[et-mgmt-tools] [PATCH 02 of 11] Cleanup on failure

[Cole Robinson]

john.levon at sun.com wrote:

Hi John,

Comments inline:

> # HG changeset patch
> # User john.levon at sun.com
> # Date 1215470371 25200
> # Node ID f0ddebbf39a3926f55045ade4fbf850706ed6c3e
> # Parent  c75d57437b7b219443580f6e9d6736d27d76ebcf
> 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):

You'll want to use a different variable other than '_' since this will
overwrite the gettext function in the local scope. Doesn't cause issues
in the current code, but could with future changes.

> +        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, did you see the comment I made in my response to this original
patch?

"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."

Any comment on this?


>  def main():
>      options = parse_args()
>      cli.setupLogging("virt-convert", options.debug)
> @@ -131,12 +162,15 @@ def main():
>  
>      vmdef.arch = options.arch
>  
> +    created_dir = False
>      unixname = vmdef.name.replace(" ", "-")
> +
>      if not options.output_dir:
>          options.output_dir = unixname
>      try:
>          logging.debug("Creating directory %s" % options.output_dir)
>          os.mkdir(options.output_dir)
> +        created_dir = True
>      except OSError, e:
>          if (e.errno != errno.EEXIST):
>              logging.error("Could not create directory %s: %s" %
> @@ -156,19 +190,19 @@ def main():
>          for d in vmdef.disks:
>              d.convert(options.input_dir, options.output_dir,
>                  vmconfig.DISK_TYPE_RAW)
> -    except Exception, e:
> -        logging.error(e)
> -        sys.exit(1)
> +    except OSError, e:
> +        cleanup("Couldn't convert disks: %s" % e.strerror, options, created_dir)
> +    except RuntimeError, e:
> +        cleanup("Couldn't convert disks: %s" % e.message, options, created_dir)
>   
>      try:
>          outp.export_file(vmdef, options.output_file)
> -    except Exception, e:
> -        logging.error(e)
> -        sys.exit(1)
> +    except ValueError, e:
> +        cleanup("Couldn't export to file \"%s\": %s" %
> +            (options.output_file, e.message), options, created_dir)
>  
>      print "\n\nConversion completed and placed in: %s" % options.output_dir
>  
> -    
>  if __name__ == "__main__":
>      try:
>          main()
> diff --git a/virtconv/vmconfig.py b/virtconv/vmconfig.py
> --- a/virtconv/vmconfig.py
> +++ b/virtconv/vmconfig.py
> @@ -77,7 +77,9 @@ class disk(object):
>              (infile, qemu_formats[output_type],
>              os.path.join(output_dir, outfile)))
>  
> -        os.system(convert_cmd)
> +        ret = os.system(convert_cmd)
> +        if ret != 0:
> +            raise RuntimeError("qemu-img failed with exit status %d" % ret)
>  
>          # Note: this is the *relative* path still
>          self.path = outfile
>