(ODBC) Fixes segfault when error string is larger than 256 chars.

SqlServer can throw custom error messages (via RaiseError) that can be
up to 8000 chars long. Fixed this with a pre-query as to the length of
the error string, then allocating enough space to retrieve the whole
error string at once.

Task-number: QTBUG-6618
Reviewed-by: Derick Hawcroft

2 files changed, 41 insertions, 6 deletions

diff --git a/src/sql/drivers/odbc/qsql_odbc.cpp b/src/sql/drivers/odbc/qsql_odbc.cpp
index e686873..fdf0c2c 100644
--- a/src/sql/drivers/odbc/qsql_odbc.cpp
+++ b/src/sql/drivers/odbc/qsql_odbc.cpp
@@ -172,28 +172,39 @@ static QString qWarnODBCHandle(int handleType, SQLHANDLE handle, int *nativeCode
     SQLSMALLINT msgLen = 0;
     SQLRETURN r = SQL_NO_DATA;
     SQLTCHAR state_[SQL_SQLSTATE_SIZE+1];
-    SQLTCHAR description_[SQL_MAX_MESSAGE_LENGTH];
+    QVarLengthArray<SQLTCHAR> description_(SQL_MAX_MESSAGE_LENGTH);
     QString result;
     int i = 1;
 
     description_[0] = 0;
+    r = SQLGetDiagRec(handleType,
+                      handle,
+                      i,
+                      state_,
+                      &nativeCode_,
+                      0,
+                      NULL,
+                      &msgLen);
+    if(r == SQL_NO_DATA)
+        return QString();
+    description_.resize(msgLen+1);
     do {
         r = SQLGetDiagRec(handleType,
                             handle,
                             i,
-                            (SQLTCHAR*)state_,
+                            state_,
                             &nativeCode_,
-                            (SQLTCHAR*)description_,
-                            SQL_MAX_MESSAGE_LENGTH, /* in bytes, not in characters */
+                            description_.data(),
+                            description_.size(),
                             &msgLen);
         if (r == SQL_SUCCESS || r == SQL_SUCCESS_WITH_INFO) {
             if (nativeCode)
                 *nativeCode = nativeCode_;
             QString tmpstore;
 #ifdef UNICODE
-            tmpstore = QString((const QChar*)description_, msgLen);
+            tmpstore = QString((const QChar*)description_.data(), msgLen);
 #else
-            tmpstore = QString::fromLocal8Bit((const char*)description_, msgLen);
+            tmpstore = QString::fromLocal8Bit((const char*)description_.data(), msgLen);
 #endif
             if(result != tmpstore) {
                 if(!result.isEmpty())
diff --git a/tests/auto/qsqlquery/tst_qsqlquery.cpp b/tests/auto/qsqlquery/tst_qsqlquery.cpp
index a8908fd..2a55c32 100644
--- a/tests/auto/qsqlquery/tst_qsqlquery.cpp
+++ b/tests/auto/qsqlquery/tst_qsqlquery.cpp
@@ -201,6 +201,8 @@ private slots:
     void QTBUG_5251();
     void QTBUG_6421_data() { generic_data("QOCI"); }
     void QTBUG_6421();
+    void QTBUG_6618_data() { generic_data("QODBC"); }
+    void QTBUG_6618();
 
 private:
     // returns all database connections
@@ -2961,5 +2963,27 @@ void tst_QSqlQuery::QTBUG_6421()
     QCOMPARE(q.value(0).toString(), QLatin1String("\"COL3\""));
 }
 
+void tst_QSqlQuery::QTBUG_6618()
+{
+    QFETCH( QString, dbName );
+    QSqlDatabase db = QSqlDatabase::database( dbName );
+    CHECK_DATABASE( db );
+    if (!tst_Databases::isSqlServer( db ))
+        QSKIP("SQL Server specific test", SkipSingle);
+
+    QSqlQuery q(db);
+    q.exec( "drop procedure " + qTableName( "tst_raiseError" ) );  //non-fatal
+    QString errorString;
+    for (int i=0;i<110;i++)
+        errorString+="reallylong";
+    errorString+=" error";
+    QVERIFY_SQL( q, exec("create procedure " + qTableName( "tst_raiseError" ) + " as\n"
+                         "begin\n"
+                         "    raiserror('" + errorString + "', 16, 1)\n"
+                         "end\n" ));
+    q.exec( "{call " + qTableName( "tst_raiseError" ) + "}" );
+    QVERIFY(q.lastError().text().contains(errorString));
+}
+
 QTEST_MAIN( tst_QSqlQuery )
 #include "tst_qsqlquery.moc"