Description:
------------
Hello, 

While configured in UTF8 mode (eg with the connection string allRequiredInfos;charset=UTF8), when we try to get a VARCHAR2 field limited to X chars, PDO is assuming accents (???...) are 2 letters length) and then generates a warning if our content is X chars length (with accents) and truncates the end of the field.

Warning:  PDOStatement::fetchAll() [scriptAdr/function.PDOStatement-fetchAll]: column 0 data was too large for buffer and was truncated to fit it in /scriptPath.class.php on line 73

We tryed to activate mbstring extension, to use func_overload=4 with no success (the database itself is in ISO-8859-1).

If we try not to communicate with the database in UTF8, accents are just ignored (? becomes e, ...) even with correct session parameters.

Reproduce code:
---------------
Considering the table 
MYTABLE {
   MYFIELD VARCHAR2(2);
}

with one record : 
MyField 
--------
?a

$pdo = new PDO ('pdo_oci:dbname=

  (DESCRIPTION =

    (ADDRESS_LIST =

      (ADDRESS = (PROTOCOL = TCP)(HOST = myhost)(PORT = 1521))

    )

    (CONNECT_DATA =

      (SID = mysid)

    )

  );charset=UTF8', 'myLogin', 'myPassword');

$stmt = $pdo->doQuery ('select MYFIELD from MYTABLE');
$stmt->fetchAll (); //warning

Expected result:
----------------
(array[0]->MYFIELD === '?a') === true;

Actual result:
--------------
(array[0]->MYFIELD === '?') === true
(array[0]->MYFIELD === '?a') === true