Partial support for index file format "3".

Extended flags are processed and available via DirCacheEntry's
new isSkipWorkTree() and isIntentToAdd() methods.  "resolve-undo"
information is completely ignored since its an optional extension.

Change-Id: Ie6e9c6784c9f265ca3c013c6dc0e6bd29d3b7233

org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheCGitCompatabilityTest.java

@@ -44,10 +44,12 @@
 package org.eclipse.jgit.dircache;
 
 import java.io.BufferedReader;
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.InputStreamReader;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.Map;
@@ -59,6 +61,7 @@ import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.treewalk.TreeWalk;
 import org.eclipse.jgit.util.FS;
+import org.eclipse.jgit.util.IO;
 import org.eclipse.jgit.util.JGitTestUtil;
 
 public class DirCacheCGitCompatabilityTest extends LocalDiskRepositoryTestCase {
@@ -179,6 +182,35 @@ public class DirCacheCGitCompatabilityTest extends LocalDiskRepositoryTestCase {
 		}
 	}
 
+	public void testReadWriteV3() throws Exception {
+		final File file = pathOf("gitgit.index.v3.skipWorkTree");
+		final DirCache dc = new DirCache(file, FS.DETECTED);
+		dc.read();
+
+		assertEquals(7, dc.getEntryCount());
+		assertV3TreeEntry(0, "dir1/file1.txt", false, false, dc);
+		assertV3TreeEntry(1, "dir2/file2.txt", true, false, dc);
+		assertV3TreeEntry(2, "dir3/file3.txt", false, false, dc);
+		assertV3TreeEntry(3, "dir3/file3a.txt", true, false, dc);
+		assertV3TreeEntry(4, "dir4/file4.txt", true, false, dc);
+		assertV3TreeEntry(5, "dir4/file4a.txt", false, false, dc);
+		assertV3TreeEntry(6, "file.txt", true, false, dc);
+
+		final ByteArrayOutputStream bos = new ByteArrayOutputStream();
+		dc.writeTo(bos);
+		final byte[] indexBytes = bos.toByteArray();
+		final byte[] expectedBytes = IO.readFully(file);
+		assertTrue(Arrays.equals(expectedBytes, indexBytes));
+	}
+
+	private static void assertV3TreeEntry(int indexPosition, String path,
+			boolean skipWorkTree, boolean intentToAdd, DirCache dc) {
+		final DirCacheEntry entry = dc.getEntry(indexPosition);
+		assertEquals(path, entry.getPathString());
+		assertEquals(skipWorkTree, entry.isSkipWorkTree());
+		assertEquals(intentToAdd, entry.isIntentToAdd());
+	}
+
 	private File pathOf(final String name) {
 		return JGitTestUtil.getTestResourceFile(name);
 	}

org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties

@@ -2,6 +2,7 @@ DIRCChecksumMismatch=DIRC checksum mismatch
 DIRCExtensionIsTooLargeAt=DIRC extension {0} is too large at {1} bytes.
 DIRCExtensionNotSupportedByThisVersion=DIRC extension {0} not supported by this version.
 DIRCHasTooManyEntries=DIRC has too many entries.
+DIRCUnrecognizedExtendedFlags=Unrecognized extended flags: {0}
 JRELacksMD5Implementation=JRE lacks MD5 implementation
 URINotSupported=URI not supported: {0}
 URLNotFound={0} not found

org.eclipse.jgit/src/org/eclipse/jgit/JGitText.java

@@ -62,6 +62,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String DIRCExtensionIsTooLargeAt;
 	/***/ public String DIRCExtensionNotSupportedByThisVersion;
 	/***/ public String DIRCHasTooManyEntries;
+	/***/ public String DIRCUnrecognizedExtendedFlags;
 	/***/ public String JRELacksMD5Implementation;
 	/***/ public String URINotSupported;
 	/***/ public String URLNotFound;

org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java

@@ -91,8 +91,6 @@ public class DirCache {
 
 	private static final int EXT_TREE = 0x54524545 /* 'TREE' */;
 
-	private static final int INFO_LEN = DirCacheEntry.INFO_LEN;
-
 	private static final DirCacheEntry[] NO_ENTRIES = {};
 
 	static final Comparator<DirCacheEntry> ENT_CMP = new Comparator<DirCacheEntry>() {
@@ -322,7 +320,7 @@ public class DirCache {
 		tree = null;
 	}
 
-	private void readFrom(final FileInputStream inStream) throws IOException,
+	private void readFrom(final InputStream inStream) throws IOException,
 			CorruptObjectException {
 		final BufferedInputStream in = new BufferedInputStream(inStream);
 		final MessageDigest md = Constants.newMessageDigest();
@@ -335,7 +333,10 @@ public class DirCache {
 		if (!is_DIRC(hdr))
 			throw new CorruptObjectException(JGitText.get().notADIRCFile);
 		final int ver = NB.decodeInt32(hdr, 4);
-		if (ver != 2)
+		boolean extended = false;
+		if (ver == 3)
+			extended = true;
+		else if (ver != 2)
 			throw new CorruptObjectException(MessageFormat.format(JGitText.get().unknownDIRCVersion, ver));
 		entryCnt = NB.decodeInt32(hdr, 8);
 		if (entryCnt < 0)
@@ -343,10 +344,13 @@ public class DirCache {
 
 		// Load the individual file entries.
 		//
-		final byte[] infos = new byte[INFO_LEN * entryCnt];
+		final int infoLength = DirCacheEntry.getMaximumInfoLength(extended);
+		final byte[] infos = new byte[infoLength * entryCnt];
 		sortedEntries = new DirCacheEntry[entryCnt];
+
+		final MutableInteger infoAt = new MutableInteger();
 		for (int i = 0; i < entryCnt; i++)
-			sortedEntries[i] = new DirCacheEntry(infos, i * INFO_LEN, in, md);
+			sortedEntries[i] = new DirCacheEntry(infos, infoAt, in, md);
 		lastModified = liveFile.lastModified();
 
 		// After the file entries are index extensions, and then a footer.
@@ -484,15 +488,19 @@ public class DirCache {
 		}
 	}
 
-	private void writeTo(final OutputStream os) throws IOException {
+	void writeTo(final OutputStream os) throws IOException {
 		final MessageDigest foot = Constants.newMessageDigest();
 		final DigestOutputStream dos = new DigestOutputStream(os, foot);
 
+		boolean extended = false;
+		for (int i = 0; i < entryCnt; i++)
+			extended |= sortedEntries[i].isExtended();
+
 		// Write the header.
 		//
 		final byte[] tmp = new byte[128];
 		System.arraycopy(SIG_DIRC, 0, tmp, 0, SIG_DIRC.length);
-		NB.encodeInt32(tmp, 4, /* version */2);
+		NB.encodeInt32(tmp, 4, extended ? 3 : 2);
 		NB.encodeInt32(tmp, 8, entryCnt);
 		dos.write(tmp, 0, 12);
 

org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCacheEntry.java

@@ -62,6 +62,7 @@ import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.FileMode;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.util.IO;
+import org.eclipse.jgit.util.MutableInteger;
 import org.eclipse.jgit.util.NB;
 
 /**
@@ -108,12 +109,19 @@ public class DirCacheEntry {
 	private static final int P_OBJECTID = 40;
 
 	private static final int P_FLAGS = 60;
+	private static final int P_FLAGS2 = 62;
 
 	/** Mask applied to data in {@link #P_FLAGS} to get the name length. */
 	private static final int NAME_MASK = 0xfff;
 
-	static final int INFO_LEN = 62;
+	private static final int INTENT_TO_ADD = 0x20000000;
+	private static final int SKIP_WORKTREE = 0x40000000;
+	private static final int EXTENDED_FLAGS = (INTENT_TO_ADD | SKIP_WORKTREE);
 
+	private static final int INFO_LEN = 62;
+	private static final int INFO_LEN_EXTENDED = 64;
+
+	private static final int EXTENDED = 0x40;
 	private static final int ASSUME_VALID = 0x80;
 
 	/** In-core flag signaling that the entry should be considered as modified. */
@@ -131,13 +139,26 @@ public class DirCacheEntry {
 	/** Flags which are never stored to disk. */
 	private byte inCoreFlags;
 
-	DirCacheEntry(final byte[] sharedInfo, final int infoAt,
+	DirCacheEntry(final byte[] sharedInfo, final MutableInteger infoAt,
 			final InputStream in, final MessageDigest md) throws IOException {
 		info = sharedInfo;
-		infoOffset = infoAt;
+		infoOffset = infoAt.value;
 
 		IO.readFully(in, info, infoOffset, INFO_LEN);
-		md.update(info, infoOffset, INFO_LEN);
+
+		final int len;
+		if (isExtended()) {
+			len = INFO_LEN_EXTENDED;
+			IO.readFully(in, info, infoOffset + INFO_LEN, INFO_LEN_EXTENDED - INFO_LEN);
+
+			if ((getExtendedFlags() & ~EXTENDED_FLAGS) != 0)
+				throw new IOException(MessageFormat.format(JGitText.get()
+						.DIRCUnrecognizedExtendedFlags, String.valueOf(getExtendedFlags())));
+		} else
+			len = INFO_LEN;
+
+		infoAt.value += len;
+		md.update(info, infoOffset, len);
 
 		int pathLen = NB.decodeUInt16(info, infoOffset + P_FLAGS) & NAME_MASK;
 		int skipped = 0;
@@ -170,7 +191,7 @@ public class DirCacheEntry {
 		// Index records are padded out to the next 8 byte alignment
 		// for historical reasons related to how C Git read the files.
 		//
-		final int actLen = INFO_LEN + pathLen;
+		final int actLen = len + pathLen;
 		final int expLen = (actLen + 8) & ~7;
 		final int padLen = expLen - actLen - skipped;
 		if (padLen > 0) {
@@ -258,14 +279,15 @@ public class DirCacheEntry {
 	}
 
 	void write(final OutputStream os) throws IOException {
+		final int len = isExtended() ? INFO_LEN_EXTENDED : INFO_LEN;
 		final int pathLen = path.length;
-		os.write(info, infoOffset, INFO_LEN);
+		os.write(info, infoOffset, len);
 		os.write(path, 0, pathLen);
 
 		// Index records are padded out to the next 8 byte alignment
 		// for historical reasons related to how C Git read the files.
 		//
-		final int actLen = INFO_LEN + pathLen;
+		final int actLen = len + pathLen;
 		final int expLen = (actLen + 8) & ~7;
 		if (actLen != expLen)
 			os.write(nullpad, 0, expLen - actLen);
@@ -400,6 +422,24 @@ public class DirCacheEntry {
 		return (info[infoOffset + P_FLAGS] >>> 4) & 0x3;
 	}
 
+	/**
+	 * Returns whether this entry should be skipped from the working tree.
+	 *
+	 * @return true if this entry should be skipepd.
+	 */
+	public boolean isSkipWorkTree() {
+		return (getExtendedFlags() & SKIP_WORKTREE) != 0;
+	}
+
+	/**
+	 * Returns whether this entry is intent to be added to the Index.
+	 *
+	 * @return true if this entry is intent to add.
+	 */
+	public boolean isIntentToAdd() {
+		return (getExtendedFlags() & INTENT_TO_ADD) != 0;
+	}
+
 	/**
 	 * Obtain the raw {@link FileMode} bits for this entry.
 	 *
@@ -575,6 +615,13 @@ public class DirCacheEntry {
 				| NB.decodeUInt16(info, infoOffset + P_FLAGS) & ~NAME_MASK);
 	}
 
+	/**
+	 * @return true if the entry contains extended flags.
+	 */
+	boolean isExtended() {
+		return (info[infoOffset + P_FLAGS] & EXTENDED) != 0;
+	}
+
 	private long decodeTS(final int pIdx) {
 		final int base = infoOffset + pIdx;
 		final int sec = NB.decodeInt32(info, base);
@@ -588,6 +635,13 @@ public class DirCacheEntry {
 		NB.encodeInt32(info, base + 4, ((int) (when % 1000)) * 1000000);
 	}
 
+	private int getExtendedFlags() {
+		if (isExtended())
+			return NB.decodeUInt16(info, infoOffset + P_FLAGS2) << 16;
+		else
+			return 0;
+	}
+
 	private static String toString(final byte[] path) {
 		return Constants.CHARSET.decode(ByteBuffer.wrap(path)).toString();
 	}
@@ -615,4 +669,8 @@ public class DirCacheEntry {
 		}
 		return componentHasChars;
 	}
+
+	static int getMaximumInfoLength(boolean extended) {
+		return extended ? INFO_LEN_EXTENDED : INFO_LEN;
+	}
 }