# SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
# SPDX-License-Identifier: Apache-2.0
import argparse
import binascii
import os
import re
import uuid
from datetime import datetime
from typing import List, Optional, Tuple
from construct import BitsInteger, BitStruct, Int16ul
# the regex pattern defines symbols that are allowed by long file names but not by short file names
INVALID_SFN_CHARS_PATTERN = re.compile(r'[.+,;=\[\]]')
FAT12_MAX_CLUSTERS: int = 4085
FAT16_MAX_CLUSTERS: int = 65525
RESERVED_CLUSTERS_COUNT: int = 2
PAD_CHAR: int = 0x20
FAT12: int = 12
FAT16: int = 16
FAT32: int = 32
FULL_BYTE: bytes = b'\xff'
EMPTY_BYTE: bytes = b'\x00'
# redundant
BYTES_PER_DIRECTORY_ENTRY: int = 32
UINT32_MAX: int = (1 << 32) - 1
MAX_NAME_SIZE: int = 8
MAX_EXT_SIZE: int = 3
DATETIME = Tuple[int, int, int]
FATFS_INCEPTION_YEAR: int = 1980
FATFS_INCEPTION: datetime = datetime(FATFS_INCEPTION_YEAR, 1, 1, 0, 0, 0, 0)
FATFS_MAX_HOURS = 24
FATFS_MAX_MINUTES = 60
FATFS_MAX_SECONDS = 60
FATFS_MAX_DAYS = 31
FATFS_MAX_MONTHS = 12
FATFS_MAX_YEARS = 127
FATFS_SECONDS_GRANULARITY: int = 2
# long names are encoded to two bytes in utf-16
LONG_NAMES_ENCODING: str = 'utf-16'
SHORT_NAMES_ENCODING: str = 'utf-8'
# compatible with WL_SECTOR_SIZE
# choices for WL are WL_SECTOR_SIZE_512 and WL_SECTOR_SIZE_4096
ALLOWED_WL_SECTOR_SIZES: List[int] = [512, 4096]
ALLOWED_SECTOR_SIZES: List[int] = [512, 1024, 2048, 4096]
ALLOWED_SECTORS_PER_CLUSTER: List[int] = [1, 2, 4, 8, 16, 32, 64, 128]
def crc32(input_values: List[int], crc: int) -> int:
"""
Name Polynomial Reversed? Init-value XOR-out
crc32 0x104C11DB7 True 4294967295 (UINT32_MAX) 0xFFFFFFFF
"""
return binascii.crc32(bytearray(input_values), crc)
def number_of_clusters(number_of_sectors: int, sectors_per_cluster: int) -> int:
return number_of_sectors // sectors_per_cluster
def get_non_data_sectors_cnt(reserved_sectors_cnt: int, sectors_per_fat_cnt: int, root_dir_sectors_cnt: int) -> int:
return reserved_sectors_cnt + sectors_per_fat_cnt + root_dir_sectors_cnt
def get_fatfs_type(clusters_count: int) -> int:
if clusters_count < FAT12_MAX_CLUSTERS:
return FAT12
if clusters_count <= FAT16_MAX_CLUSTERS:
return FAT16
return FAT32
def get_fat_sectors_count(clusters_count: int, sector_size: int) -> int:
fatfs_type_ = get_fatfs_type(clusters_count)
if fatfs_type_ == FAT32:
raise NotImplementedError('FAT32 is not supported!')
# number of byte halves
cluster_s: int = fatfs_type_ // 4
fat_size_bytes: int = (
clusters_count * 2 + cluster_s) if fatfs_type_ == FAT16 else (clusters_count * 3 + 1) // 2 + cluster_s
return (fat_size_bytes + sector_size - 1) // sector_size
def required_clusters_count(cluster_size: int, content: bytes) -> int:
# compute number of required clusters for file text
return (len(content) + cluster_size - 1) // cluster_size
def generate_4bytes_random() -> int:
return uuid.uuid4().int & 0xFFFFFFFF
def pad_string(content: str, size: Optional[int] = None, pad: int = PAD_CHAR) -> str:
# cut string if longer and fill with pad character if shorter than size
return content.ljust(size or len(content), chr(pad))[:size]
def right_strip_string(content: str, pad: int = PAD_CHAR) -> str:
return content.rstrip(chr(pad))
def build_lfn_short_entry_name(name: str, extension: str, order: int) -> str:
return '{}{}'.format(pad_string(content=name[:MAX_NAME_SIZE - 2] + '~' + chr(order), size=MAX_NAME_SIZE),
pad_string(extension[:MAX_EXT_SIZE], size=MAX_EXT_SIZE))
def lfn_checksum(short_entry_name: str) -> int:
"""
Function defined by FAT specification. Computes checksum out of name in the short file name entry.
"""
checksum_result = 0
for i in range(MAX_NAME_SIZE + MAX_EXT_SIZE):
# operation is a right rotation on 8 bits (Python equivalent for unsigned char in C)
checksum_result = (0x80 if checksum_result & 1 else 0x00) + (checksum_result >> 1) + ord(short_entry_name[i])
checksum_result &= 0xff
return checksum_result
def convert_to_utf16_and_pad(content: str,
expected_size: int,
pad: bytes = FULL_BYTE) -> bytes:
# we need to get rid of the Byte order mark 0xfeff or 0xfffe, fatfs does not use it
bom_utf16: bytes = b'\xfe\xff'
encoded_content_utf16: bytes = content.encode(LONG_NAMES_ENCODING)[len(bom_utf16):]
return encoded_content_utf16.ljust(2 * expected_size, pad)
def split_to_name_and_extension(full_name: str) -> Tuple[str, str]:
name, extension = os.path.splitext(full_name)
return name, extension.replace('.', '')
def is_valid_fatfs_name(string: str) -> bool:
return string == string.upper()
def split_by_half_byte_12_bit_little_endian(value: int) -> Tuple[int, int, int]:
value_as_bytes: bytes = Int16ul.build(value)
return value_as_bytes[0] & 0x0f, value_as_bytes[0] >> 4, value_as_bytes[1] & 0x0f
def merge_by_half_byte_12_bit_little_endian(v1: int, v2: int, v3: int) -> int:
return v1 | v2 << 4 | v3 << 8
def build_byte(first_half: int, second_half: int) -> int:
return (first_half << 4) | second_half
def split_content_into_sectors(content: bytes, sector_size: int) -> List[bytes]:
result = []
clusters_cnt: int = required_clusters_count(cluster_size=sector_size, content=content)
for i in range(clusters_cnt):
result.append(content[sector_size * i:(i + 1) * sector_size])
return result
def get_args_for_partition_generator(desc: str, wl: bool) -> argparse.Namespace:
parser: argparse.ArgumentParser = argparse.ArgumentParser(description=desc)
parser.add_argument('input_directory',
help='Path to the directory that will be encoded into fatfs image')
parser.add_argument('--output_file',
default='fatfs_image.img',
help='Filename of the generated fatfs image')
parser.add_argument('--partition_size',
default=FATDefaults.SIZE,
help='Size of the partition in bytes')
parser.add_argument('--sector_size',
default=FATDefaults.SECTOR_SIZE,
type=int,
choices=ALLOWED_WL_SECTOR_SIZES if wl else ALLOWED_SECTOR_SIZES,
help='Size of the partition in bytes')
parser.add_argument('--sectors_per_cluster',
default=1,
type=int,
choices=ALLOWED_SECTORS_PER_CLUSTER,
help='Number of sectors per cluster')
parser.add_argument('--root_entry_count',
default=FATDefaults.ROOT_ENTRIES_COUNT,
help='Number of entries in the root directory')
parser.add_argument('--long_name_support',
action='store_true',
help='Set flag to enable long names support.')
parser.add_argument('--use_default_datetime',
action='store_true',
help='For test purposes. If the flag is set the files are created with '
'the default timestamp that is the 1st of January 1980')
parser.add_argument('--fat_type',
default=0,
type=int,
choices=[FAT12, FAT16, 0],
help="""
Type of fat. Select 12 for fat12, 16 for fat16. Don't set, or set to 0 for automatic
calculation using cluster size and partition size.
""")
args = parser.parse_args()
if args.fat_type == 0:
args.fat_type = None
args.partition_size = int(str(args.partition_size), 0)
if not os.path.isdir(args.input_directory):
raise NotADirectoryError(f'The target directory `{args.input_directory}` does not exist!')
return args
def read_filesystem(path: str) -> bytearray:
with open(path, 'rb') as fs_file:
return bytearray(fs_file.read())
DATE_ENTRY = BitStruct(
'year' / BitsInteger(7),
'month' / BitsInteger(4),
'day' / BitsInteger(5))
TIME_ENTRY = BitStruct(
'hour' / BitsInteger(5),
'minute' / BitsInteger(6),
'second' / BitsInteger(5),
)
def build_name(name: str, extension: str) -> str:
return f'{name}.{extension}' if len(extension) > 0 else name
def build_date_entry(year: int, mon: int, mday: int) -> int:
"""
:param year: denotes year starting from 1980 (0 ~ 1980, 1 ~ 1981, etc), valid values are 1980 + 0..127 inclusive
thus theoretically 1980 - 2107
:param mon: denotes number of month of year in common order (1 ~ January, 2 ~ February, etc.),
valid values: 1..12 inclusive
:param mday: denotes number of day in month, valid values are 1..31 inclusive
:returns: 16 bit integer number (7 bits for year, 4 bits for month and 5 bits for day of the month)
"""
assert year in range(FATFS_INCEPTION_YEAR, FATFS_INCEPTION_YEAR + FATFS_MAX_YEARS)
assert mon in range(1, FATFS_MAX_MONTHS + 1)
assert mday in range(1, FATFS_MAX_DAYS + 1)
return int.from_bytes(DATE_ENTRY.build(dict(year=year - FATFS_INCEPTION_YEAR, month=mon, day=mday)), 'big')
def build_time_entry(hour: int, minute: int, sec: int) -> int:
"""
:param hour: denotes number of hour, valid values are 0..23 inclusive
:param minute: denotes minutes, valid range 0..59 inclusive
:param sec: denotes seconds with granularity 2 seconds (e.g. 1 ~ 2, 29 ~ 58), valid range 0..29 inclusive
:returns: 16 bit integer number (5 bits for hour, 6 bits for minute and 5 bits for second)
"""
assert hour in range(FATFS_MAX_HOURS)
assert minute in range(FATFS_MAX_MINUTES)
assert sec in range(FATFS_MAX_SECONDS)
return int.from_bytes(TIME_ENTRY.build(
dict(hour=hour, minute=minute, second=sec // FATFS_SECONDS_GRANULARITY)),
byteorder='big'
)
class FATDefaults:
# FATFS defaults
SIZE: int = 1024 * 1024
RESERVED_SECTORS_COUNT: int = 1
FAT_TABLES_COUNT: int = 1
SECTORS_PER_CLUSTER: int = 1
SECTOR_SIZE: int = 0x1000
HIDDEN_SECTORS: int = 0
ENTRY_SIZE: int = 32
NUM_HEADS: int = 0xff
OEM_NAME: str = 'MSDOS5.0'
SEC_PER_TRACK: int = 0x3f
VOLUME_LABEL: str = 'Espressif'
FILE_SYS_TYPE: str = 'FAT'
ROOT_ENTRIES_COUNT: int = 512 # number of entries in the root directory, recommended 512
MEDIA_TYPE: int = 0xf8
SIGNATURE_WORD: bytes = b'\x55\xAA'
# wear levelling defaults
VERSION: int = 2
TEMP_BUFFER_SIZE: int = 32
UPDATE_RATE: int = 16
WR_SIZE: int = 16
# wear leveling metadata (config sector) contains always sector size 4096
WL_SECTOR_SIZE: int = 4096