Commit 632a4082 authored by Chris Lamb's avatar Chris Lamb 💬

Extract archive members using an auto-incrementing integer, avoiding the need...

Extract archive members using an auto-incrementing integer, avoiding the need to sanitise filenames. (Closes: #854723)
Signed-off-by: Chris Lamb's avatarChris Lamb <lamby@debian.org>
parent b468a284
......@@ -23,6 +23,7 @@ import os.path
import ctypes
import logging
import libarchive
import collections
from diffoscope.tempfiles import get_temporary_directory
......@@ -168,11 +169,11 @@ class LibarchiveContainer(Archive):
def get_member_names(self):
self.ensure_unpacked()
return self._member_names
return self._members.keys()
def extract(self, member_name, dest_dir):
self.ensure_unpacked()
return os.path.join(self._unpacked, member_name)
return self._members[member_name]
def get_member(self, member_name):
with libarchive.file_reader(self.source.path) as archive:
......@@ -197,39 +198,25 @@ class LibarchiveContainer(Archive):
return LibarchiveMember(self, entry)
def ensure_unpacked(self):
if hasattr(self, '_unpacked'):
if hasattr(self, '_members'):
return
self._unpacked = get_temporary_directory().name
self._member_names = []
tmpdir = get_temporary_directory().name
self._members = collections.OrderedDict()
logger.debug("Extracting %s to %s", self.source.path, self._unpacked)
logger.debug("Extracting %s to %s", self.source.path, tmpdir)
with libarchive.file_reader(self.source.path) as archive:
for entry in archive:
self._member_names.append(entry.pathname)
for idx, entry in enumerate(archive):
# Maintain a mapping of archive path to the extracted path,
# avoiding the need to sanitise filenames.
dst = os.path.join(tmpdir, '{}'.format(idx))
self._members[entry.pathname] = dst
if entry.isdir:
continue
# All extracted locations must be underneath self._unpacked
force_prefix = os.path.join(self._unpacked, "")
# Try to pick a safe and reasonable candidate name
candidate_name = os.path.normpath(entry.pathname.rstrip('/' + os.sep))
if os.path.isabs(candidate_name):
candidate_name = os.path.relpath(candidate_name, os.path.join(os.path.sep))
dst = os.path.normpath(os.path.join(self._unpacked, candidate_name))
if not dst.startswith(force_prefix):
logger.warn("Skipping member because we could not make a safe name to extract it to: '%s'",
entry.pathname)
continue
# TODO: need to fix reading these cleaned members. currently
# reading will still try to use the uncleaned name.
#logging.debug("Extracting %s to %s", entry.pathname, dst)
os.makedirs(os.path.dirname(dst), exist_ok=True)
logger.debug("Extracting %s to %s", entry.pathname, dst)
with open(dst, 'wb') as f:
for block in entry.get_blocks():
......@@ -237,5 +224,5 @@ class LibarchiveContainer(Archive):
logger.debug(
"Extracted %d entries from %s to %s",
len(self._member_names), self.source.path, self._unpacked,
len(self._members), self.source.path, tmpdir,
)
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