bpo-39430: Fix race condition in lazy imports in tarfile. (GH-18161)
Use `from ... import ...` to ensure module is fully loaded before accessing its attributes.
(cherry picked from commit 9017e0bd5e124ae6d2ed94b9e9cacb2e86270980)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 2c06f91..d31b9cb 100755
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -1655,13 +1655,12 @@
raise ValueError("mode must be 'r', 'w' or 'x'")
try:
- import gzip
- gzip.GzipFile
- except (ImportError, AttributeError):
+ from gzip import GzipFile
+ except ImportError:
raise CompressionError("gzip module is not available")
try:
- fileobj = gzip.GzipFile(name, mode + "b", compresslevel, fileobj)
+ fileobj = GzipFile(name, mode + "b", compresslevel, fileobj)
except OSError:
if fileobj is not None and mode == 'r':
raise ReadError("not a gzip file")
@@ -1689,12 +1688,11 @@
raise ValueError("mode must be 'r', 'w' or 'x'")
try:
- import bz2
+ from bz2 import BZ2File
except ImportError:
raise CompressionError("bz2 module is not available")
- fileobj = bz2.BZ2File(fileobj or name, mode,
- compresslevel=compresslevel)
+ fileobj = BZ2File(fileobj or name, mode, compresslevel=compresslevel)
try:
t = cls.taropen(name, mode, fileobj, **kwargs)
@@ -1718,15 +1716,15 @@
raise ValueError("mode must be 'r', 'w' or 'x'")
try:
- import lzma
+ from lzma import LZMAFile, LZMAError
except ImportError:
raise CompressionError("lzma module is not available")
- fileobj = lzma.LZMAFile(fileobj or name, mode, preset=preset)
+ fileobj = LZMAFile(fileobj or name, mode, preset=preset)
try:
t = cls.taropen(name, mode, fileobj, **kwargs)
- except (lzma.LZMAError, EOFError):
+ except (LZMAError, EOFError):
fileobj.close()
if mode == 'r':
raise ReadError("not an lzma file")