Improve handling of checkout conflicts

This converts a checkout conflict exception into a RebaseResult /
MergeResult containing the conflicting paths, which enables EGit (or
others) to handle the situation in a user-friendly way

Change-Id: I48d9bdcc1e98095576513a54a225a42409f301f3

3 files changed, 80 insertions, 2 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeResult.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeResult.java
index 1c930ebeb3..82272168aa 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeResult.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/MergeResult.java
@@ -45,6 +45,7 @@ package org.eclipse.jgit.api;
 
 import java.text.MessageFormat;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import org.eclipse.jgit.internal.JGitText;
@@ -177,6 +178,21 @@ public class MergeResult {
 			public boolean isSuccessful() {
 				return false;
 			}
+		},
+		/**
+		 * Status representing a checkout conflict, meaning that nothing could
+		 * be merged, as the pre-scan for the trees already failed for certain
+		 * files (i.e. local modifications prevent checkout of files).
+		 */
+		CHECKOUT_CONFLICT {
+			public String toString() {
+				return "Checkout Conflict";
+			}
+
+			@Override
+			public boolean isSuccessful() {
+				return false;
+			}
 		};
 
 		/**
@@ -201,6 +217,8 @@ public class MergeResult {
 
 	private Map<String, MergeFailureReason> failingPaths;
 
+	private List<String> checkoutConflicts;
+
 	/**
 	 * @param newHead
 	 *            the object the head points at after the merge
@@ -295,6 +313,18 @@ public class MergeResult {
 	}
 
 	/**
+	 * Creates a new result that represents a checkout conflict before the
+	 * operation even started for real.
+	 *
+	 * @param checkoutConflicts
+	 *            the conflicting files
+	 */
+	public MergeResult(List<String> checkoutConflicts) {
+		this.checkoutConflicts = checkoutConflicts;
+		this.mergeStatus = MergeStatus.CHECKOUT_CONFLICT;
+	}
+
+	/**
 	 * @return the object the head points at after the merge
 	 */
 	public ObjectId getNewHead() {
@@ -450,4 +480,14 @@ public class MergeResult {
 	public Map<String, MergeFailureReason> getFailingPaths() {
 		return failingPaths;
 	}
+
+	/**
+	 * Returns a list of paths that cause a checkout conflict. These paths
+	 * prevent the operation from even starting.
+	 *
+	 * @return the list of files that caused the checkout conflict.
+	 */
+	public List<String> getCheckoutConflicts() {
+		return checkoutConflicts;
+	}
 }
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java
index 3f7feb936f..5158c8533b 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java
@@ -355,6 +355,8 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 				return RebaseResult.OK_RESULT;
 			}
 			return RebaseResult.FAST_FORWARD_RESULT;
+		} catch (CheckoutConflictException cce) {
+			return new RebaseResult(cce.getConflictingPaths());
 		} catch (IOException ioe) {
 			throw new JGitInternalException(ioe.getMessage(), ioe);
 		}
@@ -880,13 +882,18 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 		return RawParseUtils.decode(content, 0, end);
 	}
 
-	private boolean checkoutCommit(RevCommit commit) throws IOException {
+	private boolean checkoutCommit(RevCommit commit) throws IOException,
+			CheckoutConflictException {
 		try {
 			RevCommit head = walk.parseCommit(repo.resolve(Constants.HEAD));
 			DirCacheCheckout dco = new DirCacheCheckout(repo, head.getTree(),
 					repo.lockDirCache(), commit.getTree());
 			dco.setFailOnConflict(true);
-			dco.checkout();
+			try {
+				dco.checkout();
+			} catch (org.eclipse.jgit.errors.CheckoutConflictException cce) {
+				throw new CheckoutConflictException(dco.getConflicts(), cce);
+			}
 			// update the HEAD
 			RefUpdate refUpdate = repo.updateRef(Constants.HEAD, true);
 			refUpdate.setExpectedOldObjectId(head);
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseResult.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseResult.java
index a09f8c28af..59655570c0 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseResult.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseResult.java
@@ -42,6 +42,7 @@
  */
 package org.eclipse.jgit.api;
 
+import java.util.List;
 import java.util.Map;
 
 import org.eclipse.jgit.merge.ResolveMerger;
@@ -93,6 +94,15 @@ public class RebaseResult {
 			}
 		},
 		/**
+		 * Conflicts: checkout of target HEAD failed
+		 */
+		CONFLICTS {
+			@Override
+			public boolean isSuccessful() {
+				return false;
+			}
+		},
+		/**
 		 * Already up-to-date
 		 */
 		UP_TO_DATE {
@@ -148,6 +158,8 @@ public class RebaseResult {
 
 	private Map<String, MergeFailureReason> failingPaths;
 
+	private List<String> conflicts;
+
 	private RebaseResult(Status status) {
 		this.status = status;
 		currentCommit = null;
@@ -177,6 +189,18 @@ public class RebaseResult {
 	}
 
 	/**
+	 * Create <code>RebaseResult</code> with status {@link Status#CONFLICTS}
+	 *
+	 * @param conflicts
+	 *            the list of conflicting paths
+	 */
+	RebaseResult(List<String> conflicts) {
+		status = Status.CONFLICTS;
+		currentCommit = null;
+		this.conflicts = conflicts;
+	}
+
+	/**
 	 * @return the overall status
 	 */
 	public Status getStatus() {
@@ -199,4 +223,11 @@ public class RebaseResult {
 	public Map<String, MergeFailureReason> getFailingPaths() {
 		return failingPaths;
 	}
+
+	/**
+	 * @return the list of conflicts if status is {@link Status#CONFLICTS}
+	 */
+	public List<String> getConflicts() {
+		return conflicts;
+	}
 }