extmod/vfs_fat: Add .mkdir() method.

extmod/vfs_fat.c

@@ -89,10 +89,27 @@ STATIC mp_obj_t fat_vfs_remove(mp_obj_t vfs_in, mp_obj_t path_in) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(fat_vfs_remove_obj, fat_vfs_remove);
 
+STATIC mp_obj_t fat_vfs_mkdir(mp_obj_t vfs_in, mp_obj_t path_o) {
+    (void)vfs_in;
+    const char *path = mp_obj_str_get_str(path_o);
+    FRESULT res = f_mkdir(path);
+    switch (res) {
+        case FR_OK:
+            return mp_const_none;
+        case FR_EXIST:
+            // TODO should be FileExistsError
+            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, "File exists: '%s'", path));
+        default:
+            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, "Error creating directory '%s'", path));
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(fat_vfs_mkdir_obj, fat_vfs_mkdir);
+
 STATIC const mp_rom_map_elem_t fat_vfs_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_mkfs), MP_ROM_PTR(&fat_vfs_mkfs_obj) },
     { MP_ROM_QSTR(MP_QSTR_open), MP_ROM_PTR(&fat_vfs_open_obj) },
     { MP_ROM_QSTR(MP_QSTR_listdir), MP_ROM_PTR(&fat_vfs_listdir_obj) },
+    { MP_ROM_QSTR(MP_QSTR_mkdir), MP_ROM_PTR(&fat_vfs_mkdir_obj) },
     { MP_ROM_QSTR(MP_QSTR_remove), MP_ROM_PTR(&fat_vfs_remove_obj) },
 };
 STATIC MP_DEFINE_CONST_DICT(fat_vfs_locals_dict, fat_vfs_locals_dict_table);