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#!/usr/bin/env python3
# Copyright (c) 2016, Maciej Sieczka. All rights reserved.
# This program is free software under the GNU General Public License (>=v2).
import tarfile
import os
class Tarball:
def __init__(self, infile, outfile):
self.infile = infile
self.outfile = outfile
def drop_lead_comp(self):
"""Removes leading path component (top-level dir) from input tar file."""
with as tarin,, 'w:gz') as tarout:
# Identify common top-level dir for all tarball components, and proceed if it's set.
lead_comp_name = os.path.commonpath(tarin.getnames())
if lead_comp_name:
prefix_len = len(lead_comp_name + '/')
# Remove top-level dir (eg. "root.x86_64" or "root.i686" in Arch Linux bootstrap tarballs) from the
# archive.
for m in tarin.members:
# Drop top-level dir prefix in all tarball component's paths.
m.path = m.path[prefix_len:]
# If component is a link, don't fetch its content. There's no point to that, and it helps avoiding
# KeyError("linkname 'something' not found") on "broken" symlinks, which are perfectly normal in a
# root FS tarball. And for hard links, the link target needs to be stripped of the prefix same as
# the file name.
if m.linkname:
if m.islnk():
m.linkname = m.linkname[prefix_len:]
tarout.addfile(m, tarin.extractfile(m))
if __name__ == '__main__':
import argparse
parser = argparse.ArgumentParser(description="Remove leading path component from input tarball contents and save "
"the result in output tarball.", add_help=False)
group = parser.add_argument_group("Arguments")
group.add_argument("--help", action='store_true', help="Show this help message and exit.")
args = parser.parse_known_args()
group.add_argument("--input", metavar='PATH', dest='infile', type=str, help="Input tar[.gz/xz/bz2] file path.",
group.add_argument("--output", metavar='PATH', dest='outfile', type=str, help="Output tar.gz file path.",
if args[0].help:
args = parser.parse_args()
tarball = Tarball(args.infile, args.outfile)
# An error handling attempt I would like to remember. Note to self: it skips symlinks altogether.
# # Handle broken symlinks. They are perfectly normal in a root fs tarball, but tarfile module is not
# # prepared for that. Trying hard not to catch anything other than "linkname 'something' not found".
# try:
# # Write each modified component to output tarball.
# tarout.addfile(m, tarin.extractfile(m))
# except KeyError as error:
# if "linkname '" and "' not found" in str(error):
# print("Warning: the input tarball contains a dead symlink: '%s' to non-existent '%s'. No "
# "biggy, but you might want to know. It will be included in the output tarball as it "
# "is. Proceeding..." % (, m.linkname), file=sys.stderr)
# else:
# raise
# And a compound list for all tar members:
# [m.path[prefix_len:] for m in tarin.members]