From 62f9984e05d49ae19d26cca44ca9d0ee35f49d02 Mon Sep 17 00:00:00 2001
From: Kato Kazuyoshi <kato.kazuyoshi@gmail.com>
Date: Thu, 10 Apr 2014 22:07:29 +0900
Subject: [PATCH] Avoid "invalid memory address or nil pointer dereference"
 panic

libcontainer.GetNamespace returns nil on FreeBSD because
libcontainer.namespaceList is empty. In this case, Namespaces#Get should
return nil instead of being panic.

Docker-DCO-1.1-Signed-off-by: Kato Kazuyoshi <kato.kazuyoshi@gmail.com> (github: kzys)
---
 types.go      | 2 +-
 types_test.go | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/types.go b/types.go
index ffeb55a0..d4818c3f 100644
--- a/types.go
+++ b/types.go
@@ -68,7 +68,7 @@ func (n Namespaces) Contains(ns string) bool {
 
 func (n Namespaces) Get(ns string) *Namespace {
 	for _, nsp := range n {
-		if nsp.Key == ns {
+		if nsp != nil && nsp.Key == ns {
 			return nsp
 		}
 	}
diff --git a/types_test.go b/types_test.go
index 9735937b..dd31298f 100644
--- a/types_test.go
+++ b/types_test.go
@@ -18,6 +18,15 @@ func TestNamespacesContains(t *testing.T) {
 	if !ns.Contains("NEWPID") {
 		t.Fatal("namespaces should contain NEWPID but does not")
 	}
+
+	withNil := Namespaces{
+		GetNamespace("UNDEFINED"), // this element will be nil
+		GetNamespace("NEWPID"),
+	}
+
+	if !withNil.Contains("NEWPID") {
+		t.Fatal("namespaces should contain NEWPID but does not")
+	}
 }
 
 func TestCapabilitiesContains(t *testing.T) {