Require a DiffConfig when creating a FollowFilter

The various rename detection options are an inherent part of the
filter, similar to the path being followed.

This fixes a potential NPE when a RevWalk with a FollowFilter is
created without a Repository, since the old code path tried to get
the DiffConfig from the RevWalk's possibly-missing repository.

Change-Id: Idb273d5a92849b42935ac14eed73b796b80aad50

4 files changed, 35 insertions, 21 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/diff/DiffFormatter.java b/org.eclipse.jgit/src/org/eclipse/jgit/diff/DiffFormatter.java
index fe0db33d3a..11848e2c99 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/diff/DiffFormatter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/diff/DiffFormatter.java
@@ -119,6 +119,8 @@ public class DiffFormatter {
 
 	private ObjectReader reader;
 
+	private DiffConfig diffCfg;
+
 	private int context = 3;
 
 	private int abbreviationLength = 7;
@@ -173,6 +175,7 @@ public class DiffFormatter {
 
 		db = repository;
 		reader = db.newObjectReader();
+		diffCfg = db.getConfig().get(DiffConfig.KEY);
 
 		ContentSource cs = ContentSource.create(reader);
 		source = new ContentSource.Pair(cs, cs);
@@ -534,7 +537,7 @@ public class DiffFormatter {
 		String oldPath = ((FollowFilter) pathFilter).getPath();
 		for (DiffEntry ent : files) {
 			if (isRename(ent) && ent.getNewPath().equals(oldPath)) {
-				pathFilter = FollowFilter.create(ent.getOldPath());
+				pathFilter = FollowFilter.create(ent.getOldPath(), diffCfg);
 				return Collections.singletonList(ent);
 			}
 		}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/diff/RenameDetector.java b/org.eclipse.jgit/src/org/eclipse/jgit/diff/RenameDetector.java
index f229a04a06..7648a48ac7 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/diff/RenameDetector.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/diff/RenameDetector.java
@@ -111,7 +111,7 @@ public class RenameDetector {
 
 	private boolean done;
 
-	private final Repository repo;
+	private final ObjectReader objectReader;
 
 	/** Similarity score required to pair an add/delete as a rename. */
 	private int renameScore = 60;
@@ -136,11 +136,20 @@ public class RenameDetector {
 	 *            the repository to use for rename detection
 	 */
 	public RenameDetector(Repository repo) {
-		this.repo = repo;
+		this(repo.newObjectReader(), repo.getConfig().get(DiffConfig.KEY));
+	}
 
-		DiffConfig cfg = repo.getConfig().get(DiffConfig.KEY);
+	/**
+	 * Create a new rename detector with a specified reader and diff config.
+	 *
+	 * @param reader
+	 *            reader to obtain objects from the repository with.
+	 * @param cfg
+	 *            diff config specifying rename detection options.
+	 */
+	public RenameDetector(ObjectReader reader, DiffConfig cfg) {
+		objectReader = reader.newReader();
 		renameLimit = cfg.getRenameLimit();
-
 		reset();
 	}
 
@@ -310,11 +319,10 @@ public class RenameDetector {
 	 */
 	public List<DiffEntry> compute(ProgressMonitor pm) throws IOException {
 		if (!done) {
-			ObjectReader reader = repo.newObjectReader();
 			try {
-				return compute(reader, pm);
+				return compute(objectReader, pm);
 			} finally {
-				reader.release();
+				objectReader.release();
 			}
 		}
 		return Collections.unmodifiableList(entries);
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/FollowFilter.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/FollowFilter.java
index ab2cf2bccb..9928286dcd 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/FollowFilter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/FollowFilter.java
@@ -45,6 +45,7 @@ package org.eclipse.jgit.revwalk;
 
 import java.io.IOException;
 
+import org.eclipse.jgit.diff.DiffConfig;
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.treewalk.TreeWalk;
@@ -77,20 +78,25 @@ public class FollowFilter extends TreeFilter {
 	 *            the path to filter on. Must not be the empty string. All
 	 *            trailing '/' characters will be trimmed before string's length
 	 *            is checked or is used as part of the constructed filter.
+	 * @param cfg
+	 *            diff config specifying rename detection options.
 	 * @return a new filter for the requested path.
 	 * @throws IllegalArgumentException
 	 *             the path supplied was the empty string.
+	 * @since 3.0
 	 */
-	public static FollowFilter create(String path) {
-		return new FollowFilter(PathFilter.create(path));
+	public static FollowFilter create(String path, DiffConfig cfg) {
+		return new FollowFilter(PathFilter.create(path), cfg);
 	}
 
 	private final PathFilter path;
+	final DiffConfig cfg;
 
 	private RenameCallback renameCallback;
 
-	FollowFilter(final PathFilter path) {
+	FollowFilter(final PathFilter path, final DiffConfig cfg) {
 		this.path = path;
+		this.cfg = cfg;
 	}
 
 	/** @return the path this filter matches. */
@@ -112,7 +118,7 @@ public class FollowFilter extends TreeFilter {
 
 	@Override
 	public TreeFilter clone() {
-		return new FollowFilter(path.clone());
+		return new FollowFilter(path.clone(), cfg);
 	}
 
 	@SuppressWarnings("nls")
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RewriteTreeFilter.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RewriteTreeFilter.java
index 9e1f02139f..a84e80e650 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RewriteTreeFilter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RewriteTreeFilter.java
@@ -46,15 +46,15 @@ package org.eclipse.jgit.revwalk;
 import java.io.IOException;
 import java.util.List;
 
+import org.eclipse.jgit.diff.DiffConfig;
 import org.eclipse.jgit.diff.DiffEntry;
-import org.eclipse.jgit.diff.RenameDetector;
 import org.eclipse.jgit.diff.DiffEntry.ChangeType;
+import org.eclipse.jgit.diff.RenameDetector;
 import org.eclipse.jgit.errors.CorruptObjectException;
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.StopWalkException;
 import org.eclipse.jgit.lib.ObjectId;
-import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.filter.RevFilter;
 import org.eclipse.jgit.treewalk.TreeWalk;
 import org.eclipse.jgit.treewalk.filter.TreeFilter;
@@ -82,10 +82,7 @@ class RewriteTreeFilter extends RevFilter {
 
 	private final TreeWalk pathFilter;
 
-	private final Repository repository;
-
 	RewriteTreeFilter(final RevWalk walker, final TreeFilter t) {
-		repository = walker.repository;
 		pathFilter = new TreeWalk(walker.reader);
 		pathFilter.setFilter(t);
 		pathFilter.setRecursive(t.shouldBeRecursive());
@@ -142,7 +139,7 @@ class RewriteTreeFilter extends RevFilter {
 					// commit. We need to update our filter to its older
 					// name, if we can discover it. Find out what that is.
 					//
-					updateFollowFilter(trees);
+					updateFollowFilter(trees, ((FollowFilter) tw.getFilter()).cfg);
 				}
 				return true;
 			}
@@ -235,7 +232,7 @@ class RewriteTreeFilter extends RevFilter {
 		return false;
 	}
 
-	private void updateFollowFilter(ObjectId[] trees)
+	private void updateFollowFilter(ObjectId[] trees, DiffConfig cfg)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			CorruptObjectException, IOException {
 		TreeWalk tw = pathFilter;
@@ -244,14 +241,14 @@ class RewriteTreeFilter extends RevFilter {
 		tw.reset(trees);
 
 		List<DiffEntry> files = DiffEntry.scan(tw);
-		RenameDetector rd = new RenameDetector(repository);
+		RenameDetector rd = new RenameDetector(tw.getObjectReader(), cfg);
 		rd.addAll(files);
 		files = rd.compute();
 
 		TreeFilter newFilter = oldFilter;
 		for (DiffEntry ent : files) {
 			if (isRename(ent) && ent.getNewPath().equals(oldFilter.getPath())) {
-				newFilter = FollowFilter.create(ent.getOldPath());
+				newFilter = FollowFilter.create(ent.getOldPath(), cfg);
 				RenameCallback callback = oldFilter.getRenameCallback();
 				if (callback != null) {
 					callback.renamed(ent);