From 63f38d62ac7807f47d69610cf559393569e3622f Mon Sep 17 00:00:00 2001
From: Rob Pike <r@golang.org>
Date: Mon, 3 Nov 2008 15:22:15 -0800
Subject: [PATCH] in traceback, handle the case where we've called through a
 nil function pointer

R=rsc
DELTA=7  (7 added, 0 deleted, 0 changed)
OCL=18372
CL=18372
---
 src/runtime/rt2_amd64.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/runtime/rt2_amd64.c b/src/runtime/rt2_amd64.c
index 91bef543406..a3433678b2c 100644
--- a/src/runtime/rt2_amd64.c
+++ b/src/runtime/rt2_amd64.c
@@ -25,6 +25,13 @@ traceback(uint8 *pc, uint8 *sp, void* r15)
 	// store local copy of per-process data block that we can write as we unwind
 	mcpy((byte*)&g, (byte*)r15, sizeof(G));
 
+	// if the PC is zero, it's probably due to a nil function pointer.
+	// pop the failed frame.
+	if(pc == nil) {
+		pc = ((uint8**)sp)[0];
+		sp += 8;
+	}
+
 	counter = 0;
 	name = "panic";
 	for(;;){