From 0dc9f6c157392905be80df7560d625d565bd2caa Mon Sep 17 00:00:00 2001
From: gregw <gregw@webtide.com>
Date: Wed, 28 Oct 2020 12:08:11 +0100
Subject: [PATCH] Fixes #5521 ResourceCollection list NPE

NPE check.
Note that I cannot work out how the none directory resource was added in the first place, so I was unable to reproduce the exact exception.
---
 .../jetty/util/resource/PathResource.java        |  6 +-----
 .../jetty/util/resource/ResourceCollection.java  |  4 +++-
 .../util/resource/ResourceCollectionTest.java    | 16 ++++++++++++++++
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/jetty-util/src/main/java/org/eclipse/jetty/util/resource/PathResource.java b/jetty-util/src/main/java/org/eclipse/jetty/util/resource/PathResource.java
index e9931f548e43..e29e285c4b11 100644
--- a/jetty-util/src/main/java/org/eclipse/jetty/util/resource/PathResource.java
+++ b/jetty-util/src/main/java/org/eclipse/jetty/util/resource/PathResource.java
@@ -571,11 +571,7 @@ public String[] list()
             int size = entries.size();
             return entries.toArray(new String[size]);
         }
-        catch (DirectoryIteratorException e)
-        {
-            LOG.debug(e);
-        }
-        catch (IOException e)
+        catch (DirectoryIteratorException | IOException e)
         {
             LOG.debug(e);
         }
diff --git a/jetty-util/src/main/java/org/eclipse/jetty/util/resource/ResourceCollection.java b/jetty-util/src/main/java/org/eclipse/jetty/util/resource/ResourceCollection.java
index 594ba49c3b3c..4b8b8818d179 100644
--- a/jetty-util/src/main/java/org/eclipse/jetty/util/resource/ResourceCollection.java
+++ b/jetty-util/src/main/java/org/eclipse/jetty/util/resource/ResourceCollection.java
@@ -434,10 +434,12 @@ public long length()
     public String[] list()
     {
         assertResourcesSet();
-
         HashSet<String> set = new HashSet<>();
         for (Resource r : _resources)
         {
+            String[] list = r.list();
+            if (list != null)
+                Collections.addAll(set, list);
             Collections.addAll(set, r.list());
         }
         String[] result = set.toArray(new String[0]);
diff --git a/jetty-util/src/test/java/org/eclipse/jetty/util/resource/ResourceCollectionTest.java b/jetty-util/src/test/java/org/eclipse/jetty/util/resource/ResourceCollectionTest.java
index 51200037cce0..f307e57ca2c3 100644
--- a/jetty-util/src/test/java/org/eclipse/jetty/util/resource/ResourceCollectionTest.java
+++ b/jetty-util/src/test/java/org/eclipse/jetty/util/resource/ResourceCollectionTest.java
@@ -22,6 +22,7 @@
 import java.io.File;
 import java.io.InputStreamReader;
 import java.nio.file.Path;
+import java.util.Arrays;
 
 import org.eclipse.jetty.toolchain.test.FS;
 import org.eclipse.jetty.toolchain.test.MavenTestingUtils;
@@ -32,7 +33,9 @@
 import org.junit.jupiter.api.extension.ExtendWith;
 
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.nullValue;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -174,6 +177,19 @@ private void assertThrowIllegalStateException(ResourceCollection coll)
         });
     }
 
+    @Test
+    public void testList() throws Exception
+    {
+        ResourceCollection rc1 = new ResourceCollection(
+            Resource.newResource("src/test/resources/org/eclipse/jetty/util/resource/one/"),
+            Resource.newResource("src/test/resources/org/eclipse/jetty/util/resource/two/"),
+            Resource.newResource("src/test/resources/org/eclipse/jetty/util/resource/three/"));
+
+        assertThat(Arrays.asList(rc1.list()), contains("1.txt", "2.txt", "3.txt", "dir/"));
+        assertThat(Arrays.asList(rc1.addPath("dir").list()), contains("1.txt", "2.txt", "3.txt"));
+        assertThat(rc1.addPath("unknown").list(), nullValue());
+    }
+
     @Test
     public void testMultipleSources1() throws Exception
     {