1 files changed, 10 insertions, 10 deletions
diff --git a/lib-python/3/tarfile.py b/lib-python/3/tarfile.py
index edd31e96fb..3be5188c8b 100755
--- a/lib-python/3/tarfile.py
+++ b/lib-python/3/tarfile.py
@@ -1233,6 +1233,8 @@ class TarInfo(object):
 
             length, keyword = match.groups()
             length = int(length)
+            if length == 0:
+                raise InvalidHeaderError("invalid header")
             value = buf[match.end(2) + 1:match.start(1) + length - 1]
 
             # Normally, we could just use "utf-8" as the encoding and "strict"
@@ -1629,13 +1631,12 @@ class TarFile(object):
             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")
@@ -1663,12 +1664,11 @@ class TarFile(object):
             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)
@@ -1692,15 +1692,15 @@ class TarFile(object):
             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")