extmod/vfs: Introduce a C-level VFS protocol, with fast import_stat.

Following other C-level protocols, this VFS protocol is added to help
abstract away implementation details of the underlying VFS in an efficient
way.  As a starting point, the import_stat function is put into this
protocol so that the VFS sub-system does not need to know about every VFS
implementation in order to do an efficient stat for importing files.

In the future it might be worth adding other functions to this protocol.

1 files changed, 4 insertions, 13 deletions

diff --git a/extmod/vfs.c b/extmod/vfs.c
index 96d5019b3..77531b874 100644
--- a/extmod/vfs.c
+++ b/extmod/vfs.c
@@ -34,9 +34,6 @@
 
 #if MICROPY_VFS
 
-#if MICROPY_VFS_POSIX
-#include "extmod/vfs_posix.h"
-#endif
 #if MICROPY_VFS_FAT
 #include "extmod/vfs_fat.h"
 #endif
@@ -128,17 +125,11 @@ mp_import_stat_t mp_vfs_import_stat(const char *path) {
         return MP_IMPORT_STAT_NO_EXIST;
     }
 
-    // Fast paths for known VFS types
-    #if MICROPY_VFS_POSIX
-    if (mp_obj_get_type(vfs->obj) == &mp_type_vfs_posix) {
-        return mp_vfs_posix_import_stat(MP_OBJ_TO_PTR(vfs->obj), path_out);
-    }
-    #endif
-    #if MICROPY_VFS_FAT
-    if (mp_obj_get_type(vfs->obj) == &mp_fat_vfs_type) {
-        return fat_vfs_import_stat(MP_OBJ_TO_PTR(vfs->obj), path_out);
+    // If the mounted object has the VFS protocol, call its import_stat helper
+    const mp_vfs_proto_t *proto = mp_obj_get_type(vfs->obj)->protocol;
+    if (proto != NULL) {
+        return proto->import_stat(MP_OBJ_TO_PTR(vfs->obj), path_out);
     }
-    #endif
 
     // delegate to vfs.stat() method
     mp_obj_t path_o = mp_obj_new_str(path_out, strlen(path_out));