On Mon, Dec 09, 2013 at 09:17:28PM -0500, Chris Lalancette
wrote:> Hello,
> Oz is a program that does automated installation of virtual
> machines. It is written in python and uses libguestfs pretty heavily
> to manipulate ISOs and disks.
> Someone reported an error against Oz here:
>
> https://github.com/clalancette/oz/issues/140
>
> There are some more details in the issue, but it essentially looks
> like something happened during libguestfs tar_out:
>
> RuntimeError: /dev/fd/13: error in chunked encoding
>
> Has anyone seen this before? Any idea what this is about? If you
> want to comment, I would appreciate it if you could comment in the
> issue itself.
I'll make a comment here and copy it to the github issue tracker.
When libguestfs sends files over the link between the appliance and
the library (such as when running the guestfs_tar_out call), it sends
8 KByte chunks of data. If the library cannot read a chunk, it will
print this error. The normal case would be that system call (eg
read(2)) would fail. This is likely to be a "should never happen"
issue, and this code is well tested.
Oz calls guestfs_tar_out with the /dev/fd/NN parameter (there's
nothing wrong with that). This explains why /dev/fd/NN is shown in
the error message.
The bug suggests that strace shows a problem with a file descriptor
being closed, but without the complete strace output, plus the precise
version of libguestfs, this is not useful.
I can't really debug this further without knowing the precise version
of libguestfs, the full strace output, and ideally having a
reproducible bug report.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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