mirror of
https://github.com/espressif/esp-idf.git
synced 2024-10-05 20:47:46 -04:00
151 lines
8.8 KiB
Python
151 lines
8.8 KiB
Python
# SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
|
|
# SPDX-License-Identifier: Apache-2.0
|
|
from inspect import getmembers, isroutine
|
|
from typing import Optional
|
|
|
|
from construct import Const, Int8ul, Int16ul, Int32ul, PaddedString, Struct
|
|
|
|
from .exceptions import InconsistentFATAttributes, NotInitialized
|
|
from .fatfs_state import BootSectorState
|
|
from .utils import (ALLOWED_SECTOR_SIZES, ALLOWED_SECTORS_PER_CLUSTER, EMPTY_BYTE, FAT32, FULL_BYTE,
|
|
SHORT_NAMES_ENCODING, FATDefaults, generate_4bytes_random, pad_string)
|
|
|
|
|
|
class BootSector:
|
|
MAX_VOL_LAB_SIZE = 11
|
|
MAX_OEM_NAME_SIZE = 8
|
|
MAX_FS_TYPE_SIZE = 8
|
|
|
|
# the FAT specification defines 512 bytes for the boot sector header
|
|
BOOT_HEADER_SIZE = 512
|
|
|
|
BOOT_SECTOR_HEADER = Struct(
|
|
'BS_jmpBoot' / Const(b'\xeb\xfe\x90'),
|
|
'BS_OEMName' / PaddedString(MAX_OEM_NAME_SIZE, SHORT_NAMES_ENCODING),
|
|
'BPB_BytsPerSec' / Int16ul,
|
|
'BPB_SecPerClus' / Int8ul,
|
|
'BPB_RsvdSecCnt' / Int16ul,
|
|
'BPB_NumFATs' / Int8ul,
|
|
'BPB_RootEntCnt' / Int16ul,
|
|
'BPB_TotSec16' / Int16ul,
|
|
'BPB_Media' / Int8ul,
|
|
'BPB_FATSz16' / Int16ul, # for FAT32 always zero, for FAT12/FAT16 number of sectors per FAT
|
|
'BPB_SecPerTrk' / Int16ul,
|
|
'BPB_NumHeads' / Int16ul,
|
|
'BPB_HiddSec' / Int32ul,
|
|
'BPB_TotSec32' / Int32ul,
|
|
'BS_DrvNum' / Const(b'\x80'),
|
|
'BS_Reserved1' / Const(EMPTY_BYTE),
|
|
'BS_BootSig' / Const(b'\x29'),
|
|
'BS_VolID' / Int32ul,
|
|
'BS_VolLab' / PaddedString(MAX_VOL_LAB_SIZE, SHORT_NAMES_ENCODING),
|
|
'BS_FilSysType' / PaddedString(MAX_FS_TYPE_SIZE, SHORT_NAMES_ENCODING),
|
|
'BS_EMPTY' / Const(448 * EMPTY_BYTE),
|
|
'Signature_word' / Const(FATDefaults.SIGNATURE_WORD)
|
|
)
|
|
assert BOOT_SECTOR_HEADER.sizeof() == BOOT_HEADER_SIZE
|
|
|
|
def __init__(self, boot_sector_state: Optional[BootSectorState] = None) -> None:
|
|
self._parsed_header = None
|
|
self.boot_sector_state: BootSectorState = boot_sector_state
|
|
|
|
def generate_boot_sector(self) -> None:
|
|
boot_sector_state: BootSectorState = self.boot_sector_state
|
|
if boot_sector_state is None:
|
|
raise NotInitialized('The BootSectorState instance is not initialized!')
|
|
volume_uuid = generate_4bytes_random()
|
|
pad_header: bytes = (boot_sector_state.sector_size - BootSector.BOOT_HEADER_SIZE) * EMPTY_BYTE
|
|
data_content: bytes = boot_sector_state.data_sectors * boot_sector_state.sector_size * FULL_BYTE
|
|
root_dir_content: bytes = boot_sector_state.root_dir_sectors_cnt * boot_sector_state.sector_size * EMPTY_BYTE
|
|
fat_tables_content: bytes = (boot_sector_state.sectors_per_fat_cnt
|
|
* boot_sector_state.fat_tables_cnt
|
|
* boot_sector_state.sector_size
|
|
* EMPTY_BYTE)
|
|
self.boot_sector_state.binary_image = (
|
|
BootSector.BOOT_SECTOR_HEADER.build(
|
|
dict(BS_OEMName=pad_string(boot_sector_state.oem_name, size=BootSector.MAX_OEM_NAME_SIZE),
|
|
BPB_BytsPerSec=boot_sector_state.sector_size,
|
|
BPB_SecPerClus=boot_sector_state.sectors_per_cluster,
|
|
BPB_RsvdSecCnt=boot_sector_state.reserved_sectors_cnt,
|
|
BPB_NumFATs=boot_sector_state.fat_tables_cnt,
|
|
BPB_RootEntCnt=boot_sector_state.entries_root_count,
|
|
# if fat type is 12 or 16 BPB_TotSec16 is filled and BPB_TotSec32 is 0x00 and vice versa
|
|
BPB_TotSec16=0x00 if boot_sector_state.fatfs_type == FAT32 else boot_sector_state.sectors_count,
|
|
BPB_Media=boot_sector_state.media_type,
|
|
BPB_FATSz16=boot_sector_state.sectors_per_fat_cnt,
|
|
BPB_SecPerTrk=boot_sector_state.sec_per_track,
|
|
BPB_NumHeads=boot_sector_state.num_heads,
|
|
BPB_HiddSec=boot_sector_state.hidden_sectors,
|
|
BPB_TotSec32=boot_sector_state.sectors_count if boot_sector_state.fatfs_type == FAT32 else 0x00,
|
|
BS_VolID=volume_uuid,
|
|
BS_VolLab=pad_string(boot_sector_state.volume_label,
|
|
size=BootSector.MAX_VOL_LAB_SIZE),
|
|
BS_FilSysType=pad_string(boot_sector_state.file_sys_type,
|
|
size=BootSector.MAX_FS_TYPE_SIZE)
|
|
)
|
|
) + pad_header + fat_tables_content + root_dir_content + data_content
|
|
)
|
|
|
|
def parse_boot_sector(self, binary_data: bytes) -> None:
|
|
self._parsed_header = BootSector.BOOT_SECTOR_HEADER.parse(binary_data)
|
|
if self._parsed_header is None:
|
|
raise NotInitialized('The boot sector header is not parsed successfully!')
|
|
if self._parsed_header['BPB_TotSec16'] != 0x00:
|
|
sectors_count_: int = self._parsed_header['BPB_TotSec16']
|
|
elif self._parsed_header['BPB_TotSec32'] != 0x00:
|
|
# uncomment for FAT32 implementation
|
|
# sectors_count_ = self._parsed_header['BPB_TotSec32']
|
|
# possible_fat_types = [FAT32]
|
|
assert self._parsed_header['BPB_FATSz16'] == 0
|
|
raise NotImplementedError('FAT32 not implemented!')
|
|
else:
|
|
raise InconsistentFATAttributes('The number of FS sectors cannot be zero!')
|
|
# in the current code assigning self._parsed_header['BPB_TotSec32'] is not reachable
|
|
# the option to assign it is kept for possibility to implement FAT32
|
|
sectors_per_fat_cnt_ = self._parsed_header['BPB_FATSz16'] or self._parsed_header['BPB_TotSec32']
|
|
if self._parsed_header['BPB_BytsPerSec'] not in ALLOWED_SECTOR_SIZES:
|
|
raise InconsistentFATAttributes(f'The number of bytes '
|
|
f"per sector is {self._parsed_header['BPB_BytsPerSec']}! "
|
|
f'The accepted values are {ALLOWED_SECTOR_SIZES}')
|
|
if self._parsed_header['BPB_SecPerClus'] not in ALLOWED_SECTORS_PER_CLUSTER:
|
|
raise InconsistentFATAttributes(f'The number of sectors per cluster '
|
|
f"is {self._parsed_header['BPB_SecPerClus']}"
|
|
f'The accepted values are {ALLOWED_SECTORS_PER_CLUSTER}')
|
|
|
|
total_root_bytes: int = self._parsed_header['BPB_RootEntCnt'] * FATDefaults.ENTRY_SIZE
|
|
root_dir_sectors_cnt_: int = total_root_bytes // self._parsed_header['BPB_BytsPerSec']
|
|
self.boot_sector_state = BootSectorState(oem_name=self._parsed_header['BS_OEMName'],
|
|
sector_size=self._parsed_header['BPB_BytsPerSec'],
|
|
sectors_per_cluster=self._parsed_header['BPB_SecPerClus'],
|
|
reserved_sectors_cnt=self._parsed_header['BPB_RsvdSecCnt'],
|
|
fat_tables_cnt=self._parsed_header['BPB_NumFATs'],
|
|
root_dir_sectors_cnt=root_dir_sectors_cnt_,
|
|
sectors_count=sectors_count_,
|
|
media_type=self._parsed_header['BPB_Media'],
|
|
sectors_per_fat_cnt=sectors_per_fat_cnt_,
|
|
sec_per_track=self._parsed_header['BPB_SecPerTrk'],
|
|
num_heads=self._parsed_header['BPB_NumHeads'],
|
|
hidden_sectors=self._parsed_header['BPB_HiddSec'],
|
|
volume_label=self._parsed_header['BS_VolLab'],
|
|
file_sys_type=self._parsed_header['BS_FilSysType'],
|
|
volume_uuid=self._parsed_header['BS_VolID'])
|
|
self.boot_sector_state.binary_image = binary_data
|
|
assert self.boot_sector_state.file_sys_type in (f'FAT{self.boot_sector_state.fatfs_type} ', 'FAT ')
|
|
|
|
def __str__(self) -> str:
|
|
if self._parsed_header is None:
|
|
return 'Boot sector is not initialized!'
|
|
res: str = 'Properties of the FATFS:\n'
|
|
for member in getmembers(self.boot_sector_state, lambda a: not(isroutine(a))):
|
|
prop_ = getattr(self.boot_sector_state, member[0])
|
|
if isinstance(prop_, int) or isinstance(prop_, str) and not member[0].startswith('_'):
|
|
res += f'{member[0]}: {prop_}\n'
|
|
return res
|
|
|
|
@property
|
|
def binary_image(self) -> bytes:
|
|
if len(self.boot_sector_state.binary_image) == 0:
|
|
raise NotInitialized('Boot sector is not generated nor initialized!')
|
|
bin_image_: bytes = self.boot_sector_state.binary_image
|
|
return bin_image_
|