use extractall(filter=) Python 3.12+ feature (#96)

* pass tar_filter to suppress Python warning

* edit changelog

CHANGELOG.md

@@ -1,6 +1,9 @@
 [//]: # (current developments)
 
 * Add Python 3.12 to test matrix.
+* Pass Python `tarfile.extractall(filter="fully_trusted")` in addition to
+  internal filtering, when available, to avoid Python 3.12+ `DeprecationWarning`
+  (#87)
 * Improve umask handling. (#106)
 * Add `transmute_stream(...)` to create `.conda` from `(TarFile, TarInfo)`. (#90)
   iterators, allowing more creative data sources than just `.tar.bz2` inputs.

conda_package_streaming/extract.py

@@ -14,6 +14,7 @@
 from . import exceptions, package_streaming
 
 __all__ = ["extract_stream", "extract"]
+HAS_TAR_FILTER = hasattr(tarfile, "tar_filter")
 
 
 def extract_stream(
@@ -44,7 +45,13 @@ def checked_members():
                 yield member
 
         try:
-            tar_file.extractall(path=dest_dir, members=checked_members())
+            # Drop checked_members() when HAS_TAR_FILTER once we are 100%
+            # certain the stdlib filter maintains same permissions as
+            # checked_members().
+            tar_args = {"path": dest_dir, "members": checked_members()}
+            if HAS_TAR_FILTER:
+                tar_args["filter"] = "fully_trusted"
+            tar_file.extractall(**tar_args)
         except OSError as e:
             if e.errno == ELOOP:
                 raise exceptions.CaseInsensitiveFileSystemError() from e

tests/test_extract.py

@@ -167,7 +167,6 @@ def test_umask(tmp_path, mocker):
         mode,
         mode & stat_check,
     )
-    assert not mode & stat.S_IWGRP, "%o" % mode
 
 
 def test_encoding():