extmod/vfs_fat: Object-oriented encapsulation of FatFs VFS.

This implements OO interface based on existing fsusermount code and with
minimal changes to it, to serve as a proof of concept of OO interface.

Examle of usage:

bdev = RAMFS(48)
uos.VfsFat.mkfs(bdev)
vfs = uos.VfsFat(bdev, "/ramdisk")
f = vfs.open("foo", "w")
f.write("hello!")
f.close()

extmod/fsusermount.c

@@ -34,7 +34,7 @@
 #include "lib/fatfs/ff.h"
 #include "fsusermount.h"
 
-STATIC mp_obj_t fatfs_mount_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args, bool mkfs) {
+fs_user_mount_t *fatfs_mount_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args, bool mkfs) {
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_readonly, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
         { MP_QSTR_mkfs, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
@@ -67,6 +67,7 @@ STATIC mp_obj_t fatfs_mount_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp_
         if (res != FR_OK) {
             nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "can't umount"));
         }
+        return NULL;
     } else {
         // mount
         size_t i = 0;
@@ -128,6 +129,7 @@ mkfs_error:
                     goto mkfs_error;
                 }
                 MP_STATE_PORT(fs_user_mount)[i] = NULL;
+                return NULL;
             }
         } else {
             nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "can't mount"));
@@ -144,12 +146,13 @@ mkfs_error:
         f_getfree(vfs->str, &nclst, &fatfs);
         printf(" on %s with %u bytes free\n", vfs->str, (uint)(nclst * fatfs->csize * 512));
         */
+        return vfs;
     }
-    return mp_const_none;
 }
 
 STATIC mp_obj_t fatfs_mount(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
-    return fatfs_mount_mkfs(n_args, pos_args, kw_args, false);
+    fatfs_mount_mkfs(n_args, pos_args, kw_args, false);
+    return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_KW(fsuser_mount_obj, 2, fatfs_mount);
 
@@ -191,7 +194,8 @@ STATIC mp_obj_t fatfs_umount(mp_obj_t bdev_or_path_in) {
 MP_DEFINE_CONST_FUN_OBJ_1(fsuser_umount_obj, fatfs_umount);
 
 STATIC mp_obj_t fatfs_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
-    return fatfs_mount_mkfs(n_args, pos_args, kw_args, true);
+    fatfs_mount_mkfs(n_args, pos_args, kw_args, true);
+    return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_KW(fsuser_mkfs_obj, 2, fatfs_mkfs);
 

extmod/fsusermount.h

@@ -37,6 +37,7 @@
 #define BP_IOCTL_SEC_SIZE       (5)
 
 typedef struct _fs_user_mount_t {
+    mp_obj_base_t base;
     const char *str;
     uint16_t len; // length of str
     uint16_t flags;
@@ -53,6 +54,8 @@ typedef struct _fs_user_mount_t {
     FATFS fatfs;
 } fs_user_mount_t;
 
+fs_user_mount_t *fatfs_mount_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args, bool mkfs);
+
 MP_DECLARE_CONST_FUN_OBJ(fsuser_mount_obj);
 MP_DECLARE_CONST_FUN_OBJ(fsuser_umount_obj);
 MP_DECLARE_CONST_FUN_OBJ(fsuser_mkfs_obj);

extmod/vfs_fat.c

@@ -0,0 +1,74 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2014 Damien P. George
+ * Copyright (c) 2016 Paul Sokolovsky
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/mpconfig.h"
+#if MICROPY_VFS_FAT
+
+#include "py/nlr.h"
+#include "py/runtime.h"
+#include "lib/fatfs/ff.h"
+#include "lib/fatfs/diskio.h"
+#include "stmhal/file.h"
+#include "fsusermount.h"
+
+#define mp_obj_fat_vfs_t fs_user_mount_t
+
+STATIC mp_obj_t fat_vfs_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    mp_arg_check_num(n_args, n_kw, 2, 2, false);
+    mp_obj_fat_vfs_t *vfs = fatfs_mount_mkfs(n_args, args, (mp_map_t*)&mp_const_empty_map, false);
+    vfs->base.type = type;
+    return vfs;
+}
+
+STATIC mp_obj_t fat_vfs_mkfs(mp_obj_t bdev_in) {
+    mp_obj_t args[] = {bdev_in, MP_OBJ_NEW_QSTR(MP_QSTR_mkfs)};
+    fatfs_mount_mkfs(2, args, (mp_map_t*)&mp_const_empty_map, true);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(fat_vfs_mkfs_fun_obj, fat_vfs_mkfs);
+STATIC MP_DEFINE_CONST_STATICMETHOD_OBJ(fat_vfs_mkfs_obj, MP_ROM_PTR(&fat_vfs_mkfs_fun_obj));
+
+mp_obj_t fat_vfs_open(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
+    // Skip self
+    return fatfs_builtin_open(n_args - 1, args + 1, kwargs);
+}
+MP_DEFINE_CONST_FUN_OBJ_KW(fat_vfs_open_obj, 2, fat_vfs_open);
+
+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) },
+};
+STATIC MP_DEFINE_CONST_DICT(fat_vfs_locals_dict, fat_vfs_locals_dict_table);
+
+const mp_obj_type_t mp_fat_vfs_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_VfsFat,
+    .make_new = fat_vfs_make_new,
+    .locals_dict = (mp_obj_dict_t*)&fat_vfs_locals_dict,
+};
+
+#endif // MICROPY_VFS_FAT