Adding upstream version 1.4.3.upstream/1.4.3

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 300 insertions, 0 deletions

diff --git a/tarfilter b/tarfilter
new file mode 100755
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+++ b/tarfilter
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+#!/usr/bin/env python3
+#
+# This script is in the public domain
+#
+# Author: Johannes Schauer Marin Rodrigues <josch@mister-muffin.de>
+#
+# This script accepts a tarball on standard input and filters it according to
+# the same rules used by dpkg --path-exclude and --path-include, using command
+# line options of the same name. The result is then printed on standard output.
+#
+# 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
+import fnmatch
+import re
+
+
+class PathFilterAction(argparse.Action):
+    def __call__(self, parser, namespace, values, option_string=None):
+        items = getattr(namespace, "pathfilter", [])
+        regex = re.compile(fnmatch.translate(values))
+        items.append((self.dest, regex))
+        setattr(namespace, "pathfilter", items)
+
+
+class PaxFilterAction(argparse.Action):
+    def __call__(self, parser, namespace, values, option_string=None):
+        items = getattr(namespace, "paxfilter", [])
+        regex = re.compile(fnmatch.translate(values))
+        items.append((self.dest, regex))
+        setattr(namespace, "paxfilter", items)
+
+
+class TypeFilterAction(argparse.Action):
+    def __call__(self, parser, namespace, values, option_string=None):
+        items = getattr(namespace, "typefilter", [])
+        match values:
+            case "REGTYPE" | "0":
+                items.append(tarfile.REGTYPE)
+            case "LNKTYPE" | "1":
+                items.append(tarfile.LNKTYPE)
+            case "SYMTYPE" | "2":
+                items.append(tarfile.SYMTYPE)
+            case "CHRTYPE" | "3":
+                items.append(tarfile.CHRTYPE)
+            case "BLKTYPE" | "4":
+                items.append(tarfile.BLKTYPE)
+            case "DIRTYPE" | "5":
+                items.append(tarfile.DIRTYPE)
+            case "FIFOTYPE" | "6":
+                items.append(tarfile.FIFOTYPE)
+            case _:
+                raise ValueError("invalid type: %s" % values)
+        setattr(namespace, "typefilter", items)
+
+
+class TransformAction(argparse.Action):
+    def __call__(self, parser, namespace, values, option_string=None):
+        items = getattr(namespace, "trans", [])
+        # This function mimics what src/transform.c from tar does
+        if not values.startswith("s"):
+            raise ValueError("regex must start with an 's'")
+        if len(values) <= 4:
+            # minimum regex: s/x//
+            raise ValueError("invalid regex (too short)")
+        d = values[1]
+        if values.startswith(f"s{d}{d}"):
+            raise ValueError("empty regex")
+        values = values.removeprefix(f"s{d}")
+        flags = 0
+        if values.endswith(f"{d}i"):
+            # trailing flags
+            flags = re.IGNORECASE
+            values = values.removesuffix(f"{d}i")
+        # This regex only finds non-empty tokens.
+        # Finding empty tokens would require a variable length look-behind
+        # or \K in order to find escaped delimiters which is not supported by
+        # the python re module.
+        tokens = re.findall(rf"(?:\\[\\{d}]|[^{d}])+", values)
+        match len(tokens):
+            case 0:
+                raise ValueError("invalid regex: not enough terms")
+            case 1:
+                repl = ""
+            case 2:
+                repl = tokens[1]
+            case _:
+                raise ValueError("invalid regex: too many terms: %s" % tokens)
+        items.append((re.compile(tokens[0], flags), repl))
+        setattr(namespace, "trans", items)
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        description="""\
+Filters a tarball on standard input by the same rules as the dpkg --path-exclude
+and --path-include options and writes resulting tarball to standard output. See
+dpkg(1) for information on how these two options work in detail. To reuse the
+exact same semantics as used by dpkg, paths must be given as /path and not as
+./path even though they might be stored as such in the tarball.
+
+Secondly, filter out unwanted pax extended headers using --pax-exclude and
+--pax-include. This is useful in cases where a tool only accepts certain xattr
+prefixes. For example tar2sqfs only supports SCHILY.xattr.user.*,
+SCHILY.xattr.trusted.* and SCHILY.xattr.security.* but not
+SCHILY.xattr.system.posix_acl_default.*.
+
+Both types of options use Unix shell-style wildcards:
+
+       * matches everything
+       ? matches any single character
+   [seq] matches any character in seq
+  [!seq] matches any character not in seq
+
+Thirdly, filter out files matching a specific tar archive member type using
+--type-exclude. Valid type names are REGTYPE (regular file), LNKTYPE
+(hardlink), SYMTYPE (symlink), CHRTYPE (character special), BLKTYPE (block
+special), DIRTYPE (directory), FIFOTYPE (fifo) or their tar format flag value
+(0-6, respectively).
+
+Fourthly, transform the path of tar members using a sed expression just as with
+GNU tar --transform.
+
+Fifthly, strip leading directory components off of tar members. Just as with
+GNU tar --strip-components, tar members that have less or equal components in
+their path are not passed through.
+
+Lastly, shift user id and group id of each entry by the value given by the
+--idshift argument. The resulting uid or gid must not be negative.
+""",
+    )
+    parser.add_argument(
+        "--path-exclude",
+        metavar="pattern",
+        action=PathFilterAction,
+        help="Exclude path matching the given shell pattern. "
+        "This option can be specified multiple times.",
+    )
+    parser.add_argument(
+        "--path-include",
+        metavar="pattern",
+        action=PathFilterAction,
+        help="Re-include a pattern after a previous exclusion. "
+        "This option can be specified multiple times.",
+    )
+    parser.add_argument(
+        "--pax-exclude",
+        metavar="pattern",
+        action=PaxFilterAction,
+        help="Exclude pax header matching the given globbing pattern. "
+        "This option can be specified multiple times.",
+    )
+    parser.add_argument(
+        "--pax-include",
+        metavar="pattern",
+        action=PaxFilterAction,
+        help="Re-include a pax header after a previous exclusion. "
+        "This option can be specified multiple times.",
+    )
+    parser.add_argument(
+        "--type-exclude",
+        metavar="type",
+        action=TypeFilterAction,
+        help="Exclude certain member types by their type. Choose types either "
+        "by their name (REGTYPE, LNKTYPE, SYMTYPE, CHRTYPE, BLKTYPE, DIRTYPE, "
+        "FIFOTYPE) or by their tar format flag values (0-6, respectively). "
+        "This option can be specified multiple times.",
+    )
+    parser.add_argument(
+        "--transform",
+        "--xform",
+        metavar="EXPRESSION",
+        action=TransformAction,
+        help="Use sed replace EXPRESSION to transform file names. "
+        "This option can be specified multiple times.",
+    )
+    parser.add_argument(
+        "--strip-components",
+        metavar="NUMBER",
+        type=int,
+        help="Strip NUMBER leading components from file names",
+    )
+    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()
+    if (
+        not hasattr(args, "pathfilter")
+        and not hasattr(args, "paxfilter")
+        and not hasattr(args, "typefilter")
+        and not hasattr(args, "strip_components")
+    ):
+        from shutil import copyfileobj
+
+        copyfileobj(sys.stdin.buffer, sys.stdout.buffer)
+        exit()
+
+    # same logic as in dpkg/src/filters.c/filter_should_skip()
+    prefix_prog = re.compile(r"^([^*?[\\]*).*")
+
+    def path_filter_should_skip(member):
+        skip = False
+        if not hasattr(args, "pathfilter"):
+            return False
+        for t, r in args.pathfilter:
+            if r.match(member.name[1:]) is not None:
+                if t == "path_include":
+                    skip = False
+                else:
+                    skip = True
+        if skip and (member.isdir() or member.issym()):
+            for t, r in args.pathfilter:
+                if t != "path_include":
+                    continue
+                prefix = prefix_prog.sub(r"\1", r.pattern)
+                prefix = prefix.rstrip("/")
+                if member.name[1:].startswith(prefix):
+                    return False
+        return skip
+
+    def pax_filter_should_skip(header):
+        if not hasattr(args, "paxfilter"):
+            return False
+        skip = False
+        for t, r in args.paxfilter:
+            if r.match(header) is None:
+                continue
+            if t == "pax_include":
+                skip = False
+            else:
+                skip = True
+        return skip
+
+    def type_filter_should_skip(member):
+        if not hasattr(args, "typefilter"):
+            return False
+        for t in args.typefilter:
+            if member.type == t:
+                return True
+        return False
+
+    # starting with Python 3.8, the default format became PAX_FORMAT but we
+    # are still explicit here in case of future changes.
+    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 path_filter_should_skip(member):
+                continue
+            if type_filter_should_skip(member):
+                continue
+            if args.strip_components:
+                comps = member.name.split("/")
+                # just as with GNU tar, archive members with less or equal
+                # number of components are not passed through at all
+                if len(comps) <= args.strip_components:
+                    continue
+                member.name = "/".join(comps[args.strip_components :])
+            member.pax_headers = {
+                k: v
+                for k, v in member.pax_headers.items()
+                if not pax_filter_should_skip(k)
+            }
+            if args.idshift:
+                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 hasattr(args, "trans"):
+                for r, s in args.trans:
+                    member.name = r.sub(s, member.name)
+            if member.isfile():
+                with in_tar.extractfile(member) as file:
+                    out_tar.addfile(member, file)
+            else:
+                out_tar.addfile(member)
+
+
+if __name__ == "__main__":
+    main()