esp-idf/components/fatfs/fatfs_utils/entry.py
2022-06-09 15:51:03 +02:00

242 lines
12 KiB
Python

# SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
# SPDX-License-Identifier: Apache-2.0
from typing import List, Optional, Union
from construct import Const, Int8ul, Int16ul, Int32ul, PaddedString, Struct
from .exceptions import LowerCaseException, TooLongNameException
from .fatfs_state import FATFSState
from .utils import (DATETIME, EMPTY_BYTE, FATFS_INCEPTION, MAX_EXT_SIZE, MAX_NAME_SIZE, SHORT_NAMES_ENCODING,
FATDefaults, build_date_entry, build_time_entry, 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 # directory
ATTR_ARCHIVE: int = 0x20 # file
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
# this value is used for short-like entry but with accepted lower case
SHORT_ENTRY_LN: int = 0
# The 1st January 1980 00:00:00
DEFAULT_DATE: DATETIME = (FATFS_INCEPTION.year, FATFS_INCEPTION.month, FATFS_INCEPTION.day)
DEFAULT_TIME: DATETIME = (FATFS_INCEPTION.hour, FATFS_INCEPTION.minute, FATFS_INCEPTION.second)
ENTRY_FORMAT_SHORT_NAME = Struct(
'DIR_Name' / PaddedString(MAX_NAME_SIZE, SHORT_NAMES_ENCODING),
'DIR_Name_ext' / PaddedString(MAX_EXT_SIZE, SHORT_NAMES_ENCODING),
'DIR_Attr' / Int8ul,
'DIR_NTRes' / Const(EMPTY_BYTE),
'DIR_CrtTimeTenth' / Const(EMPTY_BYTE), # ignored by esp-idf fatfs library
'DIR_CrtTime' / Int16ul, # ignored by esp-idf fatfs library
'DIR_CrtDate' / Int16ul, # ignored by esp-idf fatfs library
'DIR_LstAccDate' / Int16ul, # must be same as DIR_WrtDate
'DIR_FstClusHI' / Const(2 * EMPTY_BYTE),
'DIR_WrtTime' / Int16ul,
'DIR_WrtDate' / Int16ul,
'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 * FATDefaults.ENTRY_SIZE
self._is_alias: bool = False
self._is_empty: bool = True
@staticmethod
def get_cluster_id(obj_: dict) -> int:
cluster_id_: int = obj_['DIR_FstClusLO']
return cluster_id_
@property
def is_empty(self) -> bool:
return self._is_empty
@staticmethod
def _parse_entry(entry_bytearray: Union[bytearray, bytes]) -> dict:
entry_: dict = Entry.ENTRY_FORMAT_SHORT_NAME.parse(entry_bytearray)
return entry_
@staticmethod
def _build_entry(**kwargs) -> bytes: # type: ignore
entry_: bytes = Entry.ENTRY_FORMAT_SHORT_NAME.build(dict(**kwargs))
return entry_
@staticmethod
def _build_entry_long(names: List[bytes], checksum: int, order: int, is_last: bool) -> 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(Entry.ATTR_LONG_NAME) + # 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
@staticmethod
def parse_entry_long(entry_bytes_: bytes, my_check: int) -> dict:
order_ = Int8ul.parse(entry_bytes_[0:1])
names0 = entry_bytes_[1:11]
if Int8ul.parse(entry_bytes_[12:13]) != 0 or Int16ul.parse(entry_bytes_[26:28]) != 0 or Int8ul.parse(entry_bytes_[11:12]) != 15:
return {}
if Int8ul.parse(entry_bytes_[13:14]) != my_check:
return {}
names1 = entry_bytes_[14:26]
names2 = entry_bytes_[28:32]
return {'order': order_, 'name1': names0, 'name2': names1, 'name3': names2, 'is_last': bool(order_ & 0x40 == 0x40)}
@property
def entry_bytes(self) -> bytes:
"""
:returns: Bytes defining the entry belonging to the given instance.
"""
start_: int = self.entry_address
entry_: bytes = self.fatfs_state.binary_image[start_: start_ + FATDefaults.ENTRY_SIZE]
return entry_
@entry_bytes.setter
def entry_bytes(self, value: bytes) -> None:
"""
:param value: new content of the entry
:returns: None
The setter sets the content of the entry in bytes.
"""
self.fatfs_state.binary_image[self.entry_address: self.entry_address + FATDefaults.ENTRY_SIZE] = value
def _clean_entry(self) -> None:
self.entry_bytes: bytes = FATDefaults.ENTRY_SIZE * EMPTY_BYTE
def allocate_entry(self,
first_cluster_id: int,
entity_name: str,
entity_type: int,
entity_extension: str = '',
size: int = 0,
date: DATETIME = DEFAULT_DATE,
time: DATETIME = DEFAULT_TIME,
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 date: denotes year (actual year minus 1980), month number day of the month (minimal valid is (0, 1, 1))
:param time: denotes hour, minute and second with granularity 2 seconds (sec // 2)
: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
:raises TooLongNameException: When long_names_enabled is set to False and name doesn't fit to 8.3 filename
an 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.')
if self.fatfs_state.use_default_datetime:
date = self.DEFAULT_DATE
time = self.DEFAULT_TIME
# 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 + FATDefaults.ENTRY_SIZE
if lfn_order in (self.SHORT_ENTRY, self.SHORT_ENTRY_LN):
date_entry_: int = build_date_entry(*date)
time_entry: int = build_time_entry(*time)
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,
DIR_CrtDate=date_entry_, # ignored by esp-idf fatfs library
DIR_LstAccDate=date_entry_, # must be same as DIR_WrtDate
DIR_WrtDate=date_entry_,
DIR_CrtTime=time_entry, # ignored by esp-idf fatfs library
DIR_WrtTime=time_entry
)
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)
def update_content_size(self, content_size: int) -> None:
"""
:param content_size: the new size of the file content in bytes
:returns: None
This method parses the binary entry to the construct structure, updates the content size of the file
and builds new binary entry.
"""
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)