Issue #18473: Fixed 2to3 and 3to2 compatible pickle mappings.

Fixed ambigious reverse mappings.  Added many new mappings.  Import mapping
is no longer applied to modules already mapped with full name mapping.

Added tests for compatible pickling and unpickling and for consistency of
_compat_pickle mappings.

6 files changed, 326 insertions, 30 deletions

diff --git a/Lib/_compat_pickle.py b/Lib/_compat_pickle.py
index 978c01e8ef..b1f15a77ca 100644
--- a/Lib/_compat_pickle.py
+++ b/Lib/_compat_pickle.py
@@ -6,18 +6,13 @@
 # lib2to3 and use the mapping defined there, because lib2to3 uses pickle.
 # Thus, this could cause the module to be imported recursively.
 IMPORT_MAPPING = {
-    'StringIO':  'io',
-    'cStringIO': 'io',
-    'cPickle': 'pickle',
     '__builtin__' : 'builtins',
     'copy_reg': 'copyreg',
     'Queue': 'queue',
     'SocketServer': 'socketserver',
     'ConfigParser': 'configparser',
     'repr': 'reprlib',
-    'FileDialog': 'tkinter.filedialog',
     'tkFileDialog': 'tkinter.filedialog',
-    'SimpleDialog': 'tkinter.simpledialog',
     'tkSimpleDialog': 'tkinter.simpledialog',
     'tkColorChooser': 'tkinter.colorchooser',
     'tkCommonDialog': 'tkinter.commondialog',
@@ -39,7 +34,6 @@ IMPORT_MAPPING = {
     'dbm': 'dbm.ndbm',
     'gdbm': 'dbm.gnu',
     'xmlrpclib': 'xmlrpc.client',
-    'DocXMLRPCServer': 'xmlrpc.server',
     'SimpleXMLRPCServer': 'xmlrpc.server',
     'httplib': 'http.client',
     'htmlentitydefs' : 'html.entities',
@@ -47,16 +41,13 @@ IMPORT_MAPPING = {
     'Cookie': 'http.cookies',
     'cookielib': 'http.cookiejar',
     'BaseHTTPServer': 'http.server',
-    'SimpleHTTPServer': 'http.server',
-    'CGIHTTPServer': 'http.server',
     'test.test_support': 'test.support',
     'commands': 'subprocess',
-    'UserString' : 'collections',
-    'UserList' : 'collections',
     'urlparse' : 'urllib.parse',
     'robotparser' : 'urllib.robotparser',
-    'whichdb': 'dbm',
-    'anydbm': 'dbm'
+    'urllib2': 'urllib.request',
+    'anydbm': 'dbm',
+    '_abcoll' : 'collections.abc',
 }
 
 
@@ -68,12 +59,35 @@ NAME_MAPPING = {
     ('__builtin__', 'reduce'):     ('functools', 'reduce'),
     ('__builtin__', 'intern'):     ('sys', 'intern'),
     ('__builtin__', 'unichr'):     ('builtins', 'chr'),
-    ('__builtin__', 'basestring'): ('builtins', 'str'),
+    ('__builtin__', 'unicode'):    ('builtins', 'str'),
     ('__builtin__', 'long'):       ('builtins', 'int'),
     ('itertools', 'izip'):         ('builtins', 'zip'),
     ('itertools', 'imap'):         ('builtins', 'map'),
     ('itertools', 'ifilter'):      ('builtins', 'filter'),
     ('itertools', 'ifilterfalse'): ('itertools', 'filterfalse'),
+    ('itertools', 'izip_longest'): ('itertools', 'zip_longest'),
+    ('UserDict', 'IterableUserDict'): ('collections', 'UserDict'),
+    ('UserList', 'UserList'): ('collections', 'UserList'),
+    ('UserString', 'UserString'): ('collections', 'UserString'),
+    ('whichdb', 'whichdb'): ('dbm', 'whichdb'),
+    ('_socket', 'fromfd'): ('socket', 'fromfd'),
+    ('_multiprocessing', 'Connection'): ('multiprocessing.connection', 'Connection'),
+    ('multiprocessing.process', 'Process'): ('multiprocessing.context', 'Process'),
+    ('multiprocessing.forking', 'Popen'): ('multiprocessing.popen_fork', 'Popen'),
+    ('urllib', 'ContentTooShortError'): ('urllib.error', 'ContentTooShortError'),
+    ('urllib', 'getproxies'): ('urllib.request', 'getproxies'),
+    ('urllib', 'pathname2url'): ('urllib.request', 'pathname2url'),
+    ('urllib', 'quote_plus'): ('urllib.parse', 'quote_plus'),
+    ('urllib', 'quote'): ('urllib.parse', 'quote'),
+    ('urllib', 'unquote_plus'): ('urllib.parse', 'unquote_plus'),
+    ('urllib', 'unquote'): ('urllib.parse', 'unquote'),
+    ('urllib', 'url2pathname'): ('urllib.request', 'url2pathname'),
+    ('urllib', 'urlcleanup'): ('urllib.request', 'urlcleanup'),
+    ('urllib', 'urlencode'): ('urllib.parse', 'urlencode'),
+    ('urllib', 'urlopen'): ('urllib.request', 'urlopen'),
+    ('urllib', 'urlretrieve'): ('urllib.request', 'urlretrieve'),
+    ('urllib2', 'HTTPError'): ('urllib.error', 'HTTPError'),
+    ('urllib2', 'URLError'): ('urllib.error', 'URLError'),
 }
 
 PYTHON2_EXCEPTIONS = (
@@ -130,8 +144,87 @@ PYTHON2_EXCEPTIONS = (
 for excname in PYTHON2_EXCEPTIONS:
     NAME_MAPPING[("exceptions", excname)] = ("builtins", excname)
 
-NAME_MAPPING[("exceptions", "StandardError")] = ("builtins", "Exception")
+MULTIPROCESSING_EXCEPTIONS = (
+    'AuthenticationError',
+    'BufferTooShort',
+    'ProcessError',
+    'TimeoutError',
+)
+
+for excname in MULTIPROCESSING_EXCEPTIONS:
+    NAME_MAPPING[("multiprocessing", excname)] = ("multiprocessing.context", excname)
 
 # Same, but for 3.x to 2.x
 REVERSE_IMPORT_MAPPING = dict((v, k) for (k, v) in IMPORT_MAPPING.items())
+assert len(REVERSE_IMPORT_MAPPING) == len(IMPORT_MAPPING)
 REVERSE_NAME_MAPPING = dict((v, k) for (k, v) in NAME_MAPPING.items())
+assert len(REVERSE_NAME_MAPPING) == len(NAME_MAPPING)
+
+# Non-mutual mappings.
+
+IMPORT_MAPPING.update({
+    'cPickle': 'pickle',
+    '_elementtree': 'xml.etree.ElementTree',
+    'FileDialog': 'tkinter.filedialog',
+    'SimpleDialog': 'tkinter.simpledialog',
+    'DocXMLRPCServer': 'xmlrpc.server',
+    'SimpleHTTPServer': 'http.server',
+    'CGIHTTPServer': 'http.server',
+})
+
+REVERSE_IMPORT_MAPPING.update({
+    '_bz2': 'bz2',
+    '_dbm': 'dbm',
+    '_functools': 'functools',
+    '_gdbm': 'gdbm',
+    '_pickle': 'pickle',
+})
+
+NAME_MAPPING.update({
+    ('__builtin__', 'basestring'): ('builtins', 'str'),
+    ('exceptions', 'StandardError'): ('builtins', 'Exception'),
+    ('UserDict', 'UserDict'): ('collections', 'UserDict'),
+    ('socket', '_socketobject'): ('socket', 'SocketType'),
+})
+
+REVERSE_NAME_MAPPING.update({
+    ('_functools', 'reduce'): ('__builtin__', 'reduce'),
+    ('tkinter.filedialog', 'FileDialog'): ('FileDialog', 'FileDialog'),
+    ('tkinter.filedialog', 'LoadFileDialog'): ('FileDialog', 'LoadFileDialog'),
+    ('tkinter.filedialog', 'SaveFileDialog'): ('FileDialog', 'SaveFileDialog'),
+    ('tkinter.simpledialog', 'SimpleDialog'): ('SimpleDialog', 'SimpleDialog'),
+    ('xmlrpc.server', 'ServerHTMLDoc'): ('DocXMLRPCServer', 'ServerHTMLDoc'),
+    ('xmlrpc.server', 'XMLRPCDocGenerator'):
+        ('DocXMLRPCServer', 'XMLRPCDocGenerator'),
+    ('xmlrpc.server', 'DocXMLRPCRequestHandler'):
+        ('DocXMLRPCServer', 'DocXMLRPCRequestHandler'),
+    ('xmlrpc.server', 'DocXMLRPCServer'):
+        ('DocXMLRPCServer', 'DocXMLRPCServer'),
+    ('xmlrpc.server', 'DocCGIXMLRPCRequestHandler'):
+        ('DocXMLRPCServer', 'DocCGIXMLRPCRequestHandler'),
+    ('http.server', 'SimpleHTTPRequestHandler'):
+        ('SimpleHTTPServer', 'SimpleHTTPRequestHandler'),
+    ('http.server', 'CGIHTTPRequestHandler'):
+        ('CGIHTTPServer', 'CGIHTTPRequestHandler'),
+    ('_socket', 'socket'): ('socket', '_socketobject'),
+})
+
+PYTHON3_OSERROR_EXCEPTIONS = (
+    'BrokenPipeError',
+    'ChildProcessError',
+    'ConnectionAbortedError',
+    'ConnectionError',
+    'ConnectionRefusedError',
+    'ConnectionResetError',
+    'FileExistsError',
+    'FileNotFoundError',
+    'InterruptedError',
+    'IsADirectoryError',
+    'NotADirectoryError',
+    'PermissionError',
+    'ProcessLookupError',
+    'TimeoutError',
+)
+
+for excname in PYTHON3_OSERROR_EXCEPTIONS:
+    REVERSE_NAME_MAPPING[('builtins', excname)] = ('exceptions', 'OSError')
diff --git a/Lib/pickle.py b/Lib/pickle.py
index e38ecac824..67382aee92 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -944,7 +944,7 @@ class _Pickler:
                 r_import_mapping = _compat_pickle.REVERSE_IMPORT_MAPPING
                 if (module_name, name) in r_name_mapping:
                     module_name, name = r_name_mapping[(module_name, name)]
-                if module_name in r_import_mapping:
+                elif module_name in r_import_mapping:
                     module_name = r_import_mapping[module_name]
             try:
                 write(GLOBAL + bytes(module_name, "ascii") + b'\n' +
@@ -1370,7 +1370,7 @@ class _Unpickler:
         if self.proto < 3 and self.fix_imports:
             if (module, name) in _compat_pickle.NAME_MAPPING:
                 module, name = _compat_pickle.NAME_MAPPING[(module, name)]
-            if module in _compat_pickle.IMPORT_MAPPING:
+            elif module in _compat_pickle.IMPORT_MAPPING:
                 module = _compat_pickle.IMPORT_MAPPING[module]
         __import__(module, level=0)
         return _getattribute(sys.modules[module], name,
diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
index 55205d10d5..2c496d0959 100644
--- a/Lib/test/pickletester.py
+++ b/Lib/test/pickletester.py
@@ -1,8 +1,10 @@
+import collections
 import copyreg
+import dbm
 import io
+import functools
 import pickle
 import pickletools
-import random
 import struct
 import sys
 import unittest
@@ -1645,6 +1647,51 @@ class AbstractPickleTests(unittest.TestCase):
                     unpickled = self.loads(self.dumps(method, proto))
                     self.assertEqual(method(*args), unpickled(*args))
 
+    def test_compat_pickle(self):
+        tests = [
+            (range(1, 7), '__builtin__', 'xrange'),
+            (map(int, '123'), 'itertools', 'imap'),
+            (functools.reduce, '__builtin__', 'reduce'),
+            (dbm.whichdb, 'whichdb', 'whichdb'),
+            (Exception(), 'exceptions', 'Exception'),
+            (collections.UserDict(), 'UserDict', 'IterableUserDict'),
+            (collections.UserList(), 'UserList', 'UserList'),
+            (collections.defaultdict(), 'collections', 'defaultdict'),
+        ]
+        for val, mod, name in tests:
+            for proto in range(3):
+                with self.subTest(type=type(val), proto=proto):
+                    pickled = self.dumps(val, proto)
+                    self.assertIn(('c%s\n%s' % (mod, name)).encode(), pickled)
+                    self.assertIs(type(self.loads(pickled)), type(val))
+
+    def test_compat_unpickle(self):
+        # xrange(1, 7)
+        pickled = b'\x80\x02c__builtin__\nxrange\nK\x01K\x07K\x01\x87R.'
+        unpickled = self.loads(pickled)
+        self.assertIs(type(unpickled), range)
+        self.assertEqual(unpickled, range(1, 7))
+        self.assertEqual(list(unpickled), [1, 2, 3, 4, 5, 6])
+        # reduce
+        pickled = b'\x80\x02c__builtin__\nreduce\n.'
+        self.assertIs(self.loads(pickled), functools.reduce)
+        # whichdb.whichdb
+        pickled = b'\x80\x02cwhichdb\nwhichdb\n.'
+        self.assertIs(self.loads(pickled), dbm.whichdb)
+        # Exception(), StandardError()
+        for name in (b'Exception', b'StandardError'):
+            pickled = (b'\x80\x02cexceptions\n' + name + b'\nU\x03ugh\x85R.')
+            unpickled = self.loads(pickled)
+            self.assertIs(type(unpickled), Exception)
+            self.assertEqual(str(unpickled), 'ugh')
+        # UserDict.UserDict({1: 2}), UserDict.IterableUserDict({1: 2})
+        for name in (b'UserDict', b'IterableUserDict'):
+            pickled = (b'\x80\x02(cUserDict\n' + name +
+                       b'\no}U\x04data}K\x01K\x02ssb.')
+            unpickled = self.loads(pickled)
+            self.assertIs(type(unpickled), collections.UserDict)
+            self.assertEqual(unpickled, collections.UserDict({1: 2}))
+
 
 class BigmemPickleTests(unittest.TestCase):
 
diff --git a/Lib/test/test_pickle.py b/Lib/test/test_pickle.py
index e1a88b6b58..0159b185b7 100644
--- a/Lib/test/test_pickle.py
+++ b/Lib/test/test_pickle.py
@@ -1,3 +1,6 @@
+from _compat_pickle import (IMPORT_MAPPING, REVERSE_IMPORT_MAPPING,
+                            NAME_MAPPING, REVERSE_NAME_MAPPING)
+import builtins
 import pickle
 import io
 import collections
@@ -207,9 +210,156 @@ if has_c_implementation:
             check(u, stdsize + 32 * P + 2 + 1)
 
 
+ALT_IMPORT_MAPPING = {
+    ('_elementtree', 'xml.etree.ElementTree'),
+    ('cPickle', 'pickle'),
+}
+
+ALT_NAME_MAPPING = {
+    ('__builtin__', 'basestring', 'builtins', 'str'),
+    ('exceptions', 'StandardError', 'builtins', 'Exception'),
+    ('UserDict', 'UserDict', 'collections', 'UserDict'),
+    ('socket', '_socketobject', 'socket', 'SocketType'),
+}
+
+def mapping(module, name):
+    if (module, name) in NAME_MAPPING:
+        module, name = NAME_MAPPING[(module, name)]
+    elif module in IMPORT_MAPPING:
+        module = IMPORT_MAPPING[module]
+    return module, name
+
+def reverse_mapping(module, name):
+    if (module, name) in REVERSE_NAME_MAPPING:
+        module, name = REVERSE_NAME_MAPPING[(module, name)]
+    elif module in REVERSE_IMPORT_MAPPING:
+        module = REVERSE_IMPORT_MAPPING[module]
+    return module, name
+
+def getmodule(module):
+    try:
+        return sys.modules[module]
+    except KeyError:
+        __import__(module)
+        return sys.modules[module]
+
+def getattribute(module, name):
+    obj = getmodule(module)
+    for n in name.split('.'):
+        obj = getattr(obj, n)
+    return obj
+
+def get_exceptions(mod):
+    for name in dir(mod):
+        attr = getattr(mod, name)
+        if isinstance(attr, type) and issubclass(attr, BaseException):
+            yield name, attr
+
+class CompatPickleTests(unittest.TestCase):
+    def test_import(self):
+        modules = set(IMPORT_MAPPING.values())
+        modules |= set(REVERSE_IMPORT_MAPPING)
+        modules |= {module for module, name in REVERSE_NAME_MAPPING}
+        modules |= {module for module, name in NAME_MAPPING.values()}
+        for module in modules:
+            try:
+                getmodule(module)
+            except ImportError as exc:
+                if support.verbose:
+                    print(exc)
+
+    def test_import_mapping(self):
+        for module3, module2 in REVERSE_IMPORT_MAPPING.items():
+            with self.subTest((module3, module2)):
+                try:
+                    getmodule(module3)
+                except ImportError as exc:
+                    if support.verbose:
+                        print(exc)
+                if module3[:1] != '_':
+                    self.assertIn(module2, IMPORT_MAPPING)
+                    self.assertEqual(IMPORT_MAPPING[module2], module3)
+
+    def test_name_mapping(self):
+        for (module3, name3), (module2, name2) in REVERSE_NAME_MAPPING.items():
+            with self.subTest(((module3, name3), (module2, name2))):
+                attr = getattribute(module3, name3)
+                if (module2, name2) == ('exceptions', 'OSError'):
+                    self.assertTrue(issubclass(attr, OSError))
+                else:
+                    module, name = mapping(module2, name2)
+                    if module3[:1] != '_':
+                        self.assertEqual((module, name), (module3, name3))
+                    self.assertEqual(getattribute(module, name), attr)
+
+    def test_reverse_import_mapping(self):
+        for module2, module3 in IMPORT_MAPPING.items():
+            with self.subTest((module2, module3)):
+                try:
+                    getmodule(module3)
+                except ImportError as exc:
+                    if support.verbose:
+                        print(exc)
+                if ((module2, module3) not in ALT_IMPORT_MAPPING and
+                    REVERSE_IMPORT_MAPPING.get(module3, None) != module2):
+                    for (m3, n3), (m2, n2) in REVERSE_NAME_MAPPING.items():
+                        if (module3, module2) == (m3, m2):
+                            break
+                    else:
+                        self.fail('No reverse mapping from %r to %r' %
+                                  (module3, module2))
+                module = REVERSE_IMPORT_MAPPING.get(module3, module3)
+                module = IMPORT_MAPPING.get(module, module)
+                self.assertEqual(module, module3)
+
+    def test_reverse_name_mapping(self):
+        for (module2, name2), (module3, name3) in NAME_MAPPING.items():
+            with self.subTest(((module2, name2), (module3, name3))):
+                attr = getattribute(module3, name3)
+                module, name = reverse_mapping(module3, name3)
+                if (module2, name2, module3, name3) not in ALT_NAME_MAPPING:
+                    self.assertEqual((module, name), (module2, name2))
+                module, name = mapping(module, name)
+                self.assertEqual((module, name), (module3, name3))
+
+    def test_exceptions(self):
+        self.assertEqual(mapping('exceptions', 'StandardError'),
+                         ('builtins', 'Exception'))
+        self.assertEqual(mapping('exceptions', 'Exception'),
+                         ('builtins', 'Exception'))
+        self.assertEqual(reverse_mapping('builtins', 'Exception'),
+                         ('exceptions', 'Exception'))
+        self.assertEqual(mapping('exceptions', 'OSError'),
+                         ('builtins', 'OSError'))
+        self.assertEqual(reverse_mapping('builtins', 'OSError'),
+                         ('exceptions', 'OSError'))
+
+        for name, exc in get_exceptions(builtins):
+            with self.subTest(name):
+                if exc in (BlockingIOError, ResourceWarning):
+                    continue
+                if exc is not OSError and issubclass(exc, OSError):
+                    self.assertEqual(reverse_mapping('builtins', name),
+                                     ('exceptions', 'OSError'))
+                else:
+                    self.assertEqual(reverse_mapping('builtins', name),
+                                     ('exceptions', name))
+                    self.assertEqual(mapping('exceptions', name),
+                                     ('builtins', name))
+
+        import multiprocessing.context
+        for name, exc in get_exceptions(multiprocessing.context):
+            with self.subTest(name):
+                self.assertEqual(reverse_mapping('multiprocessing.context', name),
+                                 ('multiprocessing', name))
+                self.assertEqual(mapping('multiprocessing', name),
+                                 ('multiprocessing.context', name))
+
+
 def test_main():
     tests = [PickleTests, PyPicklerTests, PyPersPicklerTests,
-             PyDispatchTableTests, PyChainDispatchTableTests]
+             PyDispatchTableTests, PyChainDispatchTableTests,
+             CompatPickleTests]
     if has_c_implementation:
         tests.extend([CPicklerTests, CPersPicklerTests,
                       CDumpPickle_LoadPickle, DumpPickle_CLoadPickle,
diff --git a/Misc/NEWS b/Misc/NEWS
index ebac8d52f6..cd72813dad 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -21,6 +21,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #18473: Fixed 2to3 and 3to2 compatible pickle mappings.  Fixed
+  ambigious reverse mappings.  Added many new mappings.  Import mapping is no
+  longer applied to modules already mapped with full name mapping.
+
 - Issue #23745: The new email header parser now handles duplicate MIME
   parameter names without error, similar to how get_param behaves.
 
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index 10eb513149..435cbaea9d 100644
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -3026,6 +3026,7 @@ fix_imports(PyObject **module_name, PyObject **global_name)
         Py_INCREF(fixed_global_name);
         *module_name = fixed_module_name;
         *global_name = fixed_global_name;
+        return 0;
     }
     else if (PyErr_Occurred()) {
         return -1;
@@ -6278,20 +6279,21 @@ _pickle_Unpickler_find_class_impl(UnpicklerObject *self, PyObject *module_name,
         else if (PyErr_Occurred()) {
             return NULL;
         }
-
-        /* Check if the module was renamed. */
-        item = PyDict_GetItemWithError(st->import_mapping_2to3, module_name);
-        if (item) {
-            if (!PyUnicode_Check(item)) {
-                PyErr_Format(PyExc_RuntimeError,
-                             "_compat_pickle.IMPORT_MAPPING values should be "
-                             "strings, not %.200s", Py_TYPE(item)->tp_name);
+        else {
+            /* Check if the module was renamed. */
+            item = PyDict_GetItemWithError(st->import_mapping_2to3, module_name);
+            if (item) {
+                if (!PyUnicode_Check(item)) {
+                    PyErr_Format(PyExc_RuntimeError,
+                                "_compat_pickle.IMPORT_MAPPING values should be "
+                                "strings, not %.200s", Py_TYPE(item)->tp_name);
+                    return NULL;
+                }
+                module_name = item;
+            }
+            else if (PyErr_Occurred()) {
                 return NULL;
             }
-            module_name = item;
-        }
-        else if (PyErr_Occurred()) {
-            return NULL;
         }
     }