Add special case to WorkingTreeIterator for matching unnormalized symlinks

If there is an unnormalized symbolic link in the index, lie that it
matches a normalized link in the working tree. This does not make the
case completely invisible everywhere though, but it helps to some
degree.

Change-Id: I599fb71648c41fa2310049d0e0040b3c9f09386b
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/treewalk/WorkingTreeIterator.java

@@ -62,11 +62,13 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
 
+import org.eclipse.jgit.api.errors.JGitInternalException;
 import org.eclipse.jgit.diff.RawText;
 import org.eclipse.jgit.dircache.DirCache;
 import org.eclipse.jgit.dircache.DirCacheEntry;
 import org.eclipse.jgit.dircache.DirCacheIterator;
 import org.eclipse.jgit.errors.CorruptObjectException;
+import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.NoWorkTreeException;
 import org.eclipse.jgit.ignore.IgnoreNode;
 import org.eclipse.jgit.ignore.IgnoreRule;
@@ -83,6 +85,7 @@ import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.submodule.SubmoduleWalk;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.IO;
+import org.eclipse.jgit.util.RawParseUtils;
 import org.eclipse.jgit.util.io.EolCanonicalizingInputStream;
 
 /**
@@ -808,7 +811,11 @@ public abstract class WorkingTreeIterator extends AbstractTreeIterator {
 	 * @deprecated Use {@link #isModified(DirCacheEntry, boolean, ObjectReader)}
 	 */
 	public boolean isModified(DirCacheEntry entry, boolean forceContentCheck) {
-		return isModified(entry, forceContentCheck, null);
+		try {
+			return isModified(entry, forceContentCheck, null);
+		} catch (IOException e) {
+			throw new JGitInternalException(e.getMessage(), e);
+		}
 	}
 
 	/**
@@ -827,10 +834,11 @@ public abstract class WorkingTreeIterator extends AbstractTreeIterator {
 	 * @param reader
 	 *            access to repository objects if necessary. Should not be null.
 	 * @return true if content is most likely different.
+	 * @throws IOException
 	 * @since 3.3
 	 */
 	public boolean isModified(DirCacheEntry entry, boolean forceContentCheck,
-			ObjectReader reader) {
+			ObjectReader reader) throws IOException {
 		MetadataDiff diff = compareMetadata(entry);
 		switch (diff) {
 		case DIFFER_BY_TIMESTAMP:
@@ -848,6 +856,8 @@ public abstract class WorkingTreeIterator extends AbstractTreeIterator {
 		case EQUAL:
 			return false;
 		case DIFFER_BY_METADATA:
+			if (mode == FileMode.SYMLINK.getBits())
+				return contentCheck(entry, reader);
 			return true;
 		default:
 			throw new IllegalStateException(MessageFormat.format(
@@ -891,8 +901,10 @@ public abstract class WorkingTreeIterator extends AbstractTreeIterator {
 	 *            acccess to repository data if necessary
 	 * @return <code>true</code> if the content doesn't match,
 	 *         <code>false</code> if it matches
+	 * @throws IOException
 	 */
-	private boolean contentCheck(DirCacheEntry entry, ObjectReader reader) {
+	private boolean contentCheck(DirCacheEntry entry, ObjectReader reader)
+			throws IOException {
 		if (getEntryObjectId().equals(entry.getObjectId())) {
 			// Content has not changed
 
@@ -908,6 +920,9 @@ public abstract class WorkingTreeIterator extends AbstractTreeIterator {
 
 			return false;
 		} else {
+			if (mode == FileMode.SYMLINK.getBits())
+				return !new File(readContentAsString(current()))
+						.equals(new File(readContentAsString(entry)));
 			// Content differs: that's a real change, perhaps
 			if (reader == null) // deprecated use, do no further checks
 				return true;
@@ -956,6 +971,21 @@ public abstract class WorkingTreeIterator extends AbstractTreeIterator {
 		}
 	}
 
+	private String readContentAsString(DirCacheEntry entry)
+			throws MissingObjectException, IOException {
+		ObjectLoader open = repository.open(entry.getObjectId());
+		byte[] cachedBytes = open.getCachedBytes();
+		return RawParseUtils.decode(cachedBytes);
+	}
+
+	private static String readContentAsString(Entry entry) throws IOException {
+		long length = entry.getLength();
+		byte[] content = new byte[(int) length];
+		InputStream is = entry.openInputStream();
+		IO.readFully(is, content, 0, (int) length);
+		return RawParseUtils.decode(content);
+	}
+
 	private long computeLength(InputStream in) throws IOException {
 		// Since we only care about the length, use skip. The stream
 		// may be able to more efficiently wade through its data.