98 lines
3.2 KiB
Python
98 lines
3.2 KiB
Python
from flask import Response
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import functools
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import os
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# 4MiB chunks
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CHUNK_SIZE = 4_194_304
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# Specification de l'entête du fichier
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# Numéro Nom Début Taille Description
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# 1 name 0 100 Nom du fichier
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# 2 mode 100 8 Permissions
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# 3 uid 108 8 Propriétaire (inutilisé si format étendu)
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# 4 gid 116 8 Groupe (inutilisé si format étendu)
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# 5 size 124 12 Taille du fichier en octets.
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# 6 mtime 136 12 Dernière modification en temps Unix.
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# 7 chksum 148 8 Somme de contrôle de l'en-tête où ce champ est considéré comme rempli d'espaces (32)
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# 8 type flag 156 1 Type de fichier
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# 9 linkname 157 100 Nom du fichier pointé par ce lien symbolique (Si le type indique un lien symbolique)
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def header_chunk(filename: str, filepath: str) -> bytes:
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stat = os.stat(filepath)
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buffer = bytearray()
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# Field 1: filename on 100 bytes
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buffer += filename.encode('ascii')
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buffer += b'\x00' * (100 - len(filename))
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# Field 2: mode, on 8 bytes
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# TODO we put 777 for test
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buffer += '0000777'.encode('ascii') + b'\x00'
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# Field 3: owner, we put 1000, default user
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buffer += '0001000'.encode('ascii') + b'\x00'
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# Field 4: group, we put 1000
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buffer += '0001000'.encode('ascii') + b'\x00'
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# Field 5: file size in bytes in ascii
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buffer += str(stat.st_size).rjust(11, '0').encode('ascii') + b'\x00'
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# Field 6: last modified, zeros for now
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# buffer += '00000000000'.encode('ascii') + b'\x00'
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buffer += '1721728914'.rjust(11, '0').encode('ascii') + b'\x00'
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# Field 7: checksum, we put spaces and we will edit it at the end
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buffer += ' '.encode('ascii')
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# Field 8: type flag, 0 because we only have regular files
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buffer += b'0'
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# Field 9: linkname, \x00s because we only have regular files
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buffer += b'\x00' * 100
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# POSIX 1003.1-1990: 255 empty bytes
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buffer += b'\x00' * 255
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# Compute the checksum
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checksum = str(functools.reduce(lambda x, y: x + y, buffer)).rjust(6, '0').encode('ascii') + b'\x00 '
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buffer[148:156] = checksum
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return bytes(buffer)
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class TarSender:
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def __init__(self):
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self.files: dict[str, str] = {}
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def add_file(self, filename: str, filepath: str):
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self.files[filename] = filepath
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def response(self):
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def generate():
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for name, file in self.files.items():
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yield header_chunk(name, file)
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bytes_sent = 0
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with open(file, 'rb') as f:
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while True:
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bytes = f.read(CHUNK_SIZE)
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if len(bytes) == 0:
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break
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bytes_sent += len(bytes)
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yield bytes
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# Because tar use records of 512 bytes, we need to pad the
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# file with zeroes to fill the last chunk
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yield b'\x00' * (512 - bytes_sent % 512)
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return Response(
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generate(),
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mimetype='application/x-tar',
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headers={'Content-Disposition': 'attachment; filename="archive.tar"'}
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)
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