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fatfsparse.py: add cluster chaining support to enable reading longer-than-sector files
Closes IDF-4975
This commit is contained in:
Martin Gano
325
components/fatfs/fatfs_utils/fs_object.py
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325
components/fatfs/fatfs_utils/fs_object.py
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# SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
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# SPDX-License-Identifier: Apache-2.0
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import os
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from datetime import datetime
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from typing import List, Optional, Tuple, Union
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from .entry import Entry
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from .exceptions import FatalError, WriteDirectoryException
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from .fat import FAT, Cluster
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from .fatfs_state import FATFSState
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from .long_filename_utils import (build_lfn_full_name, build_lfn_unique_entry_name_order,
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get_required_lfn_entries_count, split_name_to_lfn_entries,
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split_name_to_lfn_entry_blocks)
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from .utils import (DATETIME, MAX_EXT_SIZE, MAX_NAME_SIZE, FATDefaults, build_lfn_short_entry_name, lfn_checksum,
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required_clusters_count, split_content_into_sectors, split_to_name_and_extension)
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class File:
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"""
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The class File provides API to write into the files. It represents file in the FS.
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"""
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ATTR_ARCHIVE: int = 0x20
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ENTITY_TYPE: int = ATTR_ARCHIVE
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def __init__(self, name: str, fat: FAT, fatfs_state: FATFSState, entry: Entry, extension: str = '') -> None:
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self.name: str = name
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self.extension: str = extension
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self.fatfs_state: FATFSState = fatfs_state
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self.fat: FAT = fat
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self.size: int = 0
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self._first_cluster: Optional[Cluster] = None
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self._entry: Entry = entry
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@property
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def entry(self) -> Entry:
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return self._entry
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@property
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def first_cluster(self) -> Optional[Cluster]:
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return self._first_cluster
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@first_cluster.setter
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def first_cluster(self, value: Cluster) -> None:
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self._first_cluster = value
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def name_equals(self, name: str, extension: str) -> bool:
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return self.name == name and self.extension == extension
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def write(self, content: bytes) -> None:
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self.entry.update_content_size(len(content))
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# we assume that the correct amount of clusters is allocated
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current_cluster = self._first_cluster
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for content_part in split_content_into_sectors(content, self.fatfs_state.boot_sector_state.sector_size):
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content_as_list = content_part
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if current_cluster is None:
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raise FatalError('No free space left!')
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address: int = current_cluster.cluster_data_address
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self.fatfs_state.binary_image[address: address + len(content_part)] = content_as_list
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current_cluster = current_cluster.next_cluster
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class Directory:
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"""
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The Directory class provides API to add files and directories into the directory
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and to find the file according to path and write it.
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"""
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ATTR_DIRECTORY: int = 0x10
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ATTR_ARCHIVE: int = 0x20
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ENTITY_TYPE: int = ATTR_DIRECTORY
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CURRENT_DIRECTORY = '.'
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PARENT_DIRECTORY = '..'
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def __init__(self,
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name,
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fat,
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fatfs_state,
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entry=None,
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cluster=None,
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size=None,
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extension='',
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parent=None):
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# type: (str, FAT, FATFSState, Optional[Entry], Cluster, Optional[int], str, Directory) -> None
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self.name: str = name
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self.fatfs_state: FATFSState = fatfs_state
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self.extension: str = extension
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self.fat: FAT = fat
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self.size: int = size or self.fatfs_state.boot_sector_state.sector_size
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# if directory is root its parent is itself
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self.parent: Directory = parent or self
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self._first_cluster: Cluster = cluster
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# entries will be initialized after the cluster allocation
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self.entries: List[Entry] = []
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self.entities: List[Union[File, Directory]] = [] # type: ignore
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self._entry = entry # currently not in use (will use later for e.g. modification time, etc.)
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@property
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def is_root(self) -> bool:
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return self.parent is self
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@property
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def first_cluster(self) -> Cluster:
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return self._first_cluster
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@first_cluster.setter
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def first_cluster(self, value: Cluster) -> None:
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self._first_cluster = value
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def name_equals(self, name: str, extension: str) -> bool:
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return self.name == name and self.extension == extension
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@property
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def entries_count(self) -> int:
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entries_count_: int = self.size // FATDefaults.ENTRY_SIZE
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return entries_count_
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def create_entries(self, cluster: Cluster) -> List[Entry]:
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return [Entry(entry_id=i,
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parent_dir_entries_address=cluster.cluster_data_address,
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fatfs_state=self.fatfs_state)
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for i in range(self.entries_count)]
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def init_directory(self) -> None:
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self.entries = self.create_entries(self._first_cluster)
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# the root directory doesn't contain link to itself nor the parent
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if self.is_root:
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return
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# if the directory is not root we initialize the reference to itself and to the parent directory
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for dir_id, name_ in ((self, self.CURRENT_DIRECTORY), (self.parent, self.PARENT_DIRECTORY)):
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new_dir_: Entry = self.find_free_entry() or self.chain_directory()
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new_dir_.allocate_entry(first_cluster_id=dir_id.first_cluster.id,
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entity_name=name_,
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entity_extension='',
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entity_type=dir_id.ENTITY_TYPE)
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def lookup_entity(self, object_name: str, extension: str): # type: ignore
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for entity in self.entities:
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if entity.name == object_name and entity.extension == extension:
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return entity
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return None
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@staticmethod
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def _if_end_of_path(path_as_list: List[str]) -> bool:
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"""
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:param path_as_list: path split into the list
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:returns: True if the file is the leaf of the directory tree, False otherwise
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The method is part of the base of recursion,
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determines if the path is target file or directory in the tree folder structure.
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"""
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return len(path_as_list) == 1
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def recursive_search(self, path_as_list, current_dir): # type: ignore
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name, extension = split_to_name_and_extension(path_as_list[0])
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next_obj = current_dir.lookup_entity(name, extension)
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if next_obj is None:
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raise FileNotFoundError('No such file or directory!')
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if self._if_end_of_path(path_as_list) and next_obj.name_equals(name, extension):
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return next_obj
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return self.recursive_search(path_as_list[1:], next_obj)
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def find_free_entry(self) -> Optional[Entry]:
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for entry in self.entries:
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if entry.is_empty:
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return entry
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return None
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def _extend_directory(self) -> None:
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current: Cluster = self.first_cluster
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while current.next_cluster is not None:
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current = current.next_cluster
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new_cluster: Cluster = self.fat.find_free_cluster()
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current.set_in_fat(new_cluster.id)
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assert current is not new_cluster
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current.next_cluster = new_cluster
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self.entries += self.create_entries(new_cluster)
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def chain_directory(self) -> Entry:
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"""
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:returns: First free entry
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The method adds new Cluster to the Directory and returns first free entry.
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"""
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self._extend_directory()
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free_entry: Entry = self.find_free_entry()
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if free_entry is None:
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raise FatalError('No more space left!')
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return free_entry
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@staticmethod
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def allocate_long_name_object(free_entry,
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name,
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extension,
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target_dir,
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free_cluster,
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entity_type,
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date,
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time):
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# type: (Entry, str, str, Directory, Cluster, int, DATETIME, DATETIME) -> Tuple[Cluster, Entry, Directory]
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lfn_full_name: str = build_lfn_full_name(name, extension)
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lfn_unique_entry_order: int = build_lfn_unique_entry_name_order(target_dir.entities, name)
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lfn_short_entry_name: str = build_lfn_short_entry_name(name, extension, lfn_unique_entry_order)
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checksum: int = lfn_checksum(lfn_short_entry_name)
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entries_count: int = get_required_lfn_entries_count(lfn_full_name)
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# entries in long file name entries chain starts with the last entry
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split_names_reversed = reversed(list(enumerate(split_name_to_lfn_entries(lfn_full_name, entries_count))))
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for i, name_split_to_entry in split_names_reversed:
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order: int = i + 1
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lfn_names: List[bytes] = list(
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map(lambda x: x.lower(), split_name_to_lfn_entry_blocks(name_split_to_entry))) # type: ignore
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free_entry.allocate_entry(first_cluster_id=free_cluster.id,
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entity_name=name,
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entity_extension=extension,
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entity_type=entity_type,
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lfn_order=order,
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lfn_names=lfn_names,
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lfn_checksum_=checksum,
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lfn_is_last=order == entries_count)
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free_entry = target_dir.find_free_entry() or target_dir.chain_directory()
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free_entry.allocate_entry(first_cluster_id=free_cluster.id,
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entity_name=lfn_short_entry_name[:MAX_NAME_SIZE],
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entity_extension=lfn_short_entry_name[MAX_NAME_SIZE:],
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entity_type=entity_type,
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lfn_order=Entry.SHORT_ENTRY_LN,
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date=date,
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time=time)
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return free_cluster, free_entry, target_dir
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def allocate_object(self,
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name,
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entity_type,
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object_timestamp_,
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path_from_root=None,
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extension=''):
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# type: (str, int, datetime, Optional[List[str]], str) -> Tuple[Cluster, Entry, Directory]
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"""
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Method finds the target directory in the path
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and allocates cluster (both the record in FAT and cluster in the data region)
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and entry in the specified directory
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"""
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free_cluster: Cluster = self.fat.find_free_cluster()
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target_dir: Directory = self if not path_from_root else self.recursive_search(path_from_root, self)
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free_entry: Entry = target_dir.find_free_entry() or target_dir.chain_directory()
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name_fits_short_struct: bool = len(name) <= MAX_NAME_SIZE and len(extension) <= MAX_EXT_SIZE
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fatfs_date_ = (object_timestamp_.year, object_timestamp_.month, object_timestamp_.day)
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fatfs_time_ = (object_timestamp_.hour, object_timestamp_.minute, object_timestamp_.second)
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if not self.fatfs_state.long_names_enabled or name_fits_short_struct:
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free_entry.allocate_entry(first_cluster_id=free_cluster.id,
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entity_name=name,
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entity_extension=extension,
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date=fatfs_date_,
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time=fatfs_time_,
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entity_type=entity_type)
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return free_cluster, free_entry, target_dir
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return self.allocate_long_name_object(free_entry=free_entry,
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name=name,
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extension=extension,
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target_dir=target_dir,
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free_cluster=free_cluster,
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entity_type=entity_type,
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date=fatfs_date_,
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time=fatfs_time_)
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def new_file(self,
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name: str,
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extension: str,
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path_from_root: Optional[List[str]],
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object_timestamp_: datetime) -> None:
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free_cluster, free_entry, target_dir = self.allocate_object(name=name,
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extension=extension,
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entity_type=Directory.ATTR_ARCHIVE,
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path_from_root=path_from_root,
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object_timestamp_=object_timestamp_)
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file: File = File(name=name,
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fat=self.fat,
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extension=extension,
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fatfs_state=self.fatfs_state,
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entry=free_entry)
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file.first_cluster = free_cluster
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target_dir.entities.append(file)
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def new_directory(self, name, parent, path_from_root, object_timestamp_):
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# type: (str, Directory, Optional[List[str]], datetime) -> None
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free_cluster, free_entry, target_dir = self.allocate_object(name=name,
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entity_type=Directory.ATTR_DIRECTORY,
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path_from_root=path_from_root,
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object_timestamp_=object_timestamp_)
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directory: Directory = Directory(name=name,
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fat=self.fat,
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parent=parent,
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fatfs_state=self.fatfs_state,
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entry=free_entry)
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directory.first_cluster = free_cluster
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directory.init_directory()
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target_dir.entities.append(directory)
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def write_to_file(self, path: List[str], content: bytes) -> None:
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"""
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Writes to file existing in the directory structure.
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:param path: path split into the list
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:param content: content as a string to be written into a file
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:returns: None
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:raises WriteDirectoryException: raised is the target object for writing is a directory
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"""
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entity_to_write: Entry = self.recursive_search(path, self)
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if isinstance(entity_to_write, File):
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clusters_cnt: int = required_clusters_count(cluster_size=self.fatfs_state.boot_sector_state.sector_size,
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content=content)
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self.fat.allocate_chain(entity_to_write.first_cluster, clusters_cnt)
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entity_to_write.write(content)
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else:
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raise WriteDirectoryException(f'`{os.path.join(*path)}` is a directory!')
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