forked from josch/mmdebstrap
65 lines
2.2 KiB
Python
Executable file
65 lines
2.2 KiB
Python
Executable file
#!/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
|
|
import argparse
|
|
|
|
|
|
def main():
|
|
parser = argparse.ArgumentParser(
|
|
description="""\
|
|
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.
|
|
"""
|
|
)
|
|
parser.add_argument(
|
|
"idshift",
|
|
metavar="NUM",
|
|
type=int,
|
|
help="Integer value by which to shift the uid and gid of each entry",
|
|
)
|
|
args = parser.parse_args()
|
|
|
|
# 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 args.idshift < 0 and -args.idshift > member.uid:
|
|
print("uid cannot be negative", file=sys.stderr)
|
|
exit(1)
|
|
if args.idshift < 0 and -args.idshift > member.gid:
|
|
print("gid cannot be negative", file=sys.stderr)
|
|
exit(1)
|
|
|
|
member.uid += args.idshift
|
|
member.gid += args.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()
|