forked from josch/mmdebstrap
101 lines
3.4 KiB
Python
Executable file
101 lines
3.4 KiB
Python
Executable file
#!/usr/bin/env python3
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#
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# This script is in the public domain
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#
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# This script accepts a tarball on standard input and filters it according to
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# the same rules used by dpkg --path-exclude and --path-include, using command
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# line options of the same name. The result is then printed on standard output.
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#
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# A tool like this should be written in C but libarchive has issues:
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# https://github.com/libarchive/libarchive/issues/587
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# https://github.com/libarchive/libarchive/pull/1288/ (needs 3.4.1)
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# Should these issues get fixed, then a good template is tarfilter.c in the
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# examples directory of libarchive.
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#
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# We are not using Perl either, because Archive::Tar slurps the whole tarball
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# into memory.
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#
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# We could also use Go but meh...
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# https://stackoverflow.com/a/59542307/784669
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import tarfile
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import sys
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import argparse
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from fnmatch import fnmatch
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import re
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class FilterAction(argparse.Action):
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def __call__(self, parser, namespace, values, option_string=None):
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items = getattr(namespace, "filter", [])
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items.append((self.dest, values))
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setattr(namespace, "filter", items)
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def main():
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parser = argparse.ArgumentParser(
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description="""\
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Filters a tarball on standard input by the same rules as the dpkg --path-exclude
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and --path-include options and writes resulting tarball to standard output. See
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dpkg(1) for information on how these two options work in detail.
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"""
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)
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parser.add_argument(
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"--path-exclude",
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metavar="pattern",
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action=FilterAction,
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help="Exclude path matching the given shell pattern.",
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)
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parser.add_argument(
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"--path-include",
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metavar="pattern",
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action=FilterAction,
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help="Re-include a pattern after a previous exclusion.",
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)
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args = parser.parse_args()
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if not hasattr(args, "filter"):
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from shutil import copyfileobj
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copyfileobj(sys.stdin.buffer, sys.stdout.buffer)
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exit()
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# same logic as in dpkg/src/filters.c/filter_should_skip()
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def filter_should_skip(member):
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skip = False
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if not args.filter:
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return False
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for (t, f) in args.filter:
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if fnmatch(member.name[1:], f):
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if t == "path_include":
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skip = False
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else:
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skip = True
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if skip and (member.isdir() or member.issym()):
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for (t, f) in args.filter:
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if t != "path_include":
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continue
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prefix = re.sub(r"^([^*?[\\]*).*", r"\1", f)
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prefix = prefix.rstrip("/")
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if member.name[1:].startswith(prefix):
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if member.name == "./usr/share/doc/doc-debian":
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print("foo", prefix, "bar", file=sys.stderr)
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return False
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return skip
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# starting with Python 3.8, the default format became PAX_FORMAT, so this
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# is only for compatibility with older versions of Python 3
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with tarfile.open(fileobj=sys.stdin.buffer, mode="r|*") as in_tar, tarfile.open(
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fileobj=sys.stdout.buffer, mode="w|", format=tarfile.PAX_FORMAT
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) as out_tar:
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for member in in_tar:
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if filter_should_skip(member):
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continue
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if member.isfile():
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with in_tar.extractfile(member) as file:
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out_tar.addfile(member, file)
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else:
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out_tar.addfile(member)
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if __name__ == "__main__":
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main()
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