It's unclear whether PyMarshal_XXX() are part of the public or private API.

They're named as if public, so I did a Bad Thing by changing
PyMarshal_ReadObjectFromFile() to suck up the remainder of the file in one
gulp:  anyone who counted on that leaving the file pointer merely at the
end of the next object would be screwed.  So restored
PyMarshal_ReadObjectFromFile() to its earlier state, renamed the new greedy
code to PyMarshal_ReadLastObjectFromFile(), and changed Python internals to
call the latter instead.

Include/marshal.h

@@ -15,6 +15,7 @@ DL_IMPORT(PyObject *) PyMarshal_WriteObjectToString(PyObject *);
 DL_IMPORT(long) PyMarshal_ReadLongFromFile(FILE *);
 DL_IMPORT(int) PyMarshal_ReadShortFromFile(FILE *);
 DL_IMPORT(PyObject *) PyMarshal_ReadObjectFromFile(FILE *);
+DL_IMPORT(PyObject *) PyMarshal_ReadLastObjectFromFile(FILE *);
 DL_IMPORT(PyObject *) PyMarshal_ReadObjectFromString(char *, int);
 
 #ifdef __cplusplus

Python/import.c

@@ -555,7 +555,7 @@ read_compiled_module(char *cpathname, FILE *fp)
 {
 	PyObject *co;
 
-	co = PyMarshal_ReadObjectFromFile(fp);
+	co = PyMarshal_ReadLastObjectFromFile(fp);
 	/* Ugly: rd_object() may return NULL with or without error */
 	if (co == NULL || !PyCode_Check(co)) {
 		if (!PyErr_Occurred())

Python/marshal.c

@@ -631,16 +631,17 @@ getfilesize(FILE *fp)
 /* If we can get the size of the file up-front, and it's reasonably small,
  * read it in one gulp and delegate to ...FromString() instead.  Much quicker
  * than reading a byte at a time from file; speeds .pyc imports.
+ * CAUTION:  since this may read the entire remainder of the file, don't
+ * call it unless you know you're done with the file.
  */
 PyObject *
-PyMarshal_ReadObjectFromFile(FILE *fp)
+PyMarshal_ReadLastObjectFromFile(FILE *fp)
 {
 /* 75% of 2.1's .pyc files can exploit SMALL_FILE_LIMIT.
  * REASONABLE_FILE_LIMIT is by defn something big enough for Tkinter.pyc.
  */
 #define SMALL_FILE_LIMIT (1L << 14)
 #define REASONABLE_FILE_LIMIT (1L << 18)
-	RFILE rf;
 #ifdef HAVE_FSTAT
 	off_t filesize;
 #endif
@@ -668,12 +669,27 @@ PyMarshal_ReadObjectFromFile(FILE *fp)
 
 	}
 #endif
-	rf.fp = fp;
-	return r_object(&rf);
+	/* We don't have fstat, or we do but the file is larger than
+	 * REASONABLE_FILE_LIMIT or malloc failed -- read a byte at a time.
+	 */
+	return PyMarshal_ReadObjectFromFile(fp);
+
 #undef SMALL_FILE_LIMIT
 #undef REASONABLE_FILE_LIMIT
 }
 
+PyObject *
+PyMarshal_ReadObjectFromFile(FILE *fp)
+{
+	RFILE rf;
+	if (PyErr_Occurred()) {
+		fprintf(stderr, "XXX rd_object called with exception set\n");
+		return NULL;
+	}
+	rf.fp = fp;
+	return r_object(&rf);
+}
+
 PyObject *
 PyMarshal_ReadObjectFromString(char *str, int len)
 {

Python/pythonrun.c

@@ -936,7 +936,7 @@ run_pyc_file(FILE *fp, char *filename, PyObject *globals, PyObject *locals)
 		return NULL;
 	}
 	(void) PyMarshal_ReadLongFromFile(fp);
-	v = PyMarshal_ReadObjectFromFile(fp);
+	v = PyMarshal_ReadLastObjectFromFile(fp);
 	fclose(fp);
 	if (v == NULL || !PyCode_Check(v)) {
 		Py_XDECREF(v);