circuitpython/extmod/vfs.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2017 Damien P. George
 *
 * 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 <stdint.h>
#include <string.h>

#include "py/runtime.h"
#include "py/objstr.h"
#include "py/mperrno.h"
#include "extmod/vfs.h"

#if MICROPY_VFS

// ROOT is 0 so that the default current directory is the root directory
#define VFS_NONE ((vfs_mount_t*)1)
#define VFS_ROOT ((vfs_mount_t*)0)

typedef struct _vfs_mount_t {
    const char *str; // mount point with leading /
    size_t len;
    mp_obj_t obj;
    struct _vfs_mount_t *next;
} vfs_mount_t;

// path is the path to lookup and *path_out holds the path within the VFS
// object (starts with / if an absolute path).
// Returns VFS_ROOT for root dir (and then path_out is undefined) and VFS_NONE
// for path not found.
STATIC vfs_mount_t *lookup_path_raw(const char *path, const char **path_out) {
    if (path[0] == '/' && path[1] == 0) {
        return VFS_ROOT;
    } else if (MP_STATE_VM(vfs_cur) == VFS_ROOT) {
        // in root dir
        if (path[0] == 0) {
            return VFS_ROOT;
        }
    } else if (*path != '/') {
        // a relative path within a mounted device
        *path_out = path;
        return MP_STATE_VM(vfs_cur);
    }

    for (vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
        if (strncmp(path, vfs->str, vfs->len) == 0) {
            if (path[vfs->len] == '/') {
                *path_out = path + vfs->len;
                return vfs;
            } else if (path[vfs->len] == '\0') {
                *path_out = "/";
                return vfs;
            }
        }
    }

    // mount point not found
    return VFS_NONE;
}

// Version of lookup_path_raw that takes and returns uPy string objects.
STATIC vfs_mount_t *lookup_path(mp_obj_t path_in, mp_obj_t *path_out) {
    const char *path = mp_obj_str_get_str(path_in);
    const char *p_out;
    vfs_mount_t *vfs = lookup_path_raw(path, &p_out);
    if (vfs != VFS_NONE && vfs != VFS_ROOT) {
        *path_out = mp_obj_new_str_of_type(mp_obj_get_type(path_in),
            (const byte*)p_out, strlen(p_out));
    }
    return vfs;
}

STATIC mp_obj_t mp_vfs_proxy_call(vfs_mount_t *vfs, qstr meth_name, size_t n_args, const mp_obj_t *args) {
    if (vfs == VFS_NONE) {
        // mount point not found
        mp_raise_OSError(MP_ENODEV);
    }
    if (vfs == VFS_ROOT) {
        // can't do operation on root dir
        mp_raise_OSError(MP_EPERM);
    }
    mp_obj_t meth[n_args + 2];
    mp_load_method(vfs->obj, meth_name, meth);
    if (args != NULL) {
        memcpy(meth + 2, args, n_args * sizeof(*args));
    }
    return mp_call_method_n_kw(n_args, 0, meth);
}

mp_import_stat_t mp_vfs_import_stat(const char *path) {
    const char *path_out;
    vfs_mount_t *vfs = lookup_path_raw(path, &path_out);
    if (vfs == VFS_NONE || vfs == VFS_ROOT) {
        return MP_IMPORT_STAT_NO_EXIST;
    }
    // TODO delegate to vfs.stat() method
    return MP_IMPORT_STAT_NO_EXIST;
}

mp_obj_t mp_vfs_mount(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    enum { ARG_readonly, ARG_mkfs };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_readonly, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_false} },
        { MP_QSTR_mkfs, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_false} },
    };

    // parse args
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args - 2, pos_args + 2, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    // get the mount point
    mp_uint_t mnt_len;
    const char *mnt_str = mp_obj_str_get_data(pos_args[1], &mnt_len);

    // create new object
    vfs_mount_t *vfs = m_new_obj(vfs_mount_t);
    vfs->str = mnt_str;
    vfs->len = mnt_len;
    vfs->obj = pos_args[0];
    vfs->next = NULL;

    // call the underlying object to do any mounting operation
    mp_vfs_proxy_call(vfs, MP_QSTR_mount, 2, (mp_obj_t*)&args);

    // check that the destination mount point is unused
    const char *path_out;
    if (lookup_path_raw(mp_obj_str_get_str(pos_args[1]), &path_out) != VFS_NONE) {
        mp_raise_OSError(MP_EPERM);
    }

    // insert the vfs into the mount table
    vfs_mount_t **vfsp = &MP_STATE_VM(vfs_mount_table);
    while (*vfsp != NULL) {
        vfsp = &(*vfsp)->next;
    }
    *vfsp = vfs;

    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_KW(mp_vfs_mount_obj, 2, mp_vfs_mount);

mp_obj_t mp_vfs_umount(mp_obj_t mnt_in) {
    // remove vfs from the mount table
    vfs_mount_t *vfs = NULL;
    mp_uint_t mnt_len;
    const char *mnt_str = NULL;
    if (MP_OBJ_IS_STR(mnt_in)) {
        mnt_str = mp_obj_str_get_data(mnt_in, &mnt_len);
    }
    for (vfs_mount_t **vfsp = &MP_STATE_VM(vfs_mount_table); *vfsp != NULL; vfsp = &(*vfsp)->next) {
        if ((mnt_str != NULL && !memcmp(mnt_str, (*vfsp)->str, mnt_len + 1)) || (*vfsp)->obj == mnt_in) {
            vfs = *vfsp;
            *vfsp = (*vfsp)->next;
            break;
        }
    }

    if (vfs == NULL) {
        mp_raise_OSError(MP_EINVAL);
    }

    // if we unmounted the current device then set current to root
    if (MP_STATE_VM(vfs_cur) == vfs) {
        MP_STATE_VM(vfs_cur) = VFS_ROOT;
    }

    // call the underlying object to do any unmounting operation
    mp_vfs_proxy_call(vfs, MP_QSTR_umount, 0, NULL);

    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_umount_obj, mp_vfs_umount);

mp_obj_t mp_vfs_open(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    enum { ARG_file, ARG_mode, ARG_encoding };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_file, MP_ARG_OBJ | MP_ARG_REQUIRED, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
        { MP_QSTR_mode, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_QSTR(MP_QSTR_r)} },
    };

    // parse args
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    vfs_mount_t *vfs = lookup_path((mp_obj_t)args[ARG_file].u_rom_obj, &args[ARG_file].u_obj);
    return mp_vfs_proxy_call(vfs, MP_QSTR_open, 2, (mp_obj_t*)&args);
}
MP_DEFINE_CONST_FUN_OBJ_KW(mp_vfs_open_obj, 0, mp_vfs_open);

mp_obj_t mp_vfs_chdir(mp_obj_t path_in) {
    mp_obj_t path_out;
    vfs_mount_t *vfs = lookup_path(path_in, &path_out);
    if (vfs != VFS_ROOT) {
        mp_vfs_proxy_call(vfs, MP_QSTR_chdir, 1, &path_out);
    }
    MP_STATE_VM(vfs_cur) = vfs;
    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_chdir_obj, mp_vfs_chdir);

mp_obj_t mp_vfs_getcwd(void) {
    if (MP_STATE_VM(vfs_cur) == VFS_ROOT) {
        return MP_OBJ_NEW_QSTR(MP_QSTR__slash_);
    }
    mp_obj_t cwd_o = mp_vfs_proxy_call(MP_STATE_VM(vfs_cur), MP_QSTR_getcwd, 0, NULL);
    const char *cwd = mp_obj_str_get_str(cwd_o);
    vstr_t vstr;
    vstr_init(&vstr, MP_STATE_VM(vfs_cur)->len + strlen(cwd) + 1);
    vstr_add_strn(&vstr, MP_STATE_VM(vfs_cur)->str, MP_STATE_VM(vfs_cur)->len);
    if (!(cwd[0] == '/' && cwd[1] == 0)) {
        vstr_add_str(&vstr, cwd);
    }
    return mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
}
MP_DEFINE_CONST_FUN_OBJ_0(mp_vfs_getcwd_obj, mp_vfs_getcwd);

mp_obj_t mp_vfs_listdir(size_t n_args, const mp_obj_t *args) {
    mp_obj_t path_in;
    if (n_args == 1) {
        path_in = args[0];
    } else {
        path_in = MP_OBJ_NEW_QSTR(MP_QSTR_);
    }

    mp_obj_t path_out;
    vfs_mount_t *vfs = lookup_path(path_in, &path_out);

    if (vfs == VFS_ROOT) {
        // list the root directory
        mp_obj_t dir_list = mp_obj_new_list(0, NULL);
        for (vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
            mp_obj_list_append(dir_list, mp_obj_new_str_of_type(mp_obj_get_type(path_in),
                (const byte*)vfs->str + 1, vfs->len - 1));
        }
        return dir_list;
    }

    return mp_vfs_proxy_call(vfs, MP_QSTR_listdir, 1, &path_out);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_vfs_listdir_obj, 0, 1, mp_vfs_listdir);

mp_obj_t mp_vfs_mkdir(mp_obj_t path_in) {
    mp_obj_t path_out;
    vfs_mount_t *vfs = lookup_path(path_in, &path_out);
    return mp_vfs_proxy_call(vfs, MP_QSTR_mkdir, 1, &path_out);
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_mkdir_obj, mp_vfs_mkdir);

mp_obj_t mp_vfs_remove(mp_obj_t path_in) {
    mp_obj_t path_out;
    vfs_mount_t *vfs = lookup_path(path_in, &path_out);
    return mp_vfs_proxy_call(vfs, MP_QSTR_remove, 1, &path_out);
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_remove_obj, mp_vfs_remove);

mp_obj_t mp_vfs_rename(mp_obj_t old_path_in, mp_obj_t new_path_in) {
    mp_obj_t args[2];
    vfs_mount_t *old_vfs = lookup_path(old_path_in, &args[0]);
    vfs_mount_t *new_vfs = lookup_path(new_path_in, &args[1]);
    if (old_vfs != new_vfs) {
        // can't rename across filesystems
        mp_raise_OSError(MP_EPERM);
    }
    return mp_vfs_proxy_call(old_vfs, MP_QSTR_rename, 2, args);
}
MP_DEFINE_CONST_FUN_OBJ_2(mp_vfs_rename_obj, mp_vfs_rename);

mp_obj_t mp_vfs_rmdir(mp_obj_t path_in) {
    mp_obj_t path_out;
    vfs_mount_t *vfs = lookup_path(path_in, &path_out);
    return mp_vfs_proxy_call(vfs, MP_QSTR_rmdir, 1, &path_out);
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_rmdir_obj, mp_vfs_rmdir);

mp_obj_t mp_vfs_stat(mp_obj_t path_in) {
    mp_obj_t path_out;
    vfs_mount_t *vfs = lookup_path(path_in, &path_out);
    return mp_vfs_proxy_call(vfs, MP_QSTR_stat, 1, &path_out);
}
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;
    vfs_mount_t *vfs = lookup_path(path_in, &path_out);
    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);

#endif // MICROPY_VFS