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extmod: Add generic VFS sub-system.
This provides mp_vfs_XXX functions (eg mount, open, listdir) which are agnostic to the underlying filesystem type, and just require an object with the relevant filesystem-like methods (eg .mount, .open, .listidr) which can then be mounted. These mp_vfs_XXX functions would typically be used by a port to implement the "uos" module, and mp_vfs_open would be the builtin open function. This feature is controlled by MICROPY_VFS, disabled by default.
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‎extmod/vfs.c‎

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/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2017 Damien P. George
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <stdint.h>
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#include <string.h>
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#include "py/runtime.h"
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#include "py/objstr.h"
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#include "py/mperrno.h"
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#include "extmod/vfs.h"
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#if MICROPY_VFS
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// ROOT is 0 so that the default current directory is the root directory
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#define VFS_NONE ((vfs_mount_t*)1)
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#define VFS_ROOT ((vfs_mount_t*)0)
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typedef struct _vfs_mount_t {
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const char *str; // mount point with leading /
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size_t len;
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mp_obj_t obj;
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struct _vfs_mount_t *next;
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} vfs_mount_t;
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// path is the path to lookup and *path_out holds the path within the VFS
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// object (starts with / if an absolute path).
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// Returns VFS_ROOT for root dir (and then path_out is undefined) and VFS_NONE
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// for path not found.
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STATIC vfs_mount_t *lookup_path_raw(const char *path, const char **path_out) {
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if (path[0] == '/' && path[1] == 0) {
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return VFS_ROOT;
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} else if (MP_STATE_VM(vfs_cur) == VFS_ROOT) {
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// in root dir
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if (path[0] == 0) {
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return VFS_ROOT;
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}
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} else if (*path != '/') {
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// a relative path within a mounted device
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*path_out = path;
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return MP_STATE_VM(vfs_cur);
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}
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for (vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
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if (strncmp(path, vfs->str, vfs->len) == 0) {
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if (path[vfs->len] == '/') {
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*path_out = path + vfs->len;
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return vfs;
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} else if (path[vfs->len] == '\0') {
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*path_out = "/";
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return vfs;
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}
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}
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}
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// mount point not found
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return VFS_NONE;
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}
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// Version of lookup_path_raw that takes and returns uPy string objects.
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STATIC vfs_mount_t *lookup_path(mp_obj_t path_in, mp_obj_t *path_out) {
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const char *path = mp_obj_str_get_str(path_in);
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const char *p_out;
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vfs_mount_t *vfs = lookup_path_raw(path, &p_out);
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if (vfs != VFS_NONE && vfs != VFS_ROOT) {
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*path_out = mp_obj_new_str_of_type(mp_obj_get_type(path_in),
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(const byte*)p_out, strlen(p_out));
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}
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return vfs;
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}
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STATIC mp_obj_t mp_vfs_proxy_call(vfs_mount_t *vfs, qstr meth_name, size_t n_args, const mp_obj_t *args) {
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if (vfs == VFS_NONE) {
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// mount point not found
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mp_raise_OSError(MP_ENODEV);
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}
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if (vfs == VFS_ROOT) {
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// can't do operation on root dir
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mp_raise_OSError(MP_EPERM);
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}
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mp_obj_t meth[n_args + 2];
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mp_load_method(vfs->obj, meth_name, meth);
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if (args != NULL) {
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memcpy(meth + 2, args, n_args * sizeof(*args));
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}
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return mp_call_method_n_kw(n_args, 0, meth);
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}
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mp_import_stat_t mp_vfs_import_stat(const char *path) {
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const char *path_out;
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vfs_mount_t *vfs = lookup_path_raw(path, &path_out);
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if (vfs == VFS_NONE || vfs == VFS_ROOT) {
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return MP_IMPORT_STAT_NO_EXIST;
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}
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// TODO delegate to vfs.stat() method
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return MP_IMPORT_STAT_NO_EXIST;
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}
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mp_obj_t mp_vfs_mount(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
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enum { ARG_readonly, ARG_mkfs };
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static const mp_arg_t allowed_args[] = {
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{ MP_QSTR_readonly, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_false} },
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{ MP_QSTR_mkfs, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_false} },
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};
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// parse args
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mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
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mp_arg_parse_all(n_args - 2, pos_args + 2, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
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// get the mount point
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mp_uint_t mnt_len;
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const char *mnt_str = mp_obj_str_get_data(pos_args[1], &mnt_len);
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// create new object
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vfs_mount_t *vfs = m_new_obj(vfs_mount_t);
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vfs->str = mnt_str;
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vfs->len = mnt_len;
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vfs->obj = pos_args[0];
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vfs->next = NULL;
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// call the underlying object to do any mounting operation
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mp_vfs_proxy_call(vfs, MP_QSTR_mount, 2, (mp_obj_t*)&args);
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// check that the destination mount point is unused
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const char *path_out;
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if (lookup_path_raw(mp_obj_str_get_str(pos_args[1]), &path_out) != VFS_NONE) {
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mp_raise_OSError(MP_EPERM);
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}
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// insert the vfs into the mount table
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vfs_mount_t **vfsp = &MP_STATE_VM(vfs_mount_table);
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while (*vfsp != NULL) {
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vfsp = &(*vfsp)->next;
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}
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*vfsp = vfs;
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return mp_const_none;
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}
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MP_DEFINE_CONST_FUN_OBJ_KW(mp_vfs_mount_obj, 2, mp_vfs_mount);
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mp_obj_t mp_vfs_umount(mp_obj_t mnt_in) {
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// remove vfs from the mount table
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vfs_mount_t *vfs = NULL;
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mp_uint_t mnt_len;
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const char *mnt_str = NULL;
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if (MP_OBJ_IS_STR(mnt_in)) {
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mnt_str = mp_obj_str_get_data(mnt_in, &mnt_len);
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}
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for (vfs_mount_t **vfsp = &MP_STATE_VM(vfs_mount_table); *vfsp != NULL; vfsp = &(*vfsp)->next) {
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if ((mnt_str != NULL && !memcmp(mnt_str, (*vfsp)->str, mnt_len + 1)) || (*vfsp)->obj == mnt_in) {
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vfs = *vfsp;
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*vfsp = (*vfsp)->next;
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break;
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}
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}
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if (vfs == NULL) {
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mp_raise_OSError(MP_EINVAL);
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}
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// if we unmounted the current device then set current to root
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if (MP_STATE_VM(vfs_cur) == vfs) {
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MP_STATE_VM(vfs_cur) = VFS_ROOT;
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}
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// call the underlying object to do any unmounting operation
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mp_vfs_proxy_call(vfs, MP_QSTR_umount, 0, NULL);
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return mp_const_none;
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}
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MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_umount_obj, mp_vfs_umount);
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mp_obj_t mp_vfs_open(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
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enum { ARG_file, ARG_mode, ARG_encoding };
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static const mp_arg_t allowed_args[] = {
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{ MP_QSTR_file, MP_ARG_OBJ | MP_ARG_REQUIRED, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
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{ MP_QSTR_mode, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_QSTR(MP_QSTR_r)} },
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};
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// parse args
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mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
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mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
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vfs_mount_t *vfs = lookup_path((mp_obj_t)args[ARG_file].u_rom_obj, &args[ARG_file].u_obj);
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return mp_vfs_proxy_call(vfs, MP_QSTR_open, 2, (mp_obj_t*)&args);
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}
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MP_DEFINE_CONST_FUN_OBJ_KW(mp_vfs_open_obj, 0, mp_vfs_open);
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mp_obj_t mp_vfs_chdir(mp_obj_t path_in) {
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mp_obj_t path_out;
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vfs_mount_t *vfs = lookup_path(path_in, &path_out);
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if (vfs != VFS_ROOT) {
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mp_vfs_proxy_call(vfs, MP_QSTR_chdir, 1, &path_out);
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}
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MP_STATE_VM(vfs_cur) = vfs;
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return mp_const_none;
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}
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MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_chdir_obj, mp_vfs_chdir);
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mp_obj_t mp_vfs_getcwd(void) {
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if (MP_STATE_VM(vfs_cur) == VFS_ROOT) {
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return MP_OBJ_NEW_QSTR(MP_QSTR__slash_);
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}
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mp_obj_t cwd_o = mp_vfs_proxy_call(MP_STATE_VM(vfs_cur), MP_QSTR_getcwd, 0, NULL);
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const char *cwd = mp_obj_str_get_str(cwd_o);
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vstr_t vstr;
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vstr_init(&vstr, MP_STATE_VM(vfs_cur)->len + strlen(cwd) + 1);
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vstr_add_strn(&vstr, MP_STATE_VM(vfs_cur)->str, MP_STATE_VM(vfs_cur)->len);
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if (!(cwd[0] == '/' && cwd[1] == 0)) {
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vstr_add_str(&vstr, cwd);
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}
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return mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
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}
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MP_DEFINE_CONST_FUN_OBJ_0(mp_vfs_getcwd_obj, mp_vfs_getcwd);
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mp_obj_t mp_vfs_listdir(size_t n_args, const mp_obj_t *args) {
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mp_obj_t path_in;
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if (n_args == 1) {
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path_in = args[0];
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} else {
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path_in = MP_OBJ_NEW_QSTR(MP_QSTR_);
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}
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mp_obj_t path_out;
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vfs_mount_t *vfs = lookup_path(path_in, &path_out);
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if (vfs == VFS_ROOT) {
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// list the root directory
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mp_obj_t dir_list = mp_obj_new_list(0, NULL);
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for (vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
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mp_obj_list_append(dir_list, mp_obj_new_str_of_type(mp_obj_get_type(path_in),
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(const byte*)vfs->str + 1, vfs->len - 1));
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}
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return dir_list;
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}
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return mp_vfs_proxy_call(vfs, MP_QSTR_listdir, 1, &path_out);
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}
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MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_vfs_listdir_obj, 0, 1, mp_vfs_listdir);
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mp_obj_t mp_vfs_mkdir(mp_obj_t path_in) {
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mp_obj_t path_out;
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vfs_mount_t *vfs = lookup_path(path_in, &path_out);
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return mp_vfs_proxy_call(vfs, MP_QSTR_mkdir, 1, &path_out);
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}
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MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_mkdir_obj, mp_vfs_mkdir);
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mp_obj_t mp_vfs_remove(mp_obj_t path_in) {
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mp_obj_t path_out;
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vfs_mount_t *vfs = lookup_path(path_in, &path_out);
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return mp_vfs_proxy_call(vfs, MP_QSTR_remove, 1, &path_out);
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}
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MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_remove_obj, mp_vfs_remove);
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mp_obj_t mp_vfs_rename(mp_obj_t old_path_in, mp_obj_t new_path_in) {
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mp_obj_t args[2];
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vfs_mount_t *old_vfs = lookup_path(old_path_in, &args[0]);
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vfs_mount_t *new_vfs = lookup_path(new_path_in, &args[1]);
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if (old_vfs != new_vfs) {
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// can't rename across filesystems
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mp_raise_OSError(MP_EPERM);
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}
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return mp_vfs_proxy_call(old_vfs, MP_QSTR_rename, 2, args);
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}
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MP_DEFINE_CONST_FUN_OBJ_2(mp_vfs_rename_obj, mp_vfs_rename);
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mp_obj_t mp_vfs_rmdir(mp_obj_t path_in) {
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mp_obj_t path_out;
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vfs_mount_t *vfs = lookup_path(path_in, &path_out);
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return mp_vfs_proxy_call(vfs, MP_QSTR_rmdir, 1, &path_out);
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}
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MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_rmdir_obj, mp_vfs_rmdir);
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mp_obj_t mp_vfs_stat(mp_obj_t path_in) {
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mp_obj_t path_out;
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vfs_mount_t *vfs = lookup_path(path_in, &path_out);
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return mp_vfs_proxy_call(vfs, MP_QSTR_stat, 1, &path_out);
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}
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MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_stat_obj, mp_vfs_stat);
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mp_obj_t mp_vfs_statvfs(mp_obj_t path_in) {
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mp_obj_t path_out;
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vfs_mount_t *vfs = lookup_path(path_in, &path_out);
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return mp_vfs_proxy_call(vfs, MP_QSTR_statvfs, 1, &path_out);
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}
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MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_statvfs_obj, mp_vfs_statvfs);
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#endif // MICROPY_VFS

‎extmod/vfs.h‎

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/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2017 Damien P. George
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12+
* copies of the Software, and to permit persons to whom the Software is
13+
* furnished to do so, subject to the following conditions:
14+
*
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* The above copyright notice and this permission notice shall be included in
16+
* all copies or substantial portions of the Software.
17+
*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19+
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20+
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21+
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22+
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23+
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef MICROPY_INCLUDED_EXTMOD_VFS_H
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#define MICROPY_INCLUDED_EXTMOD_VFS_H
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#include "py/lexer.h"
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#include "py/obj.h"
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mp_import_stat_t mp_vfs_import_stat(const char *path);
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mp_obj_t mp_vfs_mount(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args);
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mp_obj_t mp_vfs_umount(mp_obj_t mnt_in);
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mp_obj_t mp_vfs_open(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args);
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mp_obj_t mp_vfs_chdir(mp_obj_t path_in);
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mp_obj_t mp_vfs_getcwd(void);
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mp_obj_t mp_vfs_listdir(size_t n_args, const mp_obj_t *args);
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mp_obj_t mp_vfs_mkdir(mp_obj_t path_in);
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mp_obj_t mp_vfs_remove(mp_obj_t path_in);
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mp_obj_t mp_vfs_rename(mp_obj_t old_path_in, mp_obj_t new_path_in);
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mp_obj_t mp_vfs_rmdir(mp_obj_t path_in);
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mp_obj_t mp_vfs_stat(mp_obj_t path_in);
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mp_obj_t mp_vfs_statvfs(mp_obj_t path_in);
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MP_DECLARE_CONST_FUN_OBJ_KW(mp_vfs_mount_obj);
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MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_umount_obj);
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MP_DECLARE_CONST_FUN_OBJ_KW(mp_vfs_open_obj);
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MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_chdir_obj);
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MP_DECLARE_CONST_FUN_OBJ_0(mp_vfs_getcwd_obj);
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MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_vfs_listdir_obj);
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MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_mkdir_obj);
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MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_remove_obj);
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MP_DECLARE_CONST_FUN_OBJ_2(mp_vfs_rename_obj);
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MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_rmdir_obj);
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MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_stat_obj);
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MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_statvfs_obj);
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#endif // MICROPY_INCLUDED_EXTMOD_VFS_H

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