Fix for bug #661136

Lesson learned: kids should not be allowed to use API's starting
with an underscore :-/
zipimport in 2.3a1 is even more broken than I thought: I attemped
to _PyString_Resize a string created by PyString_FromStringAndSize,
which fails for strings with length 0 or 1 since the latter returns
an interned string in those cases. This would cause a SystemError
with empty source files (and no matching pyc) in the zip archive.
I rewrote the offending code to simply allocate a new buffer and
avoid _PyString_Resize altogether.
Added a test that would've caught the problem.

Lib/test/test_zipimport.py

@@ -56,9 +56,10 @@ class UncompressedZipImportTestCase(ImportHooksBaseTestCase):
 
             mod = __import__(".".join(modules), globals(), locals(),
                              ["__dummy__"])
-            file = mod.get_file()
-            self.assertEquals(file, os.path.join(TEMP_ZIP,
-                              os.sep.join(modules) + expected_ext))
+            if expected_ext:
+                file = mod.get_file()
+                self.assertEquals(file, os.path.join(TEMP_ZIP,
+                                  os.sep.join(modules) + expected_ext))
         finally:
             z.close()
             os.remove(TEMP_ZIP)
@@ -101,6 +102,10 @@ class UncompressedZipImportTestCase(ImportHooksBaseTestCase):
                  TESTMOD + pyc_ext: (NOW, test_pyc)}
         self.doTest(pyc_ext, files, TESTMOD)
 
+    def testEmptyPy(self):
+        files = {TESTMOD + ".py": (NOW, "")}
+        self.doTest(None, files, TESTMOD)
+
     def testBadMagic(self):
         # make pyc magic word invalid, forcing loading from .py
         m0 = ord(test_pyc[0])

Modules/zipimport.c

@@ -906,7 +906,8 @@ unmarshal_code(char *pathname, PyObject *data, time_t mtime)
 		return Py_None;  /* signal caller to try alternative */
 	}
 
-	if (mtime != 0 && !eq_mtime(get_long((unsigned char *)buf + 4), mtime)) {
+	if (mtime != 0 && !eq_mtime(get_long((unsigned char *)buf + 4),
+				    mtime)) {
 		if (Py_VerboseFlag)
 			PySys_WriteStderr("# %s has bad mtime\n",
 					  pathname);
@@ -934,23 +935,23 @@ unmarshal_code(char *pathname, PyObject *data, time_t mtime)
 static PyObject *
 normalize_line_endings(PyObject *source)
 {
-	char *q, *p = PyString_AsString(source);
-	int length = PyString_Size(source) + 1;
+	char *buf, *q, *p = PyString_AsString(source);
 	PyObject *fixed_source;
 
-	fixed_source = PyString_FromStringAndSize(p, length);
-	if (fixed_source == NULL)
+	/* one char extra for trailing \n and one for terminating \0 */
+	buf = PyMem_Malloc(PyString_Size(source) + 2);
+	if (buf == NULL) {
+		PyErr_SetString(PyExc_MemoryError,
+				"zipimport: no memory to allocate "
+				"source buffer");
 		return NULL;
-
-	q = PyString_AsString(fixed_source);
+	}
 	/* replace "\r\n?" by "\n" */
-	for (;;) {
+	for (q = buf;;) {
 		if (*p == '\r') {
 			*q++ = '\n';
-			if (*(p + 1) == '\n') {
+			if (*(p + 1) == '\n')
 				p++;
-				length--;
-			}
 		}
 		else
 			*q++ = *p;
@@ -960,7 +961,8 @@ normalize_line_endings(PyObject *source)
 	}
 	*q++ = '\n';  /* add trailing \n */
 	*q = '\0';
-	_PyString_Resize(&fixed_source, length);
+	fixed_source = PyString_FromString(buf);
+	PyMem_Free(buf);
 	return fixed_source;
 }