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From: Peter Otten <__peter__@web.de>
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Subject: Re: tarfile : read from a socket?
Date: Thu, 11 Feb 2016 18:18:55 +0100
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Ulli Horlacher wrote:

> Ulli Horlacher <framstag@rus.uni-stuttgart.de> wrote:
> 
>> With
>> 
>>   taro = tarfile.open(fileobj=sock.makefile('w',kB64),mode='w|')
>> 
>> I get no more error.
> 
> Of course, this is the writing client.
> 
> Now I have a small problem with the reading client.
> 
> This code works so far:
> 
>   sfo = sock.makefile('r')
>   taro = tarfile.open(fileobj=sfo,mode='r|')
>   taro.extractall(path=edir)
> 
> But it does not writes anything to the terminal to inform the user.
> 
> When I use:
> 
>   for member in taro.getmembers():
>       print('extracting "%s"' % member.name)
>       taro.extract(member)
> 
> I get the error:
> 
>   File "/usr/lib/python2.7/tarfile.py", line 556, in seek
>     raise StreamError("seeking backwards is not allowed")
> 
> Of course, a stream is not seekable.
> 
> Any ideas?

A look into the source is often helpful ;)

$ cat extract_from_stream.py
import sys
from tarfile import TarFile

class MyTarFile(TarFile):
    def extract(self, member, path="."):
        print "extracting", member
        return TarFile.extract(self, member, path)

tf = MyTarFile.open(fileobj=sys.stdin, mode="r|")
tf.extractall()
$ touch foo bar
$ tar -cf archive.tar foo bar
$ python extract_from_stream.py < archive.tar 
extracting <TarInfo 'foo' at 0x7f2b3f394890>
extracting <TarInfo 'bar' at 0x7f2b3f3a4bd0>