From 6c7a63bbb5629cc857ef4930f81a8a70f2db6155 Mon Sep 17 00:00:00 2001
From: gregw <gregw@webtide.com>
Date: Wed, 28 Oct 2020 15:12:59 +0100
Subject: [PATCH] Fixes #5521 ResourceCollection list NPE

Minimized changes in 9.  Will do bulk of changes in 10.
---
 .../util/resource/ResourceCollection.java     | 61 +++++++++++--------
 .../util/resource/ResourceCollectionTest.java |  2 +-
 2 files changed, 37 insertions(+), 26 deletions(-)

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 e11c77136df9..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
@@ -256,40 +256,51 @@ public Resource addPath(String path) throws IOException
             return this;
         }
 
+        Resource resource = null;
         ArrayList<Resource> resources = null;
-
-        // Attempt a simple (single) Resource lookup that exists
-        for (Resource res : _resources)
+        int i = 0;
+        for (; i < _resources.length; i++)
         {
-            Resource r = res.addPath(path);
-            if (!r.exists())
-                continue;
-
-            if (!r.isDirectory())
-                return r;
-
-            if (resources == null)
-                resources = new ArrayList<>();
-            resources.add(r);
+            resource = _resources[i].addPath(path);
+            if (resource.exists())
+            {
+                if (resource.isDirectory())
+                {
+                    break;
+                }
+                return resource;
+            }
         }
 
-        if (resources == null)
+        for (i++; i < _resources.length; i++)
         {
-            return null; /* TODO this is not allowed in 10.  Instead do:
-            for (Resource res : _r1esources)
+            Resource r = _resources[i].addPath(path);
+            if (r.exists() && r.isDirectory())
             {
-                Resource r = res.addPath(path);
-                if (r.exists())
-                    return r;
+                if (resources == null)
+                {
+                    resources = new ArrayList<>();
+                }
+
+                if (resource != null)
+                {
+                    resources.add(resource);
+                    resource = null;
+                }
+
+                resources.add(r);
             }
-            return EmptyResource.INSTANCE;
-            */
         }
 
-        if (resources.size() == 1)
-            return resources.get(0);
-
-        return new ResourceCollection(resources.toArray(new Resource[0]));
+        if (resource != null)
+        {
+            return resource;
+        }
+        if (resources != null)
+        {
+            return new ResourceCollection(resources.toArray(new Resource[0]));
+        }
+        return null;
     }
 
     @Override
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 ef28688ef483..d3e212517c6f 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
@@ -187,7 +187,7 @@ public void testList() throws Exception
 
         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"), nullValue());
+        assertThat(rc1.addPath("unknown").list(), nullValue());
         // TODO for jetty-10 assertThat(rc1.addPath("unknown").list(), nullValue());
     }