[Fix JENKINS-22343] JGit now shows first revision in repo correctly

The first revision in the repository has no parent. The code assumed all commits have at least one parent.
jenkinsci · May 8, 2014 · ad1622e · ad1622e
1 parent 8b7f276
commit ad1622e
Show file tree

Hide file tree

Showing 2 changed files with 20 additions and 7 deletions.
diff --git a/src/main/java/org/jenkinsci/plugins/gitclient/JGitAPIImpl.java b/src/main/java/org/jenkinsci/plugins/gitclient/JGitAPIImpl.java
@@ -872,7 +872,25 @@ void format(RevCommit commit, @Nullable RevCommit parent, PrintWriter pw) throws
             Repository repo = getRepository();
             ObjectReader or = repo.newObjectReader();
             TreeWalk tw = new TreeWalk(or);
-            tw.reset(parent!=null ? parent.getTree() : commit.getParent(0).getTree(), commit.getTree());
+            RevTree revTree = null;
+            if (parent != null) {
+                /* Caller provided a parent commit, use it */
+                tw.reset(parent.getTree(), commit.getTree());
+            } else {
+                if (commit.getParentCount() > 0) {
+                    /* Caller failed to provide parent, but a parent
+                     * is available, so use the parent in the walk
+                     */
+                    tw.reset(commit.getParent(0).getTree(), commit.getTree());
+                } else {
+                    /* First commit in repo has 0 parent count, but
+                     * the TreeWalk requires exactly two nodes for its
+                     * walk.  Use the same node twice to satisfy
+                     * TreeWalk. See JENKINS-22343 for details.
+                     */
+                    tw.reset(commit.getTree(), commit.getTree());
+                }
+            }
             tw.setRecursive(true);
             tw.setFilter(TreeFilter.ANY_DIFF);
 
@@ -1347,7 +1365,7 @@ public List<String> showRevision(ObjectId from, ObjectId to) throws GitException
             PrintWriter pw = new PrintWriter(sw);
             RawFormatter f = new RawFormatter();
             for (RevCommit c : w) {
-                if (c.getParentCount()==1) {
+                if (c.getParentCount()<=1) {
                     f.format(c,null,pw);
                 } else {
                     // the effect of the -m option, which makes the diff produce for each parent of a merge commit

diff --git a/src/test/java/org/jenkinsci/plugins/gitclient/GitAPITestCase.java b/src/test/java/org/jenkinsci/plugins/gitclient/GitAPITestCase.java
@@ -2055,12 +2055,7 @@ public boolean apply(String detail) {
         assertTrue(commits.contains("commit 51de9eda47ca8dcf03b2af58dfff7355585f0d0c"));
     }
 
-    /* Is implemented in JGit, but returns no results.  Temporarily
-     * marking this test as not implemented in JGit so that its
-     * failure does not distract from other development.
-     */
     @Bug(22343)
-    @NotImplementedInJGit
     public void test_show_revision_for_first_commit() throws Exception {
         w.init();
         w.touch("a");