text: /*
   * 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
  
  #if MICROPY_VFS_FAT
  #include "extmod/vfs_fat.h"
  #endif
  
  // For mp_vfs_proxy_call, the maximum number of additional args that can be passed.
  // A fixed maximum size is used to avoid the need for a costly variable array.
  #define PROXY_MAX_ARGS (2)
  
  // path is the path to lookup and *path_out holds the path within the VFS
  // object (starts with / if an absolute path).
  // Returns MP_VFS_ROOT for root dir (and then path_out is undefined) and
  // MP_VFS_NONE for path not found.
  mp_vfs_mount_t *mp_vfs_lookup_path(const char *path, const char **path_out) {
      if (*path == '/' || MP_STATE_VM(vfs_cur) == MP_VFS_ROOT) {
          // an absolute path, or the current volume is root, so search root dir
          bool is_abs = 0;
          if (*path == '/') {
              ++path;
              is_abs = 1;
          }
          if (*path == '\0') {
              // path is "" or "/" so return virtual root
              return MP_VFS_ROOT;
          }
          for (mp_vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
              size_t len = vfs->len - 1;
              if (len == 0) {
                  *path_out = path - is_abs;
                  return vfs;
              }
              if (strncmp(path, vfs->str + 1, len) == 0) {
                  if (path[len] == '/') {
                      *path_out = path + len;
                      return vfs;
                  } else if (path[len] == '\0') {
                      *path_out = "/";
                      return vfs;
                  }
              }
          }
  
          // if we get here then there's nothing mounted on /
  
          if (is_abs) {
              // path began with / and was not found
              return MP_VFS_NONE;
          }
      }
  
      // a relative path within a mounted device
      *path_out = path;
      return MP_STATE_VM(vfs_cur);
  }
  
  // Version of mp_vfs_lookup_path that takes and returns uPy string objects.
  STATIC mp_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;
      mp_vfs_mount_t *vfs = mp_vfs_lookup_path(path, &p_out);
      if (vfs != MP_VFS_NONE && vfs != MP_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(mp_vfs_mount_t *vfs, qstr meth_name, size_t n_args, const mp_obj_t *args) {
      assert(n_args <= PROXY_MAX_ARGS);
      if (vfs == MP_VFS_NONE) {
          // mount point not found
          mp_raise_OSError(MP_ENODEV);
      }
      if (vfs == MP_VFS_ROOT) {
          // can't do operation on root dir
          mp_raise_OSError(MP_EPERM);
      }
      mp_obj_t meth[2 + PROXY_MAX_ARGS];
      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;
      mp_vfs_mount_t *vfs = mp_vfs_lookup_path(path, &path_out);
      if (vfs == MP_VFS_NONE || vfs == MP_VFS_ROOT) {
          return MP_IMPORT_STAT_NO_EXIST;
      }
      #if MICROPY_VFS_FAT
      // fast paths for known VFS types
      if (mp_obj_get_type(vfs->obj) == &mp_fat_vfs_type) {
          return fat_vfs_import_stat(MP_OBJ_TO_PTR(vfs->obj), path_out);
      }
      #endif
      // 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
      size_t mnt_len;
      const char *mnt_str = mp_obj_str_get_data(pos_args[1], &mnt_len);
  
      // see if we need to auto-detect and create the filesystem
      mp_obj_t vfs_obj = pos_args[0];
      mp_obj_t dest[2];
      mp_load_method_maybe(vfs_obj, MP_QSTR_mount, dest);
      if (dest[0] == MP_OBJ_NULL) {
          // Input object has no mount method, assume it's a block device and try to
          // auto-detect the filesystem and create the corresponding VFS entity.
          // (At the moment we only support FAT filesystems.)
          #if MICROPY_VFS_FAT
          vfs_obj = mp_fat_vfs_type.make_new(&mp_fat_vfs_type, 1, 0, &vfs_obj);
          #endif
      }
  
      // create new object
      mp_vfs_mount_t *vfs = m_new_obj(mp_vfs_mount_t);
      vfs->str = mnt_str;
      vfs->len = mnt_len;
      vfs->obj = vfs_obj;
      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;
      mp_vfs_mount_t *existing_mount = mp_vfs_lookup_path(mp_obj_str_get_str(pos_args[1]), &path_out);
      if (existing_mount != MP_VFS_NONE && existing_mount != MP_VFS_ROOT) {
          if (vfs->len != 1 && existing_mount->len == 1) {
              // if root dir is mounted, still allow to mount something within a subdir of root
          } else {
              // mount point in use
              mp_raise_OSError(MP_EPERM);
          }
      }
  
      // insert the vfs into the mount table
      mp_vfs_mount_t **vfsp = &MP_STATE_VM(vfs_mount_table);
      while (*vfsp != NULL) {
          if ((*vfsp)->len == 1) {
              // make sure anything mounted at the root stays at the end of the list
              vfs->next = *vfsp;
              break;
          }
          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
      mp_vfs_mount_t *vfs = NULL;
      size_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 (mp_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) = MP_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);
  
  // Note: buffering and encoding args are currently ignored
  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)} },
          { MP_QSTR_buffering, MP_ARG_INT, {.u_int = -1} },
          { MP_QSTR_encoding, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
      };
  
      // 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);
  
      mp_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;
      mp_vfs_mount_t *vfs = lookup_path(path_in, &path_out);
      MP_STATE_VM(vfs_cur) = vfs;
      if (vfs == MP_VFS_ROOT) {
          // If we change to the root dir and a VFS is mounted at the root then
          // we must change that VFS's current dir to the root dir so that any
          // subsequent relative paths begin at the root of that VFS.
          for (vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
              if (vfs->len == 1) {
                  mp_obj_t root = mp_obj_new_str("/", 1, false);
                  mp_vfs_proxy_call(vfs, MP_QSTR_chdir, 1, &root);
                  break;
              }
          }
      } else {
          mp_vfs_proxy_call(vfs, MP_QSTR_chdir, 1, &path_out);
      }
      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) == MP_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);
      if (MP_STATE_VM(vfs_cur)->len == 1) {
          // don't prepend "/" for vfs mounted at root
          return cwd_o;
      }
      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);
  
  typedef struct _mp_vfs_ilistdir_it_t {
      mp_obj_base_t base;
      mp_fun_1_t iternext;
      union {
          mp_vfs_mount_t *vfs;
          mp_obj_t iter;
      } cur;
      bool is_str;
      bool is_iter;
  } mp_vfs_ilistdir_it_t;
  
  STATIC mp_obj_t mp_vfs_ilistdir_it_iternext(mp_obj_t self_in) {
      mp_vfs_ilistdir_it_t *self = MP_OBJ_TO_PTR(self_in);
      if (self->is_iter) {
          // continue delegating to root dir
          return mp_iternext(self->cur.iter);
      } else if (self->cur.vfs == NULL) {
          // finished iterating mount points and no root dir is mounted
          return MP_OBJ_STOP_ITERATION;
      } else {
          // continue iterating mount points
          mp_vfs_mount_t *vfs = self->cur.vfs;
          self->cur.vfs = vfs->next;
          if (vfs->len == 1) {
              // vfs is mounted at root dir, delegate to it
              mp_obj_t root = mp_obj_new_str("/", 1, false);
              self->is_iter = true;
              self->cur.iter = mp_vfs_proxy_call(vfs, MP_QSTR_ilistdir, 1, &root);
              return mp_iternext(self->cur.iter);
          } else {
              // a mounted directory
              mp_obj_tuple_t *t = MP_OBJ_TO_PTR(mp_obj_new_tuple(3, NULL));
              t->items[0] = mp_obj_new_str_of_type(
                  self->is_str ? &mp_type_str : &mp_type_bytes,
                  (const byte*)vfs->str + 1, vfs->len - 1);
              t->items[1] = MP_OBJ_NEW_SMALL_INT(MP_S_IFDIR);
              t->items[2] = MP_OBJ_NEW_SMALL_INT(0); // no inode number
              return MP_OBJ_FROM_PTR(t);
          }
      }
  }
  
  mp_obj_t mp_vfs_ilistdir(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;
      mp_vfs_mount_t *vfs = lookup_path(path_in, &path_out);
  
      if (vfs == MP_VFS_ROOT) {
          // list the root directory
          mp_vfs_ilistdir_it_t *iter = m_new_obj(mp_vfs_ilistdir_it_t);
          iter->base.type = &mp_type_polymorph_iter;
          iter->iternext = mp_vfs_ilistdir_it_iternext;
          iter->cur.vfs = MP_STATE_VM(vfs_mount_table);
          iter->is_str = mp_obj_get_type(path_in) == &mp_type_str;
          iter->is_iter = false;
          return MP_OBJ_FROM_PTR(iter);
      }
  
      return mp_vfs_proxy_call(vfs, MP_QSTR_ilistdir, 1, &path_out);
  }
  MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_vfs_ilistdir_obj, 0, 1, mp_vfs_ilistdir);
  
  mp_obj_t mp_vfs_listdir(size_t n_args, const mp_obj_t *args) {
      mp_obj_t iter = mp_vfs_ilistdir(n_args, args);
      mp_obj_t dir_list = mp_obj_new_list(0, NULL);
      mp_obj_t next;
      while ((next = mp_iternext(iter)) != MP_OBJ_STOP_ITERATION) {
          mp_obj_t *items;
          mp_obj_get_array_fixed_n(next, 3, &items);
          mp_obj_list_append(dir_list, items[0]);
      }
      return dir_list;
  }
  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;
      mp_vfs_mount_t *vfs = lookup_path(path_in, &path_out);
      if (vfs == MP_VFS_ROOT || (vfs != MP_VFS_NONE && !strcmp(mp_obj_str_get_str(path_out), "/"))) {
          mp_raise_OSError(MP_EEXIST);
      }
      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;
      mp_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];
      mp_vfs_mount_t *old_vfs = lookup_path(old_path_in, &args[0]);
      mp_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;
      mp_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;
      mp_vfs_mount_t *vfs = lookup_path(path_in, &path_out);
      if (vfs == MP_VFS_ROOT) {
          mp_obj_tuple_t *t = MP_OBJ_TO_PTR(mp_obj_new_tuple(10, NULL));
          t->items[0] = MP_OBJ_NEW_SMALL_INT(MP_S_IFDIR); // st_mode
          for (int i = 1; i <= 9; ++i) {
              t->items[i] = MP_OBJ_NEW_SMALL_INT(0); // dev, nlink, uid, gid, size, atime, mtime, ctime
          }
          return MP_OBJ_FROM_PTR(t);
      }
      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;
      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);
  
  #endif // MICROPY_VFS
  