extmod/vfs_fat_file: Make file.close() a no-op if file already closed.

As per CPython semantics.  In particular, file.__del__() should not raise
an exception if the file is already closed.

1 files changed, 6 insertions, 3 deletions

diff --git a/extmod/vfs_fat_file.c b/extmod/vfs_fat_file.c
index e269ef593..76ac23685 100644
--- a/extmod/vfs_fat_file.c
+++ b/extmod/vfs_fat_file.c
@@ -120,9 +120,12 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(file_obj_flush_obj, file_obj_flush);
 
 STATIC mp_obj_t file_obj_close(mp_obj_t self_in) {
     pyb_file_obj_t *self = MP_OBJ_TO_PTR(self_in);
-    FRESULT res = f_close(&self->fp);
-    if (res != FR_OK) {
-        mp_raise_OSError(fresult_to_errno_table[res]);
+    // if fs==NULL then the file is closed and in that case this method is a no-op
+    if (self->fp.fs != NULL) {
+        FRESULT res = f_close(&self->fp);
+        if (res != FR_OK) {
+            mp_raise_OSError(fresult_to_errno_table[res]);
+        }
     }
     return mp_const_none;
 }