From c3fa07f006eb96b2ec489aae67bab91d87c16535 Mon Sep 17 00:00:00 2001 From: Johannes 'josch' Schauer Date: Tue, 14 Jan 2020 03:07:07 +0100 Subject: [PATCH] add taridshift.py --- taridshift.py | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100755 taridshift.py diff --git a/taridshift.py b/taridshift.py new file mode 100755 index 0000000..bc6aa8d --- /dev/null +++ b/taridshift.py @@ -0,0 +1,55 @@ +#!/usr/bin/env python3 +# +# This script is in the public domain +# +# This script accepts a tarball on standard input and prints a tarball on +# standard output with the same contents but all uid and gid ownership +# information shifted by the value given as first command line argument. +# +# A tool like this should be written in C but libarchive has issues: +# https://github.com/libarchive/libarchive/issues/587 +# https://github.com/libarchive/libarchive/pull/1288/ (needs 3.4.1) +# Should these issues get fixed, then a good template is tarfilter.c in the +# examples directory of libarchive. +# +# We are not using Perl either, because Archive::Tar slurps the whole tarball +# into memory. +# +# We could also use Go but meh... +# https://stackoverflow.com/a/59542307/784669 + +import tarfile +import sys + + +def main(): + if len(sys.argv) < 2: + print("usage: %s idshift" % sys.argv[0], file=sys.stderr) + exit(1) + + idshift = int(sys.argv[1]) + + # starting with Python 3.8, the default format became PAX_FORMAT, so this + # is only for compatibility with older versions of Python 3 + with tarfile.open(fileobj=sys.stdin.buffer, mode="r|*") as in_tar, tarfile.open( + fileobj=sys.stdout.buffer, mode="w|", format=tarfile.PAX_FORMAT + ) as out_tar: + for member in in_tar: + if idshift < 0 and -idshift > member.uid: + print("uid cannot be negative", file=sys.stderr) + exit(1) + if idshift < 0 and -idshift > member.gid: + print("gid cannot be negative", file=sys.stderr) + exit(1) + + member.uid += idshift + member.gid += idshift + if member.isfile(): + with in_tar.extractfile(member) as file: + out_tar.addfile(member, file) + else: + out_tar.addfile(member) + + +if __name__ == "__main__": + main()