Edit report at https://bugs.php.net/bug.php?id=69354&edit=1
ID: 69354
User updated by: php at mdjnet dot dk
Reported by: php at mdjnet dot dk
Summary: Incorrect use of SQLColAttributes with ODBC 3.0
-Status: Feedback
+Status: Assigned
Type: Bug
Package: ODBC related
Operating System: All
PHP Version: 5.6.7
Assigned To: ab
Block user comment: N
Private report: N
New Comment:
I am using a proprietary ODBC driver based on http://syware.com/products/odbc_driver_kit.php.
I just tried to set up a scenario using Microsoft Access Driver (*.mdb), but it does allow to call
SQLColAttributes with SQL_DESC_OCTET_LENGTH, so it did not have the problem.
A simple script showing the problem:
<html><body>
<?php $db = odbc_connect('TEST','','');
$res = odbc_exec($db,"select TNAME from Table1");
if ($res)
if (odbc_fetch_row($res))
{
$tname = odbc_result($res,'tname');
print("tname = $tname\n");
} ?>
</body></html>
using a simple mdb file with a table, Table1, containing a column, TNAME. The bug would cause the
content of tname to be truncated somewhere - but I suppose you do need an ODBC driver NOT allowing
SQLColAttributes with SQL_DESC_OCTET_LENGTH in order to see it. I *could* write a special edition of
my odbc driver, displaying just this behaviour? I do believe that https://msdn.microsoft.com/en-us/library/ms711003
and https://msdn.microsoft.com/en-us/library/ms713558
documents the problem, but I guess we should be careful not to patch up php just to fit a special
built odbc driver. Can't point you to any other driver triggering this problem though...
Previous Comments:
------------------------------------------------------------------------
[2015-04-02 12:02:14] ab@php.net
Hi,
please supply a code snippet illustrating the broken behavior. Are you using the ADS driver, or
which exactly?
Thanks.
------------------------------------------------------------------------
[2015-04-02 08:35:28] php at mdjnet dot dk
Description:
------------
Since php was changed to odbc 3.0 (#68964), an old hidden bug has surfaced. This bug is related to
both #68350 "SQL_DESC_OCTET_LENGTH not supported by ADS ODBC driver" and #68014
"Result data values can be truncated because of incorrect column display sizes".
In odbc 3.0, SQLColAttributes is deprecated, instead SQLColAttribute should be used, which in turn
supports SQL_DESC_OCTET_LENGTH, introduced with odbc 3.0.
The bug is in ext/odbc/php_odbc.c, the function odbc_bindcols, in the middle of the big switch. With
ODBCVER set to 0x0300 as of php 5.6.7, the extra cases of SQL_WCHAR and SQL_WVARCHAR come into
effect, setting colfieldid to SQL_DESC_OCTET_LENGTH also for SQL_CHAR and SQL_VARCHAR due to a
rather suspiscious fall-through strategy, that worked well for ODBCVER < 0x0300. However, not all
odbc drivers allow for SQLColAttributes to be called with SQL_DESC_OCTET_LENGTH.
If SQLColAttributes fails, the effect is that strings lifted from subsequent calls to odbc_result
become truncated, probably because of uninitialized variables, as the code doesn't even look at
the return value of SQLColAttributes (same effect as in #68014, which appears to be fixed judging
from looking at the code).
The correct fix would be to call SQLColAttribute instead of SQLColAttributes, if ODBCVER >=
0x0300, and to actually check the return value before using the result of the call (displaysize).
I have never figured out how to build my own php, so I have not tried to fix it directly in
php_odbc.c, but I have tried to fix my odbc driver to support SQL_DESC_OCTET_LENGTH in
SQLColAttributes, and that does indeed fix the problem.
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=69354&edit=1