Issue #1180193: When importing a module from a .pyc (or .pyo) file with

an existing .py counterpart, override the co_filename attributes of all
code objects if the original filename is obsolete (which can happen if the
file has been renamed, moved, or if it is accessed through different paths).
Patch by Ziga Seilnacht and Jean-Paul Calderone.

Lib/test/test_import.py

@@ -5,6 +5,7 @@ import shutil
 import sys
 import py_compile
 import warnings
+import marshal
 from test.test_support import unlink, TESTFN, unload, run_unittest, check_warnings
 
 
@@ -231,6 +232,97 @@ class ImportTest(unittest.TestCase):
         else:
             self.fail("import by path didn't raise an exception")
 
+class TestPycRewriting(unittest.TestCase):
+    # Test that the `co_filename` attribute on code objects always points
+    # to the right file, even when various things happen (e.g. both the .py
+    # and the .pyc file are renamed).
+
+    module_name = "unlikely_module_name"
+    module_source = """
+import sys
+code_filename = sys._getframe().f_code.co_filename
+module_filename = __file__
+constant = 1
+def func():
+    pass
+func_filename = func.func_code.co_filename
+"""
+    dir_name = os.path.abspath(TESTFN)
+    file_name = os.path.join(dir_name, module_name) + os.extsep + "py"
+    compiled_name = file_name + ("c" if __debug__ else "o")
+
+    def setUp(self):
+        self.sys_path = sys.path[:]
+        self.orig_module = sys.modules.pop(self.module_name, None)
+        os.mkdir(self.dir_name)
+        with open(self.file_name, "w") as f:
+            f.write(self.module_source)
+        sys.path.insert(0, self.dir_name)
+
+    def tearDown(self):
+        sys.path[:] = self.sys_path
+        if self.orig_module is not None:
+            sys.modules[self.module_name] = self.orig_module
+        else:
+            del sys.modules[self.module_name]
+        for file_name in self.file_name, self.compiled_name:
+            if os.path.exists(file_name):
+                os.remove(file_name)
+        if os.path.exists(self.dir_name):
+            os.rmdir(self.dir_name)
+
+    def import_module(self):
+        ns = globals()
+        __import__(self.module_name, ns, ns)
+        return sys.modules[self.module_name]
+
+    def test_basics(self):
+        mod = self.import_module()
+        self.assertEqual(mod.module_filename, self.file_name)
+        self.assertEqual(mod.code_filename, self.file_name)
+        self.assertEqual(mod.func_filename, self.file_name)
+        del sys.modules[self.module_name]
+        mod = self.import_module()
+        self.assertEqual(mod.module_filename, self.compiled_name)
+        self.assertEqual(mod.code_filename, self.file_name)
+        self.assertEqual(mod.func_filename, self.file_name)
+
+    def test_incorrect_code_name(self):
+        py_compile.compile(self.file_name, dfile="another_module.py")
+        mod = self.import_module()
+        self.assertEqual(mod.module_filename, self.compiled_name)
+        self.assertEqual(mod.code_filename, self.file_name)
+        self.assertEqual(mod.func_filename, self.file_name)
+
+    def test_module_without_source(self):
+        target = "another_module.py"
+        py_compile.compile(self.file_name, dfile=target)
+        os.remove(self.file_name)
+        mod = self.import_module()
+        self.assertEqual(mod.module_filename, self.compiled_name)
+        self.assertEqual(mod.code_filename, target)
+        self.assertEqual(mod.func_filename, target)
+
+    def test_foreign_code(self):
+        py_compile.compile(self.file_name)
+        with open(self.compiled_name, "rb") as f:
+            header = f.read(8)
+            code = marshal.load(f)
+        constants = list(code.co_consts)
+        foreign_code = test_main.func_code
+        pos = constants.index(1)
+        constants[pos] = foreign_code
+        code = type(code)(code.co_argcount, code.co_nlocals, code.co_stacksize,
+                          code.co_flags, code.co_code, tuple(constants),
+                          code.co_names, code.co_varnames, code.co_filename,
+                          code.co_name, code.co_firstlineno, code.co_lnotab,
+                          code.co_freevars, code.co_cellvars)
+        with open(self.compiled_name, "wb") as f:
+            f.write(header)
+            marshal.dump(code, f)
+        mod = self.import_module()
+        self.assertEqual(mod.constant.co_filename, foreign_code.co_filename)
+
 class PathsTests(unittest.TestCase):
     path = TESTFN
 
@@ -297,7 +389,7 @@ class RelativeImport(unittest.TestCase):
         self.assertRaises(ValueError, check_relative)
 
 def test_main(verbose=None):
-    run_unittest(ImportTest, PathsTests, RelativeImport)
+    run_unittest(ImportTest, TestPycRewriting, PathsTests, RelativeImport)
 
 if __name__ == '__main__':
     # test needs to be a package, so we can do relative import

Misc/NEWS

@@ -12,6 +12,12 @@ What's New in Python 2.7 alpha 1
 Core and Builtins
 -----------------
 
+- Issue #1180193: When importing a module from a .pyc (or .pyo) file with
+  an existing .py counterpart, override the co_filename attributes of all
+  code objects if the original filename is obsolete (which can happen if the
+  file has been renamed, moved, or if it is accessed through different paths).
+  Patch by Ziga Seilnacht and Jean-Paul Calderone.
+
 - Issue #4075: Use OutputDebugStringW in Py_FatalError.
 
 - Issue #4797: IOError.filename was not set when _fileio.FileIO failed to open

Python/import.c

@@ -909,6 +909,49 @@ write_compiled_module(PyCodeObject *co, char *cpathname, struct stat *srcstat)
 		PySys_WriteStderr("# wrote %s\n", cpathname);
 }
 
+static void
+update_code_filenames(PyCodeObject *co, PyObject *oldname, PyObject *newname)
+{
+	PyObject *constants, *tmp;
+	Py_ssize_t i, n;
+
+	if (!_PyString_Eq(co->co_filename, oldname))
+		return;
+
+	tmp = co->co_filename;
+	co->co_filename = newname;
+	Py_INCREF(co->co_filename);
+	Py_DECREF(tmp);
+
+	constants = co->co_consts;
+	n = PyTuple_GET_SIZE(constants);
+	for (i = 0; i < n; i++) {
+		tmp = PyTuple_GET_ITEM(constants, i);
+		if (PyCode_Check(tmp))
+			update_code_filenames((PyCodeObject *)tmp,
+					      oldname, newname);
+	}
+}
+
+static int
+update_compiled_module(PyCodeObject *co, char *pathname)
+{
+	PyObject *oldname, *newname;
+
+	if (strcmp(PyString_AsString(co->co_filename), pathname) == 0)
+		return 0;
+
+	newname = PyString_FromString(pathname);
+	if (newname == NULL)
+		return -1;
+
+	oldname = co->co_filename;
+	Py_INCREF(oldname);
+	update_code_filenames(co, oldname, newname);
+	Py_DECREF(oldname);
+	Py_DECREF(newname);
+	return 1;
+}
 
 /* Load a source module from a given file and return its module
    object WITH INCREMENTED REFERENCE COUNT.  If there's a matching
@@ -949,6 +992,8 @@ load_source_module(char *name, char *pathname, FILE *fp)
 		fclose(fpc);
 		if (co == NULL)
 			return NULL;
+		if (update_compiled_module(co, pathname) < 0)
+			return NULL;
 		if (Py_VerboseFlag)
 			PySys_WriteStderr("import %s # precompiled from %s\n",
 				name, cpathname);