Bug #81688 [Com]: PDO_ODBC doesn't handle fixed-length character columns with character conversio

Edit report at https://bugs.php.net/bug.php?id=81688&edit=1 ID: 81688 Comment by: calvin at cmpct dot info Reported by: calvin at cmpct dot info Summary: PDO_ODBC doesn't handle fixed-length character columns with character conversio Status: Assigned Type: Bug Package: PDO ODBC Operating System: IBM i 7.2 PHP Version: 8.0.13 Assigned To: cmb Block user comment: N Private report: N New Comment: Hi Christoph, I'll give this patch a shot (and see if Db2 has that column type...). I'm fine with the late reply considering the season (time off is more important than ODBC bugs), just chuffed at the issue tracker that it got auto-closed. Previous Comments: ------------------------------------------------------------------------ [2021-12-27 16:51:04] cmb@php.net Sorry for the late reply! From what I can tell, there may be two different issues here: (a) PHP does not allocate sufficient space for the data, and (b) the driver may deliver fewer data than PHP expects, resulting in arbitrary memory contents to be given to userland. Let's focus on (b) for now, since that should be easy to fix by zeroing the buffers before fetching. Could you please try the following patch for ODBC (PDO_ODBC could likely get a similar fix): ext/odbc/php_odbc.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/ext/odbc/php_odbc.c b/ext/odbc/php_odbc.c index d4de4ec75b..d0ee19aa07 100644 --- a/ext/odbc/php_odbc.c +++ b/ext/odbc/php_odbc.c @@ -1381,6 +1381,12 @@ static void php_odbc_fetch_hash(INTERNAL_FUNCTION_PARAMETERS, int result_type) RETURN_FALSE; } + for (i = 0; i < result->numcols; i++) { + if (result->values[i].value != NULL) { + memset(result->values[i].value, 0, result->values[i].vallen); + } + } + #ifdef HAVE_SQL_EXTENDED_FETCH if (result->fetch_abs) { if (rownum > 0) { Something else that may be worth investigating is the usage of SQL_LONGVARCHAR columns (or respective casts), if something like that is supported by the DB and the driver. Such columns are not bound, but rather SQLGetData() is used to retrieve the data, and the driver is supposed to report the length of the transferred data in the StrLen_or_IndPtr argument (so in this case neither SQLDescribeCol() nor SQLColAttribute() are used to compute the length). ------------------------------------------------------------------------ [2021-12-27 13:56:18] calvin at cmpct dot info The problem still exists, it should be re-opened. That said, I'm not entirely sure of the etiquette though around bugs on bugs.php; are these better off moved to GH Issues instead now? ------------------------------------------------------------------------ [2021-12-26 04:22:08] php-bugs at lists dot php dot net No feedback was provided. The bug is being suspended because we assume that you are no longer experiencing the problem. If this is not the case and you are able to provide the information that was requested earlier, please do so and change the status of the bug back to "Re-Opened". Thank you. ------------------------------------------------------------------------ [2021-12-14 18:53:44] calvin at cmpct dot info I can confirm that PDO::ODBC_ATTR_ASSUME_UTF8 and using the procedural ODBC extension have the same results. (Well, the garbage on the end is different, but it's still garbage and the string is still the same length.) Code for the procedural ODBC version (the attrib on PDO ver is trivial so not including): ``` $odbc = odbc_connect($dsn, $user, $pw); $sql = "select cast(x as char(150)) as X from calvin.bigchars"; $stmt = odbc_prepare($odbc, $sql); echo "before ODBC\n"; var_dump(odbc_execute($stmt)); echo "after ODBC\n"; while($record = odbc_fetch_array($stmt)){ echo "Record\n"; var_dump($record["X"]); } ``` ------------------------------------------------------------------------ [2021-12-14 13:47:41] cmb@php.net Oh, forgot: could you also please check the results of the queries with ext/odbc (i.e. the odbc_*() functions)? The implementation is quite different from PDO_ODBC. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=81688 -- Edit this bug report at https://bugs.php.net/bug.php?id=81688&edit=1