QSQL/ODBC: fix regression (trailing NUL)

When we fixed the callers of toSQLTCHAR() to use the result's size()
instead of the input's (which differ, if sizeof(SQLTCHAR) != 2), we
exposed callers to the append(0), which changes the size() of the
result QVLA. Callers that don't rely on NUL-termination (all?) now saw
an additional training NUL.

Fix by not NUL-terminating, and changing the only user of SQL_NTS to
use an explicit length.

Amends 4c445ef0bae8b36ec4a742552f0ebd81a1a90723 and
46af1fe49f7f419dc1b3231de9860e2da0ea48f8.

Done-with: Christian Ehrlicher <ch.ehrlicher@gmx.de>
Pick-to: 6.5 6.5.0 6.4 6.2 5.15
Change-Id: I6210b77e9417f46294df94cb32ab4134af8dc4c2
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/plugins/sqldrivers/odbc/qsql_odbc.cpp b/src/plugins/sqldrivers/odbc/qsql_odbc.cpp
index bcd8a72e28..1a57e8fcc6 100644
--- a/src/plugins/sqldrivers/odbc/qsql_odbc.cpp
+++ b/src/plugins/sqldrivers/odbc/qsql_odbc.cpp
@@ -80,7 +80,6 @@ inline static QVarLengthArray<SQLTCHAR> toSQLTCHAR(const QString &input)
     result.resize(enc.requiredSpace(input.size()));
     const auto end = enc.appendToBuffer(reinterpret_cast<char *>(result.data()), input);
     result.resize((end - reinterpret_cast<char *>(result.data())) / sizeof(SQLTCHAR));
-    result.append(0); // make sure it's null terminated, doesn't matter if it already is, it does if it isn't.
     return result;
 }
 
@@ -2058,7 +2057,8 @@ void QODBCDriverPrivate::checkUnicode()
         "select 'test' from dual"_L1,
     };
     for (const auto &statement : statements) {
-        r = SQLExecDirect(hStmt, toSQLTCHAR(statement).data(), SQL_NTS);
+        auto encoded = toSQLTCHAR(statement);
+        r = SQLExecDirect(hStmt, encoded.data(), SQLINTEGER(encoded.size()));
         if (r == SQL_SUCCESS)
             break;
     }