Overwrite existing read-only files when using Python's tarfile

Question

I'm attempting to use Python's tarfile module to extract a tar.gz archive.

I'd like the extraction to overwrite any target files it they already exist - this is tarfile's normal behaviour.

However, I'm hitting a snitch in that some of the files have write-protection on (e.g. chmod 550).

The tarfile.extractall() operation actually fails:

IOError: [Errno 13] Permission denied '/foo/bar/file'

If I try to delete the files from the normal command-line, I can do it, I just need to answer a prompt:

$ rm <filename>
rm: <filename>: override protection 550 (yes/no)? yes

The normal GNU tar utility also handles these files effortlessly - it just overwrites them when you extract.

My user is the owner of the files, so it wouldn't be hard to recursively chmod the target files before running tarfile.extractall. Or I can use shutil.rmtree to blow away the target beforehand, which is the workaround I'm using now.. However, that feels a little hackish.

Is there a more Pythonic way of handle overwriting read-only files within tarfile, using exceptions, or something similar?

Answer 1

I was able to get Mike's Steder's code to work like this:

tarball = tarfile.open(filename, 'r:gz')
for f in tarball:
    try: 
        tarball.extract(f)
    except IOError as e:
        os.remove(f.name)
        tarball.extract(f)
    finally:
        os.chmod(f.name, f.mode)