From 156943701a02394d18cb5083be4e0706b547f1c5 Mon Sep 17 00:00:00 2001
From: gregw <gregw@webtide.com>
Date: Wed, 28 Oct 2020 12:51:21 +0100
Subject: [PATCH] Fixes #5521 ResourceCollection list NPE

Refactor addPath in a simpler way, plus with TODOs to fix issues in 10 when merged.
---
 .../util/resource/ResourceCollection.java     | 61 ++++++++-----------
 .../util/resource/ResourceCollectionTest.java |  3 +-
 2 files changed, 27 insertions(+), 37 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 4b8b8818d179..e11c77136df9 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
@@ -256,51 +256,40 @@ public Resource addPath(String path) throws IOException
             return this;
         }
 
-        Resource resource = null;
         ArrayList<Resource> resources = null;
-        int i = 0;
-        for (; i < _resources.length; i++)
-        {
-            resource = _resources[i].addPath(path);
-            if (resource.exists())
-            {
-                if (resource.isDirectory())
-                {
-                    break;
-                }
-                return resource;
-            }
-        }
 
-        for (i++; i < _resources.length; i++)
+        // Attempt a simple (single) Resource lookup that exists
+        for (Resource res : _resources)
         {
-            Resource r = _resources[i].addPath(path);
-            if (r.exists() && r.isDirectory())
-            {
-                if (resources == null)
-                {
-                    resources = new ArrayList<>();
-                }
+            Resource r = res.addPath(path);
+            if (!r.exists())
+                continue;
 
-                if (resource != null)
-                {
-                    resources.add(resource);
-                    resource = null;
-                }
+            if (!r.isDirectory())
+                return r;
 
-                resources.add(r);
-            }
+            if (resources == null)
+                resources = new ArrayList<>();
+            resources.add(r);
         }
 
-        if (resource != null)
-        {
-            return resource;
-        }
-        if (resources != null)
+        if (resources == null)
         {
-            return new ResourceCollection(resources.toArray(new Resource[0]));
+            return null; /* TODO this is not allowed in 10.  Instead do:
+            for (Resource res : _r1esources)
+            {
+                Resource r = res.addPath(path);
+                if (r.exists())
+                    return r;
+            }
+            return EmptyResource.INSTANCE;
+            */
         }
-        return null;
+
+        if (resources.size() == 1)
+            return resources.get(0);
+
+        return new ResourceCollection(resources.toArray(new Resource[0]));
     }
 
     @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 f307e57ca2c3..ef28688ef483 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 +187,8 @@ 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").list(), nullValue());
+        assertThat(rc1.addPath("unknown"), nullValue());
+        // TODO for jetty-10 assertThat(rc1.addPath("unknown").list(), nullValue());
     }
 
     @Test