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68 lines
3.1 KiB
Python
68 lines
3.1 KiB
Python
# SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
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# SPDX-License-Identifier: Apache-2.0
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from construct import Const, Int8ul, Int16ul, Int32ul, PaddedString, Struct
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from .utils import (BYTES_PER_DIRECTORY_ENTRY, get_fatfs_type, get_non_data_sectors_cnt, number_of_clusters,
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read_filesystem)
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class FATFSParser:
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MAX_VOL_LAB_SIZE = 11
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MAX_OEM_NAME_SIZE = 8
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MAX_FS_TYPE_SIZE = 8
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# the FAT specification defines 512 bytes for the boot sector header
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BOOT_HEADER_SIZE = 512
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BOOT_SECTOR_HEADER = Struct(
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'BS_jmpBoot' / Const(b'\xeb\xfe\x90'),
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'BS_OEMName' / PaddedString(MAX_OEM_NAME_SIZE, 'utf-8'),
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'BPB_BytsPerSec' / Int16ul,
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'BPB_SecPerClus' / Int8ul,
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'BPB_RsvdSecCnt' / Int16ul,
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'BPB_NumFATs' / Int8ul,
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'BPB_RootEntCnt' / Int16ul,
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'BPB_TotSec16' / Int16ul,
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'BPB_Media' / Int8ul,
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'BPB_FATSz16' / Int16ul,
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'BPB_SecPerTrk' / Int16ul,
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'BPB_NumHeads' / Int16ul,
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'BPB_HiddSec' / Int32ul,
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'BPB_TotSec32' / Int32ul,
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'BS_DrvNum' / Const(b'\x80'),
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'BS_Reserved1' / Const(b'\x00'),
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'BS_BootSig' / Const(b'\x29'),
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'BS_VolID' / Int32ul,
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'BS_VolLab' / PaddedString(MAX_VOL_LAB_SIZE, 'utf-8'),
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'BS_FilSysType' / PaddedString(MAX_FS_TYPE_SIZE, 'utf-8'),
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'BS_EMPTY' / Const(448 * b'\x00'),
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'Signature_word' / Const(b'\x55\xAA')
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)
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assert BOOT_SECTOR_HEADER.sizeof() == BOOT_HEADER_SIZE
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def __init__(self, image_file_path: str, wl_support: bool = False) -> None:
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if wl_support:
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raise NotImplementedError('Parser is not implemented for WL yet.')
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self.fatfs = read_filesystem(image_file_path)
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# when wl is not supported we expect boot sector to be the first
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self.parsed_header = FATFSParser.BOOT_SECTOR_HEADER.parse(self.fatfs[:FATFSParser.BOOT_HEADER_SIZE])
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def print(self) -> None:
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print('Properties of the FATFS:')
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for key in self.parsed_header.keys():
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if key in ('_io', 'BS_EMPTY', 'Signature_word'):
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continue
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print(' {}: {}'.format(key.replace('BPB_', '').replace('BS_', ''), self.parsed_header[key]))
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root_dir_cnt = (self.parsed_header['BPB_RootEntCnt'] * BYTES_PER_DIRECTORY_ENTRY) // self.parsed_header[
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'BPB_BytsPerSec']
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non_data_sectors = get_non_data_sectors_cnt(self.parsed_header['BPB_RsvdSecCnt'],
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# this has to be changed when FAT32 is supported
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self.parsed_header['BPB_FATSz16'], root_dir_cnt)
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data_clusters = self.parsed_header['BPB_TotSec16'] - non_data_sectors
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clusters_num = number_of_clusters(data_clusters, self.parsed_header['BPB_SecPerClus'])
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assert self.parsed_header['BPB_BytsPerSec'] in (512, 1024, 2048, 4096)
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assert self.parsed_header['BPB_SecPerClus'] in (1, 2, 4, 8, 16, 32, 64, 128)
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print(f' Clusters number: {clusters_num}')
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print(f' FATFS type: FAT{get_fatfs_type(clusters_num)}')
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