From d9c0629ffe45ba96f853672268c391dd7caa82fe Mon Sep 17 00:00:00 2001
From: Thomas Wolf <twolf@apache.org>
Date: Wed, 20 Jul 2022 18:30:18 +0200
Subject: [PATCH] Fix adding symlinks to the index when core.symlinks=false

With core.symlinks=false, symlinks are checked out as plain files.
When such a file is re-added to the index, and the index already
contains a symlink there, add the file as a symlink. Previous code
changed the index entry to a regular file.

Bug: 580412
Change-Id: I5497bedc3da89c8b10120b8077c56bc5b67cb791
Signed-off-by: Thomas Wolf <twolf@apache.org>
---
 .../org/eclipse/jgit/api/AddCommandTest.java  | 41 +++++++++++++++++++
 .../jgit/treewalk/WorkingTreeIterator.java    |  6 +++
 2 files changed, 47 insertions(+)

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/AddCommandTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/AddCommandTest.java
index 5dfdfcfe6..57661a7ec 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/AddCommandTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/AddCommandTest.java
@@ -15,13 +15,16 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
+import static org.junit.Assume.assumeTrue;
 
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.PrintWriter;
+import java.nio.file.Files;
 import java.util.Set;
 
+import org.eclipse.jgit.api.ResetCommand.ResetType;
 import org.eclipse.jgit.api.errors.FilterFailedException;
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.api.errors.NoFilepatternException;
@@ -34,6 +37,7 @@
 import org.eclipse.jgit.lfs.BuiltinLFS;
 import org.eclipse.jgit.lib.ConfigConstants;
 import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.CoreConfig.SymLinks;
 import org.eclipse.jgit.lib.FileMode;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectInserter;
@@ -99,6 +103,43 @@ public void testAddExistingSingleFile() throws IOException, GitAPIException {
 		}
 	}
 
+	@Test
+	public void testAddLink() throws IOException, GitAPIException {
+		assumeTrue(db.getFS().supportsSymlinks());
+		try (Git git = new Git(db)) {
+			writeTrashFile("a.txt", "a");
+			File link = new File(db.getWorkTree(), "link");
+			db.getFS().createSymLink(link, "a.txt");
+			git.add().addFilepattern(".").call();
+			assertEquals(
+					"[a.txt, mode:100644, content:a][link, mode:120000, content:a.txt]",
+					indexState(CONTENT));
+			git.commit().setMessage("link").call();
+			StoredConfig config = db.getConfig();
+			config.setEnum(ConfigConstants.CONFIG_CORE_SECTION, null,
+					ConfigConstants.CONFIG_KEY_SYMLINKS, SymLinks.FALSE);
+			config.save();
+			Files.delete(link.toPath());
+			git.reset().setMode(ResetType.HARD).call();
+			assertTrue(Files.isRegularFile(link.toPath()));
+			assertEquals(
+					"[a.txt, mode:100644, content:a][link, mode:120000, content:a.txt]",
+					indexState(CONTENT));
+			writeTrashFile("link", "b.txt");
+			git.add().addFilepattern("link").call();
+			assertEquals(
+					"[a.txt, mode:100644, content:a][link, mode:120000, content:b.txt]",
+					indexState(CONTENT));
+			config.setEnum(ConfigConstants.CONFIG_CORE_SECTION, null,
+					ConfigConstants.CONFIG_KEY_SYMLINKS, SymLinks.TRUE);
+			config.save();
+			git.add().addFilepattern("link").call();
+			assertEquals(
+					"[a.txt, mode:100644, content:a][link, mode:100644, content:b.txt]",
+					indexState(CONTENT));
+		}
+	}
+
 	@Test
 	public void testCleanFilter() throws IOException, GitAPIException {
 		writeTrashFile(".gitattributes", "*.txt filter=tstFilter");
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/treewalk/WorkingTreeIterator.java b/org.eclipse.jgit/src/org/eclipse/jgit/treewalk/WorkingTreeIterator.java
index b108b0a95..d8a61ec97 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/treewalk/WorkingTreeIterator.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/treewalk/WorkingTreeIterator.java
@@ -1004,6 +1004,12 @@ public FileMode getIndexFileMode(DirCacheIterator indexIter) {
 			return wtMode;
 		}
 		final FileMode iMode = indexIter.getEntryFileMode();
+		if (iMode == FileMode.SYMLINK
+				&& getOptions().getSymLinks() == SymLinks.FALSE
+				&& (wtMode == FileMode.REGULAR_FILE
+						|| wtMode == FileMode.EXECUTABLE_FILE)) {
+			return iMode;
+		}
 		if (getOptions().isFileMode() && iMode != FileMode.GITLINK && iMode != FileMode.TREE) {
 			return wtMode;
 		}