From 3d7351ee50b2ef45613b2223856f31e5af1c7ca1 Mon Sep 17 00:00:00 2001
From: kylezhao <kylezhao@tencent.com>
Date: Fri, 12 Nov 2021 14:34:46 +0800
Subject: [PATCH] TreeRevFilter: fix wrong stop when the given path disappears
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When chgs[i] == adds[i], it indicated that a commit added some files
that pList[i] did not have, but didn't mean pList[i] is "empty tree
root".

Follow the example below:

.                           .
└── src                     └── src
    └── d1          ==>          └── d1
        └─ file1                    ├─  file1
                                    └── file2
   c.parents[i]                   c

The variable chg[i] equals to variable add[i],
but commit c.parents[i] is not "empty tree root".

We should add an additional check for no paths matching the filter.

Bug: 577227
Change-Id: I834e9ddd0de86b108b280a1139519ea962913b38
Signed-off-by: kylezhao <kylezhao@tencent.com>
---
 .../jgit/revwalk/RevWalkPathFilter1Test.java  | 20 +++++++++++++++++++
 .../eclipse/jgit/revwalk/TreeRevFilter.java   |  5 ++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkPathFilter1Test.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkPathFilter1Test.java
index 31629f3de..5cce11aa1 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkPathFilter1Test.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkPathFilter1Test.java
@@ -15,6 +15,7 @@
 
 import java.util.Collections;
 
+import org.eclipse.jgit.dircache.DirCacheEntry;
 import org.eclipse.jgit.treewalk.filter.AndTreeFilter;
 import org.eclipse.jgit.treewalk.filter.PathFilterGroup;
 import org.eclipse.jgit.treewalk.filter.TreeFilter;
@@ -253,4 +254,23 @@ public void testStringOfPearls_FilePath3_NoParentRewriting()
 		assertEquals(0, a.getParentCount());
 		assertNull(rw.next());
 	}
+
+	@Test
+	public void testStopWhenPathDisappears() throws Exception {
+		DirCacheEntry file1 = file("src/d1/file1", blob("a"));
+		DirCacheEntry file2 = file("src/d1/file2", blob("a"));
+		DirCacheEntry file3 = file("src/d1/file3", blob("a"));
+		RevCommit a = commit(tree(file1));
+		RevCommit b = commit(tree(file1, file2), a);
+		RevCommit c = commit(tree(file1, file3), a);
+		RevCommit d = commit(tree(file1, file2, file3), b, c);
+		filter("src/d1");
+		markStart(d);
+		rw.setRewriteParents(false);
+
+		assertCommit(d, rw.next());
+		assertCommit(c, rw.next());
+		assertCommit(b, rw.next());
+		assertCommit(a, rw.next());
+	}
 }
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/TreeRevFilter.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/TreeRevFilter.java
index e46502431..822fc5320 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/TreeRevFilter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/TreeRevFilter.java
@@ -211,7 +211,10 @@ public boolean include(RevWalk walker, RevCommit c)
 				// "empty tree root" and thus their history is not relevant.
 				// Cut our grandparents to be an empty list.
 				//
-				pList[i].parents = RevCommit.NO_PARENTS;
+				tw.reset(pList[i].getTree());
+				if (!tw.next()) {
+					pList[i].parents = RevCommit.NO_PARENTS;
+				}
 			}
 
 			// We have an interesting difference relative to this parent.