Re: [dev] a

From: Markus Wichmann <nullplan_AT_gmx.net>
Date: Fri, 3 Feb 2017 06:28:36 +0100

On Thu, Feb 02, 2017 at 07:20:34PM +0100, willy wrote:
> Hello everyone,
>
> While playing with sbase and musl, I encountered a strange bug: tar
> fails to extract bzip2 compressed archives when bzip2 is compiled
> against musl (I only tested static linking). Note that bzip2 uncompresses
> the files correctly. The error only occurs when the data flows through
> a pipe:
>

If an error occurs only when a pipe is involved, then in principle only
two things could go wrong: bzip2 could be failing to handle short writes
correctly or tar could be failing to handle short reads correctly.

If it was the latter then I'd expect to see weird behavior regarding
blocks and the start thereof. Like, for instance:

> chktar: invalid magic "ootfs, datadir, *argv);
> if (action == ACTION_UPDATE)
> r += update(rootfs, datadir, *argv);
> if (action == ACTION_DELETE)
> r += delete(rootfs, datadir, *argv);
> argv++;
> }
> break;
> case ACTION_INSPECT:
> if (inspect(datadir, n) != 0)
> retu"
> musl/tar: malformed tar archive
>

If it was the former, then I'd expect similar behavior, however not
exactly like this. If bzip was failing to notice that some decompressed
data isn't written, tar would be seeing start blocks too late, not
too early, as it does here.

So, looks like a tar bug.

Ciao,
Markus
Received on Fri Feb 03 2017 - 06:28:36 CET