ObjectChecker: Disallow names potentially mapping to ".git" on HFS+

Mac's HFS+ folds concatentations of ".git" and ignorable Unicode
characters [1] to ".git" [2]. Hence we need to disallow all names which
could potentially be a shortname for ".git". Example: in an empty
directory create a folder ".g\U+200Cit". Now you can't create another
folder ".git".

The following characters are ignorable Unicode which are ignored on
HFS+:

unicode   hex         name
-------------------------------------------------
U+200C    0xe2808c    ZERO WIDTH NON-JOINER
U+200D    0xe2808d    ZERO WIDTH JOINER
U+200E    0xe2808e    LEFT-TO-RIGHT MARK
U+200F    0xe2808f    RIGHT-TO-LEFT MARK
U+202A    0xe280aa    LEFT-TO-RIGHT EMBEDDING
U+202B    0xe280ab    RIGHT-TO-LEFT EMBEDDING
U+202C    0xe280ac    POP DIRECTIONAL FORMATTING
U+202D    0xe280ad    LEFT-TO-RIGHT OVERRIDE
U+202E    0xe280ae    RIGHT-TO-LEFT OVERRIDE
U+206A    0xe281aa    INHIBIT SYMMETRIC SWAPPING
U+206B    0xe281ab    ACTIVATE SYMMETRIC SWAPPING
U+206C    0xe281ac    INHIBIT ARABIC FORM SHAPING
U+206D    0xe281ad    ACTIVATE ARABIC FORM SHAPING
U+206E    0xe281ae    NATIONAL DIGIT SHAPES
U+206F    0xe281af    NOMINAL DIGIT SHAPES
U+FEFF    0xefbbbf    ZERO WIDTH NO-BREAK SPACE

[1] http://www.unicode.org/versions/Unicode7.0.0/ch05.pdf#G40025
    http://www.unicode.org/reports/tr31/#Layout_and_Format_Control_Characters
[2] http://dubeiko.com/development/FileSystems/HFSPLUS/tn1150.html#UnicodeSubtleties

Change-Id: Ib6a1dd090b2649bdd8ec16387c994ed29de2860d
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

1 files changed, 120 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ObjectCheckerTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ObjectCheckerTest.java
index 8a782b7ffd..c6578ccfae 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ObjectCheckerTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/ObjectCheckerTest.java
@@ -1308,6 +1308,126 @@ public class ObjectCheckerTest {
 	}
 
 	@Test
+	public void testInvalidTreeNameIsMacHFSGit() {
+		StringBuilder b = new StringBuilder();
+		entry(b, "100644 .gi\u200Ct");
+		byte[] data = Constants.encode(b.toString());
+		try {
+			checker.setSafeForMacOS(true);
+			checker.checkTree(data);
+			fail("incorrectly accepted an invalid tree");
+		} catch (CorruptObjectException e) {
+			assertEquals(
+					"invalid name '.gi\u200Ct' contains ignorable Unicode characters",
+					e.getMessage());
+		}
+	}
+
+	@Test
+	public void testInvalidTreeNameIsMacHFSGit2() {
+		StringBuilder b = new StringBuilder();
+		entry(b, "100644 \u206B.git");
+		byte[] data = Constants.encode(b.toString());
+		try {
+			checker.setSafeForMacOS(true);
+			checker.checkTree(data);
+			fail("incorrectly accepted an invalid tree");
+		} catch (CorruptObjectException e) {
+			assertEquals(
+					"invalid name '\u206B.git' contains ignorable Unicode characters",
+					e.getMessage());
+		}
+	}
+
+	@Test
+	public void testInvalidTreeNameIsMacHFSGit3() {
+		StringBuilder b = new StringBuilder();
+		entry(b, "100644 .git\uFEFF");
+		byte[] data = Constants.encode(b.toString());
+		try {
+			checker.setSafeForMacOS(true);
+			checker.checkTree(data);
+			fail("incorrectly accepted an invalid tree");
+		} catch (CorruptObjectException e) {
+			assertEquals(
+					"invalid name '.git\uFEFF' contains ignorable Unicode characters",
+					e.getMessage());
+		}
+	}
+
+	private static byte[] concat(byte[] b1, byte[] b2) {
+		byte[] data = new byte[b1.length + b2.length];
+		System.arraycopy(b1, 0, data, 0, b1.length);
+		System.arraycopy(b2, 0, data, b1.length, b2.length);
+		return data;
+	}
+
+	@Test
+	public void testInvalidTreeNameIsMacHFSGitCorruptUTF8AtEnd() {
+		byte[] data = concat(Constants.encode("100644 .git"),
+				new byte[] { (byte) 0xef });
+		StringBuilder b = new StringBuilder();
+		entry(b, "");
+		data = concat(data, Constants.encode(b.toString()));
+		try {
+			checker.setSafeForMacOS(true);
+			checker.checkTree(data);
+			fail("incorrectly accepted an invalid tree");
+		} catch (CorruptObjectException e) {
+			assertEquals(
+					"invalid name contains byte sequence '0xef' which is not a valid UTF-8 character",
+					e.getMessage());
+		}
+	}
+
+	@Test
+	public void testInvalidTreeNameIsMacHFSGitCorruptUTF8AtEnd2() {
+		byte[] data = concat(Constants.encode("100644 .git"), new byte[] {
+				(byte) 0xe2, (byte) 0xab });
+		StringBuilder b = new StringBuilder();
+		entry(b, "");
+		data = concat(data, Constants.encode(b.toString()));
+		try {
+			checker.setSafeForMacOS(true);
+			checker.checkTree(data);
+			fail("incorrectly accepted an invalid tree");
+		} catch (CorruptObjectException e) {
+			assertEquals(
+					"invalid name contains byte sequence '0xe2ab' which is not a valid UTF-8 character",
+					e.getMessage());
+		}
+	}
+
+	@Test
+	public void testInvalidTreeNameIsNotMacHFSGit()
+			throws CorruptObjectException {
+		StringBuilder b = new StringBuilder();
+		entry(b, "100644 .git\u200Cx");
+		byte[] data = Constants.encode(b.toString());
+		checker.setSafeForMacOS(true);
+		checker.checkTree(data);
+	}
+
+	@Test
+	public void testInvalidTreeNameIsNotMacHFSGit2()
+			throws CorruptObjectException {
+		StringBuilder b = new StringBuilder();
+		entry(b, "100644 .kit\u200C");
+		byte[] data = Constants.encode(b.toString());
+		checker.setSafeForMacOS(true);
+		checker.checkTree(data);
+	}
+
+	@Test
+	public void testInvalidTreeNameIsNotMacHFSGitOtherPlatform()
+			throws CorruptObjectException {
+		StringBuilder b = new StringBuilder();
+		entry(b, "100644 .git\u200C");
+		byte[] data = Constants.encode(b.toString());
+		checker.checkTree(data);
+	}
+
+	@Test
 	public void testInvalidTreeNameIsDotGitDot() {
 		StringBuilder b = new StringBuilder();
 		entry(b, "100644 .git.");