Attributes: fix handling of text=auto in combination with eol

In Git 2.10.0 the interpretation of gitattributes changed or was fixed
such that "* text=auto eol=crlf" would indeed still do auto-detection
of text vs. binary content.[1] Previously this was identical to
"* text eol=crlf", i.e., treating all files as text.

JGit still did the latter, which caused surprises because it changed
binary files.

[1] https://github.com/git/git/blob/master/Documentation/RelNotes/2.10.0.txt#L248

Bug: 561341
Change-Id: I5b6fb97b5e86fd950a98537b6b8574f768ae30e5
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

org.eclipse.jgit.test/tst/org/eclipse/jgit/attributes/AttributeFileTests.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2020 Thomas Wolf <thomas.wolf@paranor.ch> and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+package org.eclipse.jgit.attributes;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import java.io.BufferedInputStream;
+import java.io.File;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.Arrays;
+
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.ResetCommand.ResetType;
+import org.eclipse.jgit.dircache.DirCache;
+import org.eclipse.jgit.dircache.DirCacheEntry;
+import org.eclipse.jgit.junit.RepositoryTestCase;
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.util.IO;
+import org.eclipse.jgit.util.RawParseUtils;
+import org.junit.Test;
+
+/**
+ * End-to-end tests for some attribute combinations. Writes files, commit them,
+ * examines the index, deletes the files, performs a hard reset and checks file
+ * contents again.
+ */
+public class AttributeFileTests extends RepositoryTestCase {
+
+	@Test
+	public void testTextAutoEolLf() throws Exception {
+		writeTrashFile(".gitattributes", "* text=auto eol=lf");
+		performTest("Test\r\nFile", "Test\nFile", "Test\nFile");
+	}
+
+	@Test
+	public void testTextAutoEolCrLf() throws Exception {
+		writeTrashFile(".gitattributes", "* text=auto eol=crlf");
+		performTest("Test\r\nFile", "Test\nFile", "Test\r\nFile");
+	}
+
+	private void performTest(String initial, String index, String finalText)
+			throws Exception {
+		File dummy = writeTrashFile("dummy.foo", initial);
+		byte[] data = readTestResource("add.png");
+		assertTrue("Expected some binary data", data.length > 100);
+		File binary = writeTrashFile("add.png", "");
+		Files.write(binary.toPath(), data);
+		try (Git git = Git.wrap(db)) {
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("test commit").call();
+			// binary should be unchanged, dummy should match "index"
+			verifyIndexContent("dummy.foo",
+					index.getBytes(StandardCharsets.UTF_8));
+			verifyIndexContent("add.png", data);
+			assertTrue("Should be able to delete " + dummy, dummy.delete());
+			assertTrue("Should be able to delete " + binary, binary.delete());
+			git.reset().setMode(ResetType.HARD).call();
+			assertTrue("File " + dummy + " should exist", dummy.isFile());
+			assertTrue("File " + binary + " should exist", binary.isFile());
+			// binary should be unchanged, dummy should match "finalText"
+			String textFile = RawParseUtils.decode(IO.readFully(dummy, 512));
+			assertEquals("Unexpected text content", finalText, textFile);
+			byte[] binaryFile = IO.readFully(binary, 512);
+			assertArrayEquals("Unexpected binary content", data, binaryFile);
+		}
+	}
+
+	private byte[] readTestResource(String name) throws Exception {
+		try (InputStream in = new BufferedInputStream(
+				getClass().getResourceAsStream(name))) {
+			byte[] data = new byte[512];
+			int read = in.read(data);
+			if (read == data.length) {
+				return data;
+			}
+			return Arrays.copyOf(data, read);
+		}
+	}
+
+	private void verifyIndexContent(String path, byte[] expectedContent)
+			throws Exception {
+		DirCache dc = db.readDirCache();
+		for (int i = 0; i < dc.getEntryCount(); ++i) {
+			DirCacheEntry entry = dc.getEntry(i);
+			if (path.equals(entry.getPathString())) {
+				byte[] data = db.open(entry.getObjectId(), Constants.OBJ_BLOB)
+						.getCachedBytes();
+				assertArrayEquals("Unexpected index content for " + path,
+						expectedContent, data);
+				return;
+			}
+		}
+		fail("Path not found in index: " + path);
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/util/io/EolStreamTypeUtil.java

@@ -140,19 +140,19 @@ public final class EolStreamTypeUtil {
 		}
 
 		// new git system
+		if ("auto".equals(attrs.getValue("text"))) { //$NON-NLS-1$ //$NON-NLS-2$
+			return EolStreamType.AUTO_LF;
+		}
+
 		String eol = attrs.getValue("eol"); //$NON-NLS-1$
-		if (eol != null)
+		if (eol != null) {
 			// check-in is always normalized to LF
 			return EolStreamType.TEXT_LF;
-
+		}
 		if (attrs.isSet("text")) { //$NON-NLS-1$
 			return EolStreamType.TEXT_LF;
 		}
 
-		if ("auto".equals(attrs.getValue("text"))) { //$NON-NLS-1$ //$NON-NLS-2$
-			return EolStreamType.AUTO_LF;
-		}
-
 		switch (options.getAutoCRLF()) {
 		case TRUE:
 		case INPUT:
@@ -205,7 +205,10 @@ public final class EolStreamTypeUtil {
 		// new git system
 		String eol = attrs.getValue("eol"); //$NON-NLS-1$
 		if (eol != null) {
-			if ("crlf".equals(eol)) {//$NON-NLS-1$
+			if ("crlf".equals(eol)) { //$NON-NLS-1$
+				if ("auto".equals(attrs.getValue("text"))) { //$NON-NLS-1$ //$NON-NLS-2$
+					return EolStreamType.AUTO_CRLF;
+				}
 				return EolStreamType.TEXT_CRLF;
 			} else if ("lf".equals(eol)) { //$NON-NLS-1$
 				return EolStreamType.DIRECT;