From 93ad66dea9814b6ad59710171227d84c78bbb4b9 Mon Sep 17 00:00:00 2001
From: Tim Peters <tim.peters@gmail.com>
Date: Sat, 5 Apr 2003 17:15:44 +0000
Subject: [PATCH] Fixed new seemingly random segfaults, by moving the
 initialization of delstr from initgc() into collect().  initgc() isn't called
 unless the user explicitly imports gc, so can be used only for initialization
 of user-visible module features; delstr needs to be initialized for proper
 internal operation, whether or not gc is explicitly imported.

Bugfix candidate?  I don't know whether the new bug was backported to
2.2 already.
---
 Modules/gcmodule.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 659ee038100..10a90b14f54 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -59,8 +59,8 @@ static PyObject *garbage;
 /* Python string to use if unhandled exception occurs */
 static PyObject *gc_str;
 
-/* Python string used to looked for __del__ attribute. */
-static PyObject *delstr;
+/* Python string used to look for __del__ attribute. */
+static PyObject *delstr = NULL;
 
 /* set for debugging information */
 #define DEBUG_STATS		(1<<0) /* print collection statistics */
@@ -369,7 +369,7 @@ move_finalizers(PyGC_Head *unreachable, PyGC_Head *collectable,
 			Py_INCREF(op);
 			finalizer = PyObject_HasAttr(op, delstr);
 			if (op->ob_refcnt == 1) {
-				/* The object will be deallocated. 
+				/* The object will be deallocated.
 				   Nothing left to do.
 				 */
 				Py_DECREF(op);
@@ -525,6 +525,12 @@ collect(int generation)
 	PyGC_Head finalizers;
 	PyGC_Head *gc;
 
+	if (delstr == NULL) {
+		delstr = PyString_InternFromString("__del__");
+		if (delstr == NULL)
+			Py_FatalError("gc couldn't allocate \"__del__\"");
+	}
+
 	if (debug & DEBUG_STATS) {
 		PySys_WriteStderr("gc: collecting generation %d...\n",
 				  generation);
@@ -578,7 +584,7 @@ collect(int generation)
 	 * finalizers can't safely be deleted.  Python programmers should take
 	 * care not to create such things.  For Python, finalizers means
 	 * instance objects with __del__ methods.
-	 * 
+	 *
 	 * Move each object into the collectable set or the finalizers set.
 	 * It's possible that a classic class with a getattr() hook will
 	 * be revived or deallocated in this step.
@@ -877,7 +883,7 @@ gc_get_referrents(PyObject *self, PyObject *args)
 	int i;
 	PyObject *result = PyList_New(0);
 	for (i = 0; i < PyTuple_GET_SIZE(args); i++) {
-		PyObject *obj = PyTuple_GET_ITEM(args, i); 
+		PyObject *obj = PyTuple_GET_ITEM(args, i);
 		traverseproc traverse = obj->ob_type->tp_traverse;
 		if (!traverse)
 			continue;
@@ -969,9 +975,6 @@ initgc(void)
 	PyObject *m;
 	PyObject *d;
 
-	delstr = PyString_InternFromString("__del__");
-	if (!delstr)
-		return;
 	m = Py_InitModule4("gc",
 			      GcMethods,
 			      gc__doc__,