esp-idf/components/fatfs/fatfsgen_utils/entry.py

181 lines
8.8 KiB
Python

# SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
# SPDX-License-Identifier: Apache-2.0
from typing import Any, List, Optional
from construct import Const, Int8ul, Int16ul, Int32ul, PaddedString, Struct
from .exceptions import LowerCaseException, TooLongNameException
from .fatfs_state import FATFSState
from .utils import MAX_EXT_SIZE, MAX_NAME_SIZE, is_valid_fatfs_name, pad_string
class Entry:
"""
The class Entry represents entry of the directory.
"""
ATTR_READ_ONLY: int = 0x01
ATTR_HIDDEN: int = 0x02
ATTR_SYSTEM: int = 0x04
ATTR_VOLUME_ID: int = 0x08
ATTR_DIRECTORY: int = 0x10
ATTR_ARCHIVE: int = 0x20
ATTR_LONG_NAME: int = ATTR_READ_ONLY | ATTR_HIDDEN | ATTR_SYSTEM | ATTR_VOLUME_ID
# indexes in the entry structure and sizes in bytes, not in characters (encoded using 2 bytes for lfn)
LDIR_Name1_IDX: int = 1
LDIR_Name1_SIZE: int = 5
LDIR_Name2_IDX: int = 14
LDIR_Name2_SIZE: int = 6
LDIR_Name3_IDX: int = 28
LDIR_Name3_SIZE: int = 2
# one entry can hold 13 characters with size 2 bytes distributed in three regions of the 32 bytes entry
CHARS_PER_ENTRY: int = LDIR_Name1_SIZE + LDIR_Name2_SIZE + LDIR_Name3_SIZE
SHORT_ENTRY: int = -1
SHORT_ENTRY_LN: int = 0
ENTRY_FORMAT_SHORT_NAME = Struct(
'DIR_Name' / PaddedString(MAX_NAME_SIZE, 'utf-8'),
'DIR_Name_ext' / PaddedString(MAX_EXT_SIZE, 'utf-8'),
'DIR_Attr' / Int8ul,
'DIR_NTRes' / Const(b'\x00'),
'DIR_CrtTimeTenth' / Const(b'\x00'),
'DIR_CrtTime' / Const(b'\x00\x00'),
'DIR_CrtDate' / Const(b'\x21\x00'),
'DIR_LstAccDate' / Const(b'\x00\x00'),
'DIR_FstClusHI' / Const(b'\x00\x00'),
'DIR_WrtTime' / Const(b'\x00\x00'),
'DIR_WrtDate' / Const(b'\x21\x00'),
'DIR_FstClusLO' / Int16ul,
'DIR_FileSize' / Int32ul,
)
def __init__(self,
entry_id: int,
parent_dir_entries_address: int,
fatfs_state: FATFSState) -> None:
self.fatfs_state: FATFSState = fatfs_state
self.id: int = entry_id
self.entry_address: int = parent_dir_entries_address + self.id * self.fatfs_state.entry_size
self._is_alias: bool = False
self._is_empty: bool = True
@property
def is_empty(self) -> bool:
return self._is_empty
@staticmethod
def _parse_entry(entry_bytearray: Optional[bytearray]) -> dict:
return Entry.ENTRY_FORMAT_SHORT_NAME.parse(entry_bytearray) # type: ignore
@staticmethod
def _build_entry(**kwargs) -> Any: # type: ignore
return Entry.ENTRY_FORMAT_SHORT_NAME.build(dict(**kwargs))
@staticmethod
def _build_entry_long(names: List[bytes], checksum: int, order: int, is_last: bool, entity_type: int) -> bytes:
"""
Long entry starts with 1 bytes of the order, if the entry is the last in the chain it is or-masked with 0x40,
otherwise is without change (or masked with 0x00). The following example shows 3 entries:
first two (0x2000-0x2040) are long in the reverse order and the last one (0x2040-0x2060) is short.
The entries define file name "thisisverylongfilenama.txt".
00002000: 42 67 00 66 00 69 00 6C 00 65 00 0F 00 43 6E 00 Bg.f.i.l.e...Cn.
00002010: 61 00 6D 00 61 00 2E 00 74 00 00 00 78 00 74 00 a.m.a...t...x.t.
00002020: 01 74 00 68 00 69 00 73 00 69 00 0F 00 43 73 00 .t.h.i.s.i...Cs.
00002030: 76 00 65 00 72 00 79 00 6C 00 00 00 6F 00 6E 00 v.e.r.y.l...o.n.
00002040: 54 48 49 53 49 53 7E 31 54 58 54 20 00 00 00 00 THISIS~1TXT.....
00002050: 21 00 00 00 00 00 00 00 21 00 02 00 15 00 00 00 !.......!.......
"""
order |= (0x40 if is_last else 0x00)
long_entry: bytes = (Int8ul.build(order) + # order of the long name entry (possibly masked with 0x40)
names[0] + # first 5 characters (10 bytes) of the name part
Int8ul.build(entity_type) + # one byte entity type ATTR_LONG_NAME
Int8ul.build(0) + # one byte of zeros
Int8ul.build(checksum) + # lfn_checksum defined in utils.py
names[1] + # next 6 characters (12 bytes) of the name part
Int16ul.build(0) + # 2 bytes of zeros
names[2]) # last 2 characters (4 bytes) of the name part
return long_entry
@property
def entry_bytes(self) -> Any:
return self.fatfs_state.binary_image[self.entry_address: self.entry_address + self.fatfs_state.entry_size]
@entry_bytes.setter
def entry_bytes(self, value: int) -> None:
self.fatfs_state.binary_image[self.entry_address: self.entry_address + self.fatfs_state.entry_size] = value
def _clean_entry(self) -> None:
self.entry_bytes: bytes = self.fatfs_state.entry_size * b'\x00'
def allocate_entry(self,
first_cluster_id: int,
entity_name: str,
entity_type: int,
entity_extension: str = '',
size: int = 0,
lfn_order: int = SHORT_ENTRY,
lfn_names: Optional[List[bytes]] = None,
lfn_checksum_: int = 0,
lfn_is_last: bool = False) -> None:
"""
:param first_cluster_id: id of the first data cluster for given entry
:param entity_name: name recorded in the entry
:param entity_extension: extension recorded in the entry
:param size: size of the content of the file
:param entity_type: type of the entity (file [0x20] or directory [0x10])
:param lfn_order: if long names support is enabled, defines order in long names entries sequence (-1 for short)
:param lfn_names: if the entry is dedicated for long names the lfn_names contains
LDIR_Name1, LDIR_Name2 and LDIR_Name3 in this order
:param lfn_checksum_: use only for long file names, checksum calculated lfn_checksum function
:param lfn_is_last: determines if the long file name entry is holds last part of the name,
thus its address is first in the physical order
:returns: None
:raises LowerCaseException: In case when long_names_enabled is set to False and filename exceeds 8 chars
for name or 3 chars for extension the exception is raised
"""
valid_full_name: bool = is_valid_fatfs_name(entity_name) and is_valid_fatfs_name(entity_extension)
if not (valid_full_name or lfn_order >= 0):
raise LowerCaseException('Lower case is not supported in short name entry, use upper case.')
# clean entry before allocation
self._clean_entry()
self._is_empty = False
object_name = entity_name.upper() if not self.fatfs_state.long_names_enabled else entity_name
object_extension = entity_extension.upper() if not self.fatfs_state.long_names_enabled else entity_extension
exceeds_short_name: bool = len(object_name) > MAX_NAME_SIZE or len(object_extension) > MAX_EXT_SIZE
if not self.fatfs_state.long_names_enabled and exceeds_short_name:
raise TooLongNameException(
'Maximal length of the object name is {} characters and {} characters for extension!'.format(
MAX_NAME_SIZE, MAX_EXT_SIZE
))
start_address = self.entry_address
end_address = start_address + self.fatfs_state.entry_size
if lfn_order in (self.SHORT_ENTRY, self.SHORT_ENTRY_LN):
self.fatfs_state.binary_image[start_address: end_address] = self._build_entry(
DIR_Name=pad_string(object_name, size=MAX_NAME_SIZE),
DIR_Name_ext=pad_string(object_extension, size=MAX_EXT_SIZE),
DIR_Attr=entity_type,
DIR_FstClusLO=first_cluster_id,
DIR_FileSize=size
)
else:
assert lfn_names is not None
self.fatfs_state.binary_image[start_address: end_address] = self._build_entry_long(lfn_names,
lfn_checksum_,
lfn_order,
lfn_is_last,
self.ATTR_LONG_NAME)
def update_content_size(self, content_size: int) -> None:
parsed_entry = self._parse_entry(self.entry_bytes)
parsed_entry.DIR_FileSize = content_size # type: ignore
self.entry_bytes = Entry.ENTRY_FORMAT_SHORT_NAME.build(parsed_entry)