by: ashnazg@php.net Reported by: ashnazg@php.net Summary: LOB read loop ends early for multibyte strings Status: Feedback Type: Bug Package: OCI8 related Operating System: RHEL6, Win7 PHP Version: 5.5.30 Assigned To: sixd Block user comment: N Private report: N New Comment: My environments: RHEL6: - PHP 5.5.24 - oci8 => 1.4.10 - Oracle Run-time Client Library Version => 11.2.0.3.0 - Oracle Instant Client Version => 12.1 - Temporary Lob support => enabled Win7: - PHP 5.5.11 - oci8 => 1.4.10 - Oracle Run-time Client Library Version => 11.2.0.2.0 - Oracle Instant Client Version => 11.2 - Temporary Lob support => enabled Database: NLS_LANGUAGE AMERICAN NLS_CHARACTERSET AL32UTF8 NLS_NCHAR_CHARACTERSET AL16UTF16 NLS_LENGTH_SEMANTICS CHAR I don't run these multibyte CLOB tests against my older database that uses WE8MSWIN1252/AL16UTF16, as I've read that PDO OCI doesn't have NCLOB support implemented (that only affects my OCI8 testing because it's a DBAL/ORM system, and thus I'm trying to keep the 'available features' matched between OCI8 and PDO OCI). Previous Comments: ------------------------------------------------------------------------ [2015-10-13 02:05:43] sixd@php.net Thanks for the testcase. Can you give details of your environment - versions, NLS settings etc? The PDO_OCI and OCI8 code bases are different so the SO issue may have a different cause or solutions. ------------------------------------------------------------------------ [2015-10-12 20:26:40] ashnazg@php.net PHPT test for this bug is in PR #1569 (https://github.com/php/php-src/pull/1569) ------------------------------------------------------------------------ [2015-10-12 19:31:20] ashnazg@php.net Note, it seems at least a little plausible in my mind that #60994 might be related to this bug, as in the bug condition here might be the root cause of the bug behavior on #60994. See http://stackoverflow.com/questions/33026617/pdo-oci-truncates-large-multibyte-clobs for my rationale on that thought. ------------------------------------------------------------------------ [2015-10-12 19:29:36] ashnazg@php.net Description: ------------ When using the "while !$lob->eof() { $lob->read($chunk); fwrite($chunk) }" loop to read the contents of a long CLOB that contains only single-byte characters, everything works fine (can get a 10,000,000 char clob no problem). However, if the CLOB contains mutibyte characters, it seems as though the size of the first LOB->read() call is as far as the loop will go. Thus, reading the LOB in chunks does not succeed, though no errors are given. A workaround is to use LOB->size() to determine the full size of the CLOB, and then do one LOB->read() on a larger size chunk (thus getting the entire CLOB in one single, huge read). I have to guess this is hard on memory usage when large CLOBs are in play, and is thus not a desirable workaround. Test script: --------------- (will provide a PHPT in a PR) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=70700&edit=1