Index: ChangeLog
===================================================================
--- ChangeLog	(revision 416)
+++ ChangeLog	(working copy)
@@ -1,6 +1,8 @@
 3.51.16
 
   Functionality added or changed:
+  * Calls to SQLSetPos() could cause the driver to incorrectly calculate the
+    length of some fields. (Bug #16917)
 
   Bugs fixed:
 
Index: driver/cursor.c
===================================================================
--- driver/cursor.c	(revision 416)
+++ driver/cursor.c	(working copy)
@@ -1341,12 +1341,18 @@
                 sqlRet= SQL_SUCCESS;
                 stmt->cursor_row= (long)(stmt->current_row+irow);
                 mysql_data_seek(stmt->result,(my_ulonglong)stmt->cursor_row);
-                stmt->current_values= stmt->result->data_cursor->data;
+                stmt->current_values= mysql_fetch_row(stmt->result);
                 stmt->last_getdata_col= (uint)  ~0;; /* reset */
                 if ( stmt->fix_fields )
                     stmt->current_values= (*stmt->fix_fields)(stmt,stmt->current_values);
                 else
                     stmt->result_lengths= mysql_fetch_lengths(stmt->result);
+                /*
+                 Our call to mysql_fetch_row() moved stmt->result's internal
+                 cursor, but we don't want that. So we seek back to this row
+                 so the MYSQL_RES is in the state we expect.
+                */
+                mysql_data_seek(stmt->result,(my_ulonglong)stmt->cursor_row);
                 pthread_mutex_unlock(&stmt->dbc->lock);
                 break;
             }
Index: test/my_types.c
===================================================================
--- test/my_types.c	(revision 416)
+++ test/my_types.c	(working copy)
@@ -401,12 +401,49 @@
 }
 
 
+DECLARE_TEST(t_bug16917)
+{
+  SQLCHAR buff[255];
+  SQLLEN  len;
+
+  ok_sql(hstmt, "DROP TABLE IF EXISTS t_bug16917");
+  ok_sql(hstmt, "CREATE TABLE t_bug16917 (a TEXT)");
+  ok_sql(hstmt, "INSERT INTO t_bug16917 VALUES ('a\\0b')");
+
+  ok_stmt(hstmt, SQLFreeStmt(hstmt, SQL_CLOSE));
+
+  ok_sql(hstmt, "SELECT a FROM t_bug16917");
+
+  ok_stmt(hstmt, SQLFetch(hstmt));
+
+  /* This SQLSetPos() causes the field lengths to get lost. */
+  ok_stmt(hstmt, SQLSetPos(hstmt, 1, SQL_POSITION, SQL_LOCK_NO_CHANGE));
+
+  ok_stmt(hstmt, SQLGetData(hstmt, 1, SQL_C_CHAR, buff, 0, &len));
+  is_num(len, 3);
+
+  ok_stmt(hstmt, SQLGetData(hstmt, 1, SQL_C_CHAR, buff, sizeof(buff), &len));
+  is_num(buff[0], 'a');
+  is_num(buff[1], 0);
+  is_num(buff[2], 'b');
+  is_num(len, 3);
+
+  expect_stmt(hstmt, SQLFetch(hstmt), SQL_NO_DATA_FOUND);
+
+  ok_stmt(hstmt, SQLFreeStmt(hstmt, SQL_CLOSE));
+
+  ok_sql(hstmt, "DROP TABLE IF EXISTS t_bug16917");
+  return OK;
+}
+
+
 BEGIN_TESTS
   ADD_TEST(t_longlong1)
   ADD_TEST(t_numeric)
   ADD_TEST(t_decimal)
   ADD_TEST(t_bigint)
   ADD_TEST(t_enumset)
+  ADD_TEST(t_bug16917)
 END_TESTS