[et-mgmt-tools] [PATCH] virt-convert: check for qemu-img failure

[Cole Robinson]

John Levon wrote:
> I didn't go the "qemu-info" route (yet), as it only produces
> human-readable output: I didn't see a way to get it to print just the
> file format.
>

One potential option would be to try 'qemu-info -f vmx imagename', throw
away the output and just check the return value. I don't know if this
works for all formats but in my quick check the above command on a raw
file failed. It would prevent us from autodetecting the format, but it's
at least an option.
 
> regards
> john
> 
> 
> Cleanup on failure
> 
> If we can't convert the disks or export the file, perform some cleanup.
> 
> Signed-off-by: John Levon <john.levon at sun.com>
> 
> diff --git a/virt-convert b/virt-convert
> --- a/virt-convert
> +++ b/virt-convert
> @@ -31,6 +31,7 @@ import virtconv.vmconfig as vmconfig
>  import virtconv.vmconfig as vmconfig
>  
>  def parse_args():
> +    """Parse and verify command line."""
>      opts = OptionParser()
>      opts.set_usage("%prog [options] inputdir|input.vmx "
>          "[outputdir|output.xml]")
> @@ -93,6 +94,36 @@ def parse_args():
>  
>      return options
>  
> +def rmrf(path):
> +    """Remove a directory and all its contents."""
> +
> +    assert path is not None
> +
> +    for dirpath, _, files in os.walk(path):
> +        for filename in files:
> +            os.remove(os.path.join(dirpath, filename))
> +    for dirpath, subdirs, _ in os.walk(path, topdown=False):
> +        for dirname in subdirs:
> +            os.rmdir(os.path.join(dirpath, dirname))
> +    os.rmdir(path)
> +
> +def cleanup(msg, options, created_dir):
> +    """
> +    After failure, clean up anything we created. Take a conservative
> +    approach: only if we created the output directory do we delete
> +    anything.
> +    """
> +    logging.error(msg)
> +
> +    if created_dir:
> +        try:
> +            rmrf(options.output_dir)
> +        except OSError, e:
> +            logging.error("Couldn't clean up output directory \"%s\": %s" %
> +                (options.output_dir, e.strerror))
> +
> +    sys.exit(1)
> +

Hmm, this scares the hell out of me, even with the created_dir
check. If someone in the future ever messed up this code we could
accidently start deleting someones homedir.

I think a whitelist approach would be better: have convert_disks clean
up its own files, and keep all other file/directory creation in the
main() function (like it currently is) so it can handle the rest
of the cleanup on a per file basis. At the end, if the output_dir
is empty and we created it, we can delete it. Maybe it's overly
paranoid, but better to be safe than sorry.

- Cole