py/stream: Switch stream close operation from method to ioctl.

This patch moves the implementation of stream closure from a dedicated
method to the ioctl of the stream protocol, for each type that implements
closing.  The benefits of this are:

1. Rounds out the stream ioctl function, which already includes flush,
   seek and poll (among other things).

2. Makes calling mp_stream_close() on an object slightly more efficient
   because it now no longer needs to lookup the close method and call it,
   rather it just delegates straight to the ioctl function (if it exists).

3. Reduces code size and allows future types that implement the stream
   protocol to be smaller because they don't need a dedicated close method.

Code size reduction is around 200 bytes smaller for x86 archs and around
30 bytes smaller for the bare-metal archs.

1 files changed, 14 insertions, 16 deletions

diff --git a/extmod/vfs_fat_file.c b/extmod/vfs_fat_file.c
index 23e5aa10f..cbd013f16 100644
--- a/extmod/vfs_fat_file.c
+++ b/extmod/vfs_fat_file.c
@@ -103,22 +103,9 @@ STATIC mp_uint_t file_obj_write(mp_obj_t self_in, const void *buf, mp_uint_t siz
 }
 
 
-STATIC mp_obj_t file_obj_close(mp_obj_t self_in) {
-    pyb_file_obj_t *self = MP_OBJ_TO_PTR(self_in);
-    // if fs==NULL then the file is closed and in that case this method is a no-op
-    if (self->fp.obj.fs != NULL) {
-        FRESULT res = f_close(&self->fp);
-        if (res != FR_OK) {
-            mp_raise_OSError(fresult_to_errno_table[res]);
-        }
-    }
-    return mp_const_none;
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(file_obj_close_obj, file_obj_close);
-
 STATIC mp_obj_t file_obj___exit__(size_t n_args, const mp_obj_t *args) {
     (void)n_args;
-    return file_obj_close(args[0]);
+    return mp_stream_close(args[0]);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(file_obj___exit___obj, 4, 4, file_obj___exit__);
 
@@ -153,6 +140,17 @@ STATIC mp_uint_t file_obj_ioctl(mp_obj_t o_in, mp_uint_t request, uintptr_t arg,
         }
         return 0;
 
+    } else if (request == MP_STREAM_CLOSE) {
+        // if fs==NULL then the file is closed and in that case this method is a no-op
+        if (self->fp.obj.fs != NULL) {
+            FRESULT res = f_close(&self->fp);
+            if (res != FR_OK) {
+                *errcode = fresult_to_errno_table[res];
+                return MP_STREAM_ERROR;
+            }
+        }
+        return 0;
+
     } else {
         *errcode = MP_EINVAL;
         return MP_STREAM_ERROR;
@@ -234,10 +232,10 @@ STATIC const mp_rom_map_elem_t rawfile_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_readlines), MP_ROM_PTR(&mp_stream_unbuffered_readlines_obj) },
     { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
     { MP_ROM_QSTR(MP_QSTR_flush), MP_ROM_PTR(&mp_stream_flush_obj) },
-    { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&file_obj_close_obj) },
+    { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&mp_stream_close_obj) },
     { MP_ROM_QSTR(MP_QSTR_seek), MP_ROM_PTR(&mp_stream_seek_obj) },
     { MP_ROM_QSTR(MP_QSTR_tell), MP_ROM_PTR(&mp_stream_tell_obj) },
-    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&file_obj_close_obj) },
+    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&mp_stream_close_obj) },
     { MP_ROM_QSTR(MP_QSTR___enter__), MP_ROM_PTR(&mp_identity_obj) },
     { MP_ROM_QSTR(MP_QSTR___exit__), MP_ROM_PTR(&file_obj___exit___obj) },
 };