commit 0d418f610f2bb5db7a2f6612856d0efa0fbffa35
author Dave Borowitz <dborowitz@google.com> Tue Apr 29 11:32:25 2014 -0700
committer Dave Borowitz <dborowitz@google.com> Tue Apr 29 14:35:29 2014 -0700
tree 6121413bacc7b0d7acb69593ff9703fb7e168e3a
parent d86ff50b82ed5d52d51e18da494088cdbf0b1fc1

Fix NPE in DiffServlet for missing path

The isFile method added by Ib11706aa did not handle the case where
TreeWalk.forPath returns null, as it does for a missing path.

This affected any diff URL with a non-empty, nonexistent path, e.g.:
  /project/+diff/master/notfound

Change-Id: I5c99be0cbdc99174c4a21b4deae6ac5b5bbd13fd

gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java

diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java b/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java
index ebe89e2..7af19e2 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java
@@ -65,15 +65,22 @@
     Repository repo = ServletUtils.getRepository(req);
 
     RevWalk walk = new RevWalk(repo);
+    TreeWalk tw = null;
     try {
       boolean showCommit, isFile;
       AbstractTreeIterator oldTree;
       AbstractTreeIterator newTree;
       try {
+        tw = newTreeWalk(walk, view);
+        if (tw == null && !view.getPathPart().isEmpty()) {
+          res.setStatus(SC_NOT_FOUND);
+          return;
+        }
+        isFile = tw != null && isFile(tw);
+
         // If we are viewing the diff between a commit and one of its parents,
         // include the commit detail in the rendered page.
         showCommit = isParentOf(walk, view.getOldRevision(), view.getRevision());
-        isFile = showCommit ? isFile(walk, view) : false;
         oldTree = getTreeIterator(walk, view.getOldRevision().getId());
         newTree = getTreeIterator(walk, view.getRevision().getId());
       } catch (MissingObjectException | IncorrectObjectTypeException e) {
@@ -116,10 +123,23 @@
         out.close();
       }
     } finally {
+      if (tw != null) {
+        tw.release();
+      }
       walk.release();
     }
   }
 
+  private static TreeWalk newTreeWalk(RevWalk walk, GitilesView view) throws IOException {
+    if (view.getPathPart().isEmpty()) {
+      return null;
+    }
+    return TreeWalk.forPath(
+        walk.getObjectReader(),
+        view.getPathPart(),
+        walk.parseTree(view.getRevision().getId()));
+  }
+
   private static boolean isParentOf(RevWalk walk, Revision oldRevision, Revision newRevision)
       throws MissingObjectException, IncorrectObjectTypeException, IOException {
     RevCommit newCommit = walk.parseCommit(newRevision.getId());
@@ -130,19 +150,8 @@
     }
   }
 
-  private static boolean isFile(RevWalk walk, GitilesView view) throws IOException {
-    if (view.getPathPart().equals("")) {
-      return false;
-    }
-    TreeWalk tw = TreeWalk.forPath(
-        walk.getObjectReader(),
-        view.getPathPart(),
-        walk.parseTree(view.getRevision().getId()));
-    try {
-      return (tw.getRawMode(0) & FileMode.TYPE_FILE) > 0;
-    } finally {
-      tw.release();
-    }
+  private static boolean isFile(TreeWalk tw) {
+    return (tw.getRawMode(0) & FileMode.TYPE_FILE) > 0;
   }
 
   private String[] renderAndSplit(Map<String, Object> data) {