Re: star-1.5a64 aborts on reading archives with _small_ garbage tails

[email protected] wrote:

> > This is not a bug but intended behavior on a missusage.
> > A valid TAR archive is always a multiple of 512 bytes.
>
> I plead guilty and promise to better disguise my misbehavior
> in future. 
>
>
> Nevertheless, please consider wether it is possible to make
> sure that all uncomplained input is processed by the unpacker
> before star aborts. (Of course, the unpacker should not unpack
> obviously damaged data blocks.)
>
> At restore time, any effort of the backup tool is welcome.
> The mental state of the user is not the most stable one
> in these moments.

Well, it seems that you did convince me as star did never complain
if the read size modulo 512 was not zero but the amount itself
was > 512.

So star was not behaving orthogonal for all cases.

In addition, there was a problem related to calling

	rpm2cpio | star -xp

which sometimes caused star not to unpack all.

I am not sure whether this is caused by a bug in the rpm commands
or in GNU cpio (creating a cpio archive that is not a multiple
of 512 bytes is illegal too although the logical end may be at any
even byte count). The change in star should workaround this problem
too.


> A valid backup file is created :
>
>   $ star -c /dvdbuffer >/tmp/test.star
>   star: 10004 blocks + 0 bytes (total of 102440960 bytes = 100040.00k).
>
> I spoil a copy by appending 123 bytes :
>
>   $ cp /tmp/test.star /tmp/test_spoiled.star
>   $ dd if=/dev/zero bs=1 count=123 >>/tmp/test_spoiled.star

Why do you do this?

Note that the fix I applied set a hard EOF flag whenever such a
condition accurs. So star (the archiver process) will continue to 
work until the logical EOF is seen of the data ends.

The way I implemented the fix will e.g. prevent you from
being able to continue with multi-volume handling after this
condition did accur.

Jörg

-- 
 EMail:[email protected] (home) Jörg Schilling D-13353 Berlin
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