#19395: Raise exception when pickling a (BZ2|LZMA)(Compressor|Decompressor).

The underlying C libraries provide no mechanism for serializing compressor and
decompressor objects, so actually pickling these classes is impractical.
Previously, these objects would be pickled without error, but attempting to use
a deserialized instance would segfault the interpreter.

2 files changed, 19 insertions, 0 deletions

diff --git a/Lib/test/test_bz2.py b/Lib/test/test_bz2.py
index d087cc3ee9..8d93e2d88f 100644
--- a/Lib/test/test_bz2.py
+++ b/Lib/test/test_bz2.py
@@ -5,6 +5,7 @@ from test.support import bigmemtest, _4G
 import unittest
 from io import BytesIO
 import os
+import pickle
 import random
 import subprocess
 import sys
@@ -628,6 +629,11 @@ class BZ2CompressorTest(BaseTest):
         finally:
             data = None
 
+    def testPickle(self):
+        with self.assertRaises(TypeError):
+            pickle.dumps(BZ2Compressor())
+
+
 class BZ2DecompressorTest(BaseTest):
     def test_Constructor(self):
         self.assertRaises(TypeError, BZ2Decompressor, 42)
@@ -679,6 +685,10 @@ class BZ2DecompressorTest(BaseTest):
             compressed = None
             decompressed = None
 
+    def testPickle(self):
+        with self.assertRaises(TypeError):
+            pickle.dumps(BZ2Decompressor())
+
 
 class CompressDecompressTest(BaseTest):
     def testCompress(self):
diff --git a/Lib/test/test_lzma.py b/Lib/test/test_lzma.py
index b6af563300..26d19da5e9 100644
--- a/Lib/test/test_lzma.py
+++ b/Lib/test/test_lzma.py
@@ -1,5 +1,6 @@
 from io import BytesIO, UnsupportedOperation
 import os
+import pickle
 import random
 import unittest
 
@@ -216,6 +217,14 @@ class CompressorDecompressorTestCase(unittest.TestCase):
         finally:
             input = cdata = ddata = None
 
+    # Pickling raises an exception; there's no way to serialize an lzma_stream.
+
+    def test_pickle(self):
+        with self.assertRaises(TypeError):
+            pickle.dumps(LZMACompressor())
+        with self.assertRaises(TypeError):
+            pickle.dumps(LZMADecompressor())
+
 
 class CompressDecompressFunctionTestCase(unittest.TestCase):