extmod/vfs: Allow to statvfs the root directory.

extmod/vfs.c

@@ -421,6 +421,32 @@ MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_stat_obj, mp_vfs_stat);
 mp_obj_t mp_vfs_statvfs(mp_obj_t path_in) {
     mp_obj_t path_out;
     mp_vfs_mount_t *vfs = lookup_path(path_in, &path_out);
+    if (vfs == MP_VFS_ROOT) {
+        // statvfs called on the root directory, see if there's anything mounted there
+        for (vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
+            if (vfs->len == 1) {
+                break;
+            }
+        }
+
+        // If there's nothing mounted at root then return a mostly-empty tuple
+        if (vfs == NULL) {
+            mp_obj_tuple_t *t = MP_OBJ_TO_PTR(mp_obj_new_tuple(10, NULL));
+
+            // fill in: bsize, frsize, blocks, bfree, bavail, files, ffree, favail, flags
+            for (int i = 0; i <= 8; ++i) {
+                t->items[i] = MP_OBJ_NEW_SMALL_INT(0);
+            }
+
+            // Put something sensible in f_namemax
+            t->items[9] = MP_OBJ_NEW_SMALL_INT(MICROPY_ALLOC_PATH_MAX);
+
+            return MP_OBJ_FROM_PTR(t);
+        }
+
+        // VFS mounted at root so delegate the call to it
+        path_out = MP_OBJ_NEW_QSTR(MP_QSTR__slash_);
+    }
     return mp_vfs_proxy_call(vfs, MP_QSTR_statvfs, 1, &path_out);
 }
 MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_statvfs_obj, mp_vfs_statvfs);

tests/extmod/vfs_basic.py

@@ -57,6 +57,9 @@ for path in uos.listdir('/'):
 # stat root dir
 print(uos.stat('/'))
 
+# statvfs root dir
+print(uos.statvfs('/'))
+
 # getcwd when in root dir
 print(uos.getcwd())
 
@@ -128,6 +131,8 @@ except OSError:
 
 # root dir
 uos.mount(Filesystem(3), '/')
+print(uos.stat('/'))
+print(uos.statvfs('/'))
 print(uos.listdir())
 open('test')
 

tests/extmod/vfs_basic.py.exp

 (16384, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+(0, 0, 0, 0, 0, 0, 0, 0, 0, 4096)
 /
 1 mount False False
 ['test_mnt']
@@ -36,6 +37,9 @@ OSError
 2 umount
 OSError
 3 mount False False
+(16384, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+3 statvfs /
+(3,)
 3 ilistdir /
 ['a3']
 3 open test r