[Python-checkins] cpython (3.3): #19395: Raise exception when pickling a (BZ2|LZMA)(Compressor|Decompressor).

[nadeem.vawda]

http://hg.python.org/cpython/rev/be363c1e94fe
changeset:   86704:be363c1e94fe
branch:      3.3
parent:      86699:543c66410547
user:        Nadeem Vawda <nadeem.vawda at gmail.com>
date:        Mon Oct 28 21:35:23 2013 +0100
summary:
  #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.

files:
  Lib/test/test_bz2.py  |  10 ++++++++++
  Lib/test/test_lzma.py |   9 +++++++++
  Misc/NEWS             |   4 ++++
  Modules/_bz2module.c  |  22 ++++++++++++++++++++--
  Modules/_lzmamodule.c |  18 ++++++++++++++++++
  5 files changed, 61 insertions(+), 2 deletions(-)


diff --git a/Lib/test/test_bz2.py b/Lib/test/test_bz2.py
--- a/Lib/test/test_bz2.py
+++ b/Lib/test/test_bz2.py
@@ -5,6 +5,7 @@
 import unittest
 from io import BytesIO
 import os
+import pickle
 import random
 import subprocess
 import sys
@@ -621,6 +622,11 @@
         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)
@@ -672,6 +678,10 @@
             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
--- 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 @@
         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):
 
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -92,6 +92,10 @@
 Library
 -------
 
+- Issue #19395: Raise an exception when attempting to pickle a bz2 or lzma
+  compressor/decompressor object, rather than creating a pickle that would
+  cause a segfault when loaded and used.
+
 - Issue #19227: Try to fix deadlocks caused by re-seeding then OpenSSL
   pseudo-random number generator on fork().
 
diff --git a/Modules/_bz2module.c b/Modules/_bz2module.c
--- a/Modules/_bz2module.c
+++ b/Modules/_bz2module.c
@@ -250,6 +250,14 @@
     return result;
 }
 
+static PyObject *
+BZ2Compressor_getstate(BZ2Compressor *self, PyObject *noargs)
+{
+    PyErr_Format(PyExc_TypeError, "cannot serialize '%s' object",
+                 Py_TYPE(self)->tp_name);
+    return NULL;
+}
+
 static int
 BZ2Compressor_init(BZ2Compressor *self, PyObject *args, PyObject *kwargs)
 {
@@ -298,10 +306,11 @@
 }
 
 static PyMethodDef BZ2Compressor_methods[] = {
-    {"compress", (PyCFunction)BZ2Compressor_compress, METH_VARARGS,
+    {"compress",     (PyCFunction)BZ2Compressor_compress, METH_VARARGS,
      BZ2Compressor_compress__doc__},
-    {"flush",    (PyCFunction)BZ2Compressor_flush,    METH_NOARGS,
+    {"flush",        (PyCFunction)BZ2Compressor_flush,    METH_NOARGS,
      BZ2Compressor_flush__doc__},
+    {"__getstate__", (PyCFunction)BZ2Compressor_getstate, METH_NOARGS},
     {NULL}
 };
 
@@ -452,6 +461,14 @@
     return result;
 }
 
+static PyObject *
+BZ2Decompressor_getstate(BZ2Decompressor *self, PyObject *noargs)
+{
+    PyErr_Format(PyExc_TypeError, "cannot serialize '%s' object",
+                 Py_TYPE(self)->tp_name);
+    return NULL;
+}
+
 static int
 BZ2Decompressor_init(BZ2Decompressor *self, PyObject *args, PyObject *kwargs)
 {
@@ -502,6 +519,7 @@
 static PyMethodDef BZ2Decompressor_methods[] = {
     {"decompress", (PyCFunction)BZ2Decompressor_decompress, METH_VARARGS,
      BZ2Decompressor_decompress__doc__},
+    {"__getstate__", (PyCFunction)BZ2Decompressor_getstate, METH_NOARGS},
     {NULL}
 };
 
diff --git a/Modules/_lzmamodule.c b/Modules/_lzmamodule.c
--- a/Modules/_lzmamodule.c
+++ b/Modules/_lzmamodule.c
@@ -546,6 +546,14 @@
     return result;
 }
 
+static PyObject *
+Compressor_getstate(Compressor *self, PyObject *noargs)
+{
+    PyErr_Format(PyExc_TypeError, "cannot serialize '%s' object",
+                 Py_TYPE(self)->tp_name);
+    return NULL;
+}
+
 static int
 Compressor_init_xz(lzma_stream *lzs, int check, uint32_t preset,
                    PyObject *filterspecs)
@@ -712,6 +720,7 @@
      Compressor_compress_doc},
     {"flush", (PyCFunction)Compressor_flush, METH_NOARGS,
      Compressor_flush_doc},
+    {"__getstate__", (PyCFunction)Compressor_getstate, METH_NOARGS},
     {NULL}
 };
 
@@ -869,6 +878,14 @@
     return result;
 }
 
+static PyObject *
+Decompressor_getstate(Decompressor *self, PyObject *noargs)
+{
+    PyErr_Format(PyExc_TypeError, "cannot serialize '%s' object",
+                 Py_TYPE(self)->tp_name);
+    return NULL;
+}
+
 static int
 Decompressor_init_raw(lzma_stream *lzs, PyObject *filterspecs)
 {
@@ -991,6 +1008,7 @@
 static PyMethodDef Decompressor_methods[] = {
     {"decompress", (PyCFunction)Decompressor_decompress, METH_VARARGS,
      Decompressor_decompress_doc},
+    {"__getstate__", (PyCFunction)Decompressor_getstate, METH_NOARGS},
     {NULL}
 };
 

-- 
Repository URL: http://hg.python.org/cpython