Make a clone of one file or device. Emule the command dd, without type conversion

clone.py

import io
import mmap
from typing import Optional

_DEFAULTBS=io.DEFAULT_BUFFER_SIZE

def clone(input_file: Optional[str]='/dev/zero', output_file: Optional[str]='/dev/null', block_size: Optional[int]=_DEFAULTBS, count: Optional[int]=None, verbose: Optional[bool]=False):
    """Make a clone of one file or device. Emule the command dd, without type conversion
        >>> clone(output_file='/tmp/swap.img',bs=512,count=8*2*1024*1024*1024)
        True
        >>> clone(input_file='/dev/sde',output_file='/tmp/pendrive.clone',block_size=1024,count=7969178)
        True
        >>> clone(output_file='/dev/sde',input_file='/tmp/pendrive.clone')
        True
        >>> clone('/dev/xpto','/tmp/pendrive.clone',512,7969178)
        False           
    """
    try:
        _count = int(count) if count else -1
        _step = 0
        with io.open(file=input_file,mode='r+b',buffering=0) as _if:
            mm_in = mmap.mmap(_if.fileno(),block_size*_count if _count > 0 else 0)
            with io.open(file=output_file,mode='wb',buffering=0) as _of:
                _data = True
                while _count and _data:
                    _data = mm_in.read(block_size)
                    _of.write(_data)
                    _count -=1
                    _step += 1
                    if verbose:
                        print(f'Step {_step}: data size {block_size} bytes')
            mm_in.close()
        return True
    except Exception as e:
        if verbose:
            print(f'Error: {e}')
        return False
 
if __name__ == '__main__':
    from argparse import ArgumentParser
    parser = ArgumentParser(prog='clone.py', description='clone a file or device')
    parser.add_argument('-i', '--input', type=str, default='/dev/zero')
    parser.add_argument('-o', '--output', type=str, default='/dev/null')
    parser.add_argument('-b', '--block-size', type=int, default=_DEFAULTBS)
    parser.add_argument('-c', '--count', type=int, default=None)
    parser.add_argument('-v', '--verbose', action='store_true')
    
    args = parser.parse_args()
    if args.verbose:
        print(args)
    clone(input_file=args.input, output_file=args.output, block_size=args.block_size, count=args.count, verbose=args.verbose)